Engine Mods

[Paul Missman]

I just had the O-235-L2C in my Tomahawk overhauled, and the 125 HP mod
performed at the same time. Now it is getting 2700 RPM at just under 400
degrees CHT, during break in, and cruising between 100-105 knots. Before
the rebuild, cruise was about 2400 RPM and about 90 knots.

I'm very happy with the engine mod, and would recommend it to anyone getting
an O-235-L2C overhauled.

Paul Missman

[houstondan]

mind sharing some prices with & without the hp upgrade??

thx


dan

[Jon A.]

The CHTs are too hot. Check your fuel flow, check the baffles. Even
new, you don't want those CHTs that high! That's the recipe for
cylinder problems.

On Mon, 14 Feb 2005 21:11:42 -0500, "Paul Missman" >
wrote:

>
>I just had the O-235-L2C in my Tomahawk overhauled, and the 125 HP mod
>performed at the same time. Now it is getting 2700 RPM at just under 400
>degrees CHT, during break in, and cruising between 100-105 knots. Before
>the rebuild, cruise was about 2400 RPM and about 90 knots.
>
>I'm very happy with the engine mod, and would recommend it to anyone getting
>an O-235-L2C overhauled.
>
>Paul Missman
>
>
>

[Kyle Boatright]

Tomahawks are infamous for <relatively> high CHT's. The modification to 125
hp makes it even worse. I'd say that 400 degree CHT's on a brand new engine
at full power during break-in ain't half bad for a 125 hp Tomahawk.

Paul could post his question to the Tomahawk group in Yahoo, and I think
he'd find that these temperatures are typical or maybe better than typical
for this installation.

KB

"Jon A." > wrote in message
...
> The CHTs are too hot. Check your fuel flow, check the baffles. Even
> new, you don't want those CHTs that high! That's the recipe for
> cylinder problems.
>
> On Mon, 14 Feb 2005 21:11:42 -0500, "Paul Missman" >
> wrote:
>
>>
>>I just had the O-235-L2C in my Tomahawk overhauled, and the 125 HP mod
>>performed at the same time. Now it is getting 2700 RPM at just under 400
>>degrees CHT, during break in, and cruising between 100-105 knots. Before
>>the rebuild, cruise was about 2400 RPM and about 90 knots.
>>
>>I'm very happy with the engine mod, and would recommend it to anyone
>>getting
>>an O-235-L2C overhauled.
>>
>>Paul Missman

[[email protected]]

On Tue, 15 Feb 2005 21:46:20 -0500, "Kyle Boatright"
> wrote:

>Tomahawks are infamous for <relatively> high CHT's. The modification to 125
>hp makes it even worse. I'd say that 400 degree CHT's on a brand new engine
>at full power during break-in ain't half bad for a 125 hp Tomahawk.
>
>Paul could post his question to the Tomahawk group in Yahoo, and I think
>he'd find that these temperatures are typical or maybe better than typical
>for this installation.

Never offer up factual information to a demagogue, it's like trying to
teach a pig to sing.

Regards;

TC

[Paul Missman]

"houstondan" > wrote in message
oups.com...
> mind sharing some prices with & without the hp upgrade??
>
> thx
>
>
> dan
>

Dan,

I can't answer as to overhauls, as prices will vary from one engine shop to
another. The engine shop I used charges $13k to overhaul an O-235-L2C,
which includes inspection and casework, inspection and possible replacement
of the cam, inspection and possible replacement of the crank, new cylinders
and pistons, new mags, plugs, wires, etc..

The 125 HP upgrade consists of installing 9.3:1 compression pistons, and, if
not already in place, an external oil cooler. From Air Mods NW, which holds
the STCs, I purchased the STCs, an external oil cooler and shrouds, and an
EGT/CHT guage. I let the engine shop supply the high compression pistons,
and the oil cooler hoses, and install the oil cooler and CHT/EGT.

Between my engine not needing a few accessories in the overhaul, and the
extra work for the mods, I paid $14k to the engine shop, which also put in
new engine mounts, repainted the mounting brackets, and did a beautiful job
with the wiring. I paid Air Mods NW for the STCs, the oil cooler and
shroud, and the EGT. I cut and pasted their prices from
www.pipertomahawk.com below :

BASIC KIT PRICES FOR THIS MODIFICATION

Packet of 3 STC's, Engine, Airframe, & Oil Cooler$ 495.00
Set of 4 high compression pistons, weight matched$ 652.00
Pistons only - no rings, pins, plugs, etc. included

Basic Kit Price, plus freight and applicable tax$1,147.00
Pre-Cut Materials Kit for Oil Cooler Mount$ 245.00

Ken Blackman, from Air Mods NW, started this mod years ago with a Grumman
that he had purchased years ago. He's quite happy to talk with people about
the modification, and its history, when he has the time. He has had it
placed in quite a few Tomahawks and a lot of Cessna 152s.

Paul Missman

[Paul Missman]

"Jon A." > wrote in message
...
> The CHTs are too hot. Check your fuel flow, check the baffles. Even
> new, you don't want those CHTs that high! That's the recipe for
> cylinder problems.


Jon,

The engine shop that did the overhaul told me, for the first 10 hours, to
run it full rich, and everything short of either red line or 400 degrees
CHT. With the mod, about 2700 RPM is just below 400 degrees CHT, and the
red line is now 2800 RPM.

I bought the EGT/CHT guage at Ken Blackman's recommendation. He's the
holder of the 125 HP STCs. He recommended the guage, because, he said, in
climb, at 9.3:1 compression, it can get quite hot, very quickly, and not to
exceed 450 degrees.

Normally, the Tomahawk has no CHT/EGT guage. So, I never knew how hot the
cylinders ran before the modification.

Paul Missman

[Paul Missman]

> Between my engine not needing a few accessories in the overhaul, and the
> extra work for the mods, I paid $14k to the engine shop, which also put in
> new engine mounts, repainted the mounting brackets, and did a beautiful
> job with the wiring. I paid Air Mods NW for the STCs, the oil cooler and
> shroud, and the EGT.

Also, included in that price, they pulled the tach, and sent it out for
re-calibration and repainting of the red line.

Paul

[Jon A.]

Appreciate the reply, even the blurb from Pope Toecutter the 1st, but
if you have a look at the real data being measured today (the 21st
century) you'll see that the Old Wive's Tales aren't holding any
water. Regardless, you make your own decisions.

http://www.advancedpilot.com/



On Wed, 16 Feb 2005 19:53:19 -0500, "Paul Missman" >
wrote:

>
>"Jon A." > wrote in message
...
>> The CHTs are too hot. Check your fuel flow, check the baffles. Even
>> new, you don't want those CHTs that high! That's the recipe for
>> cylinder problems.
>
>
>Jon,
>
>The engine shop that did the overhaul told me, for the first 10 hours, to
>run it full rich, and everything short of either red line or 400 degrees
>CHT. With the mod, about 2700 RPM is just below 400 degrees CHT, and the
>red line is now 2800 RPM.
>
>I bought the EGT/CHT guage at Ken Blackman's recommendation. He's the
>holder of the 125 HP STCs. He recommended the guage, because, he said, in
>climb, at 9.3:1 compression, it can get quite hot, very quickly, and not to
>exceed 450 degrees.
>
>Normally, the Tomahawk has no CHT/EGT guage. So, I never knew how hot the
>cylinders ran before the modification.
>
>Paul Missman
>