What are the proven and reliable ways to lower the CR without changing the pistons?
I am looking to lower CR from stock 10.5 to lets say 8.5-9.0 CR to use with 6-8 pound of boost.
A thicker gaskets or different set heads?? Please explain.
Sebastian
ps. Thanks!!

 

why bother with that when the stock pistons are weak and will fry on any hint of detonation? You can get that low with a set of heads, but it'll cost the same as having a machine shop swap pistons and freshen it up.

 

I agree with the above post, the amount spent on the shortblock will vary depending on your goals. If you wanna keep costs down, freshen up the short block with a rebuild and a set of TRW or speed pro dished pistons. I know of one board member that went with TRW forged dished pistons, lt4 hotcam kit, 50# injectors and fuel pump, and ngk tr6 spark plugs. Everything else in the LT1 was completely stock and he made over 500 rwhp on 14 psi from an S-Trim without an intercooler or meth injection. The cost to do that would be about the same as some heads and would remove the weakest link from the engine (stock LT1 pistons). If theres just no way possible for you to remove the engine (which isnt much harder than changing heads in the car), I would recommend the Trick Flow LT1 heads which would bring your compression ratio down to about 9.5 to 1 and cost 1400.00, but then you would still have the crappy pistons which will most likely die on you anyway.

 

one more thing, dont just use head gaskets to lower the CR ratio, to much head gasket increases the quench hieght too much.

 

I've been researching this as well for my own turbo setup. I found a couple of guys that will convert 215cc intake runner Dart Pro 1's(they have 72cc combustion chambers compared to the stock LT1 54cc so that's the same as a -18 reverse dome piston) to LT1 format. One guy won't give me a price for the conversion (usually a red flag), while the other guy said $700. You can get bare Dart Pro 1 215cc from Summit for $4xx each. So for around $900 for the heads and $700 for the machine work (and of course some valve/springs/etc) you can just pop off the old heads, sell them for some 'rebate' and pop on some new ones. All in one weekend as opposed to pulling the old motor and machinging it, etc, getting it back when ever the machine shop owner gets off his dead a**/doing favors for his 'real racer' buddies..

 

I would consider a economy build with good rod bolts, and a blower piston.

I have somewhere less than $1400 in my short block including a core block that I ran low 7's (1/8th) at 100mph. The valve covers haven't been of in almost 3 years now!

Could be for sale soon!

 

Ok this quench area stuff is there any site that I can look at that explains a little about this? This is one of those things I just don't get.