2nd Gen Non-Engine/Transmission 4" exhaust and MPG

[DSutton]

I have decided to go ahead with the 4" exhaust(Probably Rip's). I've heard said that the 4" will provide a slight power/torque increase. Is this true? More importantly to me is will it improve fuel mileage?

 

[Big White Beast]

Probably negligible........

There isn't much gain from a 4" exhaust until you start adding other HP items. It will help the Cummins breathe a little better and is a good thing.



Garrett

 

[Mark Craig]

Big White Beast,



There will be a power increase, an average of 13-15 hp and 20-30 lbs of torque on a stock truck, modified trucks won't get as much but it will make the egt's so much better. Mileage increases are there but I wouldn't plan on any major amount. The real reason to get into an exhaust system is to spool up the turbo quicker, more power sooner at the same fuel pedal position, lower egts for future performance modifications, and a real nice exhaust tone.



Mark Craig

DPPI

 

[Big White Beast]

Mark........

I guess I should have been clearer. I still would recommend a 4" system. It's just the Seat-o-the-pants meter isn't going to notice anything. And mileage improvements are so minimal that driving conditions from day to day would make it hard to notice.



I suppose if you drove nothing but freeway all day every day you could track minor mileage shifts. Even then wind conditions and weather could effect it.



They do sound nice, are easy to install and your set for future bombing.



Garrett

 

[Mark Craig]

Big White,



I agree totally, by the way I meant to send the original response to DSutton so I hope you didn't think I was saying you were incorrect, you're not you're spot on.



Mark Craig

DPPI

 

[DSutton]

4" exhaust

Thanks for the reply guys. I plan to install the #6 plate(TST power kit) and the 4" exhaust on Sunday. I would like to go ahead with 370 injectors also, but will wait until I have the $ to upgrade the transmission.



I need to get the wife working more hours so I can afford to feed my habit!! This is both addictive and exciting.

 

[stownsend]

After I had 4" installed, I noticed an increase in power. I noticed because the direction I leave town when I'm towing, I hit a hill. I noticed that after the exhaust was installed, my truck did not shift out of OD on the hill, whereas before, it did. Not very scientific, but noticable.



Steve

 

[Fuzzy Bear]

Got my system from Rip installed a couple weeks ago. Have to agree with everything said. Definitely spools up quicker and helps going up hills. I don't think I'm pushing the right foot as hard, thus improving mileage. Of course this doesn't help when I get the urge to hear that nice throaty sound and give it a kick Definitely a good upgrade.