Getting Tuned Soon. What psi to tune for SAFELY.
07-11-2005, 02:26 PM
#21
3.0 BAR
Thread Starter
Join Date: Feb 2004
Posts: 1,558
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.
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.
07-11-2005, 02:27 PM
#22
3.0 BAR
Join Date: Apr 2003
Posts: 11,058
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!!
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!!
07-11-2005, 02:36 PM
#23
0.0 BAR
Join Date: Feb 2003
Posts: 0
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.
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.
07-12-2005, 02:06 PM
#24
3.0 BAR
Thread Starter
Join Date: Feb 2004
Posts: 1,558
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.
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.
07-12-2005, 08:40 PM
#25
3.0 BAR
Join Date: Dec 2004
Posts: 2,133
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.
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.
Thread
Thread Starter
Forum
Replies
Last Post
kuntry_boi06
General Discussion
115
11-06-2005 12:26 AM
Reddy
Forced Induction
0
11-02-2005 07:22 PM
d15bsnail
Forced Induction
31
09-06-2005 02:48 PM
jockobo
Forced Induction
9
03-25-2003 08:57 PM
