Right now am running the JE Pistons with 9:1 compression. I am pulling it back out to get re-sleeved but wanted to know if I should continue to run the 9:1 compression since I'm going turbo or raise the compression higher and not run as much boost!

Lower compression lowers HP and Torque but is safer to run more boost. Higher compression like 10:1 would give me the factory HP but could not run as much boost. If I used the 9:1 I would need to run more boost anyways to equal the power of the factory compression engine(10:1).

Post a message so it BUMPS!


Modified by crxhybrid1320 at 4:52 AM 4/11/2003

 

run 10:1 and just add mo gas!

 

Lower static compression ratio and higher boost level is much better than higher static compression and lower boost level.

When you add air, you get to add fuel. The more fuel you can burn, the more power you make.

 

if you race a lot go with the lower compression.
if you dont go with the higher one.

 

lower is always better and safer to run boost with. its better to run high boost with lower comp. tehn with high comp. and low boost. high comp will need more tuning to be safe.

 

I think it is all in the tuning. To the best of my knowledge, the higher the compression the more power you can make at any given boost level. Period. I feel that if you are gonna boost safely in the first place no matter if you a running 8.1:1 or 11.1:1 you should have sufficient engine management anyways. Such as Hondata, Motec, AEM EMS etc. Why wouldn't you want a head start on power using the high compression, other than having to buy the higher octane gas? As long as you are tuned you should be fine. Plus the higher compression will help you to spool faster. Just my .02 though.

-Ryan

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kwuaymaikrup &raquo;</TD></TR><TR><TD CLASS="quote">I think it is all in the tuning. To the best of my knowledge, the higher the compression the more power you can make at any given boost level. Period. I feel that if you are gonna boost safely in the first place no matter if you a running 8.1:1 or 11.1:1 you should have sufficient engine management anyways. Such as Hondata, Motec, AEM EMS etc. Why wouldn't you want a head start on power using the high compression, other than having to buy the higher octane gas? As long as you are tuned you should be fine. Plus the higher compression will help you to spool faster. Just my .02 though. </TD></TR></TABLE>

You cannot tune out the effects of limited fuel octane.

 

http://www.sdsefi.com/meltdown.htm
http://www.sdsefi.com/techocta.htm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dustin &raquo;</TD></TR><TR><TD CLASS="quote">http://www.sdsefi.com/meltdown.htm
http://www.sdsefi.com/techocta.htm</TD></TR></TABLE>

Not trying to bust your ***** but wasn't this pre-Hondata times that these were written? BTW...I like the pictures in your sig....

 

Go with the higher compression, run the same level of boost as you would with lower compression BUT get it TUNED TO PERFECTION..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kwuaymaikrup &raquo;</TD></TR><TR><TD CLASS="quote">

Not trying to bust your ***** but wasn't this pre-Hondata times that these were written? BTW...I like the pictures in your sig....</TD></TR></TABLE>

Proper fuel management has nothing to do with octane limitations. Those articles are a car-general treatise on the reality of octane vs. power.

Real fuel management has existed long before Hondata ever did.

This is not a Honda thing, It's an internal combustion engine thing.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by swlabhot &raquo;</TD></TR><TR><TD CLASS="quote">Go with the higher compression, run the same level of boost as you would with lower compression BUT get it TUNED TO PERFECTION..</TD></TR></TABLE>

If you were going to do this -- Why not just run the lower static compression ratio and run more boost?

1) You get the same effective dynamic compression ratio (practically).
2) You get to burn more fuel.

-so-

3) You make more power.

I don't understand this recent drive to run high static compression ratios... Do you guys have 120 octane fuel coming out your ears?

 

@ 20 psi you won/t notice the comp loss

 

I think it all depends on what your plans are. If you plan on making a full race car, running +20psi and going for that 400whp and more, go with the lower compression ratio.

If you mainly drive the car on the street, want a decent spool and more driveable power curve, running lower boost levels trying to achieve maybe 350whp or less I would go for the higher compression ratio.

But as mentioned, none of it matters without good engine management tuning.

Good luck

 

You also have to think about the fact that when you run high compression with boost there is absolutly no room for error. If you lean out even for a moment the ***** going to hit the fan. Thats all it takes and sometimes good tuning cant even prevent that.

 

9:1=security blanket, just incase, you neeever know

 

isnt it the other way around
for race car they usually use high compression pistons + big boost to get as much power as possible

i know that HKS Drag R33 running 9.8:1 CR with 40+psi to achieve 1300hp

 

I stick with the 9:1. I dont own a dyno or a crazy management system so it will be safer in the long run. If I need to add power i'll add more boost at the track with race fuel.

 

10:1 comp isn't considered high comp, we'll in my book it isn't.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ekb18c &raquo;</TD></TR><TR><TD CLASS="quote">10:1 comp isn't considered high comp, we'll in my book it isn't.</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dustin &raquo;</TD></TR><TR><TD CLASS="quote">Lower static compression ratio and higher boost level is much better than higher static compression and lower boost level.

When you add air, you get to add fuel. The more fuel you can burn, the more power you make.</TD></TR></TABLE>


RIGHT ON!

no one seem to realize what the difference is between making power with compression & timing vs. making power with air & fuel.

one of them is gonna have a REAL good chance of breaking something at 8K RPM.
I'll let you guys guess witch one that is.

 

(LOL) - VERY SIMPLE-
IF YOU ARE BROKE - GO LOW COMP high boost- and pay for more gas when u need

IF YOU GOT MONEY- GO HIGH COMP HIGH BOOST PLUS ENG MANAGEMENT- BUT HAVE A SPARE ENGINE AND PARTS- just like the dragracing teams-

they spend tons of money and most rebuild the engine for every run. some millions $$ in sponsors. This option will give u Better times- but you will have to pay for it.

THE MORE YOU BUILD THE ENGINE FOR PERFORMANCE THE LESS RELIABLE THE ENGINE WILL BE- this is why teams are constantly rebuilding.

 

If the turbo is rated at the same CFM level, regardless of boost level, it will run the same power. Simply "running more boost" may only help if the effective range of the turbocharger is designed to be at a higher boost level. Otherwise, you're going to run the same power. the difference is going to be recovery of the turbo between gears and better acceleration.

example: *Note: numbers are only for reference* -- 14psi on a GT35R = 420whp on 9.0:1 CR, but 10psi = 420whp on a 10.0:1 CR.

Yes, the power that is made is BTU limited, but at the same time, running 10.0:1 doesn't mean that you can't use 93octane. Now if you're limited in your area of octane or BTUs, you would need to run less boost anyway from the additional timing.

Its all about what's available in your area and what fuel and timing you like to use.

 

Go for the low compression and more boost. Im running 8:1 @ 20 + psi