18 psi with a 9:1 CR? I'd say you were crazed. Personally, I wouldn't boost anything with a CR above 8.0:1 (8.5:1 if i'm feeling balsy). But if you're going to keep the CR that high, I wouldn't go past 8 psi on pump gas.

 

Stock 2g's have 8.5 to 1 compression, if they up the boost on them does that make them ballsy. Without changing anything accept my compression to 8.5 I had to get even bigger injectors. Other then that tunning seems to be the same for me. Just watch close, 9 should be fine, pump gas a little bit risky, theres plenty of people who run it.

 

Also, stock EVO VIII's have 8.8:1 compression and run a 19 psi spike, from the factory. I'd say you'd be fine to run high boost ~ 20-22 psi on a b16g for example. What turbo do you have by the way? And if knock does become an isssue, a simple water injection system should help out.

 

18 psi with a 9:1 CR? I'd say you were crazed. Personally, I wouldn't boost anything with a CR above 8.0:1 (8.5:1 if i'm feeling balsy). But if you're going to keep the CR that high, I wouldn't go past 8 psi on pump gas.

WTF?!?!? we're not talking about v-tech'd hondas with stock internals here pal.

 

You will hear many different answers, because no one really knows until you assemble your set-up and run it all. Each is different for different reasons. Turbo's are different, FMIC's are different, etc. There is no one answer.

"Boost psi" is almost like a buzzword nowdays. It's all about total airflow with the air being cool. Your question screams out that you don't really understand this yet. That's ok, but 19 psi with a 14b and the stock smic is gonna be way different than 19 psi with a FP Green turbo and a 2-216 fmic.

I'd bet $$ that with 9:1 comp., a Green turbo and a decent FMIC and some tuning you could run 20 psi all day long on the highway with pump gas. Ignition timing is key.

 

I plan on running a fp 3052 ,race core front mount,272 hks cams,720cc injectors and the rest of supporting mods.I have the buschur stage three set up.

 

18 psi with a 9:1 CR? I'd say you were crazed. Personally, I wouldn't boost anything with a CR above 8.0:1 (8.5:1 if i'm feeling balsy). But if you're going to keep the CR that high, I wouldn't go past 8 psi on pump gas.

hmmm, No. each motor is different but our motors are a lil for giving. I have rode in a certain 97 gsx that runs 8:5:1 boosting 26 psi with an fp3065 on pump gas with no knock, oh yea it also has the bj 2.3 stroker. so I would say that 9:1 would probably be safe with careful tuning and alot of fuel. My cr is 7:8:1 for a safer tuning window.

 

I agree completely with what Van has said. I have an FMIC, 680cc injectors, and a Big 16g (not super efficient), and my compression tests show 180 psi (approx. 8.5:1) - I live at around 4,500 ft asl and can run over 20psi on 91 octane gasoline with no knock.

 

I agree completely with what Van has said. I have an FMIC, 680cc injectors, and a Big 16g (not super efficient), and my compression tests show 180 psi (approx. 8.5:1) - I live at around 4,500 ft asl and can run over 20psi on 91 octane gasoline with no knock.

I plan on running a fp 3052 ,race core front mount,272 hks cams,720cc injectors and the rest of supporting mods.I have the buschur stage three set up.

Chances are that you will be in great shape with that setup.

 

Ok, what about 20psi on 8.5:1 CR with the 14b, stock SMIC, 450cc injectors and stock internals (including head gasket), 91 octane and alcohol injection (and damn good tuning)? Do-able?

edit: forgot to mention I also have a walbro 255.

 

well my buddy is finishing his up.....he has 9:1 c/r, long story short, built block and head and tranny from shep, 4 bolt rear, etc. etc. So we will hopefully have it running here tomorrow or saturday and be getting it tuned at turbo trix i believe with teh EMS for the first time. So maybe i'll be able to post a response to your question. He also is using an FP3052 which we jsut bolted up a few days ago.

 

Ok, what about 20psi on 8.5:1 CR with the 14b, stock SMIC, 450cc injectors and stock internals (including head gasket), 91 octane and alcohol injection (and damn good tuning)? Do-able?

edit: forgot to mention I also have a walbro 255.

What the hell is with everyone shooting for PSI. How bout I go run 430psi through my stock T25, and see how it likes it. I say pick a set-up, and tune it where it runs good. A.K.A dont just pick a boost setting and go, up your boost in increments until you see knock, and than tune around that.