Engine/Transmission (1998.5 - 2002) What is a 4" exaust going to do for me

[Motorhead]

I'm thinking of putting a 4" exaust on my truck. What can I expect on the performance end and fuel mileage? Does it lower EGT's that much on stock to EZ enhanced engines? I run an Ez on #2. See sig below Chris

 

[TKilgore]

I'm no expert on this but at our power level (I have a comp) there isn't much preformance to be had over say a muffler elimination pipe on stock exhaust (this is what I've been told here). As for EGT's, I changed to 4" before I had a gauge or comp box so I can't compare so again I don't think much gain over an elim kit.







However, in the MHO department, I always try to get my vehicles to breath better and I would think towing would see some benefit now. Besides, it looks intimidating and sounds awsome. I have not reqretted getting mine at all except I might loose my muff somewhere along the line.



Tom

 

[John Berger]

I have no idea of what to expect, but I can't wait to get mine on. I'll let you know what I see and/or feel. I'm hoping the big brown truck has a delivery planned for my house today.

 

[EMDDIESEL]

I saw an immediate EGT drop, quicker cool down times and it sounds ALOT nicer. Turbo spools up faster too. I have the EZ box also and the combo works great, in fact, i did'nt think it could be any better, untill i made the unfourtunate mistake of driving (His TDR name is drawing a blank, but he is a friend of "MassDiesel"). His truck was so fast i am still depressed.

 

[HVAC]

4" Exhaust

EMD, you may be thinking of John's truck, he posts as MoparMuscle.



We have debated the value of the 4" exhaust many times over. You can't document a performance difference on the dyno. However, some folks feel they get down the track better with the 4". Personally I feel you need a lot more fuel then a EZ set on #2 to justify a new exhaust system.



It's your money... ... .

 

[emarsh]

Well, I don't care what the so called experts say, the 4 inch exhaust was the first engine performance mod on my truck, and it does make a difference towing, (not to mention a reduction in EGT). While towing, there is a big difference in how the truck accelerated pulling the 7k load. Yes it is true that on an empty truck, you could barely tell the difference, except the sound, which in my opinion, was worth the price alone!

 

[Motorhead]

As alot of you Guys know, there is a "justification" issue with the wives on spending money on a new truck when there is alot of other things needed around the house. I told her that it would help the truck pull "HER" trailer up the hills and run the truck cooler.



It seems that there is some benefit to the 4 inch system... . I'm sold!!!

So now I will "justify" it. Chris

 

[EMDDIESEL]

Thats him!!!, MoparMuscle, he ruined my Ram. Nothing compares to what that truck did. That thing was an animal, and he said he was going to make it even faster.

 

[RADdodge]

I didn't notice a performance increase per se, however I did notice a decrease in EGT. On the flats around 65 - 70mph, my EGT dropped about 130º F.

 

[GeneralMachine]

4" exast thought

Has any one measured the outlet size of the turbo? seem's with it choked down at the turbo hot end, bigger exast wouldn't help. I was woundering if maybe the egt you'll are seeing may be from getting the stock muffler off. For I also want more exast flow and have been doing some checking on makeing the 4" start at the turbo hot end. Harv

 

[drawson]

At your power levels the only thing you'll see is a slight drop in EGTs. I was at 340 HP when I did mine and all I saw was 35-50 deg cooler towing. The 3" system I took off was opened up alot, all i had on for a muffler was a 4" dynomax bullet where the cat once was...





There is one thing that was great The SOUND!!!!

 

[Bob Wagner]

want lower EGT's

hook up a Piers PDR HX35 before the 4"



Lower egts, lower cruising boost pressure and quicker cool down



very nice

 

[HVAC]

What's That?

Bob, did you mention the PDR 35 provides lower cruising boost pressure? Is that a good thing?

 

[Diesel Freak]

??????????????????WTF????????????????

 

[Doubleclutch]

Hey Motorhead- Just tell the wife that the air conditioner will work better!

Greg

 

[M Evan]

Re: want lower EGT's

Originally posted by Bob Wagner

hook up a Piers PDR HX35 before the 4"



Lower egts, lower cruising boost pressure and quicker cool down



very nice

Bob W what you mean lower cruising boost pressure and what is so good on it ?

M

 

[Car_nut57]

4" exhaust will definately improve exhaust flow which will let the turbo spool up faster and lower EGTs generally by about 40-50F. Cool down is faster and generally speaking you gain about 9hp give or take over stock. The systems we have are 16 gauge aluminized steel 4" down pipe and system, mandrel bent with 4" high flow muffler. Sound levels are very close to stock and the systems are bolt on.

 

[Bob Wagner]

This is what I meant





Cliff, whatever

 

[Diesel Freak]

Bob, that post is talking about the HX40, not the HX35.



the PDR HX35 has a different compressor wheel, but the exhaust side is still OEM Holset, so what this means is that at the same engine load with a stock HX35/12 on one truck and a PDR35/12 on another (we will make this simple... both trucks are stock) the turbo shafts will be running at almost the same speed, but since the PDR turbo has a slightly larger compressor, boost pressure is about 10% higher... ... untill you get to the wastgate setpoint.



HX40 cruising boost is lower because the whole turbo is larger, more specificly the exhaust side. A larger turbine housing has a larger effective nozzle area and it takes more exhaust flow to raise velocities high enough to start accelerating the turbo (spool up)

 

[Bob Wagner]

so. if I am running lower boost at cruisng speeds, I would be better off running the HY35 at higher boost level vs. running the PDR 35 at lower boost level given the same speed?





Even if the EGT's are the same or lower