Quick question for you guys with stacks

[CumminsPower98]

I installed 5" straight stacks with 4" pipe from the turbo to the bottom of the stacks. It looks like it may have increased my EGT's some. Anyone else notice this? I am wondering if having the 90º elbow and the 'Y' pipe may be slowing the flow enough to do this. The 'Y' pipe also has a steel fin in the center which I assume is to help equilize the flow. I wonder if this could slow it down at all. I went from a 4" Jardine system to the stacks.

 

[Hummin Cummins]

CP

I'd love to help ya out, but I didnt have gauges before my stack installation. I went from the factory exhaust to stacks. My down pipe is stock then I went 4" piping into 5" stacks. Love the sound though



Chris

 

[pwknapp]

My stacks did not add any EGT rise. Did you loose the cat at the same time or just are adding more fuel with the right foot to hear the stacks?

 

[Oasis-3]

CP98 I went from the stock 3'' pipe to 4" pipe to the stacks then 5" stacks and my EGT went down.

Good Luck

Cliff

P. S. I think pwknapp is correct more right foot

 

[CumminsPower98]

It could be in my head and also the outdoor temp is getting warmer to so I don't for sure but I just had a feeling it went up a bit. I will check it out more. I might unhook the pipe underneeth and see if it makes any difference. I for sure have no cat, that came off shortly after I got the truck.

 

[drees1]

Cummins... 98,



If the Y with the divider is too close to the turbo, that could be a problem. The turbo puts the exhaust in a violent spin as it exits and that fin could be restricting some strong swirl left over. Best to break up the swirl with a large dia elbow at the turbo, then it's turbulent flow on down the pipe. The guys that transition from 3 to 4 or what ever, also helps break the swirl effect. The Ys used on the semis look like mitered elbows welded together. 2 elbows cut along the centerline of the entrance and welded together. Should be 10 diameters downstream from the turbo before the split as a minimum rule of thumb.



Doug Rees

 

[CumminsPower98]

drees1, my Y pipe is just like you describe with the two cut elbows welded to each side of a piece of 4" wide flat stock in the center. I bought my parts from a big rig outfit (USA Truck Parts/Heavy Parts International). What do you mean by "10 diameters"? I have the Y pipe in the front of the bed with a 90º elbow coming into it front under the bed. Do you think this is far enough back?

 

[drees1]

By 10 diameters, I mean if you have 3" pipe, you should go at least 3 x 10 or 30 inches. 40 inches for 4 inch pipe and so on. that is just a rule of thumb to let flow settle out in duct work. Anyway, it would seem as if you have it plumbed proper. I can't think of any standard stack exit design that would inhibit flow at the top. I think unhooking the Y for a short back to back test run as you suggest is a good idea.



Doug Rees