Quote:
Originally Posted by Cam
Just a word of caution, if you have stock internals, I would expect low end failure in the near future. Adding boost to a 10:1 engine creates more problems than just knock. You need to be concerned about heat and expansion as well. Too much heat will cause many problems. You say you know what you are doing, and I trust that you do, but I figured I would give my .02 cents. Bearing failures are not uncommon with our engine (Subaru let the cranks and bearing go through the assembly line with .0002" clearance.) Thats not a type, 2 ten thousandths of an inch. You will seriously deteriorate the life of your engine.
Anyways, sounds like a fun project and I wish you luck. However, it may be time to buy a spare engine and slowly start doing a rebuild with some lower compression pistons.
Good luck with your build.
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I appreciate the input, that's exactly the kind of advice I'm looking for. To combat combustion heat, I will be throwing quite a bit of fuel at it. I have no qualms going rich to keep combustion temps down if need be. If you're talking about the cooling system in general, as opposed to just combustion temps, then I'll just have to cross that bridge when I come to it.
As far as bearing failure goes, I'm not really that concerned about it. The cylinder pressures you see from detonation are FAR higher than anything you'll see from normal combustion, even under boost and higher CRs. The burn rate during detonation can be up to 25x faster than normal, and will result in obscene cylinder pressures, and usually very premature (before TDC). This is what puts more stress on the bottom end. Even a little knock on an NA engine is harder on the engine than making twice the stock horsepower on a boosted engine with no knock. You don't have to agree with me, but I don't have to agree with you either
Like I said, I come from the world of 3000GTs/Stealths, which also pretty commonly see bearing failures...on that particular platform, even the 2-bolt bottom ends have been proven good to over 700HP at the wheels before risk of power-induced bearing failure...and there's now a fix for that, thanks to somebody pushing the issue and finding out where that point is. Insufficient oiling due to dented oil pans is far more often the cause on those cars. I appreciate the heads up, but in my experience more power does not lead to a significantly increased likelihood of bearing failure.
There's a threshold on pretty much every car that once you cross, it does become a big concern, but I'm more than happy to be the one to find out what that is the hard way. I'm not saying I won't run into a bearing issue, I'm just saying I'm not going to buy into the weak ringlands and temperamental bottom ends theory until I see it myself. Thanks for contributing, I'm interested to see how well the EG33 will hold up under my abuse, and that's kind of the point of this little project. Your concerns are my entertainment
