Effeciancy?

[Deere Freek]

I'm told that the 4l80 basicly chews up 80 hp from the engine. Are there any tranny swaps or mods that would let me get more of the hp available from my engine to the groud without sacrificing durability?

 

[THEFERMANATOR]

A manual tranny would use less HP to turn. As far as autos go, the 4L80E doesn't use nowhere near the HP as many autos do. There are a few companies out there making some bearing upgrades for them where they replace thrust bushings with torrington bearings to reduce internal drag and friction. Your 80HP estimate seems a bit high to me as well. The 6.5 turbo is rated at 195HP at the flywheel, and many have dynoed at 160-175 at the rear wheels. Obviously as your power output goes up, your power loss goes up as well because an auto tranny uses a % of your HP more or less to run itself.

 

[Turbine Doc]

I doubt it eats 80 hp more like 40 at most, I'm putting 200+ rwhp to ground with my setup, and can on occasion pull 18K mostly in OD how much Hp you figure you need, IMO the manual trans by time you convert will nto gain you that much over what you can do otherwise with the trans you have now

 

[Dave Barbieri]

The hp loss thru your 4L80 is less than 20hp - realistically, somewhere between 15 and 18. We have an electric tranny dyno at our training facility; the next time I test one of these, I'll do the amps/volts/watts thing and figure hp loss. Just for kicks, I'll also ask the GM tranny folks at the training center in Dallas about the 'official' figure.

Don't fret your hp loss - your torque converter more than makes up for that. Keep in mind that your TC is actually a torque multiplier, typically around 1.6:1. So, in direct drive, if you're putting 300# of torque into the tranny, you're getting 480# out the tailshaft. No manual trans can do that. Also, the use of multi-disc clutch packs means you have more friction surface than any single disk 12" clutch can ever have. This is why auto trannies are far better at towing than manuals will ever be.

 

[Ed HD]

Don't fret your hp loss - your torque converter more than makes up for that. Keep in mind that your TC is actually a torque multiplier, typically around 1.6:1. So, in direct drive, if you're putting 300# of torque into the tranny, you're getting 480# out the tailshaft. No manual trans can do that. Also, the use of multi-disc clutch packs means you have more friction surface than any single disk 12" clutch can ever have. This is why auto trannies are far better at towing than manuals will ever be.

That, and the fact that you don't slip the clutch, and the fact you don't have to deal with shifting with a heavy load. I'm not saying manuals are bad, i love em', but autos are better for towing in pickups.

 

[Deere Freek]

So the stock setup for the tranny isn't all that bad then i take it??

 

[Dave Barbieri]

So the stock setup for the tranny isn't all that bad then i take it??

All seriousness aside, you've got one of the best auto trannies available to the light truck market. To get any heavier/stronger, you're looking at the Allison autos, and those require more than three times the HP to turn 'em. I'm keeping my 4L80.

 

[red]

great auto, but with the statement about an auto being better for towing, in my experiance, isnt right. i'll take a manual any day over an auto, but if its an auto the allison or 4L80E hands down.

 

[GM Guy]

The hp loss thru your 4L80 is less than 20hp - realistically, somewhere between 15 and 18. We have an electric tranny dyno at our training facility; the next time I test one of these, I'll do the amps/volts/watts thing and figure hp loss. Just for kicks, I'll also ask the GM tranny folks at the training center in Dallas about the 'official' figure.

Don't fret your hp loss - your torque converter more than makes up for that. Keep in mind that your TC is actually a torque multiplier, typically around 1.6:1. So, in direct drive, if you're putting 300# of torque into the tranny, you're getting 480# out the tailshaft. No manual trans can do that. Also, the use of multi-disc clutch packs means you have more friction surface than any single disk 12" clutch can ever have. This is why auto trannies are far better at towing than manuals will ever be.

In theory, possibly, but here in farm country, the autos die all the time, and the manuals haven't been touched in many of the local trucks with around 120-160K in theory, the auto is better, but the stick sure seems to hold up better in the real world.

Although, any GM pickup auto gives my previous statement a run for its money...(maybe that is why there are sooo many GM trucks around here and there are two gm dealers in a farm town of less than 5K people)

ever seen your neighbors redlining a 1993 2500HD 6.5L TD 4x4 while putting the 4L80E's shifter between D and R? it lasted! same deal w/ a 1990 350TBI 1/2 ton 4x4, redline, pegged temp guage, D and R. both were trying to get unstuck out in the toolies of KS farm country. they got out. :Chevy_anim::Chevy_anim::Chevy_anim::thumbsup: Although the 1990 1/2 ton has 370K miles, and the last tranny was the 3rd or 4th one in.