0-320 Engine Performance Mods

Chunky · #1 02-27-2010, 11:55 PM

Hi All

I have a 6A fitted with a 320 D1A. Its coming up around 800 hours and I am thinking of having the top end done. Perhaps porting and polishing, new pistons for higher Comp and perhaps adding one Electronic mag. I am hoping to boost her up to around the 180 mark.

Are there any guys in particular that do these mods all the time I could speak to or get some advice from. What combinations and prices are available.

Thanks in advance.
Shawn

eric_marsh · #2 02-28-2010, 06:21 AM

I'm working at becoming a student of Lycoming engine development. I had a head and cylinder on my flow bench yesterday. I got about 25O cfm at 28" which doesn't seem bad. (valve out-I'm still chasing parts for my testing.) I need a carb and some intake tubes to test. I suspect that's a source of restriction.

I've been thinking about aircraft engine modifications and realized that to some extent I need to do a reset on my thinking about high performance. It's not uncommon for full open throttle peak power to be at the expense of efficiency at lower throttle openings. For example, larger carbs will give better peak power in many cases but provide no benefit at smaller openings, since by definition the carb is the restriction that causes the power to be reduced. I'm thinking that larger intake tubes may be an easy way to increase airflow at peak power but would have reduced velocity and subsequently reduced cylinder filling at smaller throttle openings. I had an old automotive intake manifold many years ago (An Offy dual port) that actually had tiny ports for high velocity air flow on the primaries and large ports on the secondaries.

I roller cam seems like it would be a plus - it would get the valves open more quickly without increasing overall duration.

What I'm still trying to wrap my head around is the effects of reduced atmospheric pressure on the tuning of a normally aspirated engine.

I guess there's no free lunch.

Mel · #3 02-28-2010, 07:18 AM

I have over 750 hours since overhaul of my O-320-E3D.

I installed 9.5:1 pistons, roller rocker arms and electronic ignition. This gave me somewhere around 178 hp. This hp was derived at from using the standard 180 hp prop that Sensenich recommended.

Because of the higher compression, I installed new cylinders and heavy wall wrist pins.

If I had it to do over again I would not go above 9:1 on compression. Smoothness becomes an issue.

LifeofReiley · #4 02-28-2010, 08:21 AM

that type of info requires a security clearance.

RV8RIVETER · #5 02-28-2010, 08:41 AM

Call Lycon. They did my neighbors 320 and they do a majority of the Reno racers.

penguin · #6 02-28-2010, 02:39 PM

Get an EI and run at 2900 rpm with a wooden prop seems to be one way to get additional power.

Pete

twsurveyor · #7 02-28-2010, 05:20 PM

Maybe I'm just old fashion but it seems to me that given all the Jack your fixin to throw at your O-320 you'd be better off to sell it and find & buy an O-360!? That way youd have a true 180 HP enging not an O-320 stretched to the limit? Like I said, "maybe I'm just old fashion"!

Tommy Walker
N 350 TW, RV-6A, O-360 A1A
492 Hrs & "Climbing"!

Low Pass · #8 02-28-2010, 05:27 PM

Quote:

Originally Posted by twsurveyor

Maybe I'm just old fashion but it seems to me that given all the Jack your fixin to throw at your O-320 you'd be better off to sell it and find & buy an O-360!? That way youd have a true 180 HP enging not an O-360 stretched to the limit? Like I said, "maybe I'm just old fashion"!

Tommy Walker
N 350 TW, RV-6A, O-360 A1A
492 Hrs & "Climbing"!

Couple of points - respectfully, this is a thread about mods to -320s, not selling 320s. Second, I know of quite a few -360s that have experienced failed cranks (when hopped up). Never heard of that on any -320. Third, with it being fairly straightforward to get 170-180 hp out of a -320, then why change? Especially if you don't have that kind of money sitting around. Please continue with the -320 power mod discussion. I'm very interested.

jtop · #9 02-28-2010, 09:43 PM

What about going to a 340 (320 stroker kit)? I haven't heard anything bad about them yet.

LifeofReiley · #10 02-28-2010, 10:15 PM

Quote:

Originally Posted by jtop

What about going to a 340 (320 stroker kit)? I haven't heard anything bad about them yet.

Don't know too much about the Stroker Kit, but it seems like an middle option.
We're cranking the HP out of my 320, it's not that hard. The O-320 has been the best engine 4 cyl platform I've ever flown behind... and yes I've flown a lot of O-360's. Set up RIGHT, I'm talking Smooth, and fast... and did I say pretty much bullet proof.

Build it yourself and build it RIGHT!