Another exhaust diameter question thread...

[Clb]

After searching pages of discussions, not seeing this topic touched upln much.
Looking for/to bullet proof my towpig.
Pulled a 20+ minute( purported )8-11.5% grade, in mid 70* weather,6 k on back..
So far the coolant temps seem to stay under 220*...
Egt's at 10-1100,here's my question!

Are there any egt benefits ( lowering egt's is the goal) to bumping the dia. From the d.p. back up from 3" to 4"?

Thoughts on this ???? Hands on "actual experience" would be cool!
Thanks in advance cb

 

[79jasper]

It sure won't hurt any.
On the powerstroke, many believe 4" is just right. 3-3.5" being slightly restrictive.
All it can do is help.

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[Clb]

@PwrSmoke is probably the guy for a tested answer( I just thought of him) hmmmm

Reading some 2012 discussions with mel now.

 

[icanfixall]

This really is an expensive and time consuming question. My rig came with the stock bullet proof factory soot filled muffler. Do not recall what the mpg was then. I had Banks install the sidewinder wastegated turbo and the down pipe plus their muffler. A year later I removed the muffler for straight pipe. Still no mpg taken. Then I decided to move up to the 4 inch from the Banks down pipe to the back side of the rear tire. Averaging 75 to 85 mph driving home from the 2009 rally in Kentucky with a new Moose pump timed to 8.5 advance I was seeing 18.9 mpg.. I attribute that to the 4 inch and my build. In double overdrive I see 1850 rpm and final gear ratio is 1.96 per Gear Vendors information. My engine pulls that rear ratio really well.

 

[jhenegh]

I'd also like to know. I have a super straight shot of 3" from downpipe to over the rear axle where my 45 degree angled down turnout is 4" (its all I had laying around.) I've considered going 4" from the downpipe all the way out if I knew it'd help temps and also take away some high RPM cackle

 

[Clb]

Yup
I have given up on chasing mpg, I would love to shed some egt without a fmic...
After runnning lots of snake oils thru her from 37k to 42k she seems to have cleaned up above 3k (rpm) haven't hit the govenor yet... The egt's may have dropped by 500* (maybe)?? Pulling Priests grade in 3rd at 3k ish with 6k on back its running much cleaner up top.
There is nothing ecept the ttb springs I NEED to do to her right now, as to towing I had to lift of the fuel for traffic not egt's.

 

[Clb]

http://www.oilburners.net/forums/showthread.php?56571-Exhaust-pipe-size

 

[towcat]

if you want a bulletproof tow rig, put in a intercooler. my exh system is a 3in straight pipe from turbo to rear axle. 4in over the axle and out the right rear. It does a good job letting the turbo spin and providing the "jake" cackle on decel.
the intercooler makes all the difference in the world. those who have driven my truck describe it as "effortless". it's tuned where you do not need to keep an eyeball glued to any of the gauges. here's a shot of the pyro pulling the CA I8 El Cajon grade on a 120* day @ 1:30pm.

 

[83ford]

Sorry to high jack but I've been wondering the same thing I was gonna get a 4 inch but I don't feel like dump in that money into it since I've got other things to buy but anyway the exhaust shop can do up to 3 inch pipe do y'all think that will be enough with my moose junior and hypermax


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[Clb]

83 ford... My 88 had the first gen non gated banks, and thier pipe (? 3 - 3 1/2"?) it was 1/2" bigger than stock...
With bb's and a junior non ic, it would not stay cool.
I'm trying to wring out everything I can without an ic.
You will need to drive by the pyro period.

 

[83ford]

83 ford... My 88 had the first gen non gated banks, and thier pipe (? 3 - 3 1/2"?) it was 1/2" bigger than stock...
With bb's and a junior non ic, it would not stay cool.
I'm trying to wring out everything I can without an ic.
You will need to drive by the pyro period.

That's what I was afraid of ive done good so far with out a pyro but I figured once I stuffed a turbo on it was over which I was planning on buying one anyway.


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[Clb]

With 40k on Stock ip/inj, 093 ats stock pipe 6k I'm at 1000*+

 

[firehawk]

Personally I don't believe there is any performance or EGT benefit to going larger than the turbo outlet or downpipe. Big restrictions are the log manifolds, turbo, and sharp 90* into the downpipe. If you run a muffler, changing to a straight through type or eliminating it should help. I would be surprised if anyone who has done real testing (same load, grade, speed, gear, RPM, weather... or dyno testing) and seen any difference, but I have not so I'll wait for the guys splitting a single 3" into dual 5" stacks to chime in.

I agree completely with this.

 

[towcat]

83 ford... My 88 had the first gen non gated banks, and thier pipe (? 3 - 3 1/2"?) it was 1/2" bigger than stock...
With bb's and a junior non ic, it would not stay cool.
I'm trying to wring out everything I can without an ic.
You will need to drive by the pyro period.

with an IC you get your EGT drop. without it, it's hot air in and hotter air out.

 

[Clb]

Yup, the issue I have is the h2o pre heating in the rad.
Everything I've read so far points to this being the next issue( egt's stay down, h2o goes up) mine rises and falls like a tach.
Wish I had the scratch for the ic you have.
I got the windowed fr. bumper.