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View Full Version : WHY DO I HAVE SO MUCH LAG??



**DONOTDELETE**
08-16-2001, 09:07 AM
Ok..i am running the stock T25 turbo, ported intake manifold and a ported Throttle body. 3" exhaust and 2.5" downpipe. 2.25" IC piping and a TRUST Pulsar GTiR Intercooler with 2.25 inlets/outlets. Running stock boost right not. Now in my old car, i would gain 2-3 psi from opening up the exhaust, but im still running 7psi. Did i hook something up wrong? and also feel alot of lag..now is that common on SR20s??

AceInHole
08-16-2001, 09:19 AM
i dunno how big the IC is you're using. . . but if it's anything bigger (or much) bigger than stock you'd logically lag more as it would require alot more air to gain boost within the IC and IC piping. The T25 AFAIK is a small turbine that is barely large enough for the stock SR, so I'm assuming it isn't compressing enough air into your IC at a fast enough rate.
Seems to me like upping the boost would help in this situation, but not being an SR guy myself, I can't say for sure. Check the wastegate and blow off valve for correct connections just in case though, as they may be leaking??

PJ

**DONOTDELETE**
08-16-2001, 09:37 AM
OK..sounds good..I am very tempted to up the boost but am running at stock fuel pump. I think it should be ok since i'm only running 370cc injectors anyways..maybe 12-14psi..

AceInHole
08-16-2001, 09:51 AM
can the T25 handle that much boost?? i'd say turn boost up little by little. . . or wait for one of the SR guru's to give u a reply. the reason i say turn the boost up is to try and force more air into the IC, but thinking about it again, I don't think it'll work that way, as the turbine will still spool up the same initially. this is because it sounds like you have a huge intercooler to pressurize with a tiny T-2-small turbo.

**DONOTDELETE**
08-16-2001, 10:01 AM
The intercooler is not that big...its size of a stock GTiR iC...damn..dont know dimensions..heehe. Yah..on 2 gen DSMs..stock boost on their t25s are set at i think 12-14 psi..so I THINK i am safe..who knows?? thanks alot for you help http://www.freshalloy.com/

AceInHole
08-16-2001, 10:30 AM
aren't DSMs 1.6L?? the SR is a 2.0 .... another obvious point. if everything is the same size it must be a leak in the wastegate or bov. . . or worse: along the piping. does it ever come under boost??

PJ

**DONOTDELETE**
08-16-2001, 10:48 AM
No the DSMs motors are 2.0 turbos as well..I use to have one but opted to go 240 w/ sr20 because I felt the 4wd tranny was the weak link.
You know what?? Sounds like I might have a leak...I'm gonna have to check it out again..hehe

**DONOTDELETE**
08-16-2001, 12:16 PM
Maybe i'm just imangining things...haha

08-16-2001, 03:14 PM
Excessive lag could be caused by an exhaust leak or an intake leak somewhere...

Asad

**DONOTDELETE**
08-16-2001, 03:18 PM
I hope thats all it is, I'm gonna have to check my car when I get a chance. By the way..the ported throttle body did make a hell of a difference on top end though.

**DONOTDELETE**
08-16-2001, 11:38 PM
I was gonna do that, too. I have an uncle that's pushing 320 to the front wheels in his 95 gst. He's looking for a 1st gen awd car now and was talking me into going this same route. I have to admit, I really wanted to, but turbo prices are actually going back up. And I know those dsm trannies in general are pretty crappy. So now that I have my S13, I'll go SR20DET.

AceInHole
08-16-2001, 11:44 PM
*cough* ka turbo *cough*

heheh

**DONOTDELETE**
08-16-2001, 11:47 PM
Stock boost in DSM is 10psi I belive. It also could be a tired turbo. My friend chnged his stock turbo in his DSM for a new one (same one) and after would reach full boost about 1000 rpm sooner and and started to spool up quicker too.

JonCarson
08-16-2001, 11:54 PM
It's not a huge deal, but in the future please don't make your topic titles in ALL CAPS. At least you didn't type your message that way....

Jonathan
Moderator

quest
08-18-2001, 12:18 PM
>>"but im still running 7psi"

if no leaks, it could simply be from too little air volume to fill the intercooler and plumbing. Ever notice the factory hardly ever intercools low boost systems ?


for the dsm comments,
how 'bout a 4g63 in an s13 ? that's what I plan to replace my ca18det/s13 with... it'll fit better than any nissan motor in a left hand drive chasis. Far easier to work on too - best little 2.0 out there, no doubt!

dsm trannies can live.... under the pedals of a sensible driver tho'. My coworkers mid 11sec awd has never broken a single driveline part - drive it like an idiot.... you'll pay!