Duramax/Powerstroke/Cummins Dyno

IGO1320 · Apr 2, 2017

Joey D said:
What I mean by the 90% is torque converter input vs output speeds. I'm sure at each gear change there is a small window of multiplication followed by slipping until it locks and if it won't lock under full throttle it's just slipping.
Like I said if it was any advantage sled pullers would let it slip vs forcing it to lockup.

Sled pulling is an apples to oranges comparison. I believe sled pullers lock the converter once imput and output get close rather than upshifting the trans. Drag racing you run the tranny through the gears then lock the converter, because you do gain with the additional torque multiplication on the gear changes. I do agree it is easier on everything to tow with the converter locked and the pedal off the floor. I need to say I've never sled pulled but that is my understanding, drag racing I do have experience with.

D.Camilleri · Apr 2, 2017

Oregonnovaguy said:
Here is a good little "layman's" explanation of the SAE J2807 test procedure by which the manufacturers rate their trucks for towing. This might explain why the 2017 GM 2500 and 3500 are rated the same for towing. And maybe why the Fords and Rams have a much higher towing capacity. It's not just engines anymore.

SAE J2807 Tow Tests - The Standard

Keep in mind that the 3500 dually is rated to tow a lot more than either the single wheel 3500 or 2500. Tow ratings are very easy to be mis understood. Many people have gone out and bought a single wheel 3500 only to find out they are maxxed out with any of the larger 5th wheels. This is the reason my new truck will be a dually. I want a safety margin. Then comes a new 5er.

Oregonnovaguy · Apr 2, 2017

D.Camilleri said:
Keep in mind that the 3500 dually is rated to tow a lot more than either the single wheel 3500 or 2500. Tow ratings are very easy to be mis understood. Many people have gone out and bought a single wheel 3500 only to find out they are maxxed out with any of the larger 5th wheels. This is the reason my new truck will be a dually. I want a safety margin. Then comes a new 5er.

I should have said SRW 2500 vs. SRW 3500. The main point I got from the linked article is that there are some 27 pages of criteria in the SAE procedure for determining tow ratings, including vehicle dynamics during lane changes and even holding power of the parking brake on a 12% slope! Has anyone noticed how the RAM 3500 long beds (both SRW and DRW) are very short from the rear bumper to the axle centerline? I suspect this may have played a part in them achieving the 30,000# towing capacity (DRW). I would love to see the SAE test results of all three Mfgrs. for comparison.

Duramax/Powerstroke/Cummins Dyno

IGO1320

D.Camilleri

Oregonnovaguy

Top Contributors this Month

Recommended Communities