Engine/Transmission (1998.5 - 2002) <300hp? 4" exhaust is a waste of money!

[jlccc]

I thought that might stir up a bit of a hornets' nest.



But seriously, the installation of my 4" exhaust did absolutely nothing for controlling my EGT's. After doing quite a bit of internet research I have found that the 12cm exhaust housing is actually the most restrictive part of the factory turbine/exhaust system.



This may not make me very popular, but I'm 100% convinced that the standard 3" exhaust is absolutely adequate at power levels up to at least 300 hp and possibly higher. If I could do things over again I would simply change out my factory (chambered) muffler for a magnaflow or other straight thru design, and retain my resonator (already a straight thru design). That should give the average guy a better sounding (more throaty) system without the dreaded droning that so many 4" systems exhibit.



Not trying to start a war, but I did want to share my experience so that others who are considering a 4" system have another point of view to consider.



jlccc

 

[emarsh]

You don't need a hammer to be a carpenter; you could use a rock!

everyone has an opinion.

 

[A. Brown]

the only reason I got one was for the sound, wasn't expecting any big performance jump

 

[LBTRS]

I put on the EZ (along with boost elbow) and the 4" exhaust at the same time and got a nice drop in EGT's. The increased boost may have been the big factor but I'd still do it again just for piece of mind.

 

[DarrellB]

Mines still stock

Well almost, it doesn't have a muffler or resonator on it anymore.



I have over 300hp and don't have any EGT problems. Still running the stock turbo and the stock clutch ( not for long )



Try and modify the air intake that will help a lot.



Darrell

 

[WadePatton]

Okay that settles it. I'll put a 5-incher on when I add the PDR HX40.



zoom zoom!

 

[Big White Beast]

Helped with my EGT's......

Spools up quicker too. No power gain to speak of but it balanced the system nicely. If you put a bigger housing on you'll be glad to have the 4" then as far as spool up goes.



Garrett

 

[jlccc]

Re: Helped with my EGT's......

Originally posted by Big White Beast

If you put a bigger housing on you'll be glad to have the 4" then as far as spool up goes.



Garrett

Yes, a bigger housing is my next step.

 

[RustyJC]

Stock, our ETH/DEE ran 1300 degF maximum pre-turbo EGT's when towing our 13,500 lb 36' 5ver. The addition of an Edge EZ with boost elbow and Jardine 4" exhaust (both done the same weekend, unfortunately) cut that to 1100 degF. I'm sure the boost elbow had the most effect, but I'm happy with my investment in the 4" exhaust system.



Rusty

 

[K_Arts]

JLCC - I couldn't agree more. I've stated my case on the TDR about losing power and having higher EGT's with my 4" Exhaust also.



Kev

 

[willyslover]

jlccc... no flame intended. . had you used the search button prior to install you would have seen MANY threads that said exactly the same thing... helll even ol Joe Donnley didn't change till he was at about 500hp saying that there was no reason to do it. . unless there was a turbo change or more to cause needed flow. .

 

[StakeMan]

Are you saying there is no need to change the exhaust if your using the stock turbo? But, that you should change the exhaust if you change the turbo exhaust housing size?

 

[RADdodge]

Except for gauges, wheels & tires, my truck was stock when I went with a Banks SS 4" exhaust. Typically, on flat ground at about 70mph, I would see the EGT in the upper 800 degree range, after the install, it hovered around the mid 700 degree range. Later I added a bigger turbo, injectors, etc. For me, there was a definite decrease in EGT. I was looking at average EGT and not peak temps. In hindsight, it would have been better to correlate EGT with boots pressure for a before/after comparison. That would be very interesting. I don't remember anyone doing that, but it should be revealing.

 

[jlccc]

Originally posted by willyslover

jlccc... no flame intended. . had you used the search button prior to install you would have seen MANY threads that said exactly the same thing...

Yes, and you would also have seen just as many people claiming that their 4" exhaust made a world of difference when compared to their stock system. I wish I'd seen Joe Donnelly's posting though.

 

[jlccc]

Originally posted by StakeMan

Are you saying there is no need to change the exhaust if your using the stock turbo? But, that you should change the exhaust if you change the turbo exhaust housing size?

If you have your stock turbo (stock on both compressor and exhaust sides) the only thing I would do is change out the stock muffler to a straight thru design.

 

[Huff N Puff]

I liked what the Banks monster system did for me

I have an early model 2001 with the small 9cm turbo with the stock air filter housing and a K&N filter the most boost I could get was 25lbs. I noticed that the filter minder was getting pulled down,indicating a restriction in the air filter. I repl the K&N with an AFE That solved the problem of the filter minder,but I didnt get any more boost. The next step for me was a 4in exhaust,it really made a big difference on my truck,boost jumped to 30lbs and the turbo spooled up alot faster needles to say EGTs dropped also. The moral of this story is,dont expect your 4in exhaust to do any thing unless you unrestrict the the other end of the turbo.

 

[fj40charles]

I think alot of people with 4" exhaust make the mistake of thinking the 4" exhaust is responsible for lower EGT and faster spool. I think an free flowing muffler with a stock exhaust would do about the same thing. Of course, if you end up with more than 300 HP, then it would be well worth having the 4" exhaust.

I like the 5" monster tip and the sound. I think having a larger exhaust lets the powerjokers know that your truck might not be stock. .



Charles

 

[andrewkoperdak]

I have more than 300 hp at the engine and 285 hp (dyno #'s) at the rears. I don't have any egt problems. My engine is not very bombed either. I am not try to tow the earth behind my truck but I do have a 5000 # trailer. I do hear that the turbo housing is the way to go though.

 

[Steve Campbell]

So how much bigger turbo exh housing...

is required in the 280-300 RWH range to free up the "system" yet keep most of the responsiveness?

 

[Mactruck]

I'll tell you my whole spin on it.

About two months ago I had the HY35 w/ stock system straightpiped. It was fun and loud. But with my DDII's and Comp, I would see very high EGT's.

Then a month ago I changed over to a PDR HX35 w/ a 14cm housing. I was not that impressed (See Post:PDR HX35/14cm - my review). It resulted in a ton of lag. I decided to switch housings to see if it would help and change my exhaust.

I ended up getting a 5" Bullydog system. (from Massdiesel) All I can say is "what a difference". My lag problems all but disapeared. And I didn't have to switch out my 14/cm housing.

Now I'm not disagreeing but I think there is a definite restriction of a stock system if you are running a 14 housing. Thats my spin on it.