|07.5-2010 LMM Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission Ect|
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|11-25-2012, 07:06 PM||eBay Motors #1 (permalink)|
Join Date: Jul 2012
Location: Casper, WY
4" vs 5".. is there really a difference.
Ok.. whats really the deal here. I have heard so many people I will like 5" better cuz it sounds awesome. Then i have alot of people telling me 4" is better and i will lose power with 5. Its almost about 50/50. What should i actually get? Id like 5 inch but not if there are downsides to it? I know i dont NEED it.. but i want it.
All im doing is EFI Live, straight pipe, lift pump, Blocking and rerouting, and transgo.
Pros and Cons GO!
2008 LMM CCLB 2500HD SLT
EFI Live by Rob. S&B Intake. 5" MBRP Straight pipe.
3" mbrp downpipe. Blocked, Rerouted, Plugged. Semi-Built tranny w/ Transgo Jr.
|11-25-2012, 07:26 PM||eBay Motors #2 (permalink)|
Join Date: Feb 2011
There is no power loss associated with a 5 inch system as compared to a 4 inch
Blocked, Rerouted, Sleeved, MP, 5"
Cobalt's, Leveled, Raptor, Profab, DDM, K2
EFI by ATP
|11-25-2012, 07:31 PM||eBay Motors #4 (permalink)|
Join Date: Mar 2010
Location: Abingdon Virginia
Sound is the only difference
2006 CCSB 4x4 ZF6
|11-26-2012, 06:58 AM||eBay Motors #5 (permalink)|
Join Date: Mar 2011
Location: Northern MN
Power wise, under 600hp there really isnt any difference between a 3.5" and a 5", maybe a little cooler EGT's.
Sound is the only real difference between them. The whole backpressure myth is still out there and a lot of guys think you need backpressure for an engine to run right. 2-strokes are about the only engine that "needs" backpressure, pretty much all 4-strokes can be tuned to run right without it. In a duramax the turbo is all the backpressure you need, anything behind it is there to get the smoke away from the cab.
2008 2500HD LTZ, EFI Live- Idaho Rob's Tunes, 4" Magnaflow Turbo Back, Raptor 150 Lift Pump, Transgo Jr, All Season Diesel EGR delete with high flow Y-bridge, Edge Insight for gauges,
|01-02-2013, 09:40 PM||eBay Motors #6 (permalink)|
Duramax Lifetime Supporter
Join Date: Jul 2009
Digging up a bit of an old thread here, but in my search for 4" vs 5" this popped up. As a response to the back pressure thing, it is not always true that lack of back pressure doesn't affect performance. I don't imagine it does for our trucks, but I had an 86 mustang with a 306 that was turbo (carbed), and when I went from a 3" down pipe and exhaust to a 4" down pipe and exhaust I lost nearly 10 lbs of boost. I know that isn't relevant with our trucks, but in case someone happens upon this thread and is working on an impractical project like my old drag car was, they won't be mis informed. Tuning a blow through carb set up isn't like plugging in efi live though.
|01-02-2013, 10:05 PM||eBay Motors #7 (permalink)|
Join Date: Feb 2010
Location: College Station, Tx
-Austin- Fightin' Texas Aggie
2001 LB7 2500HD CC/SB 2WD
Slower then a three wheeled Prius running on bio-diesel .
546hp & 1025 ft/lbs at Lone Star Dyno, Spring Branch Tx.
Best Run: 13.23 @101 with 1.90 60'
|01-03-2013, 07:21 AM||eBay Motors #8 (permalink)|
Join Date: Jul 2011
Are you also going to do a down pipe? I have a 5" and love the sound, but I also did the down pipe and I am glad I did. The factory one has a pretty nice "kink" in it for lack of a better word!
2008 CCSB w/mild build
Special thanks to Upstate Diesel Peformance & Alligator performance!
|01-03-2013, 07:33 AM||eBay Motors #9 (permalink)|
Most Known Unknown
Join Date: Jan 2012
Location: Magnolia Tx
factory LMM exhaust is 3.5"?
my LML exhaust (factory) looks huge, (thats what she said)
or maybe im just thinking it looks big, idk
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|01-03-2013, 07:37 AM||eBay Motors #10 (permalink)|
Join Date: Jan 2013
To be honest I graduated college with a diesel degree and diesel do not need back pressure at all you can run them right out of the Turbo and you'll be fine all the exhaust is doing is getting the smoke out of there the bigger the exhaust the more.smoke it can move so the bigger the better and also you would have lower egts
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