Diesel mileage



I have a 2007 2500 Duramax Diesel. I have installed and airraid air system and hypertech tuning and put nitrogen in the tires. My mileage has gone from the 16 highway and 13 city to 17.5 city and 19.6 highway. Will installing a larger exhaust help the mileage will anything else help ?


Pardon my skepticism, but I find it hard to believe that adding parts designed to increase power have increased your fuel economy, specially by that amount. (Nitrogen in the tires will increase fuel economy a staggering 0%, BTW.) How many miles were on the truck when you did your mods? How are you computing fuel economy.


helium might help milage,lighten the load a little,LMAO


Like NYBo, it is kindof hard to believe. No I don’t think a larger exhaust will improve on the gas milage.


You may see a modest increase in power, but you would have to lighten up on the pedal to increase your mileage. And you can do that without the new exhaust. How much power do you expect to gain with the less restrictive pipes?


Most diesels breath very well stock. Unless you are really heavy footed even with the tuning changes you should not need better breathing, but it is possible. I would not expect much change in either power or mileage.

I am a little suspicious of that much increase in mileage, but I can’t rule it out. For those who are more skeptical than I am, it is not all that unusual for some power tuning to increase mileage. While there appears to be some possible issues with reliability and certainly a problem with warranty, it does not appear to be all that bad.

The nitrogen in the tyres would only make a difference if they were under inflated before you did it. The nitrogen in the tyres thing is nothing more than a sales gimmick for over the road vehicles.




Its all in your right foot and not so much in your wallet. Some performance tuning programs re-write the callibration on your Engine Control Unit and make it fuel more than it needs to. Have you noticed any black smoke at idle and when taking off after putting in the hypertech tuning. It could be any ammount that was not obvious before. Also keep in mind that any extra HP you get out of the engine will also go through your drive train and cause extra stress on it.
Enough of the negatives, do you like your souped up truck. Have you done any serious work with it recently and been glad that you went for the 2500.
Duramax on its own is a very good engine. It is actually an Isuzu engine and unlike GM they know a thing or two about diesels.


well said.


Here’s a device that might help.


GM (in the past) knew a lot about diesels in their Detroit Diesel brand. They have since sold it to ( I believe ) Mercedes.


they still do know alot,just not in the civillian line,the over the road engines still work great,i assume the corp policies are not to share info from within,d…m shame. they would last forever.


Don’t be silly! Regular air is 78% nitrogen. The subject of filling tires with nitrogen has been beaten todeath here in the past, but I have a feeling the subject may start up again.

The main advantage of nitrogen is that it doesn’t add oxygen to a fire that that might occur if a tire severely overheats.


Maybe it will help. You get that sometimes.


dont want that,kill yours fast.lmao


Diesels do not like exhaust back pressure…If you think the stock system might be restrictive, opening it up will help. If it already has dual exhausts, then then that’s good enough. If not, then add a second muffler and tailpipe…


Yes, Daimler has bought that brand. But it is more of a player in 13L and above. So you will find those engines in Trucks etc.


I bought the truck new. All the additions were done after I had 3,000 miles on the truck. I compute mileage by dividing mileage by fuel consumed.


I appreciate your input as I have never owned a diesel.I do a lot of heavy towing and the truck has preformed great. I do not really care about going faster as the truck had plenty of pep when I bought it. It is just every diesel mechanic I spoke with told me extra horsepower= better mileage if you stayed off the gas pedal. It made no sense to me from a gas motor point of view but as I said I know nothing about diesel. I did see some mileage improvement after the airraid, and the hyperteck. The tuner is set on the 2nd power level not the race level. Now I have a friend who says all tuners but the Banks 6 gun are not real tuners. I don’t want to spend the bucks if it will not improve the mileage. However I have had the truck for 4 months and it already has 18,000 on it I drive alot on my job.


If you drive a lot you will be better off in the long run even with the stock diesel. A gas truck this size will give you 10 - 14 MPG. Take good care of it, changing oil at the right time. If you can get a block heater for the winter. That helps to avoid the freeze thaw cycles on your engine block. I know now there are several new synthetic oils out there which will help protect the cylinder and the pistons.
The Air, fuel and oil filters are all important and should be replaced at specified intervals.
This truck can easily give you 400,000 miles of service.
And it goes without saying that towing is where the diesel really shines.