I have a 1998 cummins that i recently straight piped. The motor is a 12 valve. Can it hurt the engine being straight piped??? I have heard both ways. One said no problem and the other said my pump could give me fits. Other than the pump being turned up it is completely stock. (pump will be going back to stock asap) possibly a k and n air filter also???? in the works THANKS
JARED


I also have a question about my fuel gauge. The intank sender has been replaced but the gauge still doesn't work. It will go to 3/4s of a tank and then just quit moving but will go back up to full when i fill up. Any suggestions as what to check now???????????

 

being straight piped is a good thing. you get the exhaust gasses out quicker for lower EGT's and the turbo spools a bit quicker too. now if your worried about noise Ive heard good things about the MBPR muffler. but being straight piped is completely harmless on a diesel.

now about the fuel gage. if the sender has been replaced I would have the dash check out. might be something is holding the needle back.


BTW, the only stupid question is the one that is not asked

 

According to Cummins engineers, your engine will run better with a muffler. You need some back pressure for good midrange power. I would reccomend a 4 inch exhaust with a quality high flow muffler. This combination will provide enough back pressure and flow for max power.

Straight pipes will not damage your engine.

 

thanks the reason i piped it was for some noise and yet let it breath alittle. I enjoy pulling up next to a building and hearing it roar. I like the turbo whistle.

 

I heard for a 12V you have enough back pressure, but you'll need a muffler for a 24V if the exhaust is bigger than stock and if the truck is stock. A guy who builds Cummins pulling trucks told me this. I don't think that you will loose too much power either way. And as Drew said, a straight pipe decreases restriction which leads to lower EGT