C

Chunky

Member
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
 
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.
 
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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.
 
Call Lycon. They did my neighbors 320 and they do a majority of the Reno racers.
 
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Get an EI and run at 2900 rpm with a wooden prop seems to be one way to get additional power.

Pete
 
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"!
 
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twsurveyor said:
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"!
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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 said:
What about going to a 340 (320 stroker kit)? I haven't heard anything bad about them yet.
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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. :D Build it yourself and build it RIGHT! :)
 
Kinda wish you didnt have to pick your engine option with the finish kit right away. I was pretty sure a year ago that I wanted to go with a 360, but the price point is high. Seems like you can pick up a strong 320 for 2/3 the price of a 360. I'm just worried about getting good performance out of it (cruise wise).

Im building my 7A to be light. Going with a composite fixed pitch (also because I can't swing the money for a CS). Thats why I was looking at the 340. But since I already have the mount for the 360, I'm kinda stuck.

So whats the "safe" amount of max HP one could pull out of a 320? Assuming one EI and one mag, maybe roller cammed. Carb or FI? I understand engines just not the specifics of one part (for power and reliability) vs another. These things are finicky.
 
"Safe" is a subjective term and better answered by those with decades of engine rebuilding experience. My neighbors Lycon 320 was dyno'd in excess of 190hp, and I believe he has over 500 hrs on it. It was fully ceramic coated, blueprinted and had other work done, I am sure it wasn't inexpensive. But if you are serious about the possibilities PM me with your email and I will give it to him.
 
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