A Simple Auto Engine Conversion

"Jim Logajan" wrote in message
.. .
Ron Wanttaja wrote:
On Tue, 26 Aug 2008 21:07:46 -0700 (PDT), "
wrote:

everyone says "ooh -- auto...dangerous" but no
one can explain exactly why.

1. Ignition systems with insufficient redundancy.
2. PSRU failures.
3. Difficulty in implementing efficient liquid cooling systems.

But doesn't the Rotax 912 have reduction gearing and liquid cooling? It is
getting put into an awful lot of aircraft models - particularly LSAs.

That's true, and the biggest annoyance (of which I am aware) is that they
have increased the recommended "idle" speed to increase the service life of
the PSRU--which is of the spur gear type. I don't know whether any of the
belt or chain type PSRU installations have a similar requirement.

As to cooling: there were a lot of liquid cooled aircraft engines in WWII,
but the the aircraft they in which they were installed looked a lot
different from their air cooled counterparts.

Peter

On Wed, 27 Aug 2008 16:11:51 -0500, Jim Logajan wrote:

Ron Wanttaja wrote:
On Tue, 26 Aug 2008 21:07:46 -0700 (PDT), "
wrote:

everyone says "ooh -- auto...dangerous" but no
one can explain exactly why.

1. Ignition systems with insufficient redundancy.
2. PSRU failures.
3. Difficulty in implementing efficient liquid cooling systems.

But doesn't the Rotax 912 have reduction gearing and liquid cooling? It is
getting put into an awful lot of aircraft models - particularly LSAs.

Certainly, and my data shows that the Rotax 912, in homebuilts at least, has a
safety record pretty much equal to that of traditional certified engines.

My posting was an attempt to answer the OP's question on why some people believe
auto engine conversions are dangerous. The three items I mentioned are in the
top four causes of auto-engine failures. Looking at my 1998-2006 homebuilt
accident database and comparing fixed-wing applications, the rate of occurrence
of ignition system problems is four times higher for auto conversions than
traditional engines. And the traditional engines had no cases of PSRU or
cooling failure.

I believe it's possible to convert an auto engine and achieve reliabilities
equal to that of a traditional certified engine. It's just that the accident
reports show that many people can't achieve that goal. It's basically the same
people installing the Continentals as the Subarus, or the Rotax 912s and the
Fords. But the average builder seems to have less problems getting the Lyconts
and Rotaxen to be reliable.

Ron Wanttaja

On Aug 26, 11:14*pm, Ron Wanttaja wrote:
On Tue, 26 Aug 2008 21:07:46 -0700 (PDT), "

wrote:
everyone says "ooh -- auto...dangerous" but no
one can explain exactly why.

1. Ignition systems with insufficient redundancy.
2. PSRU failures.
3. Difficulty in implementing efficient liquid cooling systems.

Ron Wanttaja

i heard the e racer had an inflight engine fire and eventually the
designer through in the towl on auto engines. anyone remember why?

On Aug 27, 7:01*pm, "
wrote:
On Aug 26, 11:14*pm, Ron Wanttaja wrote:

On Tue, 26 Aug 2008 21:07:46 -0700 (PDT), "

wrote:
everyone says "ooh -- auto...dangerous" but no
one can explain exactly why.

1. Ignition systems with insufficient redundancy.
2. PSRU failures.
3. Difficulty in implementing efficient liquid cooling systems.

Ron Wanttaja

i heard the e racer had an inflight engine fire and eventually the
designer through in the towl on auto engines. *anyone remember why?

Sure do.

"From: Dorothy Dickey
Sent: Monday, January 24, 2000 8:46 PM
To: Young, Ryan
Subject: Engines for E-racers
There is nothing wrong with the Buick engine it's just that I no
longer favor
auto engines for aircraft applications. This is because it is not
possible
to achieve equivalent reliability and performance of an aircraft
engine for
the same or less money... So why do it? Shirl"

Remember, this is a guy who designed an airplane around an auto
conversion, and devoted serious time, money, and twice, almost his
life to making this idea work. If you think you can do better, step
right up.

This whole thread smacks of TROLL, but you can read what more of what
I think, along with the E-Racer guy (Shirl Dickey), and a little from
the Belted Air Power reduction guy (Jess Myers) he

http://users.lmi.net/~ryoung/Sonerai/BOP.htm

You can also search this newsgroup for anything by Corky Scott, and
watch his chronicle. He never flew his auto engine conversion, after
working on it for years.

wrote in message
...
I was thumbing through a catalog from Speedway Motors. They advertise
a magneto-type distributor. Assuming you didn't come across a
thrashed race engine with magnetos, couldn't someone put together an
engine worthy of aircraft use, by simply 1) ordering an aftermarket
engine with fuel injection, such as the chevy "RamJet" crate engine,
2) adding a dry sump lubrication system to it (not too strange
addition to high perf cars nowadays), and 3)-adding the magneto from
Speedway. Use direct drive to keep the RPM low and reliability high.
I doubt that today's hi perf crate engines lack the torque to turn a
prop at 1:1.

If this is unsafe, specifically why?

I know someone could fly within 100 miles of a t-storm and have the
static electricity play with the ignition system, but stop a magneto?
If you were struck with lightning, your auto-engine might stop, but
then your resin might burn and melt, leaving you with some loose
fiberglass to negotiate a crash. Point I'm making is, experimental
planes near t-storms have bigger probs to worry about, don't they?

BTW, that magneto appears to be offered just for big and small block
chevy's. Aside from that, the models they carry are "nostalgia
engines"...1950 hemis, flat head fords and the like. Another caveat:
they cost $1100...but even with that and a $1200 dry sump system, we
are still way under the cost of an O-540.

OEM automotive engines are not usually designed to develop enough horsepower
at direct drive RPMs, to justify their finished weight, after including the
complete radiator, pump and coolant. Especially when compared to their
traditional aircraft counterparts.

Selection of an all aluminum small block, with all the lightweight and high
strength aftermarket parts can easily begin approaching the cost of a good
used aircraft engine, and still leave a lot of engineering to cost money or
build time, increase complexity and question reliability.

There is also still a question of resale value of the finished aircraft.

Lots of factors besides magnetos and dry sump systems. Why do you feel a dry
sump is necessary?

Most popular engine conversion of all times?

http://www.pilotfriend.com/aero_engi...%200%20360.htm

a dry sump isn't absolutely necessary...neither is fuel
injection....neither is a magneto.
just a good way to hedge your bets. say your're in the mountains,
it's stormy, and you have turbulence. no matter what Gs or static you
are subjected to, the engine would get a steady supply of oil, fuel
and electricity.

i know resale value is diminished and the public perception is not
good. i'm just trying to understand the specific technical reasons
why. all i hear is that 1-auto engines MUST have psru and 2-therefore
turn high/spooky rpm continuously. then i fail to hear of any case
where a conversion project stumbles for lack of a psru. everyone who
dares to run direct is glad, and most of us agree there is nothing
scary about driving all day, every day, at 2900 rpm with a car
engine. you won't get 100% hp, but a camshaft and dual plane intake
change could help with that.

the rotaries need a lot of rpm to make decent power. so much that the
propeller is spinning too fast. i'm aware of this, but the plug and
ply magnetos i'm referring to are not avail for rotaries.

maybe aircraft engines have dual spark plugs...each cylinder fed by
two independent magnetos..is that the case? is that the safety
measure lacking in auto conversions? aside from the "psru myth", the
dual plugs are all i can think of.


On Aug 25, 9:13*pm, "Ramsey" @##@.^net wrote:
wrote in message

...





I was thumbing through a catalog from Speedway Motors. *They advertise
a magneto-type distributor. *Assuming you didn't come across a
thrashed race engine with magnetos, couldn't someone put together an
engine worthy of aircraft use, by simply 1) ordering an aftermarket
engine with fuel injection, such as the chevy "RamJet" crate engine,
2) adding a dry sump lubrication system to it (not too strange
addition to high perf cars nowadays), and 3)-adding the magneto from
Speedway. *Use direct drive to keep the RPM low and reliability high.
I doubt that today's hi perf crate engines lack the torque to turn a
prop at 1:1.

If this is unsafe, specifically why?

I know someone could fly within 100 miles of a t-storm and have the
static electricity play with the ignition system, but stop a magneto?
If you were struck with lightning, your auto-engine might stop, but
then your resin might burn and melt, leaving you with some loose
fiberglass to negotiate a crash. *Point I'm making is, experimental
planes near t-storms have bigger probs to worry about, don't they?

BTW, that magneto appears to be offered just for big and small block
chevy's. *Aside from that, the models they carry are "nostalgia
engines"...1950 hemis, flat head fords and the like. *Another caveat:
they cost $1100...but even with that and a $1200 dry sump system, we
are still way under the cost of an O-540.

OEM automotive engines are not usually designed to develop enough horsepower
at direct drive RPMs, to justify their finished weight, after including the
complete radiator, pump and coolant. Especially when compared to their
traditional aircraft counterparts.

Selection of an all aluminum small block, with all the lightweight and high
strength aftermarket parts can easily begin approaching the cost of a good
used aircraft engine, and still leave a lot of engineering to cost money or
build time, increase complexity and question reliability.

There is also still a question of resale value of the finished aircraft.

Lots of factors besides magnetos and dry sump systems. Why do you feel a dry
sump is necessary?- Hide quoted text -

- Show quoted text -

wrote

OP: a dry sump isn't absolutely necessary...neither is fuel
injection....neither is a magneto.
just a good way to hedge your bets. say your're in the mountains,
it's stormy, and you have turbulence. no matter what Gs or static you
are subjected to, the engine would get a steady supply of oil, fuel
and electricity.

Morg: I think you are hung up on the features of that overpriced aircraft
engine. It is hard to believe that the dry sump will do any better than a
good old oil pan, unless you plan on some inverted flight, and if you
worried about some turbulence, an oil accumulator would keep oil flow
temporarily. Anyway, most aircraft engines do not have dry sumps.

Morg: Unless you use a header tank, fuel injection will not guarantee
keeping fuel going to run the engine. I do like fuel injection, and there
is no reason to not have it, and lots of other reasons to have it, but
again, not absolutely necessary unless you are going for an inverted
package.

Morg: Magnetos over electronic ignition? What breaks down more often, a
magneto, or electronic ignition? What is better at making an easy starting
engine, running with the spark at the appropriate timing? Magnetos are old
hat, so if you want reliable, go with dual pickup, dual coil(s) redundant
electronic ignition with a battery supplied emergency backup power source
for the ignitions. The not having a dual plug is the only slight trade off,
because you can use a two into one spark system to tie the dual ignition to
the one plug.


OP: i know resale value is diminished and the public perception is not
good. i'm just trying to understand the specific technical reasons
why. all i hear is that 1-auto engines MUST have psru and 2-therefore
turn high/spooky rpm continuously. then i fail to hear of any case
where a conversion project stumbles for lack of a psru.

Morg: PSRUs have another value over direct drive, in that the prop
gyroscopic loads and thrust loads are removed from the crankshaft. They can
be MAJOR problems, up to and including broken crankshafts. An example are
the Corvair cranks broken (in part) from prop adapters that are too long,
with heavy props. With a V-8, you are going to have a heavy prop, and a
short adapter will make an unstreamlined cowl. The PSRU also raises the
thrust line to get better prop to ground clearance. So yes, those are some
reasons a conversion stumbles without a PSRU.

Morg: Bottom line, it would be very wise to use some type of extra external
bearing to help with soaking up the thrust loads and gyroscopic loads. A
PSRU does that for you. The PSRU also gets some more HP so the HP to weight
ratio is better. As far as spooky high continuous RPMs go, I think you
have been listening to some of the critics of conversions too much.

Morg: When have you heard of people being concerned at running a marine
auto engine at too high constant RPMs? Never. They run at RPMs that would
worry me much more, and faster than most people run airplane conversions.
You can choose what drive ratio you want to run. A conversion running at
3,000 RPM is too fast for a prop, but not too fast to make me uncomfortable.
I would not worry at running a conversion at 3,800 RPM for extended periods
of time. I sure run my boat engine at higher RPMs than that.

Morg: In short, I think your concerns about PSRUs are unfounded. You can
run any speed you want to, and higher than a normal prop speed. You get the
other advantages I identified, and get more HP from your heavy engine. You
don't have to run at peak HP, but it sure would not hurt to run faster than
prop speed.

OP: everyone who
dares to run direct is glad, and most of us agree there is nothing
scary about driving all day, every day, at 2900 rpm with a car
engine. you won't get 100% hp, but a camshaft and dual plane intake
change could help with that.

OP: the rotaries need a lot of rpm to make decent power. so much that the
propeller is spinning too fast. i'm aware of this, but the plug and
ply magnetos i'm referring to are not avail for rotaries.

OP: maybe aircraft engines have dual spark plugs...each cylinder fed by
two independent magnetos..is that the case? is that the safety
measure lacking in auto conversions? aside from the "psru myth", the
dual plugs are all i can think of.

I hope I gave you a little to think about. There are companies out there
with well engineered, time tested, reliable PSRUs. To me, it is not the
myth that would keep me running direct drive, but the desire to get a better
powered package, with the isolation of prop loads on a crankshaft that IS
NOT DESIGNED to take prop loads.
--
Jim in NC

On Aug 26, 11:43 pm, "Morgans" wrote:
wrote

OP: a dry sump isn't absolutely necessary...neither is fuel
injection....neither is a magneto.
just a good way to hedge your bets. say your're in the mountains,
it's stormy, and you have turbulence. no matter what Gs or static you
are subjected to, the engine would get a steady supply of oil, fuel
and electricity.

You'd better think twice about being in the mountains in
stormy weather and turbulence. You'll have other problems besides oil
supply. In any case, wet-sump aircraft engines fly in the mountains
and turbulence all the time and have no oil issues. It's the weather
that kills the flier.

Morg: Magnetos over electronic ignition? What breaks down more often, a
magneto, or electronic ignition? What is better at making an easy starting
engine, running with the spark at the appropriate timing? Magnetos are old
hat, so if you want reliable, go with dual pickup, dual coil(s) redundant
electronic ignition with a battery supplied emergency backup power source
for the ignitions. The not having a dual plug is the only slight trade off,
because you can use a two into one spark system to tie the dual ignition to
the one plug.

The use of 100LL fouls plugs rather often. Two plugs are handy
for that, and the extra plug improves power output.

OP: i know resale value is diminished and the public perception is not
good. i'm just trying to understand the specific technical reasons
why. all i hear is that 1-auto engines MUST have psru and 2-therefore
turn high/spooky rpm continuously. then i fail to hear of any case
where a conversion project stumbles for lack of a psru.


Morg: Bottom line, it would be very wise to use some type of extra external
bearing to help with soaking up the thrust loads and gyroscopic loads. A
PSRU does that for you. The PSRU also gets some more HP so the HP to weight
ratio is better. As far as spooky high continuous RPMs go, I think you
have been listening to some of the critics of conversions too much.

Very good point. Auto cranks were designed for torsion loads only,
not thrust or gyroscopic loads, and they tend to break when subjected
to such loads.

Morg: When have you heard of people being concerned at running a marine
auto engine at too high constant RPMs? Never. They run at RPMs that would
worry me much more, and faster than most people run airplane conversions.
You can choose what drive ratio you want to run. A conversion running at
3,000 RPM is too fast for a prop, but not too fast to make me uncomfortable.
I would not worry at running a conversion at 3,800 RPM for extended periods
of time. I sure run my boat engine at higher RPMs than that.

Marine engines have a couple of advantages that aircraft
conversions do not: A ready supply of cold coolant, and a drive system
that doesn't apply and thrust or gyroscopic loads on the crank.
Running an auto engine at or near max power settings, like we do in
boats or airplanes, generates huge amounts of waste heat that autos
don't when they're cruising unless they're pulling heavy trailers, in
which case a trailer-towing package becomes necessary. This includes
much larger cooling capacity. Autos typically cruise at around 25-30%
power, boats and airplanes at 65-80%. I have experience with both
marine and aircraft liquid-cooled conversions, and believe me, the
boat is easy to keep cool.
Aircraft engines are built with big cooling capacity right from
the start. And they're designed to produce large amounts of torque at
lower RPM, which means the basic cylinder geometry is different. And
they're designed to do all this without weighing as much as a bridge.

OP: everyone who
dares to run direct is glad, and most of us agree there is nothing
scary about driving all day, every day, at 2900 rpm with a car
engine. you won't get 100% hp, but a camshaft and dual plane intake
change could help with that.

You still won't get 100% unless you're at rated redline, which no
prop will stand for. Most direct-drive conversions run a much shorter
prop to allow a higher RPM (propeller tip speed and centrifugal forces
are the concern) and shorter props lose efficiency big time, so
performance, especially takeoff and climb, suffer considerably.
One horsepower is 33,000 foot-pounds per minute. To get it we do
this: Torque x RPM x 6.28 divided by 33,000. RPM is one of the
factors, and a PSRU is usually needed to get the engine's RPM up to
its designed redline so it'll generate the claimed HP. Anything less
represents a loss, which means a heavy, underpowered airplane.


OP: maybe aircraft engines have dual spark plugs...each cylinder fed by
two independent magnetos..is that the case? is that the safety
measure lacking in auto conversions? aside from the "psru myth", the
dual plugs are all i can think of.

Boy oh boy, are we at that level of expertise? You'd better do
a LOT of research here before deciding that you have answers that the
rest of us don't.

I hope I gave you a little to think about. There are companies out there
with well engineered, time tested, reliable PSRUs. To me, it is not the
myth that would keep me running direct drive, but the desire to get a better
powered package, with the isolation of prop loads on a crankshaft that IS
NOT DESIGNED to take prop loads.

Yup. Lots of folks have done the work already and found it much
more difficult than they imagined when they started out. I wouldn't
want to think that I could improve on any of it on a first try.

Dan

wrote

"Morgans" wrote:
wrote

Ooops, you attributed the following to me, and it was the OP.

just a good way to hedge your bets. say your're in the mountains,
it's stormy, and you have turbulence. no matter what Gs or static you
are subjected to, the engine would get a steady supply of oil, fuel
and electricity.

End OP quoted paragraph.

Morg: When have you heard of people being concerned at running a marine
auto engine at too high constant RPMs? Never. They run at RPMs that
would
worry me much more, and faster than most people run airplane conversions.
You can choose what drive ratio you want to run. A conversion running at
3,000 RPM is too fast for a prop, but not too fast to make me
uncomfortable.
I would not worry at running a conversion at 3,800 RPM for extended
periods
of time. I sure run my boat engine at higher RPMs than that.

Marine engines have a couple of advantages that aircraft
conversions do not: A ready supply of cold coolant, and a drive system
that doesn't apply and thrust or gyroscopic loads on the crank.

Yes, but a well designed and performing cooling system cools all the extra
heat an engine can produce. Don't you thinik the P-51 did ok with their
cooling system? There are homebuilt auto engines flying all over the place,
for over 2,000 hours that do not have a problem dealing with waste heat.
The ONLY time they have a problem is if they have to run sitting on the
ground, or too long of a taxi. Flying, they cool just fine, after they have
all of the bugs out of the cooling system. I will not say that some people
have problems, but there are hundreds of people flying car engines that have
absolutely NO problems with cooling in the air.

As far as the crank loads, that is taken care of with a PSRU. Another non
issue.

Running an auto engine at or near max power settings, like we do in
boats or airplanes, generates huge amounts of waste heat that autos
don't when they're cruising unless they're pulling heavy trailers, in
which case a trailer-towing package becomes necessary. This includes
much larger cooling capacity. Autos typically cruise at around 25-30%
power, boats and airplanes at 65-80%. I have experience with both
marine and aircraft liquid-cooled conversions, and believe me, the
boat is easy to keep cool.

And so are water cooled airplane engines, with good cooling systems, and it
is not that hard of an issue to deal with.
--
Jim in NC