You Do Need 4" Exhaust

[Bigsaint]

Better yet...

 

[SpeedBump]

WOW That's a cool picture.





Eric

 

[Mopar-muscle]

thanks scott , much better .



chris , yes i have alot of HP and have a 4" exhaust . i put it on originally for the sound and the my pipe is bigger than yours appeal . did it help , yes , did i see a bit more boost , yes a bit , did it giive me 25-30 hp as claimed , more like 15 if i did the math correctly . then again people say that there is no increase with a freer flowing air intake , at my HP level there is , ted was standing right there when i was on the dyno scratching my head to figure out why i lost 10 hp , it was stock airbox filter vs the RE0880 filter , popped the lid of the stock air box open , used the filter to hold it open , 10 hp came back . thats was enough for me .



but i have seen and driven the DTT truck , bill k. is a seasoned drag racer , it does what it does with a 3" exhaust and supermental injectors , you can't despute it .



yes guys want a 4" exhaust , fine sell it to them if they want to spend the money , but to tell them they NEED IT ??????



someone want to explain why the kwikspool turbo is working as well as claimed ? that is a step backwards if the concern is backpressure . ???? there is one in the shop , i need to compare it to the stock 40 exhaust housing ...

 

[Steve Roseman]

I think what it all comes down to is efficiency, if you are burning enough fuel that the gasses can't escape, you need bigger exhaust.

I can also see the 4 inch working against you, heck, my 3 inch works against me at times. If you are letting the heat out so fast that your combustion temp is staying low, you are losing power.



I've got an idea for all you vendors out there. How about a thermostatically controlled, variable position exhaust brake? An exhaust brake that will engage or disengage depending on exhaust temp, of course have a manual overide to shut it off completely.

I'll bet I could get 30 mpg with a setup like this running empty. Just imagine, an exhaust that measures half inch cold and 4 inch hot.

I'm no rocket scientist, please express any ideas on the subject.

 

[Stefan Kondolay]

Ted,



I have always been told by experts in the exhaust field that your air flow is only as good as it's smallest restriction. Is the 3' exhaust the smallest restriction? I have never claimed to be an exhaust expert but I feel that we don't need 4' exhaust, some may want them, but they don't need them. I have been told of some test to do with my exhaust system that will tell me for a fact wether I would benefit from one or not. I will perform these test this week and post my findings. Who knows I may end up with a 4' exhaust.



We do sell 4' exhaust systems, only 2 in the last year and a half, but we do sell them. We don't recommend them but half our customers have them. They want them for the sound and egt's. I personally run the rhino 911 muffler but we don't sell them because you can get them at your local midas shop. I don't dislike 4' exhaust I just don't feel that they a neccessary upgrade for most.

 

[Archive]

I want a 3. 5 inch system so I'm covered either way.

 

[ftb87]

hey ted. I have a question. I live in Denver (5250 in elevation)and I believe if I added a 4" exhaust, it would raise exhaust gas temps. I can remember who had this done... but they said it raised the temps.



Question is... . it that true?



Frank

 

[Ted Jannetty]

K_Arts, posted that, I don't believe it to be true, I do believe this is an isolated case.

It goes against all logic.

 

[jwdeeming]

4" at High Altitude

Kevin,

I tool around empty and tow from here at 5000' up to 12,000+ feet. After gauges, the 4" exhaust was the first mod I did. I checked 1/4 mile times before and after the install with the pocket dyno. Much as I wanted to see a difference, the 1/2 second improvement I saw would have to be considered negligible because my launches and unmodfied TC don't permit that level of consistency. BUT, there was certainly no LOSS of power and I definitely thought the "spool up" according to my seat-o-the-pants-meter was improved. You could argue whether this mod was "necessary" but since I do tow, and the EGTs dropped at least 150deg across the board, I considered it money well spent at the time. Since I didn't have a boost fooler yet, I can't speak for what the pre-modified impact to boost really was - I never saw above 20psi. I sure don't understand the loss of power you experienced.

Now that I've gone on and done the other bombs, I am glad that the 4" is already in place. The DDIIs substantially increased my average EGTs and I would have to assume it would be much worse with 3" exhaust. And I don't think high altitude and 4" exhaust is any detriment to my boost now. With the wastegate wired shut, I see a consistent peak boost of 34psi, even at high altitudes. That's pretty much the limit for my stock turbo anyway, according to the pros.

Good luck - I sure hope to read that you found a cause for the power loss.

JimD

 

[R.ebel]

4" exhaust

I'm at 6000' and the 4" exhaust definatley lowered my EGT's by about 150*. I agree with Ted regarding K_Arts problem.

 

[KatDiesel]

Mopar-Muscle

Wasn't it you that posted many moons ago a dragstrip comparsion of a 3" vs 4" exhaust??





I bought my 4" for sound, if it helps in other areas then great.