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Max HP from an O320

Maxrate

Well Known Member
I’m looking at possibility rebuilding an O320 to get the needed 180hp. Aside from a new crank for changing from FP to CS what other considerations would the engine gurus recommend? I know the 320 is lighter than the 360. Looking for input. Thanks
 
Investigate the Titan x-340. Narrow deck 320 clone with stroker 360 crankshaft results in effectively 9:1 CR on standard 320 pistons and dyno'd 184 hp.
 
Call up Titan, Aerosport Power or other well regarded engine builder about what goes into a stroked 340. Going to be expensive...
 
I've contacted various engine suppliers but received no answers beyond their initial receipt of my request. Van's is the only site I've found that quotes a price for an IO-320. $47K for a 160 HP IO-320 Thunderbolt engine with AFP FI and E-Mags. I wonder how the other builders compare. I'll need to re-ping them. I would like to calibrate my "Going to be expensive..." meter.


Call up Titan, Aerosport Power or other well regarded engine builder about what goes into a stroked 340. Going to be expensive...
 
I bought a IO-320 Titan in 2013. Nothing special other than fuel injection and p-mags. It was dyna'ed @ 168 hp. I would assume higher compression pistons would get you close to 180 hp. Some port work wouldn't hurt either.
 
I built a custom 0320 b2b for my rv6 because it had a conical mount. Case went to divco, steel parts to aircraft specialities. Yellow tagged everything. New cylinder's from airpower and sent directly to lycon for cnc port/polish, valve regrind and paint strip. Built the cylinders up with combust tech 10-1 pistons. Topped it off with dual pmags with the new ei commander and 32 degs advance timing. Drilled the carb main jet to #37 for extra fuel flow.

Lycon estimated this configuration would be 190+hp. It is would pull my rv-6 along at 172ktas at 8000ft da on 9.8gph. It also cost me nearly $20k to build it. I planned on racing in the sarl 0320 class, but bought a harmon rocket instead.
 
Mark. Don’t put a 320 on an rv7. Even though it will work, it will be tail heavy and limit your baggage weights. The resell value if you ever sell it it horrible. Sell the 320 and get a 360.
 
I’m looking at possibility rebuilding an O320 to get the needed 180hp. Aside from a new crank for changing from FP to CS what other considerations would the engine gurus recommend? I know the 320 is lighter than the 360. Looking for input. Thanks

I had an O-320 with a Hartzell constant speed prop for years on my 20 year old RV6. At "new engine time", I went with the "340 Stroker" from ECI.

Good things and bad things to consider.

1. I needed to stay with the form factor since I have CONICAL mounts and the OLDER "320 cowl" which is more "snug" (as in problem fitting an O360. NOTE: I had an O-360 that I could have put on but that would have required changing the engine mount, cowl, and wiring.

2. The engine produces about 177-178 HP based on the data I have.

3. You can hear/feel the difference in the "stroke". Not as smooth as the O-320.

4. For constant speed, you will NOT be able to get a supported prop from Hartzell (unless things changed recently). Whirlwind has an offering.

5. I think max/peak torque is at 2500 RPM.

6. It pulls hard. Very good climb.

7. Initially had a carburetor. Many problems. Switched to an AirFlow Performance fuel injected system.


In the end, it would have been better for ME to just overhaul and keep the 160 HP original engine. There were SEVERAL unforeseen issues that kept the plane grounded for a long time:
Several prop changes.
Big issues with the carburetor and EGTs.
Work required to fit the fuel injection system under the "320 cowl" (Don Riviera and I worked to put a package together that WILL fit.)

YMMV.
 
Lycoming the ones to talk to

My neighbor has a Lancair 320 that he had Lycon do the full treatment to, ported, coated, matched, and regrind. I have seen the Dyno ticket, 218 hp.

Trade-off as has been said is you may not be able to get a hydraulic constant speed prop. He has an electric MT prop.
 
In this Quest for Fire, where does the looming switch to 92-93 octane unleaded no-ethanol Avgas fall in the equation? Just curious.
 
Compression

In this Quest for Fire, where does the looming switch to 92-93 octane unleaded no-ethanol Avgas fall in the equation? Just curious.
When the 100LL goes awaay that is the 64K question.
 
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For the OP,
I think there is an option for a longer engine mount to get the weight further forward. i.e. RV-9.
I am thinking that mine is a little longer than some. That would allow the lighter engine and keep the CG off the tail.
 
If you think of the 360 as a stroked 320 you will quickly find that both engines use the same piston, same size bore, but a very slightly longer stroke on the crankshaft for the 360. The crank and the slightly longer cylinders are the only things causing an increase in weight, and that is very little weight.

What you get is the ability to use as low as 90 octane fuel ( I use 90 oct and my IO-360 is retarded on timing to 23 degrees) or any of the coming no lead aviation fuels.
 
In this Quest for Fire, where does the looming switch to 92-93 octane unleaded no-ethanol Avgas fall in the equation?

High-compression pistons not only reduce engine reliability, they also restrict what kinds of fuel you can use. IMHO, a few extra pounds in the nose is more than worth the knowledge that your engine will (1) make it to 2000 hours without any off-airport landings and (2) have some kind of fuel available well into the post-100LL future.
 
High-compression pistons not only reduce engine reliability, they also restrict what kinds of fuel you can use. IMHO, a few extra pounds in the nose is more than worth the knowledge that your engine will (1) make it to 2000 hours without any off-airport landings and (2) have some kind of fuel available well into the post-100LL future.

Well, that was my thought when I asked the question…my bent for firewall-forward is factory’s-factory-factory. I love Experimental Aviation (now) but am not inclined to experiment, especially with something that subjects me to such a large amount of potential energy as an airplane. If I were smarter about this stuff, and had more airplanes, I might be more inclined to tinker. I do know my way around internal combustion engines in many things, but not airplanes.

Anyway, now that G100UL is FAA-encouraged, I wonder how that changes my original question. Reportedly…it’s a drop-in replacement for 100LL.
 
PORTING!

Cylinder porting on your o-320 is your best bang for the buck. See Lycon.
NO CHANGE IN OCTANE requirement.

No trying to make the cowl fit, changing out the airbox, etc.
 
High CR ... still?

Why are folks still into "raise the compression ratio"?
Any number of engineering textbooks, web sites, etc., will tell you that the HP increase is going to be about 6 HP for 10:1 vs. 9:1

Not 20 HP. And then you have a 10:1 engine ...

https://powersports.jepistons.com/blog/compression-ratio-theory-and-how-to-calculate-in-powersports#:~:text=The%20generally%20accepted%20gauge%20for,the%20power%20to%2051.5%20horsepower.

I guess if you think the only options are:
  • More Compression
  • More Displacement

Then yeah, the O-360 is the only option.
But as I mentioned above - porting the parallel valve head gives significant power (as in more than 6 HP)
 
The internal combustion engine is an air pump. The more efficiently it operates, the more power it'll make. Efforts made to improve flow are most beneficial.
These engines are ancient tech and have the ability to make big improvements.
I too am concerned about the loss of 100LL, but there are options/techniques to compensate. Will likely sacrifice some power to do so.
Most of us don't fly enough to have the engine make TBO or beyond. So the minor sacrifice of 10:1 in my book is acceptable. Ideal? We'll see. I owned the engine which helped make the decision. Wanted 180+ and by the calcs I'm close.
Speed costs money, how fast do you want to go?
 
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High-compression pistons not only reduce engine reliability, they also restrict what kinds of fuel you can use. IMHO, a few extra pounds in the nose is more than worth the knowledge that your engine will (1) make it to 2000 hours without any off-airport landings and (2) have some kind of fuel available well into the post-100LL future.

One data point here. The builder of my previous RV-8 bought a brand new Lycoming O-360-A1A 180 HP parallel valve engine (8.5:1 CR) through Van's. Before it was installed it was shipped to Ly-Con in California for some mods. Ly-Con installed 10:1 high compression pistons, ported and flow balanced the cylinders, installed Bendix FI, and installed the LASAR EI system.

I bought the airplane with 110 hours on it and flew it for about 1900 hours (leaning it carefully due to reduced detonation margins). I sold it to a friend at my airport and the airplane now has about 2300 hours on it and it's still running well. The engine has been wonderful, it's never had a stuck valve and never had a cylinder off. Compressions are still good. As expected due to its high time, the oil consumption has gone up, but still well within Lycoming limits. It still has the LASAR EI too.

Oh, yea, the airplane has never had an off-airport landing either!

i-V6knJj9-Th.jpg
 
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