According to this site, my RPM would be 2481 @ 70MPH
with 265 60R 14 tires and .68 transmission ratio with the 4.11 gears.
That works well for me.
Larry
http://www.csgnetwork.com/multirpmcalc.html
According to this site, my RPM would be 2481 @ 70MPH
with 265 60R 14 tires and .68 transmission ratio with the 4.11 gears.
That works well for me.
Larry
http://www.csgnetwork.com/multirpmcalc.html
Larry Smith
1964 Futura
347 stroker
That tool is definitely simpler. I plugged your tire size into the other one just to see if I would get the same answer and I did. It is kind of cool to push the throttle up and see what happens. With 400hp, tach at 4237, if your car is 3000 lbs, you're running 119.52. I have no idea if I did any of this right but I'm starting to think after I finish Granddad's falcon, I'm going to need another one so we can race each other.
Don Bartlett
Federal Way, WA
61 Four Door Sedan
144-6, 3 on the tree
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....
Gary MacDonald
ROGER's...
EX... '63 Hardtop
Had...
Scarebird front discs
200 w/ CI alum head
C4
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.
Don Bartlett
Federal Way, WA
61 Four Door Sedan
144-6, 3 on the tree
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....
Gary MacDonald
ROGER's...
EX... '63 Hardtop
Had...
Scarebird front discs
200 w/ CI alum head
C4
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!
Gary MacDonald
ROGER's...
EX... '63 Hardtop
Had...
Scarebird front discs
200 w/ CI alum head
C4
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!!!!!!!!!!!
Larry Smith
1964 Futura
347 stroker
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!
Gary MacDonald
ROGER's...
EX... '63 Hardtop
Had...
Scarebird front discs
200 w/ CI alum head
C4
Tire growth!! I never thought about that!
Just like the dragsters.
Don Bartlett
Federal Way, WA
61 Four Door Sedan
144-6, 3 on the tree
Gary MacDonald
ROGER's...
EX... '63 Hardtop
Had...
Scarebird front discs
200 w/ CI alum head
C4
I could only find this one. Not the one you mentioned though. Larry
https://www.youtube.com/watch?v=FjQJ8btRbLY
Larry Smith
1964 Futura
347 stroker
Received the 9" ford housing and axles today along with the backing plates and bearings. I don't have the money to get the third member yet, but will have plenty to do over the next couple of months.
I need to paint the housing and get it installed. Install the line lock assembly and drive shaft loop.
I am ordering a shift light tomorrow and hope it isn't too hard to understand the installation. I hate electronics and a lot of you can remember from my thousand questions during the build of my Falcon.
Hope to get the 3rd member ordered after the first of the year and will go with 4.11 gears with the trac-loc.
Larry
Larry Smith
1964 Futura
347 stroker
Sweet...throw us a pic when you have a chance.
Don Bartlett
Federal Way, WA
61 Four Door Sedan
144-6, 3 on the tree
Gary MacDonald
ROGER's...
EX... '63 Hardtop
Had...
Scarebird front discs
200 w/ CI alum head
C4
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