2021 Ram 3500 H.O.

4x4ord wrote:

ShinerBock wrote:


Now imagine each tune going up the Ike at 80F. What would happen? Would I need to back down the 400 rwhp heavy tow tune? No, and I could not back it down even further even if I had to. Would I need to back down the 475 rwhp tune? Yes, I would probably have to back it down to my 400 rwhp heavy tow tune shortly after starting. I may be able to utilize the the 475 rwhp on the onramp at the start of the test to get a good 30-60 mph head start, but I would eventually have to back it down to my 400 rwhp as temps got hot.

Now, will the times of my 400 rwhp tune at both temps change that much? How about my 475 rwhp tune will it's time change that much between the two temps?

I’m not sure what you’re trying to say .... if you ran your 400 rwhp tune up the Ike with 30000 lbs in tow on an 80 degree day vs a 30 degree day, do you think your times would change much?

Not nearly as much as it would versus running the 375 hp tuned engine at 30F and then having to back down to 400 rwhp at 80F run. I am not trying to bash your favorite truck or anyone else's Super duty. I am just saying that from my experiences and knowledge of electronically controlled diesels, the high power rated engines generally back down to the same power levels as the lower power rated units under sustained loads.

A plus for the Powerstroke is that unloaded or loaded with really cold temps, it will be quicker since the Cummins(even though it is the slightly bigger engine) cannot make more than 400 hp do to the max amount of fuel allowed in it's tuning. The PSD can make up to 475 hp due to a higher amount of fuel allowed in its tuning. However, that changes as temps rise. The Cummins is already at the conservative safe limits while the PSD will have to decrease its fuel to get to safer limits.

Tuned and deleted, the Powerstroke and Cummins make about the same amount of horsepower at the wheels which is roughly around 525 hp (@ 600hp at the crank). They both have the same fuel pump now and deliver the same volume of fuel, but both are limited by their turbo. The CP4 can get you up to around 600 rwhp until you start running out of fuel. The older CP3 on the Cummins was able to pump more volume of fuel and limit out around 700 rwhp. Change the turbo on either engine(like I did) and you will more hp and/or be able to run the same hp at safer temps. The new L5P Duramax tuned and deleted, can get up to around 550 rwhp deleted, again due to it's turbo and intake design.