Gear ratio and Tire size

zstroken said:
Burhart has stated that he hits 4th gear 4000 rpm with 33" tires. That comes out to about 38 mph if I am correct. Tomac is running 315 tires which are like 34.5" and he gets into 4th quite often. The Dmax guys love the long tracks!
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Isn't 4th gear, 4.10, 33in tire @ 4000rpm, more like 35 mph.

Tomac is only spinning about 3500 rpm in 4th I bet. = 32.5 mph
 
joeservo said:
if you think your buddies CR can spin 5k down the track, i would love to hear how your PSD pulls.
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Good point Servo.

SEOHPowerstroke, how many trucks do you think are spinning over 5000rpm going down the track that don't have Sigmas' or 12 cyl. pumps on them. I would bet very few.
 
Well yea I guess it is 35 mph. I was thinking 35" tires.

If tomac is spinning 3500 in 4th. Wouldn't that be 35.4 mph? Last time I knew he still had the 3.73's
 
From my calculator there both around 35+ Tony had 4.10s Mike had 3.73 .. They have an advantage with the A1000 IMO an extra gear over the 4LE
 
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zstroken said:
Well yea I guess it is 35 mph. I was thinking 35" tires.

If tomac is spinning 3500 in 4th. Wouldn't that be 35.4 mph? Last time I knew he still had the 3.73's
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Wasn't sure what gear Tomac was running??
 
crazy RPM. On my 12valve I was holding on average 4200rpm down right to the end leaving the line at 4800-5000rpm in 4th low, left once at 5300 on a loose track and the rpm didn't drop below 4600. Blew the tires out the whole way and landed up in 3rd but my over all speed was 4mph faster than the other two trucks. Nuts how gearing, rpm and traction work!

RyanB
 
Tcolesanti said:
I have no doubt Burkhart hits fourth gear with 33" tires but sure don't sound like he is spinning 4k in 4th gear.

-Tom
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Hello guys, Yes I have logged files showing 39MPH wheel speed running 4100 RPM's going down the track in fourth, I can look at the logged files to see what the RPM's are when it shifts from third to fourth cause i just put the silly shifter in fourth and let it eat, shift by itself. Its so easy a caveman could drive it. Shieds track was a little tighter, I was only able to spin the tires 34 MPH and RPM's of 3747, I was running out of fuel supply to the CP3's. I gained more power later and upgrades are on there way.
 
Tony Burkhard said:
Hello guys, Yes I have logged files showing 39MPH wheel speed running 4100 RPM's going down the track in fourth, I can look at the logged files to see what the RPM's are when it shifts from third to fourth cause i just put the silly shifter in fourth and let it eat, shift by itself. Its so easy a caveman could drive it. Shieds track was a little tighter, I was only able to spin the tires 34 MPH and RPM's of 3747, I was running out of fuel supply to the CP3's. I gained more power later and upgrades are on there way.
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Is this the correct set up that you have Tony or are we missing somthing.

5th/Low
RPM 4100
Gear 2.72
Tire 33 diam, in
Rear end 4.1
36.1 mph
 
Tony Burkhard said:
Hello guys, Yes I have logged files showing 39MPH wheel speed running 4100 RPM's going down the track in fourth, I can look at the logged files to see what the RPM's are when it shifts from third to fourth cause i just put the silly shifter in fourth and let it eat, shift by itself. Its so easy a caveman could drive it. Shieds track was a little tighter, I was only able to spin the tires 34 MPH and RPM's of 3747, I was running out of fuel supply to the CP3's. I gained more power later and upgrades are on there way.
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My point was the tighter the track the lower the rpm you will be able to sustain. It all depends on the sled too. I can put my truck in 5th low and carry 5200rpm on a loose track.

-Tom
 
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