CivicDude2k4

so me and my buddy were talking about lowering compression on turbo apps and we raised a few questions. we're not experts, so expert advice would be awesome here. I need cold hard facts. In an NA motor, lowering compression would really hurt horsepower, thats a given. but in turbo apps, even though you lose that same amount of horsepower, you gain it all back and some when you run boost. so you still come out on top. now one question here is even though the compression changes, the capacity doesn't. so if you turbo a d16y8 (stock ratio 9.6:1) and drop compression to say 8.5:1, its STILL a 1.6L engine, so will it really help in terms of added horsepower? is it worth it? or would forged pistons/rods that keep the stock compression be a better and more beneficial way to go?

knockout

theres really no need to drop your compression unless youre dropping it back to stock. its all about tuning. you can boost higher psi levels on stock c/r motors, the tuning is the key.

cambopheonix56

I believe it goes like this:

Higher compression is more prone to detination. People really only lower compression, usually 8.8:1-9:1. when building motors for boost. You really dont want to run 20 psi on 10.2:1 c/r.

CivicDude2k4

i don't plan on running more than 8, only 6 on a day to day basis. i'm going to get it tuned, i just was wondering whether it would be worth it perfomance wise to dop compression. i didnt know if the horsepower change would be that dramatic enough to make me drop 500 extra to lower it or just leave it at stock

knockout

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CivicDude2k4 &raquo;</TD></TR><TR><TD CLASS="quote">i don't plan on running more than 8, only 6 on a day to day basis.</TD></TR></TABLE>

8 psi is easily done on stock internals with stock compression.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cambopheonix56 &raquo;</TD></TR><TR><TD CLASS="quote">I believe it goes like this:

Higher compression is more prone to detination. People really only lower compression, usually 8.8:1-9:1. when building motors for boost. You really dont want to run 20 psi on 10.2:1 c/r.</TD></TR></TABLE>

its been done, like i said, it is all about the tune.

jsilva

If you only wanna run 8 pounds save your money. That motor will handle 10+ pounds with a good tune. The key to turbo is like they said get a good tune from a reputable tuner. Nothing like getting your new turbo setup in with a shitty tune and blow stuff up. Keep the stock c/r until you wanna crank up the boost which eventually will happen

cambopheonix56

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jsilva &raquo;</TD></TR><TR><TD CLASS="quote">If you only wanna run 8 pounds save your money. That motor will handle 10+ pounds with a good tune. The key to turbo is like they said get a good tune from a reputable tuner. Nothing like getting your new turbo setup in with a shitty tune and blow stuff up. Keep the stock c/r until you wanna crank up the boost which eventually will happen </TD></TR></TABLE>

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by knockout &raquo;</TD></TR><TR><TD CLASS="quote">8 psi is easily done on stock internals with stock compression.

</TD></TR></TABLE><TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CivicDude2k4 &raquo;</TD></TR><TR><TD CLASS="quote">i don't plan on running more than 8, only 6 on a day to day basis. i'm going to get it tuned, i just was wondering whether it would be worth it perfomance wise to dop compression. i didnt know if the horsepower change would be that dramatic enough to make me drop 500 extra to lower it or just leave it at stock</TD></TR></TABLE>

Its not about the psi, its about how much whp the motor can handle. If you have a y8, I wouldnt exceed 220 whp. After that, it just becomes unreliable. However I have seen a 375whp stock block. Obviously, its not reliable and wont last long. So remember, its not about psi

cambopheonix56

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CivicDude2k4 &raquo;</TD></TR><TR><TD CLASS="quote">i don't plan on running more than 8, only 6 on a day to day basis. i'm going to get it tuned, i just was wondering whether it would be worth it perfomance wise to dop compression. i didnt know if the horsepower change would be that dramatic enough to make me drop 500 extra to lower it or just leave it at stock</TD></TR></TABLE>

Leave the compression alone. Many many many people boost b16's and b18's with comression over 10:1

knockout

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cambopheonix56 &raquo;</TD></TR><TR><TD CLASS="quote"> So remember, its not about psi </TD></TR></TABLE>

well i know that. but honestly, do you think 8 psi on a y8 can make more than 220whp? id say 180-190 average. but like i said, the stock compression is perfectly fine for those boost levels.

CivicDude2k4

sweet, i know it can handle the horses i just wasn't sure if in the end it would be worth the investment. alot of good points thanks alot guys. and on the topic the other question we had was fuel injectors. i've heard the stock 240's can handle about 200 hp fine, but EVERYONE around here has told me to get them. i haven't b/c i don't believe i need them running the small set up i am. but if i don't get like a pump or rail or some other volume increasing part, how would 440's help me? without a bigger part to help deliver fuel i don't see how 440's would help with stock fuel components. its the same amount of fuel being deliverd regardless of the injectors size, am i right?

cambopheonix56

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by knockout &raquo;</TD></TR><TR><TD CLASS="quote">well i know that. but honestly, do you think 8 psi on a y8 can make more than 220whp? id say 180-190 average. but like i said, the stock compression is perfectly fine for those boost levels.</TD></TR></TABLE>


Well, yes. A different cam/springs/valves for higher revs, intake manfold, and other bolt ons and a big turbo I bet you could. A bigger turbo at the same psi is going to make more power then a little turbo. IE gt42r compared to a T25.

knockout

id stay with stock, but 440's might be a little big for ~200whp.
an upgraded fuel rail, new fuel filter, and maybe slightly bigger injectors (under 440) would be good.

cambopheonix56

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by CivicDude2k4 &raquo;</TD></TR><TR><TD CLASS="quote">sweet, i know it can handle the horses i just wasn't sure if in the end it would be worth the investment. alot of good points thanks alot guys. and on the topic the other question we had was fuel injectors. i've heard the stock 240's can handle about 200 hp fine, but EVERYONE around here has told me to get them. i haven't b/c i don't believe i need them running the small set up i am. but if i don't get like a pump or rail or some other volume increasing part, how would 440's help me? without a bigger part to help deliver fuel i don't see how 440's would help with stock fuel components. its the same amount of fuel being deliverd regardless of the injectors size, am i right?</TD></TR></TABLE>

Nope, bigger injector = more fuel. Each pulse will result in more fuel. 310's would probably be fine.

cambopheonix56

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by knockout &raquo;</TD></TR><TR><TD CLASS="quote"> 440's might be a little big for ~200whp.
an upgraded fuel rail, new fuel filter, and maybe slightly bigger injectors (under 440) would be good.</TD></TR></TABLE>

knockout

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cambopheonix56 &raquo;</TD></TR><TR><TD CLASS="quote">
Well, yes. A different cam/springs/valves for higher revs, intake manfold, and other bolt ons and a big turbo I bet you could. A bigger turbo at the same psi is going to make more power then a little turbo. IE gt42r compared to a T25. </TD></TR></TABLE>

sure a bigger turbo may make slightly more power and with a cam you get a good boost in power, however i doubt a slightly larger turbo can make over 220whp when a medium sized turbo makes 180whp. besides, if you upgrade the valves/retainers/springs, youve already built half the motor. and even then, a good tuner can make it more reliable or if need be, make a more conservative tune.

CivicDude2k4

yeah without other units to support it i didn't see how that could possibly be effective. i have a fuel cut-out problem but i'm pretty sure its the ECU cutting it out. MAP sensor threw a CEL so its probably electronic. thats my guess anyway. i might as well keep asking questions since i'm gettin everything else answered. Anyone with cam gears can help me here. especially if you have a turbo. does the car perform better when you retard or advance? especially on an SOHC its critical to get it adjusted just right. we were thinkin since VTEC only work in the intake side, if you slid the timing towards the exhaust it would help even it out and get a smoother cycle. anyone?

knockout

generally advancing the timing increases horsepower however i wouldnt recommend touching anything. besides a tuner will set you up with the perfect timing for your engine/setup.

knockout

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cambopheonix56 &raquo;</TD></TR><TR><TD CLASS="quote"> 310's would probably be fine. </TD></TR></TABLE>

310's

CivicDude2k4

oh yeah absolutely. just wanting to know, just so i know. you never learn unless you ask and i don't know how interactive these tuning guys are going to be in what they do, so its just for my own knowledge.