Mating 6.0 lsx to 4l60e or T400

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cuisinartvette
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Mating 6.0 lsx to 4l60e or T400

Post by cuisinartvette » Tue Mar 15, 2016 3:45 am

02 silverado 1500 has the 5.3 and 4l60e now

Looking at a few lower mile 6.0 to stick in the 5.3 just doesnt have enough umph

Read the 6 wont bolt up to the 4.60e due to some flange thickness problem?

If so what will and wont work? Motor Im looking at is out of an 03




Have thought that a T400 would be great behind a mild 6.0 for towing. Strong and cheap to rebuild and could now be a dual duty truck both for DD and towing

What all is involved in this, want the truck to operate like it always has just not break as often those OD trannies arent cheap.

Dont ever drive much more than 60-65 so if there was any differnce in mpg I wouldnt notice it. Had an issue with my current trans 2 yrs ago so had to not use OD
Even though cruise rpms were higher (in it sweet spot)? mileage was exatly the same
If I got closer to 70 then I noticed

Thoughts?

Only want to do this once

peejay
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Re: Mating 6.0 lsx to 4l60e or T400

Post by peejay » Wed Mar 16, 2016 7:04 am

Unbolt the 5.3, bolt up the 6.0.

The only thing to be concerned with is some early 6 liters in HD applications had +.400 flywheel flanges, probably so GM could keep using 6-bolt flexplates/torque converters made for the small blocks. If you're getting an engine out of something newer or light duty then you don't need to orry about it. 2003 should be "standard LS" aka -.400 compared to small block.

I'd still CHECK the depth, because you never know what someone did to a truck before you get the parts from it, but that is the only thing to be concerned with. Bellhousing bolt pattern is the same. Maybe there will be a bolt hole you can't use, it seems GM felt like leaving the top passenger side one undrilled then later in production they decided to use it anyway. Doesn't hurt a thing either way.

Swapping a TH400 into a newer truck would be a real pain in the ass. It would be easier to swap in a 4L80, which is a TH400 with overdrive. It's electronic but so is the trans you already have. Or you could just keep driving the 4L60 and don't use overdrive when towing, it'll be fine.

ChevyEFI
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Re: Mating 6.0 lsx to 4l60e or T400

Post by ChevyEFI » Fri Mar 18, 2016 8:24 pm

Does it look like you can remove 0.400" from the back of the crank before hitting RMS?
No: Buy the 6.0.
Yes: Skip it.

peejay
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Re: Mating 6.0 lsx to 4l60e or T400

Post by peejay » Sat Mar 19, 2016 5:37 pm

An '03 will not have the SBC-depth crank. That was only the first year or two of production - 1999ish? And only some applications.

cuisinartvette
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Re: Mating 6.0 lsx to 4l60e or T400

Post by cuisinartvette » Tue Apr 05, 2016 10:20 am

Sounds like I oughta leave it alone
This would flat tow ok but theres a stretch of 5 fwy headed towards Famoso raceway called the grapevine I dont see this truck doing much other than waiting for a tow truck lol

Looking at an older Dually now

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Re: Mating 6.0 lsx to 4l60e or T400

Post by A_VAS » Tue Apr 05, 2016 1:28 pm

I have a 2001 6.0L mated to a 86 th400 chevy trans in my truck.

All I did was order a convertor with the snout that mates to crank, longer. It reaches the crank like it should to take up the space. Since I was buying a convertor anyway, this was a no brainer as it was not any extra to get that conversion snout put on
too lazy to make power w/o boost

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