5.7 Vortec Tow Tune

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stutaeng

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My dad had a 92 K2500 with 6.5, 4L80, and 4.10 gears. :p


Well, you got me! I was thinking the 96-00 generation...still trying to find my owner manual!

I thought it had to do with diesels not spinning as fast, no? You can't just keep adding gearing on diesels, since the redline is, what, like 4,000 RPM? And was that the 6.2? Non-turbo?
 

Supercharged111

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Well, you got me! I was thinking the 96-00 generation...still trying to find my owner manual!

I thought it had to do with diesels not spinning as fast, no? You can't just keep adding gearing on diesels, since the redline is, what, like 4,000 RPM? And was that the 6.2? Non-turbo?

6.5 turbo diesel, first year I think. Thing was done just north of 3000. Had a WOT 3-4 upshift in the 70 something mph range.
 

L31MaxExpress

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I tow with an Express van that has a 383/4L85E and 5.13s with 31.5" tall tires. 2,850 rpm @ 70 mph in overdrive with the converter locked. Cammed 350 towed very well with the same gear. I get better mileage towing and around town than I did with the 350 and 3.73 gears, never got into OD towing with that setup and OD was not really useable under 60 mph unloaded. So much more pulling power with a deeper gear.
 

L31MaxExpress

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If you convert to an 0411 you can add tow/haul. The 0411 needs to be tuned for it and a momentary push switch that grounds 1 PCM pin added. I used the stock shifter lever from a newer Astro van that had the button but was otherwise identical to the Express van shifter. This was with a mild cam, marine intake and thorley tri-ys. 30.5" tall tires and 3.73s at the time. WOT upshifts at 4,600 rpm and locked the converter in 2nd gear at WOT.

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What's the purpose of locked up shifting? Seems like it would be a little easier on the drivetrain. But I dont know anything

Sent from my SM-G892U using Tapatalk
 

Supercharged111

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What's the purpose of locked up shifting? Seems like it would be a little easier on the drivetrain. But I dont know anything

Sent from my SM-G892U using Tapatalk

I don't see where he shifted locked, that's harder on the drivetrain. What he's referring to is when you floor it and the trans is in 2nd, the converter locks. This is stock for the 4L80 trucks.
 
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Ahhh I see. I'm pretty new to the truck scene. I've always had hondas and 240sx's before I bought my grandpa's truck.

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L31MaxExpress

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I don't see where he shifted locked, that's harder on the drivetrain. What he's referring to is when you floor it and the trans is in 2nd, the converter locks. This is stock for the 4L80 trucks.
I shift with the TCC locked just like the factory did on all newer 4L80Es including the ones behind the 8.1s. In my tow/haul mode once it is locked I do not unlock it for anything up or down.
 
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