Top Speed in Acceleration Event

[Dan Deussen @ Weber Motor]

I was wondering what kinda of top speeds people datalog during acceleration runs. We (SVSU) just datalog engine stuff and when I do the match based on rpm, gearing and tire diameter, we hit just around 70mph across the finish line. How does that compare to what everyone else runs?

[Colin]

we usually hit around 116 kmh (72mph) but have gone over 120kmh before (75 mph)(acording to our wheel speed calibration)

[Kerry]

70 MPH seems a little fast... in our fastest run this year (4.17 sec) our car was doing ~55 MPH across the finish line.

[Dan Deussen @ Weber Motor]

Kerry,

I don't hink your 55mph figure is right. You cannot do a 75 meter run in 4.17 seconds and only peak out at that speed. Your car was less then one tenth faster than ours so unless you made up all your time at the launch your trap speed should be higher than 70 mph. We even logged over 65 mph in rain.

How did you log this number?

[Buckingham]

We've hit 60 to 65 mph running ET's in the low and sub 4's. We use a Stalker 5000 Radar gun for trap speed and a MyChron Beacon at each line for ET.

[Kerry]

Dan,
Unfortunately I do not have my data in front of me to double check my numbers, but I will be sure to do that tonight. We are using a DAQ with a magnetic-type sensor and two magnets to compute wheel speed and although we have never checked the accuracy of our method, we have never noticed (or had reason to doubt) any large errors with our wheel speeds. I will look into this a bit, however.

[Underthefloor]

This is slightly off topic but I was wondering if anyone is willing to share what their slowest speed was durring autocross or endurance.

[CMURacing - Prometheus]

yea. we stopped after a spin, so our low speed was 0 mph.


ahh, late night fsae humor.

[BryanH]

Daniel, On a 1/4 mile E.T. is a measure of launch eff.
MPH @ finish line is almost entirely a measure of horsepower/weight. You can have low ET and low MPH.
The science behind pro drag racing is a whole other world I know zilch about. BUT the dyno shop where I spend a fair part of my life is owned by Mike Stewart, who has run drag & speedway cars for 35 years, mostly Top Alcohol. In a recent US mag an Aussie crew chief of a leading pro team was asked how he got interested in drag racing. he replied " I used to race home from school, grab something to eat and ride around to West Torrens Dyno to see what Mike was working on"
They used to fire up the engines quite often late at night and Mike remembers him as the kid that could tell him which engine had been running the night before- from about 3 miles away!

Mike would tell you it's all in the chassis.

[Kerry]

I now have my data right in front of me...

Our fast run (4.170 sec) had a speed across the finish line of 59.04 MPH. Our other runs were 4.355 @ 58.20, 4.407 @ 56.43 and 4.350 @ 60.58 MPH.

So it looks like my memory was a little under the actual numbers, but it also looks like top speed and ET's don't go hand in hand... interesting...

[95M3Racer]

Its very dependant on the pavement and tire setup quite frankly. The pavement in MI SUCKs! We did a LOT of acceleration testing, however our mistake was we only used one slot of pavement, and we'd consistently get 4.01's. Oh well, i guess there's alwasy a vriable you cant control.

[Timmay!]

I drag race quite often...

Heres a good rule of thumb.

If you hook up at the launch, your MPH will be LOWER than if you were to spin on the launch and cross the traps at a higher ET.


I cant get my truck to hook for crap.. its a 97 Dodge Dakota Club Cab and its best is 12.42@114.8MPH

Yet, I can race 11 sec cars on the interstate and blow their doors off...

I hope this helps out.