I was just curious what sort of HP/TQ you diesel guys are making, and what final drive ratio you are pulling the sled with.

For comparison......My puller is a '77 Chevy K-30 with a 454 (gasser).

I am at about 500hp/500tq +or- pulling the sled, with a 28.76 final at approx 7,000 engine RPMs.

This, according to the sled operators, gives me about 19MPH max sled speed.



Also, who on here sells the oversized axle shafts for the 11.5" AAM rear? I believe it is one of this site's supporting vendors.

Thanks,
Eng

that Dirty Hooker Tony):h

Here is a hypothetical for you: If you are running 33" tires, most do, at 3800rpms, in low lock and third gear....You would be at 26.08mph and 14.3 final drive ratio.



If you have enough to hit hero gear, ie 4th at say 3200, you would be at 29mph and 10.01 final drive ratio.


hope this help.;)

My open stock truck is at 27.2 final with 35's on it, probably around 600hp. All of the diesel trucks run some wicked finals in them!

Like Zeb said, Tony Burkhardt has the big shafts for the AAM.

I run 12.403 final drive at around 32mph wheel speed

How do you calculate the final drive ratio? And what do you learn from this? THANKS for teaching me something- Steven

Final drive is the transmission gear ratio x transfer case gear ratio x rear axle ratio.

In the case of my truck I pull in 1st gear on my SM465......not granny, but the actual "1" on the shift knob. My NP205 transfer case is in lo-loc as well. My truck has 4.10s in the pumpkins.

3.58 x 1.96 x 4.10 = 28.7688.

My truck is a manual, so assuming no clutch slippage you should be able to caluculate rear axle RPM just simply by dividing engine RPM by 28.7688.

Pro-Fab makes a regear kit for the SM465, so I hope to someday go to 5.38s in the axles, and change the tranny to give me a final in the 26:1 range. The awesome thing about the Pro-Fab gears is the fact that all three tranny gears are usually within 1 full number on the final so a different gear can be selected that changes you from, lets say, 25:1 in granny, 26:1 in 1st gear, and 27:1 in 2nd gear. 3rd gear still remains direct like it always did. All those final drives are available just by moving the shifter on the transmission.

This in no way makes a streetable 465 tranny, but for the track it is perfect if you need to drop a slight amount to get a little more from your truck on a "biting" track, or need more wheel speed to gather momentum.

Also, what kind of torque are you guys making to get to the 14:1 final drive?

The big diesels are 1200-1500 ft/lbs

Torque is close to double the HP numbers in diesel trucks.

Here is a hypothetical for you: If you are running 33" tires, most do, at 3800rpms, in low lock and third gear....You would be at 26.08mph and 14.3 final drive ratio.



If you have enough to hit hero gear, ie 4th at say 3200, you would be at 29mph and 10.01 final drive ratio.


hope this help.;)


can i ask how you are coming up with them numbers
how do u get final drive and wheel speed im still confused

thanks

can i ask how you are coming up with them numbers
how do u get final drive and wheel speed im still confused

thanks


Final Drive=Transmission gear ratio (changes each time tranny shifts) x Transfer Case ratio x Ring and pinion ratio.

If you know your engine RPM's, Final Gear Ratio, and tire circumference (which can be calculated using the diameter), you can figure out your wheel MPH.

mph = (rpm x tire diameter) / (gear ratio x 336)

Remember, "advertised" tire diameter and actual tire diameter can vary quite a bit.


I know each sled/track is different, but I wonder what the average difference is at 270 feet between sled MPH and wheel MPH.......

ok i was doing final drive right then, the numbers i was getting just seemed wrong for some reason, but now i know how to do wheel speed

do u use the same 336 all the time even if u were to switch gears to say 4.10s


thanks alot

Yes you use 336 for all gear ratios. I am running a 12.4:1 final drive with 33" tires should run 4200-4500rpm down the track.