I'm trying to get an idea on the horsepower output on my engine.
I have a O320e2d 150 hp. When rebuilding the engine 3 years ago, I did the RAM 160 stc +10hp, a PowerFlow exhaust +23hp, K&N air filter +2hp. This spring I was caught up in the ECI AD and put on new cylinders. I had the new cylinders sent to Lycon for flow matching and polishing +20hp. Add these all up and I should be putting out 205hp.
But I expect like speed mods 2+2 dose not always equal 4.
So what would you think would be a reasonable estimate of power output for this engine?
Robert

My guess is.................................................


150 - 160 = putting in 75089 higher comp pistons and thicker pins..= 8 HP

23 for the exhaust... maybe 17 or so

ported and polished and maybe matched = 4 a cyl == 16

On a good day it mathmatically works out to 191. my gut feeling is maybe 180-185..

IMHO................... <GG>

First, you have to remember that those engines are RATED originally at their advertised horsepower in a test cell, on a dyno, WITH NO ACCESSORIES, NO EXHAUST SYSTEM, etc. No alternator (which requires power to turn), no vacuum pump (ditto), no exhaust system, just straight stacks, no air filter, etc, etc.

Sooooooo, your "150" hp engine, installed in an airplane MAY have actually made 135 hp, at sea level, on a good day, assuming it was in the top 50 % of its class.

I once asked an engine company rep how these modifiers could get away with increasing horsepower in an engine without more stringent (or in some cases, any) FAA certification. His response, with a chuckle, was that these mods MAY just be recovering that power lost to accessories.

SO, start adding/modifying, etc. and you will probably come up with something resembling 150 or 160 hp.

Pull that engine out, and replace it with an O-360 and you'll probably still see a significant improvement in performance, not all of which, by the way, is related to horsepower. Torque is a big player as well.

I've flown at least one engine that was ported and polished, etc, etc, and really couldn't tell any difference in performance. No scientific measurements, and it probably did help some, but not huge.

The exhaust systems are often a great mod, not so much for any hp gain, but better reliability and often better cabin heat, tec.

In any case, the only way you will actually KNOW what you've got, horsepower-wise is to put the engine on a dyno. BUT, what really matters is how it performs in the airplane, which is a VERY different story, and largely a function of engine AND PROPELLER.

Horsepower isn't what we're concerned with, primarily--THRUST is what equates to performance, and horsepower is just one factor that goes into that equation.

So, the question back to you is this: How does it perform?

MTV

You are correct about 2+2 not =ing 4. While the HP increasing mods do work, in most cases the HP gain listed by the manufacturer is somehow always less in the the real world.

If you know what your static run-up was before the mod, take a look at what it is after the mods. That will give you an idea of the percentage of HP increase if you are still using the same prop.

I just found my notes from run ups before the clyinder flow matching.
On three different days in April:
Temp 20f
Alt 30.10
Full fuel
1 POB
Static run up 2225 rpm
Take off Vr 2350 rpm
Climb out Vy 2375 rpm
Level 3000' WOT 2675 rpm

All flights gave numbers within 10/20 rpm of each other.

Yesterdays flight:
Temp 60f
Alt 30.12
Full fuel
2 POB
Static run up 2380/2400 rpm
Take off Vr 2500
Climb out 2550
3000' WOT would easliy go past 2700 rpm I didn't want to find how far it could go! $$$$$
This is with the same prop. McCauley 74x52? I think.

Robert

So, send that prop out and have em steepen up the pitch a bit. Or, hang a bigger prop on it.

Sounds like SOMETHING helped.

MTV