1/4 mile vs 1/8 mile times

[dhughins]

Does anyone know of a calculator to convert 1/4 mile times to 1/8 mile? The only tracks around here run 1/8 mile and I would like something to compaer it to.

[kaoru-tochiro]

there is a progressive difference between 1/4 and 1/8 acceleration rates, so the results would be erroneous.

[redimpss5]

my car in the 1/8 mile runs the same e.t. every time. if i run the full quarter, it varies! it could be the way the cam comes in or something, and i dont know if all cars do that or not, but because of what i see from car, i would say its hard to calculate.

[Modeman]

Most use

¼ Mile ET = (1/8 Mile ET + .22) / .655

Here are a couple

http://www.tciauto.com/tech_info/calculators.htm#3
http://www.velocidad-maxima.com/calcu/calcu.htm

[JekylandHyde]

There is no way to have a "Calculator" that would work for every car or even the same car on every run.
Power is not that linear and not all car make the same amount of power at the same points in the rpm band.
... even tire size will play a role. Depending on set up you may or may not have to shift another time at the top of the track.

The best an 1/8 mile time will get you is a "ball park" possiblity of what you can run based on your car on past 1/4 mile runs or on similar cars/set ups.

[leew347]

would it also depent on the gearing and aerodynamics of the car

[JekylandHyde]

Originally Posted by leew347

would it also depent on the gearing and aerodynamics of the car

.. and altitude .... and humidity ... and ambient temperatures .. track surface ...

I wish there was such a thing as a good 1/4 (or 1/8)-mile calculator, but there are just too many factors involved - particulalry if you want to be able to compare different cars.

[4ss4s1n]

Theres got to be a calculator for this SOMEWHERE.That calculates the humidity,track temp. and all the sorts.I can see it in the near future.

[ridge_runner]

i doubt it.. maybe jus maybe if they ask you detailed questions about your engine, but other then that theres no way,youd be better off tryin your luck with a stop watch and a friend and a 1/4 stretch

[ridge_runner]

there is no way.. and if there was i bet its wrong

[ridge_runner]

what kinda vechical do you have and whats done to it?

[chevytrucks92]

We've got a 1972 Chevrolet Vega, it weighs around 2700 lbs, has a 406 small block Chevrolet. The shop that did the engine estimated about 550hp anywyas, We've never run the car at a 1/8th with this engine (used to run a 355, best ever time in 1/8th was 6.71 @ 101 mph) but run it all the time on a 330 ft. local drag strip. My question is about what could I expect this car to do on a 1/8th and even maybe a 1/4?

Some info about the car: 31x13 in. slicks, .513 rear end, powerglide transmission, roughly 2700 lbs, 406 with 5.7 in rods, steel crank, big double hump pistons, not sure of the compression, but they are big, .630 lift roller cam, Dart II aluminum heads, 2.05 intake and 1.60 exhaust valves, fully ported, and a Holley racing carb. (something like 840 cfm, or maybe 740, can't remember now) Anyways, the shop estimated 550 hp, maybe more, and its best 330 ft. e.t. (before overhaul, engine was overhauled this winter, also was balanced, was prevousily un-balanced, and the pistons are slightly bigger compression) was 4.25. The old 355's best was like 4.40s and it run 6.71 in 1/8th, so I figure this car should do atleast 6.50s, and probably go low 10.0s in 1/4 with a .456 gear, but def. not the .513. Any thoughts would be appreciated! Thanks.

[ridge_runner]

yea i would expect 10s from it also

[chevytrucks92]

10-4, thanks. That's about what I figured.

[ridge_runner]

anytime...i kno someone who has a vega with a 454 with barly anything done to it runnin like 11s or 12s,i 4got what he said...