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Thread: 8.1 4l85e

  1. #21
    Tuner 1970ss8.1's Avatar
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    Sounds like a cool project.
    I read the whole book and learned a few things I didn?t know. Still good book got from amazon.
    I?m finishing my chevelle swap right now.
    https://www.google.com/amp/s/www.che...p.html%3famp=1

  2. #22
    70 my fave chevelle which t56 and clutch etc did you go with

  3. #23
    Tuner 1970ss8.1's Avatar
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    Tremec T56 magnum with 0.50 6th. Mcloud clutch and throw out bearing. Hayes 427 flywheel. Ford 9? with 3:00 gear. We engineered it to do 75mph at 1400 rpm.

  4. #24
    ok new one to load in, changed the pe, I really like that idea of ramping it in at low rpm. not sure why I didn't think of that cause I do that on my s10.
    Proably be the last change I do to it for now until I get a wideband installed and the convertor fixed. I will update it when I get the fueling dialed in.
    I want to buy that 8.1 book too, just waiting for the right time might be buying a house so gotta watch spending lol. Does it talk about tuning at all or mostly just about the hard parts?
    Attached Files Attached Files

  5. #25
    1970ss out of curiosity how different are your commuting and towing tunes. Mostly just timing changes?
    I may PM you later about getting a tune from you between not driving it much and cost of driving it i can burn up a long time and fuel figuring it out. The fueling I can do once I get a sensor in it.
    One day I want to get my intake sent out and flow and port the runners but cant justify the cost yet.
    I started looking at your chevelle build looks sweet. I love chevelles
    Last edited by dmaxs10; 02-05-2020 at 12:07 AM.

  6. #26
    Tuner 1970ss8.1's Avatar
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    I run a lot more timing for a non tow tune. Also remove most of the burst knock, have a leaner PE, and lower lock up and shifting. There?s no point to flow the intake, just have the inside plate removed and re-welded. The intake gaskets don?t ever line up well so that will create turbulence. On my chevelle I port matched my intake gasket but it was a pain in the ass. Here?s another link to what I did to my truck.
    https://www.silveradosierra.com/vort...s-t706443.html

  7. #27
    Oh man your making me really want to put a cam in it!
    I think his name is Timm, he has some older post on prefornacetrucks forum I think. He talked about flowing each runner and match the flows between all of them. Says they can be way different from factory and can free up some milage that way too.

  8. #28
    Tuner 1970ss8.1's Avatar
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    It not going to make enough impact to help with mileage. If you are searching for maximum horsepower then spend the money, but I wouldn?t do all that for mpg hunting.

  9. #29
    Tuner 1970ss8.1's Avatar
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    My best mpg mod was a 1/2inch thick piece of rubber under the gas petal to keep it from going wot. Lol

  10. #30
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    1970ss8.1 how much you charge for a tune for a 2002 Avalanche.. Stock other that spark plug mod that you mentioned earlier. Combination of towing/daily driver tune.. Not really worried about mpg.. Just a good tune for towing, daily driving, and a little fun every now and then. I have hptuners and the vehicle licensed already. Just new to tuning and dont really know what all to do to these 8.1s.. Towing would probably be around the 8k weight range but need it to pull hills good. Also what payment type you accept?

    Thanks!

  11. #31
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    Best thing a person can do to get fuel mileage out of the 8.1 running unloaded is to enable lean cruise. Just watch out for signs of detonation. At 75 mph I can get 17-18 mpg turning the 8.1 at 1,800 rpm in my 99 Tahoe. Has a 4L80E with a 3.42 geared 9.5" 14-bolt and P305/50R20s on it. Has an 01 Van 8.1 with a Mercruiser 425HP mag cam, edelbrock shorty headers for a GMT800 Suburban/Avalanche, dual 3" exhaust to the dual in/single out muffler with 4" tail. Intake tubing and airbox is a stock GMT400 3500HD setup. I started with the van throttle map but found it was too aggressive for anyone but myself driving the truck. I used a 6.5 diesel pedal so that may be part of the over sensitivity. Ended up taming it down substantially under 1/2 pedal. On flat road, a/c on, no headwind or tailwind the 8.1 runs at 40-45 KPA MAP at 1,800 rpm @ 75 MPH. I run an air/fuel ratio of 16.5:1 and 42* timing at that load.

  12. #32
    Just thought I would update this
    Fast sorry I never actually saw your post, will have to look at my notification settings. Lean cruise has been a thought after swapping to dbc one day maybe.
    1970ss get your chevelle going?
    I fixed a few mechanical issues with it and took it on a trip towing, got p0101 for maf and lean bank codes. now rereading this I wonder if its due to the maf or ve table. I get lots of KR too, tried copying the low octane of to the high and, its less but still there. Someone mentioned the knock sensors are to sensitive, but after some research that seems to be controversial to change those tables. So without knowing a whole lot about it I haven't change them.
    I haven't changed to much on the tune. going to need to get a wideband for this sometime, finally got one for my truck and gave back the borrowed one haha.

  13. #33
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    do you think that the 7.4L fueling is close to the 8.1? Just looking at options. I opened the exhaust from 2.5 to 3" with no cats and just the pre cat oxygen sensors. Everything else is stock. I will have to review the 8.1 tune and see if there is a huge difference in VE tables... hmmmmm

  14. #34
    Couldn't tell you, I have never messed with one. You could proably find some tunes in the repository and compare them. I do that a bit when I trying to figure somethings out.

  15. #35
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    Brand new to the forum and tuning but I have really enjoyed reading this thread. I'm waiting on my new laptop to come in tomorrow and then will do some data logging on my 2001 Suburban 2500 8.1. What's the latest on your tuning dmaxs10? 1970ss8.1, are you still messing with these big blocks?

  16. #36
    Tuner 1970ss8.1's Avatar
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    Yes I am still working with these 8.1s. I am in the process of tuning my chevelle with the highly modified 8.1

  17. #37
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    new here and buying hp tuner to delete the cats on our equinox but came across this post i have a 2001 cab and chassis zf6 8.1l reg cab flat bed, i know it was gutless compared too a 2004 U-Haul huge truck that u haul would move does the manual trans 8.1 have torque management or detuned in anyway? its totally stock and so was the U-Haul do you have a stock tune for a 01 manual trans i could investigate i have yet to order the hp tuner so i cant look in the tune repocity yet

  18. #38
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    Quote Originally Posted by 1970ss8.1 View Post
    Yes I am still working with these 8.1s. I am in the process of tuning my chevelle with the highly modified 8.1
    Awesome, I'm just getting my new laptop up and running. I have to finish a project for my son on his wife's Yukon and then I'll start digging into my tuning. Would you mind if I leaned on you as I'm learning? Great looking Chevelle btw.

  19. #39
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    Quote Originally Posted by cj599 View Post
    new here and buying hp tuner to delete the cats on our equinox but came across this post i have a 2001 cab and chassis zf6 8.1l reg cab flat bed, i know it was gutless compared too a 2004 U-Haul huge truck that u haul would move does the manual trans 8.1 have torque management or detuned in anyway? its totally stock and so was the U-Haul do you have a stock tune for a 01 manual trans i could investigate i have yet to order the hp tuner so i cant look in the tune repocity yet
    If you don't know the history on plugs, start there. I thought mine ran good until I installed the 41-993's and gapped to .045. My plugs were bad to begin with and then doing the plug mod really woke mine up.

  20. #40
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    plugs are fresh this truck has ran the same since i bought it new ive read the cad and chassis trucks are detuned quite a bit its 100% on the mechanical side good fuel pressure etc