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.

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

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.

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

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.

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

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.

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.

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

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

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

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.

yea i would expect 10s from it also

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

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...

We used to run a 454, it was bored .030, and had a little bit better cam and minor head work. It ran 4.50s in 330 ft. but was tearing the front end of the car all to piecies.

The 406 is much stronger then it though, but it has been worked on quiet a bit. Before we put the 4-link rear end, it was branging the front tires about 2 feet off the ground, and we only left the line at 3800 rpms when it did that. Now it's not as radical out of the hole, and ususally just brings the tires 4 or 5 inches. Next weekend we should get to see what the new bottom end in the motor will do. At the very least it should go what it did, but it has better compression pistons, and its balanced, with longer rods, and of course everything will be fresh. I'll post the numbers next weekend if we get to race. I would just about bet that with the right gear, the car would do low 10's, and maybe a 9.90s in the 1/4. It's pretty stout, it pulls hard all the way up to the chip we got in it (7000 rpms).

this site:

http://www.dragtimes.com/

has a couple thousand timeslips to compare 1/4 and 1/8 times....

i dont understand how they can even make a calculator to do this... Chevytrucks92 - according to the "Calculator" you can run a mid 10 with your car! i would expect better from what you were saying! well see how off the "Calculator" is!


We used to run a 454, it was bored .030, and had a little bit better cam and minor head work. It ran 4.50s in 330 ft. but was tearing the front end of the car all to piecies.

The 406 is much stronger then it though, but it has been worked on quiet a bit. Before we put the 4-link rear end, it was branging the front tires about 2 feet off the ground, and we only left the line at 3800 rpms when it did that. Now it's not as radical out of the hole, and ususally just brings the tires 4 or 5 inches. Next weekend we should get to see what the new bottom end in the motor will do. At the very least it should go what it did, but it has better compression pistons, and its balanced, with longer rods, and of course everything will be fresh. I'll post the numbers next weekend if we get to race. I would just about bet that with the right gear, the car would do low 10's, and maybe a 9.90s in the 1/4. It's pretty stout, it pulls hard all the way up to the chip we got in it (7000 rpms).


4.5 in the 1/8th on the "Calculator" it states you can run a 7.206 in the 1/4... damn thats pretty inpressive! only if the thing works right!!! which is hard to believe!

EclipseRST, I must have made a typo in my first post about teh 1/8th times for our car. We've never had the car on an 1/8th mile track with the 406 engine, but with a 355 with 13.5:1 pistons, 6 in. rods, steel crank, .630 lift roller cam, 2.05 intake 1.60 exhaust, victor jr. intake, and 850 holley, powerglide tranny and the same .513 rear end the best time we got was 6.71 @101 mph. That run had something like a 4.30 330 ET (at our track that would have been a 4.40 though). The track we race at all the time is ony 330 ft, but it is alwasy atlesat a tenth slower then every other track.

Just last night, the fastest time our car ran with the 406 was 4.299 w/1.478 60 ft, so at the track we go to occasionally that is 1/8th that woudl have been a 4.199 roughly. The fastest pass this year (we've raced the past 3 weekends) is a 4.27(can't remember the thousandths number) with a 60 ft. of 1.46. So I'm just guessing the car would run about 6.40s in the 1/8 mile. One of our friends has a Camaro and it runs very similar to our car (his best run last night was 4.280) and at the 1/8 mile track his car went a 4.17 in the 330 and 6.50 something in the 1/8th. Our car is stronger then his in high gear thouhg so I would guess 6.40s for us in the 1/8th, and according to the "calculator", that is 10.10 in the 1/4. Of course change the gear in our car and this will change everything! And anyways, it woudl never make it to the end with the .513 gear! lol.

oh i see where it was... my bad, i saw your time @ 330ft and mistakingly took that as an 1/8 mile instead of a 1/16!!! btw thats kinda weird to only run 330ft, whats up with that, why is the track so short?

Just the location of it. They used to run 440 ft, but that made it hard to stop for the faster cars. Its located in a big bottom, but the people that own the land only lease half of it, so 330 ft. is all they can run. Plus there is a dirt track (1/4 mile I believe) right beside the track.

I'd say the 1/8th times would be 6.40s though for the car. Our biggest problem is weight, lol. 2700 lbs for a race car is pretty heavy, lol. If we could shed 500 lbs, the car could run 3.90s or better in 330 ft. Anyways, it runs low 4.30s and high 4.20s in 1/16th the way it is, which is about 90 mph.