compression and boost
 

An age old question that I'm curious applies differently to our LT1 motors.

I have a very solid 383 stroker that was built with nitrous in mind, but I really want to go turbo now that it is together. I am running 10.9:1 compression, and am curious what kid of boost I could get away with on race gas.

I think that I could possibly get up to 15 lbs on C16 or something similar.

Just looking for opinions here.

Nah, high boost and high compression aren't a good mix, even in our LT1's. Most people run 9:1 compression and 15 PSI with race gas (well, maybe a little more boost), so I don't know what your 11:1 compression will do. Probably won't be pretty though.

The short answer is "no". The slightly expanded answer is "it depends". If you have a lot of money and time (and parts) to experiment with it might be possible with the use of a high efficiency intercooler, water injection, coatings, etc. But it ain't something you could bolt together and run.

And in any case, it wouldn't be desirable. I think it's clear that higher boost/lower CR makes more more hp than lower boost/higher CR. My simplistic explanation is that the low CR setup will have a larger volume combustion space. This will allow a larger mass fuel-air charge to enter the cylinder during the intake cycle. The greater mass of the intake charge more than compensates for the greater combustion efficiency of the higher CR. It's quite similar to a larger displacement motor. Note that this only works with a forced induction motor. Passive cylinder filling on an NA application will not result in an appreciably different mass fuel-air charge with a larger combustion space.

Rich Krause

Anyone who has spent some time with forcedinduction will tell you that you will always make mor power with less compression and more boost than you will with more compressiona and less boost. I would explain why but Rick has done a god job of that already. Not to mention that it will be the biggest PIA if you are always trying to tune your car to make the best power on a combo that is extremly prone to detination. If you can't get that tune right then it will be time for a new motor.

Michael

Whats the rule of thumb then for an LT1, I rebuilt mine with 9.2 and I have two friends in the 9.3 range. I plan on running about 10-12lbs of intercooled boost and hope not to rebuild for a very long time. My friend jeff is about has 9.35cr and runs 15lbs with a large front mount intercooler and pump gas. I could never imagine wanting over 9.5cr with 15lbs on the pump. Especially for us southern boys.