So, I recently went out to the track with my single turbo G35 (low boost, 354 whp as of July 2010) and the results were pretty disappointing… namely, I was trapping only 102 mph. Prior to the turbo I was trapping about 99 mph usually, and now I’ve only seen a 3 mph increase after an additional 100 whp was added to the car (with that whp, I should at least be trapping 112 mph…).

Also, the launch was good; I pulled a 2.1 60-ft. time easily and had no wheel hop, or really any wheel spin for that matter (which might be strange too, not sure…). I’m on Federal 595ss tires, a week earlier I added the SPL differential bushing too (eliminated all my wheel hop). But, regardless, the 60-ft. time should really have little bearing on my trap speed.

As for the clutch, I’m running the original OEM clutch and flywheel, roughly 90k miles on it too. Now, I know that should be an instant red flag, 90k miles on an OEM clutch and pushing an additional 100 whp and 100 torques on it, it’s pretty easy to blame it on the clutch. However, I’m not noticing any obvious signs of slipping or anything, everything seems normal. When my brother’s single turbo 350Z was slipping, it was super obvious as you’d run 2nd and 3rd gear to redline and only be at 60 mph or so. That’s not happening with my car, it feels like its grabbing and not leaving anything on the table.

Could it just be in its initial stages of slipping? Is it possible it’s slipping under certain temps/conditions only?

Just want to know if there’s anything else I should look for, or if the clutch is the real culprit?

Thanks!

 

It's possible that it is only slipping under heavy load in high gear. It's easy enough to tell by just getting out to the highway and boosting it hard in high gear. If the tach flies and you'r not really movin, there's your answer. But yeah, haha, red flag. Time to change that bad boy out anyway.

 

Thanks!
Yeah, I’ll be replacing it soon anyways; I just wanted to hear a few opinions and confirm that this was the issue that caused my trap speed loss, and there’s not something else I should be looking for.

I’ll try a pull later today maybe…

I’ve already got a new Exedy Stage 1 clutch sitting in the garage, just need to pick up a flywheel now…

 

So, just an update, I’m getting ready to replace my clutch and flywheel in the next week or so…I picked up an Exedy stage 1 clutch and I’ll be ordering a Jim Wolf Flywheel later this week, then the install will commence… I’m going to also picking up a chromoly clutch pivot ball and stainless steel clutch line.

I'm really hoping this is the solution to the terribly low trap speed…because it really doesn’t feel like its slipping.

 

Put it on a dyno if the clutch doesn't help. I've trapped anywhere from 108 to 115 with TT's pushing >400WHP. Sometimes tracks/days are slow...maybe you got alot of heatsoak as well.

Unless you're running slicks/DR's the fact you have no wheelspin issue concerns me a bit... I always struggle to stay planted in 1st and 2nd, and sometimes going into 3rd if I shift too hard... even with NT555 275's

 

Yeah same thing had me puzzled too; I was cutting 2.1 sec. 60 ft. times with no wheel spin. I’m running Federal 595ss tires, 200 threadwear (245/45 18's), really nothing more than an aggressive summer tire. I was launching between 2,500 rpm and 3,000 rpm, since the tires weren’t spinning I was almost ready to dump the clutch at 5,000 rpm to see what happened, lol… one thing to note, I did install an SPL solid aluminum differential bushing and that helped tremendously with wheel hop, but still no tire spin, and even now if I floor it around 3,000 rpm in first gear, I have no wheel spin.

About 1,000 miles before I hit the drag strip I made 354 whp on the dyno, it seemed like it held fine then.

 

Threw a quick video together the other night, car felt sluggish again…in the first clip, I started off in 1st gear and cut at just over 100 mph at the top of 4th gear. Based off the factory gear ratios the top of 4th gear should have taken me to 115 – 117 mph…I think the clutch is slipping pretty bad…

http://www.youtube.com/watch?v=KRCYSLo7vrg

RPM 1st 2nd 3rd 4th 5th 6th

6200 37 60 86 109 139 175
6300 37 61 87 111 141 178
6400 38 62 88 113 144 181
6500 38 63 90 115 146 184
6600 39 64 91 117 148 186