I recently bought my first turbo diesel, a 1994 dodge ram 5 spd, meticulosly cared for with only 70k miles, and I am in love. The previous owner had added some tow mods to the truck and also cut the muffler out and welded in a straight pipe.

I have been using it to haul around work and one of the guys there told me that I would get more power out of it and better fuel efficiency if I put on an aftermarket muffler. He claimed that increasing backpressure would reduce the workload on the turbo and increase my boost psi.

From my knowledge, reducing back pressure on a normal gas engine improves its power and efficiency, right? does this also apply to turbo diesels? this forum has been an AMAZING help to me maintaining this truck and I would apreciate any thoughs or reccomendations you guys have on the subject of mufflers.

although i do have to admit, i love the sound without one!!!

 

nope leave her straight piped, the more air you move through her the better she'll perform,more power,lower egt's,quicker spool up .

 

That guy has it EXACTLY backward. The turbo spins because of pressure differential-higher on the manifold side (inlet), lower in the downstream exhaust (outlet). Putting a muffler in there, or increasing restriction downstream in any way, is the perfect way to reduce boost. This is because increasing backpressure after the turbo reduces the pressure differential across the exhaust turbine, which reduces the force driving it.

This kinda reminds me of one time when some idiot told a guy to freeze his nitrous bottle so the kit would hit harder and make more power.

 

and really, you won't see much power difference between a somewhat restrictive muffler and straight pipe... but you'll see lower EGT's and quicker turbo spoolup

Forrest

 

I personally like my 4" with straight threw muffler better then the 3" straight I had. I actually saw spool up remain the same, lower EGTs, more boost and much, much, much quieter in the cab while towing. I can actaually plesently talk to my wife now. But I might be to old and strange by wanting to talk to the woman.

 

Funny

seems to me i have the opposite effect. I have lower egts without the muffler, better noise without the muffler, and quicker spoolup...... I have not got it since..

Tx

 

Yeah, but he didn't just put a muffler back in-he went from 3" to 4" in the process. Backpressure may well have been reduced somewhat even with a muffler in the system.

 

True

 

and a quality straight through muffler shouldn't really hurt performance over straight pipe...

 

1994appyhauler,

Forrest Nearing is right if you have a well designed and built muffler the back pressure will not change. The mufflers out there that will change the back pressure are those that are hollow cans with no internal packing materials that allow the exhaust gasses to get into the outer can and then fight to exit the muffler with the gasses that are in the center of the 4 inch tube in the muffler can. It's a real cheap way to build a muffler but it's not a good flowing one and the sound is usually not that great either, kind of boomey and has a lot of resonance too! You also have to be careful about the mufflers that use low temp packing as it blows out pretty fast and results in the same situation.

Not wanting to make anyone upset, if you like straight pipe sound go for it and enjoy, mentioned this as we have lots of customers that want low EGT's and better spool up but do not want the added volume, for them this is important info etc. We also sell a ton of muffler deletes for our MBRP system too so there are a lot of you "volume" users out there!

Mark @ DPPI

 

Thanks Mark, I will be talking with you soon.