8-Lug Truck Performance Duramax, 8.1L, and HD tech | Intakes | Exhaust | Tuning | Suspension | Drivetrain

8.1L factory intake mods, homebrew style?

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Old Apr 3, 2015 | 10:40 PM
  #51  
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I'm thinking now to bore and sleeve the throttle body bigger so as to not worry about the thin spots. I'll post when I'm done with the air intake system, found more gains there than I did last time. Almost done with the TB and manifold flowbench adaptors too. TIMINATOR
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Old Apr 4, 2015 | 05:32 PM
  #52  
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I finally finished the air box and fender mods, round II, and picked up more cool air and went from 864 cfm total flow with the previous airbox/fender mods, to 1100 cfm total air flow @ 20.2" H2O. That should be enough especially since it looks still looks stock from under the hood. I think now I'm gonna start mapping ports on the two stock manifolds that are spare. Then I'll figure the restrictions in the feed to the plenum. Then I cut, and modify, and flow some more.
That's how I got so much gain from the airbox.
Geez, I'm ****, but I consider that short for analyze...
P.S. broke the drivers side motor mount today on the test drive, but the throttle response is great! TIMINATOR
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Old Apr 5, 2015 | 12:07 AM
  #53  
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Just a straight tube from the airbox, intake mods and now stainless works and mine runs great. Torque and throttle response are awesome
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Old Jan 2, 2016 | 12:50 PM
  #54  
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Whipped383 and TIMINATOR Any new updates or feedback on your set up's?

I am looking at doing this and I am wondering about the breather mods you did.

Any issues, or things you would have done differently if you did it again?
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Old Jan 17, 2016 | 09:57 AM
  #55  
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So far so good. Only thing I would have done was put a 4 bolt throttle body flange on
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Old Jan 17, 2016 | 10:09 AM
  #56  
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Originally Posted by Whipped383
So far so good. Only thing I would have done was put a 4 bolt throttle body flange on
Awesome! Glad you chimed back in.

After looking a few modded intakes over it seemed like a good Idea. I have 92MM flange on order as I figured it may help.
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Old Jan 17, 2016 | 10:16 AM
  #57  
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This is what was ordered. It's for a friend so as soon as he can bring me the adapter I will get started. I also need to get it cleaned before cutting and welding commences.
Race Proven Motors Store - Flange - LSX 92mm Throttle Body Flange
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Old Jan 21, 2016 | 10:20 PM
  #58  
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Rather than boring and sleeving the throttle body, its probably going to be a lot easier to just cut the neck off your modified intake manifold and weld on a 92mm 4 bolt flange. This way you can bolt on the larger truck throttle body. Here's a a couple pictures of one we did for a customer with the 102mm nick williams throttle body, hope it helps!





I love that last picture - you can fit an arm inside the manifold.

More random 8.1L related images in our picture gallery here.

Last edited by Raylar Engineering; Jan 21, 2016 at 10:27 PM.
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Old Jan 22, 2016 | 04:47 PM
  #59  
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Yes, That's basically what we planned on doing for the flange.

I got the flange from ---> Race Proven Motors Store - Flange - LSX 92mm Throttle Body Flange

I still have not decided on How I want to do the PCV setup.
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Old Mar 18, 2018 | 12:33 AM
  #60  
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Sorry to bump an old thread, but....

I see Tim posting about removing the Helmholtz resonator. I haven't looked under the hood of my truck yet (bought it with a bad rod knock, prepping to build a new motor now), but has anybody actually done any math and calculated the tuning frequency of the Helmholtz resonator on these trucks? I imagine with significantly more airflow (and especially a different cam) it's not going to end up being tuned correctly anyways to absorb that pressure pulse coming off the intake valve anymore. But data is always good to know.

*Common misconception - the Helmholtz resonator is not designed to quiet the intake - thats the airbox's job. The Helmholtz resonators job is to damp the pressure pulses off the backside of the intake valve so as they don't create inaccurate MAF readings as they travel out to and bounce off the air filter.

Last edited by kendogg; Mar 18, 2018 at 12:46 AM.
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