WS6.Jay

iTrader: (2)

UPDATE: Race Weight including driver for this run was 3830lbs :UPDATE

I am trying to figure out what the deal is with my times from saturday, it seems like I should be in the 11's. Is it just weight?

Full weight, spare and all + 240lbs driver
All my mods are in sig, for the track I threw on stock 16" wheels w/ M/T ET Streets 26x10.5x16.

My best time of the night:
60' - 1.71
1000' - 10.410
1/4 - 12.43 @ 112

The printer was broken so all the slips were hand written and they didn't provide 1/8th or 330' info.

My pinion angle is set at -3.5*, I twisted my driveshaft on my last run with 30 minutes left of racing, I don't think my pinion angle had anything to do with it, I think it was just that I deadhooked from a better burnout. I still have stock panhard bar and control arms. My car is lowered only 3/4" or so from removing the rear isolators and the fronts koni's on the lower perch. My shock settings are:
Front - 4.5 clicks from Full hard
Rear - .8 or .9 turn from Full soft
Stock springs

The only thing I can think of that's adding .5 to 1 full second to my time is the weight of the car or possibly my shifting but it doesn't seem like it would add that much. I think I shift pretty well for not powershifting. I weigh 240lbs + the added weight of my 3pt SFC's + the added weight of my UMI tunnel mounted torque arm + the weight of the Moser 9". I also have been running on 17x9 TT2's in the front.

I put down 406rwhp/374rwtq in mid December 06'. Before the cam/sfcs/tq arm/shocks I ran a 13.2@105.

What do you guys think? Is it my setup? Is it the weight? Possibly the shifting? Or is it something deeper?

Old Geezer

iTrader: (3)

In reviewing the info I have, it appears you have an issue with the 60' time. A car with the chassis set up at max efficiency, should show approximately the following times, based on the trap MPH you provided.
60'=1.58
330'=4.76
660'=7.47
1320'=11.75
1320' MPH=112.2
Comparing these to your results, indicates to me that the car is losing the ET during the first 60'.[And, on the other segments, too.] The terminal MPH appears to be close, so HP is not the issue. Until you increase the HP, the trap speed won't go up.

If the car "dead hooks", then I'd do more runs, keep records, and look at segment times, to see exactly where the fault[s] are.
It could be leave rpm, shift points, torque range on the engine combo, weight vs torque, etc...
Obviously, a lighter car will accelerate quicker, given the same circumstances.

Bottom line.. work on the short time, and get it to the absolute best you can, thru experimentation.
Data logs are a great tool to use for comparison, as is a weather station.

WS6.Jay

iTrader: (2)

Thanks for the info, I had been leaving at 5000-5500 for all my runs early in the night including my best one, but I wasn't able to keep the car from bogging which I thought I should be able to do. So on my last run of the night when I was almost out of gas, I did a very nice burnout, rolled forward, held it at 6200rpm and dropped it and hammered the gas, started bouncing off the limiter and I wasn't going anywhere, let off and shut off the car and I hear this clank clank clanking sound and my driveshaft twisted completely in half. Do you think that 15" wheels w/ some ET drags is what I might need to pull off that kind of 60' or should I be able to get there with my current setup? I'm waiting on my new driveshaft to come in and i'm thinkin about ordering LCA's and relocation brackets before the next track day.

Old Geezer

iTrader: (3)

That problem w/ the driveshaft is common, once the hook gets decent..My driveshaft guy, [PST, in Fl.] tells me that 8 of 10 stock driveshafts, from F-bodies, that he tries to balance for vib problems are bent. Excessive torque application, and exceeding the critical speed, will assure a short life.

If the hook is so good, that the engine is bogging, I'd look at some datalogs.. Pulling timing? Fat?, etc. A 26" tire, and a 4.11 gear should not be a cause, unless the car weighs 4000#.. You don't say what the car weighs, so I'd guess at 3700?? Putting it on a diet would definately help.. How far do you want to go??

Hitting the rev limiter:
Clutch slipping?
Wheel hop?
Wheel spin?
What material is the flywheel?
Maybe a few videos will help look at suspension behavior.
9" wheels on the ft are about 4" toooo wide!
Lots of unsprung wt there.

As for 15" and slicks.. We did some tests w/ M/T engineering, some yrs ago. With the limited HP we had in the test mule, the ET Streets actually went slightly quicker than the slicks..[The car was fully instrumented for accuracy.]

HTH,

Back to

WS6.Jay

iTrader: (2)

Heh, I think you may have misunderstood me... I twisted the driveshaft IN HALF. That's why I was hitting the limiter cause all of a sudden the engine was only spinning the tranny. The clutch was grabbing very well, I didn't notice it slip at all.

Actually the new driveshaft I ordered this weekend is from PST and shipped today. The 3.5" Aluminum one rated at 1200hp is the one I ordered, shouldn't have a problem with that one right?

Well I don't really have any software for datalogging. I had the car tuned by TSP in Lubbock, TX. I have some videos of my car from the runs but they were at night time so all you can see is tail lights, wouldn't help ya much. I think i'll try to find some skinnies for the front.

I had wheel hop one run but not any of the others. I can go weigh the car anytime at a meat packing plant here. I have no idea of the actual weight but i'd guess 100lbs added to the stock weight + 240lbs driver. When the car was dynotuned back in the middle of December 06', there was no knock retard and it was tuned pretty much completely flat at 13:1.

As far as the diet goes, I looked over the weight reduction thread and I don't mind removing the seats and spare/jack for the track but other then that I didn't see anything else that appealed to me for my DD cause the rest are pretty much permanent. Oh and the front swaybar, I wouldn't mind removing that for the track.

tektrans

iTrader: (23)

Your 112 mph might be because of the weak 60'. With a better 60' your mph might go down. I still think you can sneak into the 11's.

WS6.Jay

iTrader: (2)

Update, I got my car weighed today with the same amount of gas as I had at the track 2 weeks ago and my race weight that night including driver was 3830lbs.

So given this new information, does this run seem about right or should I be lower?