high or low comp pistons
09-07-2007, 01:54 PM
#1
0.0 BAR
Thread Starter
Join Date: Oct 2003
Location: Mile High--HMT
Posts: 0
high or low comp pistons
as you know we are building a b16 and it is sleeved, it will also be turbod, now i know low comp pistons are good for turbo 8.5-9.0 but why cant I use high comp pistons say 10.0-10.5-1 in this build and get better results on hp & tq. any input will be greatly taken in consideration
09-07-2007, 02:55 PM
#3
3.0 BAR
Join Date: Apr 2005
Posts: 6,036
Re: high or low comp pistons
your forcing pressurized air into a cylinder, the more dome on the piston, the less air can be forced through there , meaning you cant run as much boost as safely look at like you can run 28 psi on 8.5:1 and 24 psi on 10:1 obviously the 8.5:1 c/r with more boost will be faster 
09-07-2007, 03:45 PM
#6
1.5 BAR
Join Date: Jul 2007
Posts: 752
Re: high or low comp pistons
its about octane and retard...
if you have lots of octane, you can have lots of comp and lots of boost
do you wanna run it on street gas? if so, you will make more power on the lower compression because you will be able to have it advanced correctly without detonation.
if you wanna run it on some funky ---- like i currently run mine on, go ahead and keep it high.
with high comp on pump gas, you will be limited to lower boost with good advance, and less gains as you increase the boost. however, for track use, chucking some high octane at it and upping the boost is a real possibility...
hope that helps you. if not, there are acres of reading material out there to mull over.
read this :
http://www.sdsefi.com/techocta.htm
and also these if you are bored...
http://www.sdsefi.com/meltdown.htm
http://www.sdsefi.com/tech400.htm
if you have lots of octane, you can have lots of comp and lots of boost
do you wanna run it on street gas? if so, you will make more power on the lower compression because you will be able to have it advanced correctly without detonation.
if you wanna run it on some funky ---- like i currently run mine on, go ahead and keep it high.
with high comp on pump gas, you will be limited to lower boost with good advance, and less gains as you increase the boost. however, for track use, chucking some high octane at it and upping the boost is a real possibility...
hope that helps you. if not, there are acres of reading material out there to mull over.
read this :
http://www.sdsefi.com/techocta.htm
and also these if you are bored...
http://www.sdsefi.com/meltdown.htm
http://www.sdsefi.com/tech400.htm
09-08-2007, 04:20 AM
#7
0.0 BAR
Join Date: Dec 2002
Posts: 0
Re: high or low comp pistons
JG was a huge fan of high compression motors and high boost. I also saw them spit out motors at the track alot too but those 700 whp passes looked nice while they lasted. Low compression allows for errors in tuning mechanical failure etc. FWD cars cant lay down huge #'s so follow what has worked
09-08-2007, 04:31 AM
#8
3.0 BAR
Join Date: Apr 2005
Posts: 6,036
Re: high or low comp pistons
Originally Posted by chris
JG was a huge fan of high compression motors and high boost. I also saw them spit out motors at the track alot too but those 700 whp passes looked nice while they lasted. Low compression allows for errors in tuning mechanical failure etc. FWD cars cant lay down huge #'s so follow what has worked
09-08-2007, 10:06 AM
#9
0.0 BAR
Thread Starter
Join Date: Oct 2003
Location: Mile High--HMT
Posts: 0
Re: high or low comp pistons
thanx for some input, being here in Denver were already have low compression so that is the reason for ?'s. havent decided yet if we are going
to use 91 oct. or set it up for e-85 and we do have a excellent tuner
fe3tcourier-- those are some goor reading material you found thanx. even though I'm an old bastered I can still be taught new tricks
and that is why I keep coming back here
I LOVE THIS PLACE!!! There are great pros and cons on this matter and they just about equal out so now we have to decide how far we want to take it.
I just want to get this thing done and get it on the road
More input Please Mark
to use 91 oct. or set it up for e-85 and we do have a excellent tuner
fe3tcourier-- those are some goor reading material you found thanx. even though I'm an old bastered I can still be taught new tricks
and that is why I keep coming back here
I LOVE THIS PLACE!!! There are great pros and cons on this matter and they just about equal out so now we have to decide how far we want to take it.
I just want to get this thing done and get it on the road
More input Please Mark
