Turbo diesel dilema!
 

I have a little dilema.....I drive a 2006 Dodge Ram 2500 with the cummins turbo diesel. My most current mod was that I blocked the grill approx 90%. What I have noticed by doing this is that the water temp now runs in the 190-200 degree range which is up approx 10 degrees and the intercooler is much hotter than before. Much hotter as in the outlet of the intercooler is almost too hot to touch after just cruising at 3-4psi vs before when you could barely feel the temp difference between ambient and outlet under the same conditions. My question is the much hotter air going in my motor hurting me more than my grill block off is helping? I am getting better mileage but I have been doing a lot of "N" coasting during my daily driving in the order of around 20% of the trip. Any help and/or tips appreciated.

You could certainly benefit from an intercooler water spray. High temps at your intercooler are drag on your fuel economy and hP. Try looking through these links to do something about it. I would guess that the aero benefit is less than the thermodynamic hit you are taking.

I just calculated that at 3psi boost the block off is causing about a 5% decrease in power and at 10psi boost it is causing about 15% decrease in power. I'm sure the block off does not cancel these loses! What should I do? Lose the grill block off and focus on driving style?

Yes, or relocate/enlarge the intercooler.

If the IC is in only inline with part of the radiator/grille, leave that section uncovered. Focus on other parts of the truck for aero gains, if you can't relocate the IC.

OK... the guy blocked off the air flow over his intercooler and you say, Oh no, don't let air flow over an air-to-air heat exchanger, spray water on it or re-engineer it instead!

Come on! :rolleyes:

The raised air intake temp is certainly going to reduce the max HP available to you, but I'd think it would improve fuel economy because the lower density air reduces pumping losses. If I'm wrong about this I'd sure like to know it, because I went to some trouble to provide a hot air intake for my turbo diesel street car (mine's a Kubota with no intercooler, but the principle should be the same, right?)

Yes, I was going to say the cooler is more a performance and horsepower thing than anything; there are plenty of successful turbo installs with no intercooler at all.

My guess is there would be some loss of peak power but if you aren't using peak power anyway you won't notice anything different.

Except under load, it may start knocking like crazy, due to the increased temp.

If you're going to go cooler-less, at least watch your IAT and EGT for awhile, to make sure that when you're pushing higher boost numbers that you're not getting too hot.

I suggested moving or getting a larger intercooler because typically, on a diesel, (at least from what I know, admittedly not alot.) you won't get any better economy using cold air vs. warm air.

I Would Remove The Grill Block. I'm No Genius When It Comes To Diesels But A Couple Of My Buddys Have Diesels And I Know That Hotter Air Going In Can Raise The Exuast Gas Temperature And If That Gets To Hot It Can Cause Damage To The Motor. The Trucks Are Engineered To Stay Within A Specific Operating Temperature And Unless You Install A Pyrometer To Keep An Eye On The EGT You Really Have No Idea How Hot Its Getting.

Diesel knock? :confused: