FastKat

iTrader: (10)

What is the parasitic loss on a 4L80E compared to a built 4L60E? I know the 80 is much heavier duty and probably leeches more power from the engine... any ideas or personal experience??

Also, anyone had problems reving the 4L80E up to 6000-6500RPM's? I know it's a truck transmission.

I have a 2003 6.0L w/4L80E trans out of a 2003 2500 cargo van that I am putting in a 1985 Jaguar XJ6. The total vehicle weight will be between 3800lbs and 4000lbs. Also using a turbo setup, so torque is going to be abundant... looking for around 625hp and 550ft/lb of torque at the rear wheels... don't know if a 4L60E can reliably hold that down.

john kilgore

remember a 4L80 overdrives the whole trans in 4th gear and it is heavy. a real plus is that is very strong, you can't say that about 4L60 good luck

FastKat

iTrader: (10)

So you're saying it's safe up to 6,000 RPM's? Can you push it higher or what's the deal?

How an automatic transmission works is one thing I am not familiar with... but I guess what you're saying suggests you experience more drag and parasitic loss in overdrive than a 4L60E?

Dutch SS

iTrader: (3)

My car *only* made 575ft-lbs last season, and i had no trouble running my 4l80 to 6800

I think you will be fine with the 80 on your set up

James B.

iTrader: (1)

All drums, carriers, housings, and other rotating parts of the 80 are all steel. If you want to take it to higher RPM apply the same logic as doing so with a TH400. If it frags it can kill you, so put a shield around it.

I've seen several people take them past 6500. Mine sees only light duty at only 5500RPM max, so I can't really speak from first-hand experience.

'JustDreamin'

I think thats good advice for any transmission that you push hard with big power, regardless of what the internals are made of.

'Dreamin'