3SGTE Engine rebuild; What compression ratio to go with.

[Howieau]

Ive been doing some research on compression ratio setups, but am still a little vague/confused in some areas. Im currently rebuilding a 2nd generation 3SGTE. Its going to run lumpier cams (approx intake/exhaust lift of 9mm), head ported and polished, forged internals, standard CT26 turbo, FMIC etc. Im unsure of what compression ratio to go with? I wanted to get into track racing so I'd need good power throughout the entire rev range I guess. My car was pretty laggy down low before I blew the engine, Id imagine because of the bigger cams and also because TVIS was disabled by the previous owner. So would it be better to go with a higher comp ratio (stock being 8.8:1) so I can get better power down low (to go with the TVIS manifold that will go in with the newly rebuilt engine)? I reckon the turbo works great from mid range out until redline. Its hard to tell when the cams are kicking in but as soon as I hit full boost (12psi) at about 3500rpm the car pulls hard out to 7000rpm where its limited.

Am I on the right track here? Higher comp for power down low, turbo from mid to redline, cams up high to redline I guess? Also with higher compression Ill have to upgrade my injectors/pump to the match wouldnt I?

All inputs much appreciated.

[Crazyracer]

One of the guys on here was running 10.5+ static compression in his 3SGTE. He said it made it really drivable on the street with great low down responsiveness.

Obviously if you do this you can't pump as much boost into it to make the big HP figures.

Its always going to be a trade off between power and response but you probably want to stick in the 8.5 - 10.5 static range. If its going to be a dedicated track car, the power is probably going to be more important to you so you'd want to go lower in the static compression and then probably source a close ratio box to keep it on song.

See if you can get hold a a book called "Forced Induction Performance Tuning" by A. Graham Bell. It has a discussion on Compression Ratio vs Boost as well as lots of other helpful information on tuning and building turbo and super charged engines.

[Roundy]

i wouldn't go lower then 9:1

when i get around to rebuilding my engine i am going to aim for somewhere between 9-9.5:1 CR

however, running the std CT26 turbo you are wasting the big cams on it, the std cams are more then big enough for the std turbo!

as for fuel injectors, once again, the std fuel injectors should be adequate for the std turbo