|
Re: Getting Tuned Soon. What psi to tune for SAFELY.
Just to clear some things up.
I didnt NOT go out, and build a 7.5 c/r motor on purpose. I bought a low mileage jdm d15 vx for 100 bucks. Longblock. AS A SPARE. So when I blew my 10.1:1 c/r y7/b7 block setup, this is what I had laying around, and I used it. So i threw the y7 head and z1 block together and made 7.5 c/r. It doesnt bother me 1 bit. And the off boost power isnt as bad as people expect. Plus with a turbo this small I have boost a bit after 2k so how can I complain ? Anyway, I like it. Its quick. Its currently enough for me. |
Re: Getting Tuned Soon. What psi to tune for SAFELY.
Originally Posted by Joseph Davis
All other things being equal, a lower CR is going to allow you to make more power. Much more.
Look at the point you reach detonation as having reached a certain density with the compressed air/fuel. With a lower CR, you have significantly MORE combustion chamber volume and can fit significantly MORE compressed charge before you hit a dangerous/knock prone density... ... it's not that simple, because when you start making more power you also start making more heat, but there is still a significant general trend of lower compression being capable of more power and being more detonation resistant for a given power output. Melted pistons are a problem with cylinder temps - broken ringlands a problem with combustion pressure spikes - broken rods due to being jackhammered on by detonation - etc. YAAAARR!! |
Re: Getting Tuned Soon. What psi to tune for SAFELY.
Yes and no. Mostly yes, but sometimes no. Dick's 8:1 LS with the high lift 250 duration cams that idled pissy was quite a bit more powerful than a stock LS even without the turbo on. Dynamic cylinder filling and camshaft plays more of a part than CR.
Guy in this case might have lucked into a good combination of engine dynamics... but unless you've got something up your sleeve not being mentioned here, I agree that intentionally building 7.5:1 CR for a streetcar is like shooting yourself in the foot. Guy says he threw together what was laying around to save $0.44, and everything turned out pretty well, I believe him. |
Re: Getting Tuned Soon. What psi to tune for SAFELY.
Track times soon.
If traction is there, Ill be golden. I just swapped in an s20 B000. On the street it smokes 2nd gear bouncing off the rev limiter, but i doubt it will at the track. Its got the infamous 3rd gear grind though that kills my life. |
Re: Getting Tuned Soon. What psi to tune for SAFELY.
got that grind to man. :'(
I have to let my RPM get below 2500prm before I can put it into 3rd and sometimes that takes quite a while. I found a trick though. if you put it into fourth real quick then put it in 3rd as if you are downshifting, it doesnt grind, but you gotta be fast/precise to pull that off at crunch time. |
Re: Getting Tuned Soon. What psi to tune for SAFELY.
I just double clutch the upshift and its fine.
But of course ill be beating it at the track full throttle shifting. |
| All times are GMT -5. The time now is 11:45 PM. |
© 2024 MH Sub I, LLC dba Internet Brands