More compression 460
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Junior User
Joined: Nov 2003
Posts: 83
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From: TX
More compression 460
I have a stock '90 460 and I want to get higher compression from the engine by machining the heads down as much as I can. I don't want to change pistons or use other heads. The engine is being converted to run on propane.
What is the stock CR on that year 460 and does anyone know how much you can machine off without running into trouble with the valves? I can get new pushrods and machine the intake to match the heads if neccessary.
What is the stock CR on that year 460 and does anyone know how much you can machine off without running into trouble with the valves? I can get new pushrods and machine the intake to match the heads if neccessary.
Elder User
Joined: Jan 2000
Posts: 966
Likes: 2
From: Crooked River Ranch, OR
I'm guessing your stock compression is between 8.0-8.5 to 1
I don't think you will be able to mill the heads enough to make up for the loss of HP you get by running propane. Propane has less BTU energy than gasoline. The benefit of running propane is it has a octane rating well above 100 so you can bump up the compression high enough to make up for the initial loss. With propane you could run 12 to 1 or maybe even higher. Of course if your setting up to run dual fuel (propane and gasoline) then your limited since you can't run much more than 10 to 1 with premium. Just my 2 cents worth...
Deen
I don't think you will be able to mill the heads enough to make up for the loss of HP you get by running propane. Propane has less BTU energy than gasoline. The benefit of running propane is it has a octane rating well above 100 so you can bump up the compression high enough to make up for the initial loss. With propane you could run 12 to 1 or maybe even higher. Of course if your setting up to run dual fuel (propane and gasoline) then your limited since you can't run much more than 10 to 1 with premium. Just my 2 cents worth...
Deen
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Junior User
Joined: Nov 2003
Posts: 83
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From: TX
propane has a 104 octane rating. That's why i wanna get more compression. But like I said, i don't want to take the engine apart other than the heads. With headers and a good intake system i should be able to be back at about stock hp or a bit higher. I just wanted to know how much you can machine off and to what compression you get by that. If I can get to 9:1 or 9.5:1 it would be better than before.
