Tomahawk 125 hp STC performance?

[virtuPIC]

Well, there is this kit to boost your Tomahawk to 125 hp. However, so
far I could not find statements on speed gain and fuel burn.

So my questions are
o How fast do you go with it?
o How much fuel do you burn?

Thanks
virtuPIC

--
Airspace V - international hangar flying!
http://www.airspace-v.com

[Kingfish]

On Apr 27, 5:19 am, virtuPIC > wrote:
> Well, there is this kit to boost your Tomahawk to 125 hp. However, so
> far I could not find statements on speed gain and fuel burn.
>
> So my questions are
> o How fast do you go with it?
> o How much fuel do you burn?
>

A 12hp gain over the factory engine would not do much for cruise speed
(5kt?) or change fuel burn noticeably. The climb rate might be a bit
better though

[Kingfish]

On Apr 27, 10:25 am, Kingfish > wrote:
> On Apr 27, 5:19 am, virtuPIC > wrote:
>
> > Well, there is this kit to boost your Tomahawk to 125 hp. However, so
> > far I could not find statements on speed gain and fuel burn.
>
> > So my questions are
> > o How fast do you go with it?
> > o How much fuel do you burn?
>
> A 12hp gain over the factory engine would not do much for cruise speed
> (5kt?) or change fuel burn noticeably. The climb rate might be a bit
> better though

Oops. That's a whopping *13* HP gain over the stock PA38-112.

Weak math skills. My bad.

[Ron Natalie]

Kingfish wrote:
> On Apr 27, 5:19 am, virtuPIC > wrote:
>> Well, there is this kit to boost your Tomahawk to 125 hp. However, so
>> far I could not find statements on speed gain and fuel burn.
>>
>> So my questions are
>> o How fast do you go with it?
>> o How much fuel do you burn?
>>
>
> A 12hp gain over the factory engine would not do much for cruise speed
> (5kt?) or change fuel burn noticeably. The climb rate might be a bit
> better though
>
You can soup up a VW, it's still a VW.

[Robert M. Gary]

On Apr 27, 8:31 am, Ron Natalie > wrote:
> Kingfish wrote:
> > On Apr 27, 5:19 am, virtuPIC > wrote:
> >> Well, there is this kit to boost your Tomahawk to 125 hp. However, so
> >> far I could not find statements on speed gain and fuel burn.
>
> >> So my questions are
> >> o How fast do you go with it?
> >> o How much fuel do you burn?
>
> > A 12hp gain over the factory engine would not do much for cruise speed
> > (5kt?) or change fuel burn noticeably. The climb rate might be a bit
> > better though
>
> You can soup up a VW, it's still a VW.

One of the best things about the Tramahawk is that you can sit aloft
for hours on end on next to no gas. The 125hp engine must suck more
gas.

[Morgans[_2_]]

"Kingfish" <> wrote

> Oops. That's a whopping *13* HP gain over the stock PA38-112.
>
> Weak math skills. My bad.

That is still around a 10% improvement in HP, so it should be noticeable,
most likely in climb and in fuel burn.
--
Jim in NC

[Kingfish]

On Apr 27, 11:23 am, "Robert M. Gary" > wrote:
>
> One of the best things about the Tramahawk is that you can sit aloft
> for hours on end on next to no gas. The 125hp engine must suck more
> gas.

I thought the best thing about that airplane was its sturdy landing
gear. I can personally attest to its strength after several carrier
landings when I was training for my PPL.

Nowadays, the 125hp Conti-powered Katana is just the thing to buzz
around in and not burn much gas - at 130kts to boot

[Kyle Boatright]

"virtuPIC" > wrote in message
ups.com...
> Well, there is this kit to boost your Tomahawk to 125 hp. However, so
> far I could not find statements on speed gain and fuel burn.
>
> So my questions are
> o How fast do you go with it?
> o How much fuel do you burn?
>
> Thanks
> virtuPIC
>
> --
> Airspace V - international hangar flying!
> http://www.airspace-v.com

I owned a Tomahawk for several years. Realistically, it was a 100-105 knot
aircraft - the book said 108, but that was for a factory new airplane.

Anyway, I just ran the numbers and you should expect to burn 7 gph at 75%,
and you'll see maybe 4 additional knots of airspeed. The biggest improvement
will be in climb performance. At sea level, you should see an additional 250
fpm...

KB

[Peter Dohm]

"Kingfish" > wrote in message
oups.com...
> On Apr 27, 11:23 am, "Robert M. Gary" > wrote:
> >
> > One of the best things about the Tramahawk is that you can sit aloft
> > for hours on end on next to no gas. The 125hp engine must suck more
> > gas.
>
> I thought the best thing about that airplane was its sturdy landing
> gear. I can personally attest to its strength after several carrier
> landings when I was training for my PPL.
>
I rattled my own teeth, and my instructor's, a few times; before the
extended float float from a couple of faster than normal approaches gave me
enough time to observe and learn. After that it was easy to be fairly
smooth--even though the undercarriage is a bit stiffer than on a Cessna 152.

OTOH, you definitely *can* break it. The FBO I rented from had two
Tomahawks--until some fool stalled one much too high. (Truth be told, I
never found out whether he simply slammed it down on the mains or let the
nose drop as well--it happened at a remote field and IIRC there was
additional damage from the recovery and transport.)

> Nowadays, the 125hp Conti-powered Katana is just the thing to buzz
> around in and not burn much gas - at 130kts to boot
>
>
I am looking forward to trying the Katana, as well as the Sport Cruiser.

Peter

[Peter Dohm]

"Kyle Boatright" > wrote in message
. ..
>
> "virtuPIC" > wrote in message
> ups.com...
> > Well, there is this kit to boost your Tomahawk to 125 hp. However, so
> > far I could not find statements on speed gain and fuel burn.
> >
> > So my questions are
> > o How fast do you go with it?
> > o How much fuel do you burn?
> >
> > Thanks
> > virtuPIC
> >
> > --
> > Airspace V - international hangar flying!
> > http://www.airspace-v.com
>
> I owned a Tomahawk for several years. Realistically, it was a 100-105 knot
> aircraft - the book said 108, but that was for a factory new airplane.
>
> Anyway, I just ran the numbers and you should expect to burn 7 gph at 75%,
> and you'll see maybe 4 additional knots of airspeed. The biggest
improvement
> will be in climb performance. At sea level, you should see an additional
250
> fpm...
>
> KB
>
>
That confirms what I have long suspected: I could only justify it to
operate from a higher altitude airport--which is just not in the cards.

Peter

[Morgans[_2_]]

"Peter Dohm" > wrote

> That confirms what I have long suspected: I could only justify it to
> operate from a higher altitude airport--which is just not in the cards.

I wouldn't think that would be the only justification.

If your are going to operate at a lower airport, that will see some high
density altitudes, due to high temperatures, for one.

If you are going to operate close (or slightly over) to gross, would be
another.

If you plan to go into and out of airports that might be a little short, or
have high obstructions at the end of the runways, as another.

If you want to do cross countries often, that involving climbing to
relatively high altitudes, it would be nice to have better climb.

If you combine two or three (or more) of the above, it would be a slam dunk
reason to go with the more HP engine!
--
Jim in NC

[Scott Skylane]

Peter Dohm wrote:

> "Kyle Boatright" > wrote in message
> . ..
/snip/
>>
>>Anyway, I just ran the numbers and you should expect to burn 7 gph at 75%,
/snip/
> That confirms what I have long suspected: I could only justify it to
> operate from a higher altitude airport--which is just not in the cards.
>
> Peter
>
>
Peter,

I used to maintain a fleet of 152's (virtually the same engine) that we
converted to 125hp. As a maintenance decision, we did it simply to
reduce lead fouling problems in the spark plugs, a BIG issue in the
original configuration. How did it work out? Great. Why did it work?
The kit merely installs higher compression pistons. This causes a
more efficient burn, and more complete combustion.

All the folks who assume this mod will increase your fuel burn are
incorrect. It really makes a more efficient powerplant, so you are able
to realize a small HP increase at no noticeable fuel penalty. In fact,
the POH supplement that comes with the STC simply states that the
performance of the modified aircraft is guaranteed to meet, or exceed
the original figures. You couldn't make such a simple statement if fuel
burns had to be recalculated at any given power setting.

There must be some sort of compromise, though, right? Yeah, in the 152
at least, the kit also comes with modified (improved) engine baffling,
and warns about monitoring CHT's during hot or high climbs, as well as
the importance of correct mag timing. In other words, detonation
becomes more of a danger, if your not paying attention.

In the many thousands of hours of training fleet operations that I saw,
not once did we find evidence of harmful detonation. What we did see,
on about 50% of the fleet, was a noticeable reduction in compressions
around the 1500 hour mark. Removing the cylinders revealed compression
rings as soft as butter. You could almost twist them into a pretzel! A
quick hone, and new rings, sent the engines off to a succesful
completion of their run (typically 3000-3500 hours).

Mind you, these were trainers, flown by pilots who had no idea how to
properly care for the engine. All they knew was throttle in, go up.
Throttle out, go down. As an owner, I would expect you to get as much
service life out of a modified engine, maybe even more, than an
unmodified one.

Happy Flying!
Scott Skylane