b18-crx

hey everyone i just rebuilt my block and head. im thinking about going boost but i dont know people are telling me it not a good idea because of the high compression. bottom end has a block guard new acl race bearing, oil pump,water pump,cometic head gasket,balance and polish crank arp rod bolts eagle head bolts dual valve springs, ctr cams. so what im wondering is it safe for me run a turbo on this set up. running low boost

Ruben19

yes you can run low boost.
compression ratio should be around 10.6ish.
run 8 lbs with good tuning.

QuadUp621

you should do fine with running low boost.

keepinitrehaal

make sure you have a good tune.

boosteddohczc

well your compression will be 11:59.1 you could turbo it but its gonna be hard to tune and with those pistons being stock cast pistons and that compression any detonation is gonna burn them up. Im not saying you cant turbo it but its gonna have to be low boost and a awesome tune. But low boost on a high compression motor is gonna seem like high boost, so if you get it running right it should go good

99Geeezer

I wouldn't boost with those pistons. Shoulda went for 9:1-10:1. comp. for reliable boosting or better have a good tuner on hand. If so, I'm guessing no more than 6 pounds.

Schister66

You can boost on any compression so don't listen to people who tell you otherwise. The problem you'll run into is finding a fuel that will stand up to the added compression. I guess the best way for me to describe this is as follows:

You have 2 engine setups: 1 GSR with 9:1 and another with 11.5:1. The same turbo setup is used on both engines. Now, the lower comp GSR is going to make less power per pound of boost than the higher compression setup meaning you have to run more boost to get to the same power goal. The limiting factor here is how much power you can make on a certain grade fuel. If you have a higher compression setup, you'll make more power per psi, but at some point, you'll have to upgrade to something higher than pump gas...be it E85 or 100+ octane fuel.

Now for this "you can run low boost" mentality. That's completely wrong as well. You can run only as much boost as it takes to hit that point at which pump gas becomes unstable. If that takes 8psi on a 60-1, 11 psi on a 57 trim, or 22psi on a 16g, its all the same gross air flow and power. You can learn more about this in the Forced Induction FAQ...

b18-crx

thanks for the great info guys. so let me ask 91 octane not gonna cut it huh to run the turbo and all

Schister66

91 octane will cut it, but you have to keep your goals in check with that fuel. I'm not going to give you an exact number but less than 300whp for sure. That fuel is pretty good with a standard compression or low compression setup...even on a stock block. I made 315whp/216wtq on it with a GT3255b on 10.5psi. Twas a good time