The Big Three's New Diesels put on a Dyno

FishOnOne wrote:

blofgren wrote:

ShinerBock wrote:

4x4ord wrote:
Here's a theory. All three trucks ran up the hill in about the same time, therefore they were all three putting about the same power to the ground during the run. The Duramax likely ran up in a lower gear than the other two trucks and likely revved a little higher. If the trucks were making the power that the manufacturers claim the Ram would have been significantly behind the other two. I believe the more refined engines, the new Duramax and Powerstroke were not making the kind of power they should have because the computers were slightly limiting the max fuel delivery on account of the high altitude....lower oxygen. Maybe in order to keep emission levels in check? Obviously if more fuel would have been injected in any of those engines they would have performed better. I would really have liked to see the outgoing Duramax involved in the challenge.

I agree with you as to why the GM won over the Ram. It was in a lower gear at higher rpm making a lot more power. Although it should have been more than just fifteen seconds ahead with its rated power numbers. With traffic, 15 seconds is basically equal time in my book.

The performance of the Ford in the test is more of a head scratcher and I am still thinking it was computer programmed defueling due to high exhaust gas temps. Adding power(more fuel) to any diesel increase EGT's very quickly. With my brother's 450whp(estimated 515hp at the crank) custom tune on his 2012 F350, he can get to 1,200°F EGT's in a matter of seconds at WOT. What decreases EGT's is lower intake temps and a free flowing exhaust. There is not much the manufacturers can do about exhaust back pressure due to the emissions regulations, but they can do something about the intake temps.

Currently Ford is only one without a front air intake which greatly reduces intake temps. GM has it's hood scoop and Ram has it's active air through the grille. IIRC, I wanna say that for every 1°F you lower your intake temp then you lower EGT's by 10-20°F, but I cannot remember the correct numbers. The Ford is also the only one of the three that has a liquid cooled intercooler which are good and efficient with normal driving or towing, but they get heat soaked under long periods of load like the Ike tests. If that intercooler got heat soaked, then the Ford's EGT's would have skyrocketed requiring the ECM to defuel to cool them down on top of already having less power due to hot incoming air.

This actually makes a lot of sense. It's surprising that Ford hasn't addressed the intake air issue, though.

The Ford pulling 30k lbs up the Ike didn't have a intake air issue and I believe it outperformed the ram with similar fuel economy.