Tire spin vs. mph

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500/600

Royal Smart Person
Nov 17, 2018
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West Virginia
Since forever this has been discussed, so let's talk about it some more.

I have always been told that spinning at the starting line doesn't affect trap speed mph (or kph). In the past I have never had the slightest issue with spinning at the track because the cars were always wearing slicks and set up for maximum weight transfer. With my old Skylark in the 1/8 mile, I was never concerned when I would 91.6mph on one pass and 92.4 on another, and the ET was always consistent (in my case high mph = worse ET, and low mph = better ET), but never worse than 7.41 vs 7.47 or something like that. That was until yesterday.

I left my car set up in 'road race' mode with big sway bars, coilovers set up for handling, 20" Nitto 555r, 18" street tires on the front. I literally did nothing to improve the situation for drag racing. I wanted to shake off the rust from a 6 year track hiatus and I was also interested in seeing what the mph was going to be just to punch into the Wallace calculator to see how close I was to my hp estimate.

Well, I got zero weight transfer and the car burned and shook the tires for more than 200 feet. Pass number 2 spun through second gear past the 330 foot lights. Fortunately the 18" fronts kept the car going nice and straight.
At stopped at 3 passes for fear of the tire shake breaking something because I had to drive it 50 miles home.

You can see from the 3 slips that on the second pass I spun further and lost 3mph in the process. I'm sitting here wondering what I was actually capable of from a mph standpoint...........because the ETs were going to suck no matter what with that kind of tireslickery. My thought is that if you spin 300 feet accelerating at a lower rate then I'll never hit optimum attainable speed by 660 feet. But this flies in the face of what I've always heard.

I did find this interesting article https://www.w8ji.com/tire_spin_and_...isconception,a thermostat or restrictor" myth

Does anyone have any real world experience that shows spinning and trap speed having a big correlation?

10.17.20 timeslips.jpg
 

gnvair

Royal Smart Person
Sep 1, 2018
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Southern New Jersey near Philly
I am certainly not an expert on it. But I have had cars that had high mph on crappy 60 foot times. Once the car was properly set up and the 60 foot times improved, the mph dropped several mph but the ET improved.
 

500/600

Royal Smart Person
Nov 17, 2018
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West Virginia

lilbowtie

Comic Book Super Hero
Jan 7, 2006
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Canton Mi
My car is set-up to shift @ 6200 and go through the traps @ 6200 and the converter instantly puts it in the power band . If I spin there isn't any sig difference in my MPH. You will probably see a little more change in a car not specifically set up for drag that when it spins it allows the rpm to come up faster and get on the cam. Staging your car is another variable as to how much roll out you have. I've seen the wind and the weather make changes (shows on my weather station) but in all there isn't much change because it's the last 66 ft of the run where it's measured.
 

500/600

Royal Smart Person
Nov 17, 2018
1,167
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West Virginia
When you spin, how far are you talking about? Because I’m talking about 200+ feet of smoke hazing off of the tires and backpedaling of the throttle that failed to control it.

You know that feeling that you get when you are in the water box, you pull up and start your burnout, and as the tires lose the water and you move forward you feel the rear dig in and start launching the car?

Well I got none of that sensation yesterday.

I’ll probably be answering my own question on this one by going back to the track. And that will probably be spring.
 

bracketchev1221

Royal Smart Person
Jan 18, 2018
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I have seen it where mph goes up with tire spin. I think it’s more on tight converter, low numerical gears cars where it allows the engine to speed up quicker.
 
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lilbowtie

Comic Book Super Hero
Jan 7, 2006
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Canton Mi
When you spin, how far are you talking about? Because I’m talking about 200+ feet of smoke hazing off of the tires and backpedaling of the throttle that failed to control it.

Nothing like that, and if I really loop the tires I quit which you should to. It's not worth risking an accident over a run that's useless. I switched to drag radials and have been extremely happy with them and never had a traction problem the last 2 years no mater what track. You have some work ahead of you.

 
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39F

G-Body Guru
Sep 9, 2019
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Pittsburgh PA
My regal made its first pass at 14.07 spun all the way through the traps all 4 gears on the 7.5 rear end ,slicks, 9in with 430s ended in a best of 10.35 so I'd say tire spin makes a difference lmao
 
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fleming442

Captain Tenneal
Dec 26, 2013
13,046
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My car and launch technique are scattered all over the place so far that I can't even give an answer. I've yet to duplicate my best run ever at 12.11@116. The most consistent day I've had was this summer with some 12.30s around 110-112. The track where I ran the quickest/fastest has closed, so I can't even determine if that was a factor or not.
 
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