3 1/2" straight pipe exhaust

[bison]

I finallly got around installing my 3 and half inch exhaust(no muffler) and mandrel bend crossover on my 98.
The crossover fitted perfect but building back from of the downpipe from scratch took a bit of juggling.
I decided to keep the stock down pipe as it has not enough restrictions as i thought it had and it fits better than the 3" mandrel bend
I also wanted to be able to remove the down pipe to get to #6 glowplug so i cut the flange of the soot trap and welded it to the exhaust tubing.

10" pipe,three 45% and one 90% elbows did the trick.
I also took the opportunity to swap the GM 5 turbo for the rebuild #8

It was a breeze getting to the downpipe clamp and turbo bolts with just the airfilter and turbo shield removed,everything done just trough the top.
Ofcourse it helps that i have no longer the AC crap in the way(in the trash heap incl the pump and rad core)

 

[Mad Maxx]

Moved to "Intakes & Exhausts".

 

[Crankme69]

Very nice thanks for sharing the pics & description Bison :thumbsup:

I'll bet it sounds great

 

[ak diesel driver]

I didn't realize you could get 3 1/2" pipe looks good tho

 

[bison]

I don't know how people get a 4" in there without rattling against the cab or frame,i had enough trouble getting this one to clear a 1/2" over the mid cross member.

 

[Crankme69]

I had to flatten my DE 4" exhaust in 2 places (tranny & carrier bearing cross braces) to gain enough clearance on my 1500. My down pipe also required some influence from the sledge it's still very close & I suspect it touches a tad under heavy acceleration.

 

[NVW]

I don't know how people get a 4" in there without rattling against the cab or frame,i had enough trouble getting this one to clear a 1/2" over the mid cross member.

Precise bends instead of a hack job is my guess.:rolleyes5:












JK, looks real good, did you have the tubing kicking around?

AK, I think Kennedy uses 3 1/2"

 

[bison]

Precise bends instead of a hack job is my guess.:rolleyes5:












JK, looks real good, did you have the tubing kicking around?AK, I think Kennedy uses 3 1/2"

After i bought it i had
$80 10' aluminized

 

[bison]

I took a 1000 km trip today.
That straight pipe sounds sweet,a nice rumble as long as i keep my foot in it but hardly noticeable when cruising.
The GM 8 runs in cruise on the flat 5 lbs at 2000 rpm ,a lb and a half better than the GM 5 at the same rpm.
EGT's stay at 450 degrees,was over 500 before.

Mileage did suffer a bit but the power is definitely up.
I'm happy.

 

[NVW]

My guess is the drop in mileage is due to operator error.

 

[ak diesel driver]

My guess is the drop in mileage is due to operator error.

and how exactly do you know the power is up lol

 

[bison]

My guess is the drop in mileage is due to operator error.

Not realy.i had it on cruise 95% of the time.
I only played a bit with the trottle when on the yellow head in Edmonton,it was fun to hear the sound bounce off the retaining walls
I got 17.5 mls to the gallon on this trip,used to be better than 18.

 

[ak diesel driver]

any headwind?

 

[bison]

any headwind?

hell,i make my own all the time,its hard to to get around that unless i park da trock

But yeah there was some at times,usually there always is.

 

[ak diesel driver]

hmm I'm just suprised by the loss of mpgs

 

[NVW]

Maybe it's due more to the higher boost?

 

[bison]

and how exactly do you know the power is up lol

By the reaction of my wife when i floored it ,when she said.. "WTHF was that!!" after she had climbed back in the front seat. :rof:

 

[tanman_2006]

x2 more boost make the PCM throw in more fuel I thought, if not it does create more back pressure. What does the boost peak at?

 

[bison]

I had it up to 15,depended on the hill grade.
About the same as with the old turbo, altough that one would top out at 18 when it down shifted a gear.
With the GM 8 it doesn't down shift no more,it just keeps pulling.

 

[NVW]

By the reaction of my wife when i floored it ,when she said.. "WTHF was that!!" after she had climbed back in the front seat. :rof:

I can't believe an old goat like you would pass up on that.:agreed: