Need some help/ideas...can't get any better than 13.7..

[MunsonAuto]

Hey guys and gals,
For those of you that don't know my setup I've got a 1991 Nissan 240sx with a 2003 5.3l, stock cam & heads & bottom end, flex fuel injectors (33lb/hr), 99 LS1 intake, true cold air intake (plumbed below bumper), "tune", 99 T56 (stock gears), Monster Stage 3 6puck clutch with 15lb chromoly flywheel, stock 4.08 geared 240sx rear end (welded diff.), long tube headers, true duals, 3" exhaust up to the high flow cats, 2.5" exhaust after the cats, and a Dynotune 100hp dry nitrous setup. And 275/50/15 BFG drag radials.

So, I've been going to the local track since May 1st, between then and now i've added the cold air intake at one point, the nitrous, then the clutch and drag radials. Up until last night i was running on a set of 265/40/17 Michelin Pilot Ps2's. Between all the changes I've only seen tiny gains and always, always run around 14.1-13.8 @ 99-105. I've tried launching in 1st, i've tried launching in 2nd, i've tried not warming the drag radials, I've tried just about everything and can only best 13.703 @ 107.932. Spraying the 100shot last night with the drag radials, i only picked up 2 tenths!?!?!? I was spraying at the top of second once i got traction, then through third and fourth. I'm crossing the line at about 5800-5900rpms at the top of fourth.

Now my father and i and everyone else who's worked on the car are wondering if I'm squeezing the most I will ever get out of the stock heads and cam combo??? or if it's something else? Possibly a better tune? I have no idea but to me I feel with a car that only weighs 2800-2900lbs I should be running a bit better than that *shrug*.

Even with the BFG drag radials, with a good warm up, i still spin through all of 1st gear, and then the beginning of 2nd. Launching in 2nd it just spins for a while then ends up catching traction and pulling around 4500rpms.

I'm out of ideas and hoping that you guys out there will be able to help me out a bit
Here's a bunch of my times/slips:

May 22nd (Michelin 265/40/17, cold air intake, no nitrous, old LS6 clutch)
Reaction: .449
60': 2.292
1/8th: 9.237
1/4: 13.970
Mph: 104.289

Reaction: .136
60': 2.425
1/8th: 9.269
1/4: 13.991
mph: 102.393

Reaction: .583
60': 2.521
1/8th: 9.499
1/4: 14.258
mph: 105.475

June 5th (Michelin 265/40/17, cold air intake, nitrous, LS6 clutch slipping bad causes me to coast from just after the 1/8th mile. This is where last weekend and this weekend don't make sense to me at all. The only thing i can think of is i added the new clutch with the lightweight flywheel and maybe i lost some top end power with the lack of rotating mass??? But these times are with the old slipping clutch...)

First run, coasted from literally just after the 1/8th.
Reaction: .144
60': 2.311
1/8th: 9.063
1/4: 14.055
mph: 89.460

2nd & last run, car had a solid 45 min to cool down, clutch slipped again, just after the 1/8th.
Reaction: .294
60': 2.301
1/8th: 8.993
1/4: 13.628
mph: 102.023

June 19th (BFG 275/50/15 Drag radials, cold air intake, 100shot nitrous, Monster Stage 3 clutch w/ 15lb chromoly flywheel).

No nitrous runs...
Reaction: .639
60': 2.467
1/8th: 9.425
1/4: 14.264
mph: 105.248

Reaction: .124
60': 2.194
1/8th: 9.226
1/4: 14.079
mph: 98.973

Reaction: .533
60': 2.241
1/8th: 9.102
1/4: 13.907
mph: 99.050

Reaction: .368
60': 2.341
1/8th: 9.183
1/4: 13.955
mph: 103.298

Reaction: .072
60': 2.351
1/8th: 9.141
1/4: 13.881
mph: 102.972



Now here's the last two runs where i sprayed the 100shot....
Reaction: .303
60': 2.393
1/8th: 9.245
1/4: 13.915
mph: 105.915

Reaction: .449
60': 2.222
1/8th: 9.128
1/4: 13.703
mph: 107.932


So my MPH definitely increased between the non nitrous runs and the nitrous runs which makes me believe that the nitrous is working properly. But I'm still confused...
If anyone's got any ideas or tips or suggestions or anything please let me know...or maybe this is what i should be running and i'm just hoping for too much *shrug*.

I currently have a LS6 cam, yellow beehive springs, 7.400 pushrods and the rest of the goodies for the cam swap, I'm just wondering if I AM maxing out the current cam/heads or if there is something else i should figure out first. I'm thinking it might be the tune too...maybe it's time for a Nelson mail order (there's no good dyno's around here and I'm still weary about doing it myself).

Any help would be greatly appreciated guys..and sorry for the length of the post.
Thanks,
Tanner

[oleshifty]

i'd venture to say, work on traction before more power. If you can't put it down, it's not helping. Lower pressure in tires, change pinion angle slightly, traction/ladder bars, go with slicks, etc etc.

It's been a few years since I've been to the track, but I BELIEVE those are pretty bad 60' times for the setup you have.

[MunsonAuto]

There's no changing pinion angle or trac-bars with this car, it's independent rear suspension on coilovers (9k front, 6k rear rates aka stiff).

We started with 12psi in the drag radials, went to 15psi, down to 11psi, back to 15psi, up to 17psi, up to 20psi...none seemed to make much of a difference. When we were in the lower psi range the burnout was only leaving marks on the outer edges of the tire, so we bumped up the pressure until the entire middle (where the tire is more like a slick) was burning. It helped a bit but not much.
For traction it seems like our only option is going to be running slicks, which is what we thought we ordered, but there was a mix up so we decided to just try these anyway.

Thanks for the thoughts though....everything helps at this point haha.

[oleshifty]

only other thing is move as much weight as possible to the rear, battery, etc

[brobradh77]

I agree with fixing the "off the line" issue...your 60' times are not that great

[Frenchy]

maybe less spring rate in the rear, gotta get that sucker to squat down and get the weight transferred, is there any adjustabilty in the rear camber, just to make sure all the tire is on the ground when you launch? You gotta get that 60' down, it looks like mine, no bueno

[MunsonAuto]

I have very little camber adjustment with the stock control arms, but it's a tad on the negative side right now. And due to the fitment of the big 275's on stock sheet metal i can't squat it more than around an inch or so before the tires rub *shrug*. I've been debating rolling the lip so i can get more out of it, but i just got the drag radials thursday haha.

[GasGuzzler]

Every point of measurement you can look at is all over the map. Not only does this signify a traction issue but a full on suspension issue. Wish I could help more.

[MunsonAuto]

Yeah, it's not really a drag oriented suspension system..being IRS and really stiff. The car's a drift car that I'm trying to make a drag car at the same time, the main priority is drifting though, but the dragstrip is open every friday and the drift events are far and few between around here. Supposedly the stock strut and spring combo is the best for drag racing with a 240 besides serious custom fab with a solid axle, so i've been thinking about throwing the stock strut/spring combo in the rear some friday and seeing how that goes *shrug*.