Celica Forums General Discussion Engine and Performance Supercharging and Compression ratios

Hey,

I'm new here, and being that my knowledge ain't so great. I have recently picked myself up a 2000 model Celica SX (same engine as GTS, just right hand drive). Anyways, I have been looking at a whole range of performance parts for my new little car. From the owner, the car came with a Blitz cat-back exhaust and TRD headers. Looking to pull some more kilowatts from the engine, and have been considering a Blitz supercharger kit.

I have a fair knowledge of turbo's, and the differences between S/C and turbo power. So i would prefer no lectures on these. I would like to know if supercharging creates an affect similar to turbo's where the engine's compression levels have to be lowered to achieve higher boost pressure. I am looking at the 13.0 ratio pistons to upgrade to as well. Would i be better off just skipping the pistons if i plan to supercharge her?

- Marcus

Think of it this way, forced induction is forced induction. Your still craming a whole lotta air into you motor. So if you want to raise the boost level your goin to need to lower your compression, so 13.0 pistons is not a good idea. Higher compression pistons is used for N/A tuning. By lowering the compression you giving more room for all that air. more air=more fuel= bigger boom= more power. As far as raising the boost level with a s/c you would have to change the pulley. This is my understanding, anyone correct me if I'm wrong.

^^Yup

If you lower compression with pistons first, how much HP and TQ would you lose initially?

Sorry to get slightly off topic.

You can boost with the factory GTS compression of 11.5:1, but you must keep the boost levels conservative, unless you take the needed steps to reduce detonation.

Things like alcohol/water injection, running racing fuel or some form of fuel enrichment, or adding low-compression pistons will all help do this.

You will lose HP/torque initially if you lower the compression before adding forced induction, the exact amount isn't easily determined, since we don't know how much you're lowering compression, or the exact amount of HP your motor is putting out from the get-go. you can probably figure it out witha desktop dyno program pretty easy.

Awesome responses guys!

Thanks heaps. I'll have to look into obtaining some lower compression pistons or even just run stock for a while. Here in australia, there is virtually no support for these cars. Might have to look into a custom job.

if you want to go S/C I would suggest a custom setup. the blitz kit isn't that great for making a lot of power and it's expensive. IMO it's too small. it also doesnt boost more then 7psi which drops to about 3-4 during lift. we only hit 218 whp outa my teamates.

whats the best supercharger for the 7th gen celica GTS??? TRD? Blitz?

^^ neither. custom is the only way to do it right. TRD doesnt make an S/C for the GTS.

How is the amount of boost at lift controlled? Wouldnt you want boost to drop down at lift for reliability issues? I know trd had a hell of a time trying to get their supercharged gts to not break down. Know anyone that has had a custom gts supercharged celi for a long time?