Engine/Transmission (1994 - 1998) 4" Exhaust: Lowers EGT?

[Gifford]

Will replacing my stock exhaust with a 4" kit signifigantly reduce EGT while towing?

 

[BFC]

Reduce, yes. Depend on what you call significant, you will get around 100* less, give or take a few.



Glenn

 

[Blackcloud]

I just replaced my exhaust system completely. ATS 3 piece manifold,16cm turbo housing and 4" exhaust turbo to tail. My results are as Murphy's Law would predict,no real drop in exhaust temps to speak of. Needless to say,I am disappointed for the results vs. money spent. Just my bad luck and now empty pockets I guess.

 

[DSutton]

4" exhaust reduces EGT's

I definately reduced my EGT's after going to the 4" exhaust. For sure about 125-150 degrees. This does help, but I still need to reduce them more. I also like the sound/noise.

 

[Mark Craig]

EGT reduction

Gifford,



We see up to a 200 degree drop depending on if the truck is stock or modified etc. The average is around 125-150. We have just recently added a bracket kit to our 1998-2002 24 valve exhaust system to allow it to fit the 12 valve trucks. What it consists of is the Chrysler factory bracket and rubber hangers that bolts to the frame in a 24 Valve, you add it to a 12 valve frame and hang the system in just like a 24 valve truck. It also eliminates the visible hanger on the tail pipe on the 12 valve trucks, much better looking set up this way.



Mark

Diesel Performance Parts Inc.

 

[Forrest]

A 4" system does reduce EGT ... significantly ... eh ... ?.



There are 2 other benefits to the 4" exhaust that are significant, IMO. First, the stock exhaust system is definately more restrictive than a 4" system. The muffler is more restrictive than the straight thru & the stock system has the catalytic convertor. When I put the test pipe in place of the cat, 1st thing, better sound, but even better was spool up. Taking a look inside the cat tells it all ... wholly brick wall to exhaust! I would have to say that quicker spool up is significant to towing.



Secondly, stock exhaust is just that ... stock. A majority of the Cummins Rams out there have stock systems. That in itself is a significant reason to have a 4" custom exhaust system.



Life is too short to drive a stock Cummins RAM.

 

[1dslram]

When I added my 4" system my EGT's dropped about 100*. now 8 months and lots of boming later I added the ATS manifold and have quicker turbo spool and a drop of 125* and the temps rise a lot slower above 1400*.

Bruce

 

[wsmalley]

BlackCloud,

When you have a larger exhaust housing, your EGT's while cruising will rise a small amount. My guess is your boost is lower while cruising. Most 4-inch exhaust will reduce EGT's 100* or so; but a larger housing, either by way of an upgraded housing or an entire turbo, will drop your cruising boost and up your cruising EGT. My guess is you did see a reduction but it was canceled out by the 16-cm housing.



Just a little FYI



And to answer the thread, mine dropped about 100 while cruising at speed. Actually dropped mine all around. Before I was cruising 700 and uphill 800, now cruise @~600 and uphill @~700. And that was also with the addition of the 370's, so I would say it works

 

[Tom C]

wsmalley,



I agree ! I just (but two hours ago) put a 16cm housing on my truck. Temps at cruising speed (70mph in 5th gear) went up from 650° with the stock turbo housing to 900° with the 16cm housing (level road). Not exactly what I wanted. Spool up (response) is greatly diminished and power is also down. I was slipping the clutch with the stock housing. It will now not slip the clutch with the 16cm. Also temps at full throttle went from 1450° to pegging the gauge. You guessed it. that housing is coming off tomarrow and the stock one is back in business.



Tom C



PS: I dont even want to think what the temps would now be while towing. the new 16cm housing was also non-waste gated, boost would hit 32PSI.



PSS: I have the stock exhaust less the muff.

 

[Doubleclutch]

Tom- I can't argue with your numbers, but it sure sounds bass-ackwards! Only had good things happen when I changed out my exhaust housing. I had a #6plate and stock exhaust but had to "lift" to keep temps down, while horsing around (no towing). Went to 4" exhaust but didn't get much relief. Went to the 16cm exhaust with the 4" exhaust and things got livable. Can't come up for a reason why it didn't work for you though. (Got rid of #6 for a proper #10). What's your timing set at?

Greg

 

[Roger rodbolt]

My take..........

Larger exhaust gain depends on the engine and setup. A stock 12V will see little gain because the pump defuels before egts are too high. When you start overfueling a 12V the pyro quickly pegs and the engine need more air. 4" exhaust will help but the pyro will still peg just may take a little longer and this is what disappoints people, they didn't know the max temp before the exhaust install.



24V engines have signifcantly less restriction internally (head/cam flows) so the gain from 4" is much greater on the ISB.



Put in a good cam, port the head, larger valves (etc) and install a good turbo on a 12V and it will scream for larger exhaust. Everything is relative when it comes to restrictions... ... ... ... same thing with air intakes... ... ... ... ... ... ... just my $00. 02,

Larry

 

[Tom C]

Greg, don't know what the timing is at. The previous owner said he had it timed at a diesel shop in Cal. . Ive been wanting to check it for a while.



Larry wrote:" Everything is relative when it comes to restrictions"



Larry, I agree with that. for the setup I have I beleave putting a 16cm housing on my truck is the same as putting a holly 850 double pump carb on a stock chevy 305 motor. just plain over kill and not a good match for the system. A 14cm housing may be a better choice for me. I have put my stock housing back on and temps are back down and there is no lag in throttle responce.



For more of what this thread was started as (4" exhaust): which do you think would help more... . remove the cat or put 4" from turbo back.



Can the center be punched out of the cat?

 

[Dieseldemon]

Egt

Take the cat off that will lower the egt at higher rpm also how far did you move the afc housing when you installed your plate if you moved it all the way forward like most people move it back about 1/16" and let the afc control some of the fuel also a 4" system would help if you put on a 4" get as large a muffler as you can I use a 44" and move the bracket forward

 

[Tom C]

afc was full forward when I installed the new spring. I have been slowly turning it back. it is now about 36 clicks back. smoke seems to be the same.

 

[1dslram]

The exit of the cat is 4" you can cut the front back as I did to make it also 4" and that way you will have a 4" system all the way back. I don't understand why a 16cm housing with stock exhaust that is a major restriction anyway, especially at the turbo exit, the aftermarket systems make a smoother exit fro the turbo. Why not remove the cat as the muffler is already gone.

Bruce