DIY Two-Stroke Engine

[durabol[_2_]]

For the last few years I have toyed with the idea of building a
homemade two-stroke engine for UL use. What keyed my interest was
reading about homemade model aircraft engines and reading and watching
a re-enactment of the Wright brother's first flight with a replica
engine (not a two-stroke engine).

Has anyone made a 2-stroke engine from scratch? One may need to cast
aluminium, may need a lathe and milling machine with boring head and
hone or perhaps the boring and honing of the cylinder and bearing
journals could be farmed out. A commercial carburetor and piston could
be used. Two-stroke engines seem simple enough that home construction
may be possible, if not practical.

A direct drive engine will be that much heavier when you take into
account the weight of the drive reduction system. I have calculated
the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
cylinder and crankcase wall thickness and a 1.25" dia crank.

I have got some idea of port-time-area from the freeware computer
program called "BiMotion". I'm not sure how good the data is for
lowish speed engines but I guess it is a start. I have also worked up
a spreadsheet for similar information.

I don't think a reed valve system is needed for this engine since it
is only going to operate at a fairly narrow rpm range and the port
timing isn't critical. Piston ported valves offer similar performance
to other induction types but only over a narrow rpm range which is
what I have planned for the engine. I plan to build an engine with a
restrictive exhaust to ensure no fuel escapes. I have heard that
piston ported engines can spit some fuel out of the carb at idle but
this doesn't seem like a major problem. Rotary valves via crank shaft
induction (disk or drum valves as well) is an interesting idea but I
don't think I need the critical timing they provide.

I was planning on using the largest two-stroke piston (not a diesel
piston) I could find and using the largest stoke that was reasonable,
something like 90x105mm

Brock

[Tim Wescott]

durabol wrote:
> For the last few years I have toyed with the idea of building a
> homemade two-stroke engine for UL use.

Underwriter's Laboratories?

> What keyed my interest was
> reading about homemade model aircraft engines and reading and watching
> a re-enactment of the Wright brother's first flight with a replica
> engine (not a two-stroke engine).
>
> Has anyone made a 2-stroke engine from scratch? One may need to cast
> aluminium, may need a lathe and milling machine with boring head and
> hone or perhaps the boring and honing of the cylinder and bearing
> journals could be farmed out. A commercial carburetor and piston could
> be used. Two-stroke engines seem simple enough that home construction
> may be possible, if not practical.

Certainly not practical in the "it saves you money" sense, but who cares?

> A direct drive engine will be that much heavier when you take into
> account the weight of the drive reduction system. I have calculated
> the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
> it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
> cylinder and crankcase wall thickness and a 1.25" dia crank.
>
> I have got some idea of port-time-area from the freeware computer
> program called "BiMotion". I'm not sure how good the data is for
> lowish speed engines but I guess it is a start. I have also worked up
> a spreadsheet for similar information.
>
> I don't think a reed valve system is needed for this engine since it
> is only going to operate at a fairly narrow rpm range and the port
> timing isn't critical. Piston ported valves offer similar performance
> to other induction types but only over a narrow rpm range which is
> what I have planned for the engine.

Piston porting isn't optimum at any speed -- crank-timed or reed valve
induction is much better.

But piston porting is certainly easier.

> I plan to build an engine with a
> restrictive exhaust to ensure no fuel escapes. I have heard that
> piston ported engines can spit some fuel out of the carb at idle but
> this doesn't seem like a major problem. Rotary valves via crank shaft
> induction (disk or drum valves as well) is an interesting idea but I
> don't think I need the critical timing they provide.
>
> I was planning on using the largest two-stroke piston (not a diesel
> piston) I could find and using the largest stoke that was reasonable,
> something like 90x105mm

I'm still a home-built engine wannabe, but I'm working on it. Here are
some resources:

http://www.lindsaybks.com/prod/sub/engines.html
http://www.modelenginenews.org/

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[Don Stauffer]

durabol wrote:
> For the last few years I have toyed with the idea of building a
> homemade two-stroke engine for UL use. What keyed my interest was
> reading about homemade model aircraft engines and reading and watching
> a re-enactment of the Wright brother's first flight with a replica
> engine (not a two-stroke engine).
>
> Has anyone made a 2-stroke engine from scratch? One may need to cast
> aluminium, may need a lathe and milling machine with boring head and
> hone or perhaps the boring and honing of the cylinder and bearing
> journals could be farmed out. A commercial carburetor and piston could
> be used. Two-stroke engines seem simple enough that home construction
> may be possible, if not practical.
>
> A direct drive engine will be that much heavier when you take into
> account the weight of the drive reduction system. I have calculated
> the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
> it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
> cylinder and crankcase wall thickness and a 1.25" dia crank.
>
> I have got some idea of port-time-area from the freeware computer
> program called "BiMotion". I'm not sure how good the data is for
> lowish speed engines but I guess it is a start. I have also worked up
> a spreadsheet for similar information.
>
> I don't think a reed valve system is needed for this engine since it
> is only going to operate at a fairly narrow rpm range and the port
> timing isn't critical. Piston ported valves offer similar performance
> to other induction types but only over a narrow rpm range which is
> what I have planned for the engine. I plan to build an engine with a
> restrictive exhaust to ensure no fuel escapes. I have heard that
> piston ported engines can spit some fuel out of the carb at idle but
> this doesn't seem like a major problem. Rotary valves via crank shaft
> induction (disk or drum valves as well) is an interesting idea but I
> don't think I need the critical timing they provide.
>
> I was planning on using the largest two-stroke piston (not a diesel
> piston) I could find and using the largest stoke that was reasonable,
> something like 90x105mm
>
> Brock


There are several organizations for hobbyists building smaller (model
sized) IC engines. Check out Model Engine Builder magazine (they have a
web site.

I suggest you build a model engine first. That would help answer the
question of whether it is practical for you. Sounds like you may not be
a skilled machinist yet, and I would become a master machinist before I
bet my life on a homemade engine.

[PaPa Peng]

On Mar 5, 6:56*pm, durabol > wrote:
> For the last few years I have toyed with the idea of building a
> homemade two-stroke engine for UL use. What keyed my interest was
> reading about homemade model aircraft engines and reading and watching
> a re-enactment of the Wright brother's first flight with a replica
> engine (not a two-stroke engine).
>
> Has anyone made a 2-stroke engine from scratch? One may need to cast
> aluminium, may need a lathe and milling machine with boring head and
> hone or perhaps the boring and honing of the cylinder and bearing
> journals could be farmed out. A commercial carburetor and piston could
> be used. Two-stroke engines seem simple enough that home construction
> may be possible, if not practical.
>
> A direct drive engine will be that much heavier when you take into
> account the weight of the drive reduction system. I have calculated
> the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
> it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
> cylinder and crankcase wall thickness and a 1.25" dia crank.
>
> I have got some idea of port-time-area from the freeware computer
> program called "BiMotion". I'm not sure how good the data is for
> lowish speed engines but I guess it is a start. I have also worked up
> a spreadsheet for similar information.
>
> I don't think a reed valve system is needed for this engine since it
> is only going to operate at a fairly narrow rpm range and the port
> timing isn't critical. Piston ported valves offer similar performance
> to other induction types but only over a narrow rpm range which is
> what I have planned for the engine. I plan to build an engine with a
> restrictive exhaust to ensure no fuel escapes. I have heard that
> piston ported engines can spit some fuel out of the carb at idle but
> this doesn't seem like a major problem. Rotary valves via crank shaft
> induction (disk or drum valves as well) is an interesting idea but I
> don't think I need the critical timing they provide.
>
> I was planning on using the largest two-stroke piston (not a diesel
> piston) I could find and using the largest stoke that was reasonable,
> something like 90x105mm
>
> Brock

I met a guy in Edmonton (St. Albert ) who made working models of
historical engines such as the Liberty engine. Really beautiful piece
of modeling and was featured in a modeling magazine. Its power/weight
output was not enough to power a model plane.

If your intention is to power a model plane you are much better off
buying a model engine and tinker with that to boost its performance.
Not much reward in building a two stroke engine from scratch. For a
large two stoke you can modify a weedwacker engine (25 cc) A
snowmobile engine powers those military drones.

[Morgans[_2_]]

"durabol" > wrote

> Has anyone made a 2-stroke engine from scratch? One may need to cast
> aluminium, may need a lathe and milling machine with boring head and
> hone or perhaps the boring and honing of the cylinder and bearing
> journals could be farmed out. A commercial carburetor and piston could
> be used. Two-stroke engines seem simple enough that home construction
> may be possible, if not practical.
>
> A direct drive engine will be that much heavier when you take into
> account the weight of the drive reduction system.

I am assuming you meant to write "will _(not)_ be that much heavier",
right?

If so, when is the last time you saw a direct drive 2 stroke aircraft
engine? Not me. Closest I can think of is a model airplane engine, and
that is only practical because of the small prop sizes. If you put a large
enough prop on a 2 stroke to soak up 50 hp, you will have to keep rpm's way
down to keep from having a real noisy, inefficient prop. You keep the RPM's
that low, and you now have a real inefficient 2 stroke engine. That is why
all 2 stroke engines have gearboxes or belt drives to reduce prop speed.

You might do well to consider a 2 stroke supercharged diesel engine. You
make one of those, and make it scaleable by adding more banks of cylinders,
and the flying world will beat a path to your doorstep.
--
Jim in NC

[TonyW]

Suzuki built a 650cc water cooled 2 stroke twin for Arctic Cat. I think
that engine is about the ultimate in big bore 2 stroke twins... At one
time I considered getting 2 of these and putting them in a small sports
car like a Triumph Spitfire but I've since moved to a state that does
emissions testing and that won't pass here...

Suzuki just about ruled the 2 stroke motorcycle market with their rock
solid reliable engines. You could count on a 75k miles out of a Suzuki
triple when the other companies' bikes would only go 15 to 20k miles on
a set of pistons...

There were also some big bore 2 stroke dirt bikes. I know all the major
players in the market built them but the one that comes to mind was a
500cc Husqvarna single. Sleeves, pistons ect are all available for
these bikes could be used to build your own. The easiest way to go is
to use someone else's engineering and machine work to build your engine.
That way the major parts to make would be the cases, barrels and
cylinder heads since the bike ones won't have adequate cooling. I
imagine that a 1000cc 2 stroke opposed twin would be pretty cool and
could be tuned to run at an RPM low enough for direct drive. However
it's not a good idea to put a prop on a built up crankshaft like all 2
strokes use and a belt drive or some such would be required.

I would highly recommend reading the 2 stroke tuners handbook if you can
find a copy. I have a PDF version but it's too big to eMail. Also talk
to Charlie at Superior Sleeve in Millwaukie, OR. Charlie has built more
custom 2 stroke engines than just about anybody alive today... If you
can catch him when he has time to talk, he will enlighten you a great
deal. It's been more than 20 years since I was building high
performance 2 stroke engines and I've forgotten a lot over the years...

Good luck and keep us posted if you go on with this project.

Tony

[[email protected]]

On Mar 5, 6:56*pm, durabol > wrote:
> For the last few years I have toyed with the idea of building a
> homemade two-stroke engine for UL use. What keyed my interest was
> reading about homemade model aircraft engines and reading and watching
> a re-enactment of the Wright brother's first flight with a replica
> engine (not a two-stroke engine).
>
> Has anyone made a 2-stroke engine from scratch? One may need to cast
> aluminium, may need a lathe and milling machine with boring head and
> hone or perhaps the boring and honing of the cylinder and bearing
> journals could be farmed out. A commercial carburetor and piston could
> be used. Two-stroke engines seem simple enough that home construction
> may be possible, if not practical.
>
> A direct drive engine will be that much heavier when you take into
> account the weight of the drive reduction system. I have calculated
> the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
> it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
> cylinder and crankcase wall thickness and a 1.25" dia crank.
>
> I have got some idea of port-time-area from the freeware computer
> program called "BiMotion". I'm not sure how good the data is for
> lowish speed engines but I guess it is a start. I have also worked up
> a spreadsheet for similar information.
>
> I don't think a reed valve system is needed for this engine since it
> is only going to operate at a fairly narrow rpm range and the port
> timing isn't critical. Piston ported valves offer similar performance
> to other induction types but only over a narrow rpm range which is
> what I have planned for the engine. I plan to build an engine with a
> restrictive exhaust to ensure no fuel escapes. I have heard that
> piston ported engines can spit some fuel out of the carb at idle but
> this doesn't seem like a major problem. Rotary valves via crank shaft
> induction (disk or drum valves as well) is an interesting idea but I
> don't think I need the critical timing they provide.
>
> I was planning on using the largest two-stroke piston (not a diesel
> piston) I could find and using the largest stoke that was reasonable,
> something like 90x105mm
>
> Brock

There's any amount of engineering info out there on two-strokes,
books have been written. They were a staple project in The Model
Engineer magazine for years, should you want to look that up. What's
UL use?

You'd be basically recreating a commodity item. Resurrect one from a
defunct snowblower, weed-whacker or Lawnboy and spend more time on
figuring out the project you want to drive. The engineering's done,
you aren't likely to improve on what's already been built. Want
overhead valves? Been done. Rotary valves, ditto. Fuel injection,
same. Separate lube system, been done. Opposed twins, flat fours,
square fours, Vs, Xs, Ws, all been done. Separate forced air pumping,
too. They basically suck thermodynamically except the one feature
they've got going is power-to-weight ratio, the small ones pump out a
lot of horsepower, usually at high RPM, for their size. For that you
can go with an existing engine and spend more time on the rest of the
project.

Stan

[Jim Wilkins]

On Mar 6, 8:45*pm, wrote:
> On Mar 5, 6:56*pm, durabol > wrote:

> > For the last few years I have toyed with the idea of building a
> > homemade two-stroke engine for UL use.
> > Brock
>
> ...What's UL use?
> Stan

I think UL here means UltraLight, a minimally regulated, tiny but
MANNED aircraft.
http://www.eaa.org/Ultralights/

I looked into it, flew a hang glider a few times, then gave it up for
the safer hobby of racing dirt bikes.

jsw

[bizguy]

You could look at outboard motors as a starting point. In the past I
read of someone using a Mercury to get 100 hp in an aircraft.
Harold

[jan olieslagers[_2_]]

Morgans schreef:

> You might do well to consider a 2 stroke supercharged diesel engine. You
> make one of those, and make it scaleable by adding more banks of cylinders,
> and the flying world will beat a path to your doorstep.

Hm. The flying world did not exactly beat any kind of path to the
doorstep of www.dair.co.uk, though they did exactly that. Wilksh company
wasn't far off, either, with equal lack of big success.

[jan olieslagers[_2_]]

Jim Wilkins schreef:
> On Mar 6, 8:45 pm, wrote:
>> ...What's UL use?
> I think UL here means UltraLight, a minimally regulated, tiny but
> MANNED aircraft.
> http://www.eaa.org/Ultralights/

I thought the same, but should like to add that in several countries the
"ultralight" definition allows bigger planes, closer to the newer US
light sport aircraft definition.

[jan olieslagers[_2_]]

jan olieslagers schreef:
> Jim Wilkins schreef:
>> On Mar 6, 8:45 pm, wrote:
>>> ...What's UL use?
>> I think UL here means UltraLight, a minimally regulated, tiny but
>> MANNED aircraft.
>> http://www.eaa.org/Ultralights/
>
> I thought the same, but should like to add that in several countries the
> "ultralight" definition allows bigger planes, closer to the newer US
> light sport aircraft definition.

Come to think of it, several countries even allow them to FEMALES !

[Nigel Eaton]

In article
>,
bizguy > writes
>You could look at outboard motors as a starting point. In the past I
>read of someone using a Mercury to get 100 hp in an aircraft.

That seems unlikely, to be honest. I've never met an outboard that
wasn't cooled by pumped water.

--
Nigel

When the only tools you have are an X3 mill, a
Colchester and assorted other stuff, every problem looks like a steam engine.

[Ed Huntress]

"Nigel Eaton" > wrote in message
...
> In article
> >, bizguy
> > writes
>>You could look at outboard motors as a starting point. In the past I
>>read of someone using a Mercury to get 100 hp in an aircraft.
>
> That seems unlikely, to be honest. I've never met an outboard that wasn't
> cooled by pumped water.
>
> --
> Nigel

There have been other uses of outboards that involved using a car-type
cooling system, with a radiator. A Bobsy SR2 sports-racing car of the 1960s
was very successful in the H-modified class using a Mercury outboard. I
think that was a 750 cc class.

--
Ed Huntress

[[email protected]]

On Sat, 6 Mar 2010 17:45:22 -0800 (PST), wrote:

>On Mar 5, 6:56Â*pm, durabol > wrote:
>> For the last few years I have toyed with the idea of building a
>> homemade two-stroke engine for UL use. What keyed my interest was
>> reading about homemade model aircraft engines and reading and watching
>> a re-enactment of the Wright brother's first flight with a replica
>> engine (not a two-stroke engine).
>>
>> Has anyone made a 2-stroke engine from scratch? One may need to cast
>> aluminium, may need a lathe and milling machine with boring head and
>> hone or perhaps the boring and honing of the cylinder and bearing
>> journals could be farmed out. A commercial carburetor and piston could
>> be used. Two-stroke engines seem simple enough that home construction
>> may be possible, if not practical.
>>
>> A direct drive engine will be that much heavier when you take into
>> account the weight of the drive reduction system. I have calculated
>> the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
>> it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
>> cylinder and crankcase wall thickness and a 1.25" dia crank.
>>
>> I have got some idea of port-time-area from the freeware computer
>> program called "BiMotion". I'm not sure how good the data is for
>> lowish speed engines but I guess it is a start. I have also worked up
>> a spreadsheet for similar information.
>>
>> I don't think a reed valve system is needed for this engine since it
>> is only going to operate at a fairly narrow rpm range and the port
>> timing isn't critical. Piston ported valves offer similar performance
>> to other induction types but only over a narrow rpm range which is
>> what I have planned for the engine. I plan to build an engine with a
>> restrictive exhaust to ensure no fuel escapes. I have heard that
>> piston ported engines can spit some fuel out of the carb at idle but
>> this doesn't seem like a major problem. Rotary valves via crank shaft
>> induction (disk or drum valves as well) is an interesting idea but I
>> don't think I need the critical timing they provide.
>>
>> I was planning on using the largest two-stroke piston (not a diesel
>> piston) I could find and using the largest stoke that was reasonable,
>> something like 90x105mm
>>
>> Brock
>
>There's any amount of engineering info out there on two-strokes,
>books have been written. They were a staple project in The Model
>Engineer magazine for years, should you want to look that up. What's
>UL use?
>

I believe he's talking UltraLight Aircraft.

Why a two stroke? The commercially available ones are bad enough. I
hate even taking my chainsaw up a ladder - why would I want to fly
behind one???
A good, small, light supercharged 4 stroke or diesel??? Now that's
something completely different!!!


>You'd be basically recreating a commodity item. Resurrect one from a
>defunct snowblower, weed-whacker or Lawnboy and spend more time on
>figuring out the project you want to drive. The engineering's done,
>you aren't likely to improve on what's already been built. Want
>overhead valves? Been done. Rotary valves, ditto. Fuel injection,
>same. Separate lube system, been done. Opposed twins, flat fours,
>square fours, Vs, Xs, Ws, all been done. Separate forced air pumping,
>too. They basically suck thermodynamically except the one feature
>they've got going is power-to-weight ratio, the small ones pump out a
>lot of horsepower, usually at high RPM, for their size. For that you
>can go with an existing engine and spend more time on the rest of the
>project.
>
>Stan

[[email protected]]

On Sun, 07 Mar 2010 13:51:46 +0000, jan olieslagers
> wrote:

>Jim Wilkins schreef:
>> On Mar 6, 8:45 pm, wrote:
>>> ...What's UL use?
>> I think UL here means UltraLight, a minimally regulated, tiny but
>> MANNED aircraft.
>> http://www.eaa.org/Ultralights/
>
>I thought the same, but should like to add that in several countries the
>"ultralight" definition allows bigger planes, closer to the newer US
>light sport aircraft definition.
Like up here in Canada - 1238 lbs? as long as it stalls under 45 MPH.
It can have a Lycoming IO-235 in it if you want.

[[email protected]]

On Sat, 6 Mar 2010 21:36:28 -0800 (PST), bizguy
> wrote:

>You could look at outboard motors as a starting point. In the past I
>read of someone using a Mercury to get 100 hp in an aircraft.
>Harold
Had a 100HP Evinrude V4 I was thinking of putting in a plane - untill
I remembered all the problems I'd had with 2 strokes in boats, lawn
mowers, mototcycles, weed-eaters, and chain saws over the years.

[Morgans[_2_]]

"jan olieslagers" > wrote in message
...
> Morgans schreef:
>
>> You might do well to consider a 2 stroke supercharged diesel engine. You
>> make one of those, and make it scaleable by adding more banks of
>> cylinders,
>> and the flying world will beat a path to your doorstep.
>
> Hm. The flying world did not exactly beat any kind of path to the doorstep
> of www.dair.co.uk, though they did exactly that. Wilksh company wasn't far
> off, either, with equal lack of big success.

I suspect the two cylinders with 4 pistons is a bit unconventional, and will
have to work all the harder to prove itself.

I think the web page is about 10 years old, since much activity has taken
place. It looks like it is a bit heavy when you add all it needs to run in
an airplane, too. How about price? No mention of that, on the current
pages.
--
Jim in NC

[vaughn[_3_]]

"Morgans" > wrote in message
...
>
> I suspect the two cylinders with 4 pistons is a bit unconventional, and will
> have to work all the harder to prove itself.
>
2 pistons per cylinder is not unconventional in the stationary diesel world.

Vaughn

[[email protected]]

On Mar 6, 2:44 pm, "Morgans" > wrote:

> If so, when is the last time you saw a direct drive 2 stroke aircraft
> engine? Not me.

McCullough made two-stroke opposed four-bangers for miltary target
drones in several different sizes. Many of those were sold surplus and
found their way into several homebuilts and a lot of Bensen
Gyrocopters. I once owned one; the vibration was awesome, as was the
fuel consumption.

http://www.combatairmuseum.org/engines/mcculloch0-100-1.html
http://media.photobucket.com/image/McCullough%20drone%20engine/mrbigsawz/tractoshow026.jpg

And here's a video of one powering a Hummel Bird:

http://www.youtube.com/watch?v=ITB_dxbCTUk

Dan

[[email protected]]

On Sun, 7 Mar 2010 23:04:37 +0000, Nigel Eaton
> wrote:

>In article
>,
>bizguy > writes
>>You could look at outboard motors as a starting point. In the past I
>>read of someone using a Mercury to get 100 hp in an aircraft.
>
>That seems unlikely, to be honest. I've never met an outboard that
>wasn't cooled by pumped water.
Can be cooled very well with a radiator - the interface to connect a
rad instead of the raw water cooling was possible, but not simple.
There were "saltie" conversions that used a sealed cooling system and
a heat exhanger availble for some of the outboards of the period, but
they were not common. Very common with stern-drives (4 stroke)

Actually, there WAS a commercially available helicopter kit that DID
use the V4 Evinrude power head - and I believe I've seen refference to
the 6 cyl Merc "black max" in experimental aircraft use too.

[cavelamb[_2_]]

Nigel Eaton wrote:
> In article
> >,
> bizguy > writes
>> You could look at outboard motors as a starting point. In the past I
>> read of someone using a Mercury to get 100 hp in an aircraft.
>
> That seems unlikely, to be honest. I've never met an outboard that
> wasn't cooled by pumped water.
>


I had a really nice 5 HP Briggs and Stratton outboard on my previous
sailboat. It was air cooled. But it was the exception that proved
the rule...

http://www.duckworksmagazine.com/03/r/columns/cupp/06/index.htm
--

Richard Lamb
http://www.home.earthlink.net/~cavelamb/

[Peter Fairbrother]

cavelamb wrote:
> Nigel Eaton wrote:
>> In article
>> >,
>> bizguy > writes
>>> You could look at outboard motors as a starting point. In the past I
>>> read of someone using a Mercury to get 100 hp in an aircraft.
>>
>> That seems unlikely, to be honest. I've never met an outboard that
>> wasn't cooled by pumped water.
>>
>
>
> I had a really nice 5 HP Briggs and Stratton outboard on my previous
> sailboat. It was air cooled. But it was the exception that proved
> the rule...
>
> http://www.duckworksmagazine.com/03/r/columns/cupp/06/index.htm

Without knowing anything much about ultralights (beyond they look fun
but dangerous) wouldn't the obvious source of lightweight engines in
that power range be motorcycle engines?

-- Peter Fairbrother

[Anyolmouse]

"durabol" > wrote in message
...
> For the last few years I have toyed with the idea of building a
> homemade two-stroke engine for UL use. What keyed my interest was
> reading about homemade model aircraft engines and reading and watching
> a re-enactment of the Wright brother's first flight with a replica
> engine (not a two-stroke engine).
>
> Has anyone made a 2-stroke engine from scratch? One may need to cast
> aluminium, may need a lathe and milling machine with boring head and
> hone or perhaps the boring and honing of the cylinder and bearing
> journals could be farmed out. A commercial carburetor and piston could
> be used. Two-stroke engines seem simple enough that home construction
> may be possible, if not practical.
>
> A direct drive engine will be that much heavier when you take into
> account the weight of the drive reduction system. I have calculated
> the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
> it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
> cylinder and crankcase wall thickness and a 1.25" dia crank.
>
> I have got some idea of port-time-area from the freeware computer
> program called "BiMotion". I'm not sure how good the data is for
> lowish speed engines but I guess it is a start. I have also worked up
> a spreadsheet for similar information.
>
> I don't think a reed valve system is needed for this engine since it
> is only going to operate at a fairly narrow rpm range and the port
> timing isn't critical. Piston ported valves offer similar performance
> to other induction types but only over a narrow rpm range which is
> what I have planned for the engine. I plan to build an engine with a
> restrictive exhaust to ensure no fuel escapes. I have heard that
> piston ported engines can spit some fuel out of the carb at idle but
> this doesn't seem like a major problem. Rotary valves via crank shaft
> induction (disk or drum valves as well) is an interesting idea but I
> don't think I need the critical timing they provide.
>
> I was planning on using the largest two-stroke piston (not a diesel
> piston) I could find and using the largest stoke that was reasonable,
> something like 90x105mm
>
> Brock

How about a 2 stroke radial developed by Pontiac for their X-4 1,500lb
car in 1969.
http://www.popsci.com/archive-viewer?id=EyoDAAAAMBAJ&pg=43&query=homebuilt+airplanes

Popular Science has just released ALL of their archives for free
http://www.popsci.com/archives and found it while searching for
homebuilt airplanes.

--
A man is known by the company he keeps- Unknown

Anyolmouse

[bod43]

On 8 Mar, 22:28, "Anyolmouse" > wrote:
> "durabol" > wrote in message
>
> ...
>
>
>
> > For the last few years I have toyed with the idea of building a
> > homemade two-stroke engine for UL use. What keyed my interest was
> > reading about homemade model aircraft engines and reading and watching
> > a re-enactment of the Wright brother's first flight with a replica
> > engine (not a two-stroke engine).
>
> > Has anyone made a 2-stroke engine from scratch? One may need to cast
> > aluminium, may need a lathe and milling machine with boring head and
> > hone or perhaps the boring and honing of the cylinder and bearing
> > journals could be farmed out. A commercial carburetor and piston could
> > be used. Two-stroke engines seem simple enough that home construction
> > may be possible, if not practical.
>
> > A direct drive engine will be that much heavier when you take into
> > account the weight of the drive reduction system. I have calculated
> > the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
> > it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
> > cylinder and crankcase wall thickness and a 1.25" dia crank.
>
> > I have got some idea of port-time-area from the freeware computer
> > program called "BiMotion". I'm not sure how good the data is for
> > lowish speed engines but I guess it is a start. I have also worked up
> > a spreadsheet for similar information.
>
> > I don't think a reed valve system is needed for this engine since it
> > is only going to operate at a fairly narrow rpm range and the port
> > timing isn't critical. Piston ported valves offer similar performance
> > to other induction types but only over a narrow rpm range which is
> > what I have planned for the engine. I plan to build an engine with a
> > restrictive exhaust to ensure no fuel escapes. I have heard that
> > piston ported engines can spit some fuel out of the carb at idle but
> > this doesn't seem like a major problem. Rotary valves via crank shaft
> > induction (disk or drum valves as well) is an interesting idea but I
> > don't think I need the critical timing they provide.
>
> > I was planning on using the largest two-stroke piston (not a diesel
> > piston) I could find and using the largest stoke that was reasonable,
> > something like 90x105mm

www.deltahawk.com

Too big for ultralight I would guess but seems like
a very fine plan for a light aircraft engine.

160 hp and upwards

V4 two stroke diesel.

Has crank driven air pump + turbo.

No electrics *at_all* for engine operation.

Will continue running if air pump OR turbo fails.
Will run at about 50% power (check web site for details)
if all water is lost.

Seems a *very* fine thing to me.

Expected to be accepted as a FAA certified
aero engine this year.

200hp planned.

V8 in the future.

[bod43]

On 9 Mar, 03:47, bod43 > wrote:
> On 8 Mar, 22:28, "Anyolmouse" > wrote:
>
>
>
> > "durabol" > wrote in message
>
> ...
>
> > > For the last few years I have toyed with the idea of building a
> > > homemade two-stroke engine for UL use. What keyed my interest was
> > > reading about homemade model aircraft engines and reading and watching
> > > a re-enactment of the Wright brother's first flight with a replica
> > > engine (not a two-stroke engine).
>
> > > Has anyone made a 2-stroke engine from scratch? One may need to cast
> > > aluminium, may need a lathe and milling machine with boring head and
> > > hone or perhaps the boring and honing of the cylinder and bearing
> > > journals could be farmed out. A commercial carburetor and piston could
> > > be used. Two-stroke engines seem simple enough that home construction
> > > may be possible, if not practical.
>
> > > A direct drive engine will be that much heavier when you take into
> > > account the weight of the drive reduction system. I have calculated
> > > the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
> > > it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
> > > cylinder and crankcase wall thickness and a 1.25" dia crank.
>
> > > I have got some idea of port-time-area from the freeware computer
> > > program called "BiMotion". I'm not sure how good the data is for
> > > lowish speed engines but I guess it is a start. I have also worked up
> > > a spreadsheet for similar information.
>
> > > I don't think a reed valve system is needed for this engine since it
> > > is only going to operate at a fairly narrow rpm range and the port
> > > timing isn't critical. Piston ported valves offer similar performance
> > > to other induction types but only over a narrow rpm range which is
> > > what I have planned for the engine. I plan to build an engine with a
> > > restrictive exhaust to ensure no fuel escapes. I have heard that
> > > piston ported engines can spit some fuel out of the carb at idle but
> > > this doesn't seem like a major problem. Rotary valves via crank shaft
> > > induction (disk or drum valves as well) is an interesting idea but I
> > > don't think I need the critical timing they provide.
>
> > > I was planning on using the largest two-stroke piston (not a diesel
> > > piston) I could find and using the largest stoke that was reasonable,
> > > something like 90x105mm
>
> www.deltahawk.com
>
> Too big for ultralight I would guess but seems like
> a very fine plan for a light aircraft engine.
>
> 160 hp and upwards
>
> V4 two stroke diesel.
>
> Has crank driven air pump + turbo.
>
> No electrics *at_all* for engine operation.
>
> Will continue running if air pump OR turbo fails.
> Will run at about 50% power (check web site for details)
> if all water is lost.
>
> Seems a *very* fine thing to me.
>
> Expected to be accepted as a FAA certified
> aero engine this year.
>
> 200hp planned.
>
> V8 in the future.

Oh yes - direct drive. No gears needed.

[Tim Wescott]

bod43 wrote:
> On 8 Mar, 22:28, "Anyolmouse" > wrote:
>> "durabol" > wrote in message
>>
>> ...
>>
>>
>>
>>> For the last few years I have toyed with the idea of building a
>>> homemade two-stroke engine for UL use. What keyed my interest was
>>> reading about homemade model aircraft engines and reading and watching
>>> a re-enactment of the Wright brother's first flight with a replica
>>> engine (not a two-stroke engine).
>>> Has anyone made a 2-stroke engine from scratch? One may need to cast
>>> aluminium, may need a lathe and milling machine with boring head and
>>> hone or perhaps the boring and honing of the cylinder and bearing
>>> journals could be farmed out. A commercial carburetor and piston could
>>> be used. Two-stroke engines seem simple enough that home construction
>>> may be possible, if not practical.
>>> A direct drive engine will be that much heavier when you take into
>>> account the weight of the drive reduction system. I have calculated
>>> the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
>>> it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
>>> cylinder and crankcase wall thickness and a 1.25" dia crank.
>>> I have got some idea of port-time-area from the freeware computer
>>> program called "BiMotion". I'm not sure how good the data is for
>>> lowish speed engines but I guess it is a start. I have also worked up
>>> a spreadsheet for similar information.
>>> I don't think a reed valve system is needed for this engine since it
>>> is only going to operate at a fairly narrow rpm range and the port
>>> timing isn't critical. Piston ported valves offer similar performance
>>> to other induction types but only over a narrow rpm range which is
>>> what I have planned for the engine. I plan to build an engine with a
>>> restrictive exhaust to ensure no fuel escapes. I have heard that
>>> piston ported engines can spit some fuel out of the carb at idle but
>>> this doesn't seem like a major problem. Rotary valves via crank shaft
>>> induction (disk or drum valves as well) is an interesting idea but I
>>> don't think I need the critical timing they provide.
>>> I was planning on using the largest two-stroke piston (not a diesel
>>> piston) I could find and using the largest stoke that was reasonable,
>>> something like 90x105mm
>
> www.deltahawk.com
>
> Too big for ultralight I would guess but seems like
> a very fine plan for a light aircraft engine.
>
> 160 hp and upwards
>
> V4 two stroke diesel.
>
> Has crank driven air pump + turbo.
>
> No electrics *at_all* for engine operation.
>
> Will continue running if air pump OR turbo fails.
> Will run at about 50% power (check web site for details)
> if all water is lost.
>
> Seems a *very* fine thing to me.
>
> Expected to be accepted as a FAA certified
> aero engine this year.
>
> 200hp planned.
>
> V8 in the future.
>
That link redirects to a poster site.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[Jim Wilkins]

On Mar 8, 11:55*pm, Tim Wescott > wrote:
> ...
> >www.deltahawk.com

> That link redirects to a poster site.
> Tim Wescott

http://www.deltahawkengines.com/

Any day now.....

jsw

[Anna]

Jim Wilkins wrote:
> On Mar 8, 11:55 pm, Tim Wescott > wrote:
>> ...
>>> www.deltahawk.com
>
>> That link redirects to a poster site.
>> Tim Wescott
>
> http://www.deltahawkengines.com/
>
> Any day now.....
>
> jsw

saw the price? 71 Thou $$$$$$

[Anna]

Anna wrote:
> Jim Wilkins wrote:
>> On Mar 8, 11:55 pm, Tim Wescott > wrote:
>>> ...
>>>> www.deltahawk.com
>>
>>> That link redirects to a poster site.
>>> Tim Wescott
>>
>> http://www.deltahawkengines.com/
>>
>> Any day now.....
>>
>> jsw
>
> saw the price? 71 Thou $$$$$$

sorry, 'only' 62.500$ for Deltahawk

[jan olieslagers[_2_]]

bod43 schreef:
>
> www.deltahawk.com
>
> Too big for ultralight I would guess but seems like
> a very fine plan for a light aircraft engine.
>
> 160 hp and upwards
>
> V4 two stroke diesel.

Yes yes, nice stuff though expensive. But the original question was
about building one's engine from scratch.

[Jim Wilkins]

On Mar 9, 10:37*am, jan olieslagers >
wrote:
> bod43 schreef:
> ...
> > V4 two stroke diesel.
> Yes yes, nice stuff though expensive. But the original question was
> about building one's engine from scratch.

After spray cans you want yet another safety rant?

jsw

[Tim Wescott]

Anna wrote:
> Jim Wilkins wrote:
>> On Mar 8, 11:55 pm, Tim Wescott > wrote:
>>> ...
>>>> www.deltahawk.com
>>
>>> That link redirects to a poster site.
>>> Tim Wescott
>>
>> http://www.deltahawkengines.com/
>>
>> Any day now.....
>>
>> jsw
>
> saw the price? 71 Thou $$$$$$

Not out of line for an engine that's capable of being certified but
hasn't been yet.

Aero engines are expensive. That's why folks go to great lengths to
modify car engines to fly airplanes. When they're done, the engines are
-- expensive.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[cavelamb[_2_]]

Jim Wilkins wrote:
> On Mar 9, 10:37 am, jan olieslagers >
> wrote:
>> bod43 schreef:
>> ...
>>> V4 two stroke diesel.
>> Yes yes, nice stuff though expensive. But the original question was
>> about building one's engine from scratch.
>
> After spray cans you want yet another safety rant?
>
> jsw



THAT, more than likely, just won't happen.

Fred Blanton did it.
But it took his entire adult life time.

So this thread is about TALKING about building
and engine from scratch.

Not actually building one...

--

Richard Lamb
http://www.home.earthlink.net/~cavelamb/

[Tim Wescott]

cavelamb wrote:
> Jim Wilkins wrote:
>> On Mar 9, 10:37 am, jan olieslagers >
>> wrote:
>>> bod43 schreef:
>>> ...
>>>> V4 two stroke diesel.
>>> Yes yes, nice stuff though expensive. But the original question was
>>> about building one's engine from scratch.
>>
>> After spray cans you want yet another safety rant?
>>
>> jsw
>
>
>
> THAT, more than likely, just won't happen.
>
> Fred Blanton did it.
> But it took his entire adult life time.
>
> So this thread is about TALKING about building
> and engine from scratch.
>
> Not actually building one...
>
Henry Ford did it, in his garage, over the space of a year or two.

But the performance wasn't high.

The Wright Brothers did it, over the space of a year or two, and even
though the performance wasn't high it was still good enough!

Talking about building stuff can get you a lot more bang for the buck
than actually doing it. Witness me, with several engine parts sitting
next to a lathe that's been idle for days, and last had an accessory for
a completely different engine built on it, not a part for the engine
that's half-done and sitting next to it.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[Tim Wescott]

durabol wrote:
> For the last few years I have toyed with the idea of building a
> homemade two-stroke engine for UL use. What keyed my interest was
> reading about homemade model aircraft engines and reading and watching
> a re-enactment of the Wright brother's first flight with a replica
> engine (not a two-stroke engine).
>
> Has anyone made a 2-stroke engine from scratch? One may need to cast
> aluminium, may need a lathe and milling machine with boring head and
> hone or perhaps the boring and honing of the cylinder and bearing
> journals could be farmed out. A commercial carburetor and piston could
> be used. Two-stroke engines seem simple enough that home construction
> may be possible, if not practical.
>
> A direct drive engine will be that much heavier when you take into
> account the weight of the drive reduction system. I have calculated
> the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
> it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
> cylinder and crankcase wall thickness and a 1.25" dia crank.
>
> I have got some idea of port-time-area from the freeware computer
> program called "BiMotion". I'm not sure how good the data is for
> lowish speed engines but I guess it is a start. I have also worked up
> a spreadsheet for similar information.
>
> I don't think a reed valve system is needed for this engine since it
> is only going to operate at a fairly narrow rpm range and the port
> timing isn't critical. Piston ported valves offer similar performance
> to other induction types but only over a narrow rpm range which is
> what I have planned for the engine. I plan to build an engine with a
> restrictive exhaust to ensure no fuel escapes. I have heard that
> piston ported engines can spit some fuel out of the carb at idle but
> this doesn't seem like a major problem. Rotary valves via crank shaft
> induction (disk or drum valves as well) is an interesting idea but I
> don't think I need the critical timing they provide.
>
> I was planning on using the largest two-stroke piston (not a diesel
> piston) I could find and using the largest stoke that was reasonable,
> something like 90x105mm
>
> Brock

http://www.s363.com/Elbridge/aee.html

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[cavelamb[_2_]]

Tim Wescott wrote:
> cavelamb wrote:
>> Jim Wilkins wrote:
>>> On Mar 9, 10:37 am, jan olieslagers >
>>> wrote:
>>>> bod43 schreef:
>>>> ...
>>>>> V4 two stroke diesel.
>>>> Yes yes, nice stuff though expensive. But the original question was
>>>> about building one's engine from scratch.
>>>
>>> After spray cans you want yet another safety rant?
>>>
>>> jsw
>>
>>
>>
>> THAT, more than likely, just won't happen.
>>
>> Fred Blanton did it.
>> But it took his entire adult life time.
>>
>> So this thread is about TALKING about building
>> and engine from scratch.
>>
>> Not actually building one...
>>
> Henry Ford did it, in his garage, over the space of a year or two.
>
> But the performance wasn't high.
>
> The Wright Brothers did it, over the space of a year or two, and even
> though the performance wasn't high it was still good enough!
>
> Talking about building stuff can get you a lot more bang for the buck
> than actually doing it. Witness me, with several engine parts sitting
> next to a lathe that's been idle for days, and last had an accessory for
> a completely different engine built on it, not a part for the engine
> that's half-done and sitting next to it.
>

Yep!
Tha's how it happens...
:)

--

Richard Lamb
http://www.home.earthlink.net/~cavelamb/

[TonyW]

This isn't aviation related but this guy built a replica of a 1919
motorcycle. The info on the work involved is well worth reading...
http://www.flashbackfab.com/pages/excel00.html

Tony

[[email protected]]

On Tue, 9 Mar 2010 04:36:58 -0800 (PST), Jim Wilkins
> wrote:

>On Mar 8, 11:55Â*pm, Tim Wescott > wrote:
>> ...
>> >www.deltahawk.com
>
>> That link redirects to a poster site.
>> Tim Wescott
>
>http://www.deltahawkengines.com/
>
>Any day now.....
>
>jsw
For the last 10 years.

[Morgans[_2_]]

"Peter Fairbrother" > wrote

> Without knowing anything much about ultralights (beyond they look fun but
> dangerous) wouldn't the obvious source of lightweight engines in that
> power range be motorcycle engines?

You would think, but how they are designed is a major problem.

Most have the gearbox made as one with the lower crankcase. You can't get
the weight off of the engine, and the gears in the bike tranny are not tough
enough to run a prop, so you have to live with the weight and figure out a
way to get the power out of the case without using the gearbox. Big
problem.
--
Jim in NC

[Morgans[_2_]]

"bod43" > wrote

> www.deltahawk.com
>
> Too big for ultralight I would guess but seems like
> a very fine plan for a light aircraft engine.

> Expected to be accepted as a FAA certified
> aero engine this year.

I'll believe it when I see that the first 25 are sold and flying. It has
been ready for production for the past 10 or more years, yet, it always a
year away from being released for production.

Hint: I'll win this bet.
--
Jim in NC

[Stu Fields]

> wrote in message
...
> On Tue, 9 Mar 2010 04:36:58 -0800 (PST), Jim Wilkins
> > wrote:
>
>>On Mar 8, 11:55 pm, Tim Wescott > wrote:
>>> ...
>>> >www.deltahawk.com
>>
>>> That link redirects to a poster site.
>>> Tim Wescott
>>
>>http://www.deltahawkengines.com/
>>
>>Any day now.....
>>
>>jsw
> For the last 10 years.

Surprise, Surprise. There is a two seat experimental Helicopter in
Australia that is undergoing flight tests as I write this. It is using the
Deltahawk two stroke diesel engine. see www.deltahelicopters.com.au
Unfortunately the Deltahawk engines are priced right up there with the long
time proven Lycomings. It will take some time to really see if this engine
will demonstrate all the potential advantages inherent in the diesel
concept.

[vaughn[_3_]]

"Morgans" > wrote in message
...
> Most have the gearbox made as one with the lower crankcase. You can't get
> the weight off of the engine, and the gears in the bike tranny are not tough
> enough to run a prop, so you have to live with the weight and figure out a
> way to get the power out of the case without using the gearbox. Big
> problem.

Of course, that is not so with Harley & clone V-twins and at least some BMW
engines (Yes, I know. They are 4-stroke and this thread is about 2-stroke
engines)

Vaughn

[durabol[_2_]]

Thanks for the responses. I meant for ultralight or light aircraft
with 20-40hp from 1 or 2 cylinders. I definitely want to copy as much
as I can since I'm not engineer. I planned to have the RPM at about
4000 in order to get enough power out of the engine but I may reduce
the rpm if I can get enough power. Also I may have to weld the crank
together to handle the propeller loads.

Brock

[Tim Wescott]

durabol wrote:
> Thanks for the responses. I meant for ultralight or light aircraft
> with 20-40hp from 1 or 2 cylinders. I definitely want to copy as much
> as I can since I'm not engineer. I planned to have the RPM at about
> 4000 in order to get enough power out of the engine but I may reduce
> the rpm if I can get enough power. Also I may have to weld the crank
> together to handle the propeller loads.
>
> Brock

That RPM isn't going to give you much prop efficiency.

A more spindly engine with higher displacement may be lighter overall --
and certainly mechanically simpler -- than a little fast engine and a
speed reducer.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[Grider Pirate]

On Mar 14, 11:30*pm, durabol > wrote:
> Thanks for the responses. I meant for ultralight or light aircraft
> with 20-40hp from 1 or 2 cylinders. I definitely want to copy as much
> as I can since I'm not engineer. I planned to have the RPM at about
> 4000 in order to get enough power out of the engine but I may reduce
> the rpm if I can get enough power. Also I may have to weld the crank
> together to handle the propeller loads.
>
> Brock

'Restrictive' exhaust isn't a good way to avoid venting unburnt fuel,
and it will really clobber performance. If you're really trying to
get good performance, especially over a narrow band, then you really
need to consider using tuned pipes (AKA "Expansion Chambers"). Gordon
Jennings "Two Stroke Tuners Handbook" covers most everything you need
to design a two-stroke.
4000 RPM is pretty low for a two-stroke. The tuned length for the
pipe(s) would be around 6 FEET.

[Tim Wescott]

Grider Pirate wrote:
> On Mar 14, 11:30 pm, durabol > wrote:
>> Thanks for the responses. I meant for ultralight or light aircraft
>> with 20-40hp from 1 or 2 cylinders. I definitely want to copy as much
>> as I can since I'm not engineer. I planned to have the RPM at about
>> 4000 in order to get enough power out of the engine but I may reduce
>> the rpm if I can get enough power. Also I may have to weld the crank
>> together to handle the propeller loads.
>>
>> Brock
>
> 'Restrictive' exhaust isn't a good way to avoid venting unburnt fuel,
> and it will really clobber performance. If you're really trying to
> get good performance, especially over a narrow band, then you really
> need to consider using tuned pipes (AKA "Expansion Chambers"). Gordon
> Jennings "Two Stroke Tuners Handbook" covers most everything you need
> to design a two-stroke.
> 4000 RPM is pretty low for a two-stroke. The tuned length for the
> pipe(s) would be around 6 FEET.

Ship's two-stroke diesel engines top out at less than 200RPM.

I don't think they use tuned pipes, but if they did I suppose they'd
have room.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

[Jim Stewart]

Tim Wescott wrote:
> Grider Pirate wrote:
>> On Mar 14, 11:30 pm, durabol > wrote:
>>> Thanks for the responses. I meant for ultralight or light aircraft
>>> with 20-40hp from 1 or 2 cylinders. I definitely want to copy as much
>>> as I can since I'm not engineer. I planned to have the RPM at about
>>> 4000 in order to get enough power out of the engine but I may reduce
>>> the rpm if I can get enough power. Also I may have to weld the crank
>>> together to handle the propeller loads.
>>>
>>> Brock
>>
>> 'Restrictive' exhaust isn't a good way to avoid venting unburnt fuel,
>> and it will really clobber performance. If you're really trying to
>> get good performance, especially over a narrow band, then you really
>> need to consider using tuned pipes (AKA "Expansion Chambers"). Gordon
>> Jennings "Two Stroke Tuners Handbook" covers most everything you need
>> to design a two-stroke.
>> 4000 RPM is pretty low for a two-stroke. The tuned length for the
>> pipe(s) would be around 6 FEET.
>
> Ship's two-stroke diesel engines top out at less than 200RPM.
>
> I don't think they use tuned pipes, but if they did I suppose they'd
> have room.

Don't need them. They all have massive
blowers for scavenging.

I believe EMD built locomotive 2-strokes that
had a set of exhaust valves in the head and
a blower port that was opened at the bottom of
the stroke. No tuning, the blower was plenty
to force out the exhaust and fill the cylinder
with fresh air.

[[email protected]]

On Thu, 18 Mar 2010 13:39:45 -0700, Tim Wescott >
wrote:

>Grider Pirate wrote:
>> On Mar 14, 11:30 pm, durabol > wrote:
>>> Thanks for the responses. I meant for ultralight or light aircraft
>>> with 20-40hp from 1 or 2 cylinders. I definitely want to copy as much
>>> as I can since I'm not engineer. I planned to have the RPM at about
>>> 4000 in order to get enough power out of the engine but I may reduce
>>> the rpm if I can get enough power. Also I may have to weld the crank
>>> together to handle the propeller loads.
>>>
>>> Brock
>>
>> 'Restrictive' exhaust isn't a good way to avoid venting unburnt fuel,
>> and it will really clobber performance. If you're really trying to
>> get good performance, especially over a narrow band, then you really
>> need to consider using tuned pipes (AKA "Expansion Chambers"). Gordon
>> Jennings "Two Stroke Tuners Handbook" covers most everything you need
>> to design a two-stroke.
>> 4000 RPM is pretty low for a two-stroke. The tuned length for the
>> pipe(s) would be around 6 FEET.
>
>Ship's two-stroke diesel engines top out at less than 200RPM.
>
>I don't think they use tuned pipes, but if they did I suppose they'd
>have room.
They are also supercharged. (forced induction)

[[email protected]]

On Thu, 18 Mar 2010 14:17:50 -0700, Jim Stewart >
wrote:

>Tim Wescott wrote:
>> Grider Pirate wrote:
>>> On Mar 14, 11:30 pm, durabol > wrote:
>>>> Thanks for the responses. I meant for ultralight or light aircraft
>>>> with 20-40hp from 1 or 2 cylinders. I definitely want to copy as much
>>>> as I can since I'm not engineer. I planned to have the RPM at about
>>>> 4000 in order to get enough power out of the engine but I may reduce
>>>> the rpm if I can get enough power. Also I may have to weld the crank
>>>> together to handle the propeller loads.
>>>>
>>>> Brock
>>>
>>> 'Restrictive' exhaust isn't a good way to avoid venting unburnt fuel,
>>> and it will really clobber performance. If you're really trying to
>>> get good performance, especially over a narrow band, then you really
>>> need to consider using tuned pipes (AKA "Expansion Chambers"). Gordon
>>> Jennings "Two Stroke Tuners Handbook" covers most everything you need
>>> to design a two-stroke.
>>> 4000 RPM is pretty low for a two-stroke. The tuned length for the
>>> pipe(s) would be around 6 FEET.
>>
>> Ship's two-stroke diesel engines top out at less than 200RPM.
>>
>> I don't think they use tuned pipes, but if they did I suppose they'd
>> have room.
>
>Don't need them. They all have massive
>blowers for scavenging.
>
>I believe EMD built locomotive 2-strokes that
>had a set of exhaust valves in the head and
>a blower port that was opened at the bottom of
>the stroke. No tuning, the blower was plenty
>to force out the exhaust and fill the cylinder
>with fresh air.
And at 200 RPM there is LOTS of time to purge and fill. Volumetric
efficiencies are pretty good.

[bizguy]

This thread is going all over the place - so here goes.

Consider building a Kemp G2 replica. If you can do that there might
even be others that would want to buy them.

2 cyl - 4 cycle low end HP.

[bizguy]

On Mar 20, 9:00*pm, bizguy > wrote:
> This thread is going all over the place - so here goes.
>
> Consider building a Kemp G2 replica. *If you can do that there might
> even be others that would want to buy them.
>
> 2 cyl - 4 cycle low end HP.

http://bourkeengine.net/home.htm

http://www.rogerrichard.com/14507.html

Another very interesting project worthy of following.

[wesley marceaux[_2_]]

your too late,, Mr. Chotia made an engine for the weedhopper that is exactly
what you described..you can go to the weedhopper site and buy one for under
a hundred bucks...........try,,,,you'll be surprised
"durabol" > wrote in message
...
> For the last few years I have toyed with the idea of building a
> homemade two-stroke engine for UL use. What keyed my interest was
> reading about homemade model aircraft engines and reading and watching
> a re-enactment of the Wright brother's first flight with a replica
> engine (not a two-stroke engine).
>
> Has anyone made a 2-stroke engine from scratch? One may need to cast
> aluminium, may need a lathe and milling machine with boring head and
> hone or perhaps the boring and honing of the cylinder and bearing
> journals could be farmed out. A commercial carburetor and piston could
> be used. Two-stroke engines seem simple enough that home construction
> may be possible, if not practical.
>
> A direct drive engine will be that much heavier when you take into
> account the weight of the drive reduction system. I have calculated
> the weight of an 80x80mm bore and stroke 2 cylinder opposed engine and
> it was a bit under 40lbs which should give about 1hp/lbs. I used 10mm
> cylinder and crankcase wall thickness and a 1.25" dia crank.
>
> I have got some idea of port-time-area from the freeware computer
> program called "BiMotion". I'm not sure how good the data is for
> lowish speed engines but I guess it is a start. I have also worked up
> a spreadsheet for similar information.
>
> I don't think a reed valve system is needed for this engine since it
> is only going to operate at a fairly narrow rpm range and the port
> timing isn't critical. Piston ported valves offer similar performance
> to other induction types but only over a narrow rpm range which is
> what I have planned for the engine. I plan to build an engine with a
> restrictive exhaust to ensure no fuel escapes. I have heard that
> piston ported engines can spit some fuel out of the carb at idle but
> this doesn't seem like a major problem. Rotary valves via crank shaft
> induction (disk or drum valves as well) is an interesting idea but I
> don't think I need the critical timing they provide.
>
> I was planning on using the largest two-stroke piston (not a diesel
> piston) I could find and using the largest stoke that was reasonable,
> something like 90x105mm
>
> Brock

[cavelamb[_2_]]

wesley marceaux wrote:
> your too late,, Mr. Chotia made an engine for the weedhopper that is exactly
> what you described..you can go to the weedhopper site and buy one for under
> a hundred bucks...........try,,,,you'll be surprised


I was surprised - to see that the site hasn't been updated since 2005...

I didn't see anything about an engine for under $100 either.

[Fred the Red Shirt]

On Mar 27, 4:18*pm, cavelamb > wrote:
> wesley marceaux wrote:
> > your too late,, Mr. Chotia made an engine for the weedhopper that is exactly
> > what you described..you can go to the weedhopper site and buy one for under
> > a hundred bucks...........try,,,,you'll be surprised

I would indeed be very much surprised to find such an engine
available
for that price, unless it is a very simple model engine, as opposed to
one that might be used on a weedhopper.

>
> I was surprised - to see that the site hasn't been updated since 2005...
>
> I didn't see anything about an engine for under $100 either.

There are least three (3) weedhopper Yahoo groups:

http://groups.yahoo.com/group/weedhopper/

http://groups.yahoo.com/group/WUPA/

http://groups.yahoo.com/group/Weedhopper-Ultralights/

The third appears to have fallen victim to spam, but there
may be something of interest in the earliest postings.

--

FF

[Fred the Red Shirt]

On Mar 27, 4:18*pm, cavelamb > wrote:
> wesley marceaux wrote:
> > your too late,, Mr. Chotia made an engine for the weedhopper that is exactly
> > what you described..you can go to the weedhopper site and buy one for under
> > a hundred bucks...........try,,,,you'll be surprised
> ...
>
> I didn't see anything about an engine for under $100 either.

Perhaps he was looking at a weedwhacker website...

--

Ff