454 tbi with 4l85E swap into c1500 350tbi

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Sam Cooper

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4l80e is definitely stout enough for a normal NA 8.1, I'd almost say most NA 8.1s.

I do think that the 8.1s are cool. IMO though if anyone wants to mod them more than just a cam swap it might be more beneficial to just start with a L29, turn it into a 496, and throw some really good heads at it and a good intake manifold.

I have definitely considered the idea of building a stroker L29, but then I would want to add the individual coil over plug and maybe even the 7-4 firing update. The timing sensor for the computer can be handled with a 8.1 timing cover or maybe an aftermarket (I saw one somewhere online), I haven't yet sourced a cam for the firing order update. I might even consider spread port heads if I can get a the companion pieces. But then why not start with a big bore block? This can quickly turn into a rabbit hole. But what a rabbit.


The tuning for the 2014+ 6l80e is definitely complex, I can vouch for that lol from what I've read they're quite strong when tuned correctly, even stock. Apparently a bad tune can kill them though.

Where can I find information about the 6L80 tuning?
 

Supercharged111

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Where can I find information about the 6L80 tuning?

Good luck. I've been casually strolling the EFILive forums for that myself. If you're MAFless, you'll need to bump the torque the ECM reports to the TCM. Shift times can be shortened too, but I want to say I read it was more iffy than the 4 speeds because the one has to release before the next applies whereas with the older stuff one gear would just overrun the next in a 4L80 or with the 4L60 it was the band coming on and off.
 

df2x4

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That is quite true but those 4L80e transmissions are far from stock.

Not really. Matt Happel of Sloppy Mechanics built a turbo LQ4 LS Colorado that broke 1K HP to the wheels and ran several sub 10 second quarter mile passes at around 150MPH through a junkyard 4L80E with a TransGo HD2 kit. That was the only modification. There are lots of guys pushing stupid power through nearly bone stock 4L80Es. Additionally...

I have researched the Hughes

:waytogo:

and Monster transmissions.

:thumbsdown:

Jake's Performance is another good resource for 4L80E stuff. I'd stay far, far away from Monster.
 

Supercharged111

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Not really. Matt Happel of Sloppy Mechanics built a turbo LQ4 LS Colorado that broke 1K HP to the wheels and ran several sub 10 second quarter mile passes at around 150MPH through a junkyard 4L80E with a TransGo HD2 kit. That was the only modification. There are lots of guys pushing stupid power through nearly bone stock 4L80Es. Additionally...



:waytogo:



:thumbsdown:

Jake's Performance is another good resource for 4L80E stuff. I'd stay far, far away from Monster.

This is consistent with my research. Shift kit only or shift kit plus sprag usually gets it done.
 

Christian Steffen

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Where can I find information about the 6L80 tuning?

Hptuners forum, ls1tech, maybe some stuff on performance trucks. Pretty much have to piece together forum posts and slowly try stuff.

All I've done to mine is change shift points, tcc settings, and made the shifts firmer. So far I'm really happy with the changes.

Sloppy mechanics definitely proved what a 4l80e can withstand.
 

L31MaxExpress

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Yeah they used the 8.1 for several years in the GMT800's but those trucks would only serve as an engine (and possibly PCM) donor; you'd still need to figure everything else out or custom hack the harness. I do believe some of them came with the Allison transmission, too. Talk about your literal can of worms for a swap donor! The 2001-2002 3500HD IMO is a far better donor. (Or 2001-2006ish if you can get one from Mexico! shhhhhh...)

Richard

Express/Savanna vans are good 8.1 donors as well. Thats where both of my 8.1s came from. The one in my 99 Tahoe and the one in my 83 G20 van. The 8.1s are also DBW and use an electronic pedal like the 6.5s.
 

L31MaxExpress

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There's GMT800 dudes making serious power, drag racing boosted LS's and 4L80E is the way they go. 'nuff said :D You won't be finding any Allisons in that bunch. A few are running 6L80E's but apparently the tuning is a lot trickier.

Richard

The 4L85Es are seriously strong even in stock form. I tuned a Duramax that came with one behind it up to about 800 ft/lbs of torque. It has towed a heavy enclosed trailer around for more than 100,000 miles. It had 80K of fleet use on it before it was tuned. Only mods to that trans were a HD2 shift kit and a deep sump pan.
 

stutaeng

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The 01-02 3500HD and Vans had 4L80Es and Avalanche/Suburban/Dmax vans had 85Es.

Thanks. I forgot to note the 4L80e also came behind the 15,000 GVWR GMT-400 3500HDs. Some motorhomes also had them. Not sure if those were stock or not though.

The 4L85Es are seriously strong even in stock form. I tuned a Duramax that came with one behind it up to about 800 ft/lbs of torque. It has towed a heavy enclosed trailer around for more than 100,000 miles. It had 80K of fleet use on it before it was tuned. Only mods to that trans were a HD2 shift kit and a deep sump pan.

So perhaps the largest advantage of the Allison over the 4L85e is the additional gears then? I mean, you can't really compare them directly, as I imagine they are different designs. I don't know anything about Allisons, but I thought they were 5 or 6 speed on that generation? Sorry OP for derailing your thread :)
 
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