81Z28355

Well i went to the track this past fall with my 81 Z and have been woundering why my MPH is so much slower than the LS1 - LT1 cars.

well this is what I ran on a 265-50-15 cooper cobra radial's

60' 1.84

1/8 8.45

1/4 13.34

MPH 99.7

I do have a 3000 RPM stall, but its one of the 300 B&M ones I am concerned that it is slipping and thats why my MPH is so low. Any Ideas? Does my 1/8 mile time line up with my 1/4 time?

94GrayV6

Your 1/4 and 1/8 ETs line up pretty well, but your MPH is about 2 MPH low. It could very well be slipping at the big end.

scott9050

I would say that converter is a stalls a little too high for your hp levels. If you are going to upgrade your engine then keep the converter, if not then go to a lower 2400-2600 stall speed to help with your mph.

81Z28355

I do intend to upgrade of perf. I have a decent head and a good bottom end. I have sportsman II heads stock out of the box and all forged internals with wiesco pistons, it figures out to about 10.6:1 comp. I'm trying to decide right now what path to take.

1. Port the darts and the RPM perf. and install a bigger cam

2. put on a set of AFR 195 or 210, Victor JR. and a Solid roller

The car runs pretty good for how heavy 2nd gens are and how small of a cam I have 223in 231 ex. @.050 and 465in and 485ex on a 110 center.

My goal is a 11.99 in the 1/4.

scott9050

What gears are you running and do you have a posi rear? My only other thought is how old is your tranny? I'm wondering if it's starting to slip a little internally or not.

81Z28355

I have a 3:73 rear gear with 26" tires and A Auburn posi. The tranny is a 350 turbo that has the added clutches and a shift kit. Only 1000MI. I Just put Nitto 555R on the back 275-50-15 so I hope to lower my 60' this spring. I has 21 gallons of gas in the car for traction on my last trip.

WS Sick

I think its your car weight thats making the mph appear low. if you plug your #s in, youll see youre making plenty of power .

81Z28355

I agree the car is heavy I have never put it on a scale, but its just the way it came from the factory. I did have some trouble with wheel spin, I was running Cooper Cobra tires and had to fill the gas tank to the brim (21gal) for traction. I put on a set of Nittos in the fall 275-50-15 I really hope with a empty tank and the sticky tires that I will get a 12.99 out of it. I have also added a Xpipe this winter, so I'll have to see if that helps. I may also try running open header on a couple of passes.

WS Sick

I agree if you were on street tires you have a tenth or two in traction at least. Weight is like hp.