5" Exhaust lowers EGT 200* towing ???

[jelag]

So I just read an article about using a 5" exhaust and seeing 200* lower EGT when towing a 5er.... I'm a little worried that just that change would drop the EGT that much.... so I thought I'd ask to see if any of you have seen that kind of change...

BTW Stock Engine..

Thanks for your thoughts...
"

 

[Powder Extreme]

On older trucks, absolutely. I've seen it myself and I'm sure others will chime in as well. Factory exhaust was pretty restrictive.

 

[AEdelheit]

Older being trucks with a 3 or 3.5" exh going to 5" or even the factory 4" exh trucks going to 5"?

 

[jelag]

OK so I'm looking at a 5" kit... but with a muffler... I can't have the sound go up too much... I'm getting more deaf all the time and the wife and I like to listen to an audio book or chat... do you think I can expect the 5", I think my stock 05 is the 4", will give me the lower EGT's and still not be more than say 10% louder...

 

[Cummins12V98]

IMHO 5" is overkill unless you have a lot of power!

 

[GAmes]

Even a 4 inch wouldn't decrease the EGTs of a stock engine. I know, my stock exhaust rotted out at about 750k so I replaced it with a 4" MBRP. No change in mileage, EGTs, acceleration, nothing. My engine is a bit more than stock too. Joe Donnelly did the testing a long time ago. Stock exhaust is good up to about 400HP.

 

[SnoKing]

What he ^^^ said. Snoking

 

[JR]

If your worried about noise stay far far away from 5" exhausts. Very deep and loud compared to OEM.

 

[Tractorat]

The exhaust system rotted out on my 02 about 2 years ago. I was going to replace with oem size. But the only system they had in stock was a magnaflow 4 inch. Truck is mostly stock. I dont remember what my egts used to be. But the are now at least 100d lower. Maybe a little better than that. (it is a little louder but not bad. I got used to it)

 

[Joseph Donnelly]

Good info above! I found that power-wise, the 3" is good to about 350 HP and above that 4" helps; both were using straight through mufflers, Walker 21468 and 21471 respectively. I saw no gain until well over 500 HP from 5" vs. 4" with a straight through muffler. As for egt's, those results pretty much parallel the HP breakdown. The only way you could possibly save 200 deg. with 5" would be going from a fully restrictive stock 3" system with a partly plugged catalytic converter to a zero restriction 5" with a high HP engine.

 

[Cummins12V98]

Unless you love NOISE stay away from a 5" system.

 

[Bob V]

First, the ONLY reason we look at EGTs is to get an idea what the combustion temps are. High EGTs do not hurt anything, High combustion temps do. That being said you have to ask " did I lower the combustion temps or JUST the exhaust temps?" A good example would be moving the EGT probe. We all know, for the most part, that the EGTs POST turbo are lower than PRE turbo. If you move the probe post turbo did you lower EGTs and combustion temps? The gage is reading lower but you really didn't change anything.
Did freeing up the exhaust lower just the exhaust temps? How would you know?

 

[PC12Driver]

Agreed on the noise. Not so much what's coming out the tailpipe - the resonance in the cab is awful.

 

[mwilson]

I don't know about the older trucks, I wouldn't even bother with it on the '97.

HOWEVER the 5" system that I installed on the '06 did lower pre-turbo temps by at least 150 Degrees and slowed the temperature ramp up times a lot if you are not dumping ignorant amounts of fuel and boost down it's throat.

It is loud, if it gets to the point where I can't stand it I will remove the existing muffler (hollowish bulge in pipe) and chuck a Donaldson truck muffler or resonator under there.

So maybe for '06 and '07 5.9L trucks it is worth doing.

Those are my results, yours may vary.

Edit...My main motivation for installing the 5" was to get some stainless under there as the tail pipe rotted off the stock system at the three year mark. The reduced temps were just a bonus.

Mike.

 

[Deleted member 995608]

IMHO 5" is overkill unless you have a lot of power!

If your worried about noise stay far far away from 5" exhausts. Very deep and loud compared to OEM.

Unless you love NOISE stay away from a 5" system.

All of this

 

[mwilson]

The cat falling off in that time period may have reduced the heat as well in all fairness.

 

[Cummins12V98]

The cat falling off in that time period may have reduced the heat as well in all fairness.

Big time!!!

 

[Wingate]

yep.. if you have an 05 model... just change to MBRP or Silverline... Just do NOT go with the cheapest line they offer which is aluminized. I would spend the $$$$ for the T304 or 409 Stainless.
I dont think its gonna do anything for EGT though unless the Cat or factory muffler had become clogged and restricting airflow.

 

[AH64ID]

I am not sure I believe that, the single biggest restriction in the OEM exhaust system is the turbine housing, followed closely buy the exhaust manifold. Neither of those are going to be effected by a post turbo mod when the 4" flows more than is needed on a stock truck anyhow. The stock 4" doesn't seem to make any difference until about 550-600rwhp, so the 275rwhp in stock form won't benefit from it.

If all you are trying to gain is an EGT drop I wouldn't bother, the stock tuning is designed to run hot and it does it with cooler cylinder temps.

 

[Deleted member 995608]

yep.. if you have an 05 model... just change to MBRP or Silverline... Just do NOT go with the cheapest line they offer which is aluminized. I would spend the $$$$ for the T304 or 409 Stainless.
I dont think its gonna do anything for EGT though unless the Cat or factory muffler had become clogged and restricting airflow.

I bought a high end stainless kit for my truck that developed rust spots within a year. I switched that section to aluminized and 4 years later, it looks better than the SS ever did.