im hearing this new fad that people are boosting high compression. so my question is whats better? low compression or high compression boost?, i have any 93 jdm h22a and im resleeving, piston and rods, i just wanted to know whats better for my application.

 

Definitely high compression boost...you'll make a lot more power, but it's a lot riskier with detonation. If you have a good tuner/know what you're doing the only scary time should be during tuning.

Low compression boost= why the 4g63 needs 14psi to make 200hp at the crank.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sportyaccordy &raquo;</TD></TR><TR><TD CLASS="quote">
Low compression boost= why the 4g63 needs 14psi to make 200hp at the crank.</TD></TR></TABLE>

That has more to do with thier small turbo and restrictive head flow. Low c/r is better in my opinion. you dont get trophies or brownie points for making power on low boost. I mean they do make large turbos, boost controllers and 20 lbs wg springs for a reason. And I certianly dont have reservations about making my turbo earn its keep.

 

im going
84mm
rs closed deck sleeve's
arias 11:1 pistons
eagle rods
gt35r

ect..
hoping to make 500+ on just turbo and maybe a 50shot

 

im running a little above 10:1 compression and 10 psi. you simply make more power on less boost, and the turbo will spool quicker...at least it did in my application.(i had the same kit on 2 different motors) i suppose it just depends on when you want your power, and what the application is.

 

hahahaha, thats funnny damn right dude, im runnin 8lbs with a customized 18g greddy kit on my jdm gsr, compression is slightly lowered via thicker cometic headgasket and arp headstuds but im makin 260whp and 215wtq, thats crazy for a greddy kit customized or not, this is with greddy small downpipe and nothin done to manifold or turbine housing. some people dont believe me but its simply cuase of my 10.3:1 cr, if i had anything less i'd be down at like 220-230whp on 8lbs with the greddy kit on a gsr like most of the people on here. car runs like stock to, perfect tune, slightly rich but i guess safer its all good.

 

JDM B18c (10.6:1) + 7psi = 272whp for me

can't wait to turn it up to 10

 

there's really not that much power difference, i seen a 9.1 motor and 10.1 with the same setup and the spool difference and midrange was pretty close. but i think 9.8 to 10.5 is the best turbo motor. everybody is so used to oldschool cause all they had was an fmu for tunning thats why.

 

so will i benefit more from high compression

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by spurge &raquo;</TD></TR><TR><TD CLASS="quote">so will i benefit more from high compression</TD></TR></TABLE>

Not really. I didn't notice any real change in spool up from high compression. A little bit better throttle response and a little more power at lower boost levels, but nothing that isn't made up for with another pound of boost. I like my 9:1 motor for the street, and you'll find a lot of tuners and engine builders (Not H-T heros) will recommend around 9:1 compression for the street.

 

You whole deal comes down to there are many ways to build things to fit specific needs, i personally run 10.6 compression and make 500 whp stock sleeves
b series vtec 1.6 liter

next motor ill build will run at least 10.to 1 compression, ITS ALL IN THE TUNING, lower compression allows for more mistakes/ including tuning, bad gas, etc

higher compression wont allow for as many mistakes

hope this helps
dan

 

Yup. I will be boosting a fresh 01 GSR this summer going with a stock bottem end just cosmetic head gasket and studs hope to make 350+ High Compression + Boost = Good w/ the right tuning at least. I would say for a track only/race car application low compression pistons and lots of fooking boost.

 

yea i wouldnt recommend at all trying to boost over an 11:1 motor but anywhere between 9.5-10.5 isnt bad, its just in the tune. im not sure but i dont think a little bit of compression will severely alter spool times anyhow, but it will make the car feel better/faster because of the "lag" of low compression pistons. i personally built an 10.4:1 ls/v with forged pistons/rods. going to run about 10-12 lbs w/ an sc61 using hondata, ill post back here on numbers i put down. hoping for over 300whp. i would suggest about a 10:1 motor with some good management/tuner. research

 

Increasing engine compression is just like running more boost, but with less efficiency. Yeah, you'll make more power per PSI of boost with high engine compression, but that really doesn't mean anything because your actual cylinder pressures are plenty high. If you lowered the engine compression and raised the boost level so that you get the same cylinder pressures, you would make more power, because it's more efficient to have the turbo doing the compression (assuming that the turbo is properly sized).

The only real reason you would want more engine compression with boost is for better low-end / low-boost power and possibly quicker spool up. Once you have the turbo going, it makes more sense to have it doing the compression.

 

lower compression = more power on pump gas.