(Z31 10psi) 248rwhp, so what?

[revlis240]

hey guys,i have yet to make my big ole post about my long KAT process, which i think can help a lot of you guys, but i have a question in the meanwhile. i notice that all of us talk about who made what horsepower. see the thing that concerns me is this. with my old 60mm exhaust, i made 248rwhp on a dynapack. (members.aol.com/revlis240/dyno.jpg) but see, even tho i can claim 250 hp, the car really isnt that fast. look at the torque curve, see how sharply it drops? im wondering how this compares to other kat's and what ive done wrong for it to be that way. dont get me wrong, the car is fun to drive, but above 5500, its useless. how am i supposed to hang with a SR/FC/whatever, if ive basically got no top end? i guess i have to upgrade the turbo w/ a t4 50 trim wheel to get better top end or something, but i didnt realize it would be this bad, even at 10psi... the lack of top end reflects on my 1/4 times, which are in the high 14s w/ the old exhaust, and maybe mid to low 14's with the new exhaust, but still shy of my 14.0 minimum goal. iirc, i ran 14.8 @ 94mph w/ a 2.2 60' at an ok but high elevation (4000 feet) track...

heres the basic setupZ31 turbo9.5:1 rebuilt stock ka2.5" downpipe, no catslog mani85mm hks hi powerlog mani370cc injectorsjwt ecu, 18º base timing (or else it pings)

thoughts?-Abe

[Silent Drifter]

I dont know about a ka-t yet but even with my stock ka i shift at 5500 just so i stay in the power band. O yea try an get your 60' faster, an thought of gettin a lsd, or fmic?

[:: orion ::]

Couple things...

I'm not familar with the dyna-pack, but the graph says flywheel HP...so take out 15% and you're looking at 210rwhp...quite low for 10psi.

I was gonna guess that the Stage I exhaust setup on the T3 was causing the loss (choking), but this last weekend I got pulled on by a guy with a very similar setup to you...

I'm running a T3/T4 (57 trim, .63 turbine A/R, Stage III wheel), RevHard manifold, and 8psi...he was running 9-10psi with a T3 and JGS manifold - My car did have 300extra lbs in it, but his top end was just fine...it was quick.

Have you checked your timing with an MDM Techtom or anything...? The ECU could be pulling timing for some reason - Maybe bad knock sensor, maybe faulty temp sensor...???

Dunno...???

Have you checked compression? What cams do you have???

Good luck - Brian

[95_240sx]

Blah, JWT Sucks, get a stand alone and you can do whatever you want...

Rick

[Nathan]

Looks like the 232/232 cams...drops off up top. BUT, it still doesn't explain the relatively low amount of power your putting down. Compression check?

[ADAMHU]

i shift at 5900 and can smoke 99% of the cars that come out road racing in our race series... the KAT is fine...

and after driving 3 sr's now... the KAT would decimate them all ..hands down..

[Flamereka]

maybe is the turbo choking your engine? do u have any thing to see if the it gets richer at that point? cause if it is choking your engine u should notice really rich conditions.

[TrunkMonkey]

hey abe, did you ever get this detonation problem fixed? what year Z31 t3 are you using? do you have any pics of your setup? try to give us more details as to what's going on.

-demetrius

[revlis240]

i solved the detonation problem by basically backing the timing to ~18º, making the car slower, but what can i do. im using a 1985 T3 off the Z31. i will take more detailed pics and do a writeup for all us Z31 guys asap...

-Abe

[Und3rprshUr]

Your problem is the turbo.. seen the exhaust wheel on that thing ?

I have pics..

[revlis240]

well then how come tony with the same turbo is having such good results? im down to blame the turbo, but i cant justify it if the same dang thing is doing so well w/ someone else...eh?

[240nismo]

well a turbo from an 85 has a LOT of time on it...might not be in its prime!

[float_6969]

It is straight up the turbo you are using. Those things are small. They only ran about 4lbs on the Z31's. Trying to run 10lbs through it isn't a good idea in my mind. I think it's only a T25. I mean, the SR STOCK uses a T28. Most companies that build turbo kits for the KA use a t3/t4 or a T04. I think the turbo that comes with the NSport kit is a good turbo and I've never heard anyone complaing about it. It was modified SPECIFICALLY for that motor. A 2.4L L4 is a decent sized motor and moves alot of gasses. I'll bet that if you turned the boost down to like 5lbs, it wouldn't do it as bad. I just rode in an anniversary edition Z31 today so it's pretty fresh in my mind. Those things were sorely under-turboed. Even the Z32 had 2 T28's. The Z31 only has one T25. Too much boost and not enough turbo is your problem.

[Xero]

the 85-86 Z31s have T3s, it's NOT a T25, and shouldn't be running out of it's efficiency

[revlis240]

nissan used a T3 (.63ar exhaust, .60 compressor) from 84 till 86 man, the later 87 and 88's were the T25, "0-30mph performers". also, the SR uses the T25 for the S13 redtop/blacktops. and lastly, if you read orions post, tony with my **identical** turbo, (Z31 t3 read: identical) is pulling pretty hard. how can i blame the turbo now?

-Abe

[Und3rprshUr]

Every car is diff. you can't build to of the same and have them perform the same.

me and my friends all have Z31's i would pull much much stronger than them but i had a rebuilt unit and a rebuilt motor as they didn't. I was running 10psi on my 3.0 with it. although it generated so much heat it was rediculous. due to size and lack of flow.

Since you have a t-3 set-up why not have them modify the stock turbine housing to accept a t3/to4e 50-60trim with a larger exhaust wheel.

[Und3rprshUr]

Abe- also how is your boost controller set-up ?

where are you getting boost singnal from for the controller ?

hit me up on aim: ZUnd3rprshUr

[float_6969]

Well I stand corrected. Thank you. I was under the impression all the Z31's had T25's, thanks for updating me. A T3 is a lot better, but still small for that kina boost isn't it? What was the stock boost on the Z31? Are you using the stock cams? How do your A/F ratios look up top?

[Xero]

the T3 was built for the 3.0L of the VG, it'll be easily adapted to a mild 2.4L with good results. It's aspect ratios aren't very small, .60/.63 IIRC.

[float_6969]

Thanks Xero. So with a rebuild is it a good idea to run with the KA? If so, what would the max boost be? Anybody have any effeciency maps for these?

[revlis240]

im using the stock ka 92 cams, which are hotter than tonys (s14 that im raving about). stock Z31 boost is ~6psi w/ no IC or BOV stock on that car. A/F up top was 10.5-11.5 from 4k to redline IIRC...bit rich, but keeps the detonation down (i had jwt tune the car)

-Abe