Drag Racing

[MacDee]

Okay... I ran the numbers.
From the best I can figure, based on the 235-60x14 tire size, the tire diameter should be about 32.5 inches. That computes to 102 inches per revolution (pi x diameter). At 70 mph, that would be 724 rpm at the wheel. Multiply by 4.11 for the rear end gear, and then again by .68 for the transmission (overdrive), I get 2023 rpm at the crankshaft.

This seems inconsistent with the previous calculations. Can't explain it....

[dhbfaster]

Humm...we seem to have two tire sizes in the thread (but I'm not sure that's it alone), but the tire calculator I have been using is giving a different diameter and circumference than what you are showing.
According to: https://tiresize.com/calculator/

235/60 R14 should be 25.1" diameter, 78.8 circumference
265/60 R14 should be 26.5" diameter, 83.3 circumference

If this tire calculator is correct, that might be the difference.

[MacDee]

Yeah, I forgot the aspect ratio.
Tire diameter should be 25.1 inches.
937 rpm at the wheel;
2311 rpm at the crank.

I stand corrected... as usual....

[MacDee]

I am absolutely no good at arithmetic. I goofed again!!

This time I used .60 at the trans instead of .68!!

Should be 2620 rpm at the crank!

[BadBird]

Okay you guys, this is getting over my head again. On the site I sent it said that my tire size equates to 26.5" tall. They also mention that the tire will grow in circumference as the speed increases, but this is supposedly incorporated into the equation.

If I enter in 26.5 in the charts of most of the different sites it comes out almost exactly the same at 2480 RPM at 70 MPH. Let me know if you find something else and thanks for all your help.

NOW..... Lets get more of our cars at the drag strip this year and see what kind of fun we can have. The cars don't have to be fast to have a blast. My car won't come close to the times and speeds that are listed. I would be happy if it ran in the 12's at around 105MPH. This would be a great trip for our club to go to the drag strip!!!!!!!!!!!

[MacDee]

Yeah! Using 26.5 for the tire diameter I get 2481 rpm also.
My calculations do not include tire growth, nor do I trust the tire diameter I came up with originally (25.1). There is a theoretical size that can be computed from the size designation, but in actual practice, the diameter can deviate from that by quite a bit!

[MacDee]

I would be happy if it ran in the 12's at around 105MPH.

I stumbled upon a video a while back of a 12-second Falcon. It was tubbed, and powered by a radical, but naturally aspirated, 200 six! It made a 1/4-mile pass in 12-something seconds at 98 mph. But now I when I look for that video again, I CAN'T FIND IT!!

[BadBird]

I could only find this one. Not the one you mentioned though. Larry

https://www.youtube.com/watch?v=FjQJ8btRbLY

[MacDee]

I stumbled upon a video a while back of a 12-second Falcon. It was tubbed, and powered by a radical, but naturally aspirated, 200 six! It made a 1/4-mile pass in 12-something seconds at 98 mph. But now I when I look for that video again, I CAN'T FIND IT!!

FOUND IT!
https://video.search.yahoo.com/searc...f2&action=view

[MacDee]

I would be happy if it ran in the 12's at around 105MPH.

Larry,
You have more HP than the little Falkito Falcon, so I'll predict your trap speed will higher. With the big slicks his probably launches a little harder that yours will, but, again I predict at least the same E.T. ... if not BETTER!

Go, Larry, GO!

[Luva65wagon]

Oops - I see I twisted Gary's words for Dennis's. Funny "quote" switcharoo. It was Gary saying his previously ascribed Saturn V rocket isn't quite getting the same results as that Argentine Falcon. As I look back and see, this was abouyt 4 years ago and so much has happened since then. My apologies.

http://www.rainierfalcons.com/forums...&postcount=110