JaysZee

I'm sorry if this has been asked a million times. The only time I had the Z at the track I was able to make 2 passes. On the first pass, the car in front of me blew a radiator and dumped anti-freeze on the starting line. They cleaned it up but the lane was still slippery. On that pass I had a 2.5 60ft and a 1/4 of 15.4 @ 95MPH. For my second pass I switched to the better lane and had a 2.27 60ft and ran the ET and MPH in my sig. I've noticed that cars can have the same ET but the MPH seems to vary some. Can someone please explain? Thanks

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1991 5.7L Z28
14.456 @ 92.78 MPH

AlkyIROC

It's hard to explain it as a simple answer other than ET depends on traction and MPH depends on HP.

The best example I can give is when my race car used to have a 383 and 3.27 gears. I would run 12.0 against other cars that also ran 12.0. Because of my poor gears, the other cars would accellerate quicker at the start line but my top end HP would start pulling at around the 1000 foot mark and we would cross the finish line at the same time. The difference being I would cross at 117 mph and they would cross at 110. The ET was the same but because of my greater HP combined with poor gears, I wasn't at the engines red line at the end of the 1/4 mile. If I had something closer to 3.90 gears, my ET would have been about 11.5 but the MPH would have still been 117 and I would have crossed the finish line at the engines red line.

From looking at your numbers you can see that the better traction from the better 60 foot time resulted in a quicker ET. The lower MPH could be from a number of reasons that gave the engine lower HP. Usually different shift points but things like engine, tranny etc temperatures, head winds, and many other variables can affect the HP of an engine.

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Follow my racing progress on Stephen's racing page
and check out the race car

87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.242 altitude corrected to 10.89
Best MPH on a time slip: 121.52 altitude corrected to 125.89
Altitude corrected rear wheel HP: 497.9
Best 60 foot: 1.546

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

89gta383

iTrader: (5)

ET is how fast you get from the start line to the finish line and is determined by traction, gearing, rollout, weight, etc.

MPH is actually calculated within the last 10 feet before the finish line by the computer, based on how fast you cover that last 10 feet. MPH is a good judge of horsepower.

I've seen cars run 12.98 @ 99 mph, and 12.98 @ 120 mph. The difference between the 2 is horsepower and and traction/gearing. The first car had a 4000 stall convertor, 4.11 gears, slicks, and was a '71 skylark. The second one was a corvette with nitrous that spun the tires off the line.

Hope this helps.

NJ SPEEDER

ET is all about the 2 great G's. GRIP= always look for perfect hook, and GEARS= the proper gearing can be worth a tenth over the next closest wrong choice.
MPH is all about HP. there is no way to fake it.

lata
tim

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91 Camaro RS-LO3,Auto.
14.209@95.46mph
Best 60' 1.917
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whiteroc

What the other guys said and...

Something else that was not mentioned is the fact that your MPH is calculated by an average of 2 speeds from crossing 2 points at the end of the track. You may very well be past the first set of lights and get a good E.T. but not a correct MPH because you didn't stay in the throttle until you past the second MPH time light. This would cause a good E.T. and a slower MPH.

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89 IROC-Z 5.7L
130,000 MILES
2.77 GEARS
K&Ns FILTERS
ALL FREE MODS
FLOWMASTER MUFFLER
PERFORMANCE RESOURCE CHIP
Best 1/4 E.T. 14.37 @ 95 MPH
Best 1/8 E.T. 9.22 @ 76 MPH
Best 60ft. 2.07

quickL98

iTrader: (2)

thats pretty weird ****. i know extactly what you mean though. when i stalled it up in my car i obliterrated my sportsman's and ran a 13.34 @99.6 mph then when i just rolled out at 1000 and nailed it bogged then spun but i moving the whole time rather than just sitting there and spinning , and ran 12.9 @ 110.5. i couldnt believe i picked up 10 mph from that, and i was still spinning both times!

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87GTA ,10.5:1,4-bolt 355,afr 190's, super ram ,stock poerted base,58mmTB,24 lb FMS inj. ed wright chip, .510/230 (nr) 1&5/8 hooker shorty's, flow master single 3", 2800 ameri-torque non lk-up, 3.73. best to date with stk 48mm tb and lack of traction in 1st gear netted me a 12.9 @110mph /91 TA daily driver LB9 A4 2.73,
sitting in the garage : 26-11.5-16 et streets, sphon LCA's &rlb's, SFC's, b&m mega shifter....hope to install before the next century!!!

Basett_Racing

Quick L98,
Just out of curiousity, Are you talking MT Sportsman Pros?? If so, what air pressure are you running?? I was able to run 12.50's @ 108 on a set of 26 X 10.5's. And I friend of mine is currently running the size set on his 71 Camaro and has ran a best of 12.22 @ 110.8 He and I ran them at 13#, and my car pulled a best of a 1.82 60' w/ a basically stock suspension. And he is pulling high 1.70's (1.78-1.79,not sure of his best) on them. I'm not trying to start anything by no means, It just seemed strange to hear that they were not hooking.

BTW, when you do get it hooking, judging by your 110 MPH trap speed, your "quick L98" is going to be all in the low 12's , which is very quick for your mods.
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82 Z28 383, Ported 215cc Dart Iron Eagle Heads 72 cc Comb. Chambers, Comp custom grind Hyd roller cam, Speed Pro .250" domes, Wheeler Motorsports 4340 I beam rods, Eagle 5140 steel crank, Weiand Team G intake, Holley 830 DP, hedman headers
Trans: Turbo 350 w/ 4000 stall -- Rearend 7.5 w/ Richmond 4.10's, Auburn Minispool
Best ET:11.63 @ 113.25, w/ a 7.39 1/8 @ 93.04, and a 1.626 60'


89 RS, L03 305, Hypertech Chip,cat delete, Dynomax exhaust,K&N open element Filter,160 stat, MSD coil --Trans:700R4 Corvette Servo -- Rearend: 7.5 GM 3.42 w/ posi-lock
New Best ET: 14.91 @92.9
Bassett Racing



[This message has been edited by Basett_Racing (edited June 27, 2001).]