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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269

Just my two cents:

High compression w boost is an interesting combination. I suspect it is mostly helpful with drivability below 4000rpm. Above that boost becomes more effective and hight compression becomes a limiting factor.

Are you sure you need to replace the rods? For most applications, even to 600hp+ they seem to be fine. It is not typically the power stroke that is the problem. It is the centrifugal force that comes with higher than stock RPM. Thus, if you are planning on running over say 7K rpm do the rods.

I could be wrong but I believe that your combination is equal to about a 13/1 CR motor. Inter-cooler and turbo efficiency becomes very important and is probably where most effort should be placed. I suspect it is Protomotoves IC and choice of turbos for there efficiency is what allows them to somewhat bend the boost to compression rules of thumb.

Not sure that managing boost by RPM is going to add much in your case as you are running so close to the edge already. I do not know if it can take much more boost at lower rpm's. It might help to pull boost back a bit at TQ peak where combustion pressures are at there highest. Also, I suspect you might start to run into decreasing turbo efficiency as you approach higher rpm so trying to add boost will increase inlet temps and increase susceptibility to detonation.

I would think managing boost by rpm and load might be best used for filling in low rpm and pulling back boost to stay withing other limitations like stress limits of the drive train or decreasing efficiencies in other areas like a fuel limit, turbo limit, inter-cooler limit.

If me, I would put effort into keeping the heads sealed like adding fire rings and by all means, get forged pistons and consider having the heads and piston tops coated to reduce heat transfer.

Not an expert on this, just what I think.
Old 11-14-2009, 04:16 PM
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