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BlakeB

Well Known Member
Guys,

I have a 0-360 A1A fixed pitch RV 8 with low compression pistons. (7.3 to 1). I think it is producing 180 hp but not sure. The engine builder built the engine as requested from the previous owner. The engine has angle valves and was converted from fuel injected to carb. The previous owner planned on running auto gas. I on the other hand don't want to run auto, I perfer AV gas because of the availablility at all airports and would like the increase in hp. I would like to change the pistons from (7.3 to 1) to (8.7 to 1). Does anyone out there think that this would be a problem? And what would it do to the hp?

Thanks,

Blake
 
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Angle Valve?

The standard O-360-A1A is a carburated parallel valve engine with a compression ratio of 8.7:1. So if you have angle valves it aint a A1A. If it is an A1A then going from 7.3 to 8.7:1 compression will net 180HP
 
100LL over mogas, no extra power just extra detonation margin. You can run either mogas or autogas even with 8.7:1 pistons (I do, but my pistons are 8.5:1.) I have a friend that has a Smith Cub with a lyc set up just like your engine but with std. pistons. You will get a few hp going to the higher compression, but not enough to notice much of a difference in speed. If I were you I'd leave everything as-is.
 
zilik said:
The standard O-360-A1A is a carburated parallel valve engine with a compression ratio of 8.7:1. So if you have angle valves it aint a A1A. If it is an A1A then going from 7.3 to 8.7:1 compression will net 180HP
Click to expand...

Gary: Slight correction. The O-360-A1A is a parallel head engine, but the stock compression is 8.5:1 on all parallel head 360/540. The IO-360-A1A, however is an angle head engine with stock 8.7:1 compression pistons. The engine in question was originally the angle head fi 360, but the original owner converted it to run a carb and reduced the compression. With 8.7:1 compression pistons, this engine would be rated at 200 hp.
 
?

Ladies & Gents,

So if I change the pistons I would go from 180hp to 200hp. Seems to me like it might be worth the money. What do yall think?
 
BlakeB said:
Guys,

I have a 0-360 A1A fixed pitch RV 8 with low compression pistons. (7.3 to 1). I think it is producing 180 hp but not sure. The engine builder built the engine as requested from the previous owner. The engine has angle valves and was converted from fuel injected to carb. The previous owner planned on running auto gas. I on the other hand don't want to run auto, I perfer AV gas because of the availablility at all airports and would like the increase in hp. I would like to change the pistons from (7.3 to 1) to (8.7 to 1). Does anyone out there think that this would be a problem? And what would it do to the hp?

Thanks,

Blake
Click to expand...
THe big question I have is:

Does the engine need to be torn down anyway, or are you just looking for an additional 20 HP?

The existing setup will run just fine on 100LL, and still allow you to run mogas if you change you're mind. The additional HP won't net you much more than 7 - 8 knots in cruise, at a cost of 10% more fuel consumption.

If the engine needs to be torn down anyway, it's a no brainer kind of decision..... you don't need to use the extra HP if you install it, but have it there if you want it, at no substantial extra cost.

But tearing down a perfectly good engine just for an extra 7 knots.....
 
I agree!

There were a few issues I was looking into anyway. I just bought the plane and wanted to open her up anyway. So yes I was taking it apart to look at it, I plan on flying it quite a bit for a long time. I'm currently running a 3 blade Catto prop that needs to be re pritched. For some reason it was pitched for 160hp. so I was over reving it already.

Blake
 
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