ez2cdave

In case anyone has questions about HP loss when swapping a 4L80E for a 4L60E, this should answer that question . . .

Source: http://www.performancetrucks.net/for...esults-503358/

Burken01

iTrader: (88)

Hardly anything and twice as strong!


I'll take that all day!

thunderstruck507

iTrader: (18)

That thread also mentions the 4l80 run also included more timing which offset some of the loss. Still impressive though.

Jake's Performance

iTrader: (2)

Half a degree more timing but a converter that weighs ~30 lbs more... Probably about equal.

I consider the 4L60E a fairly efficient design as far as parasitic loss, but I also believe that the loss due to rotating mass is WAY overevaluated for most enthusiasts.
The short story is that if you are making enough power to worry about the parastic loss, you NEED the strength of the 4L80E (or TH400).

My experience is that a car usually needs to be DEEP into the 9's to see any difference in internal rotating mass.
One of our customers went from 8.12 quarter mile, 5.25 1/8th mile to 5.10 1/8th mile (no full 1/4 runs) but also launching in 1st to a 2nd gear launch on a TH400. We took about 18 lbs out of the internal mass and did some other tricks to free up HP on that unit.

mrvedit

I recall another thread from 3 or 4 months ago where the OP documented his ET/Speed before and after swapping from a 4L60E to a 4L80E without making any other significant changes and with similar stall speed converters. IIRC, his ET dropped by a tenth, which I thought was definitive proof that a swap to a 4L80E will not slow you down, at least not with a similar rearend ratio and cam. I suspect that a 3.42 or higher rearend ratio is needed for good starts with a 4L80E.

Jake's Performance

iTrader: (2)

The rear gear ratio depends on the combo, many of the turbo combos we deal with work well with a 3.2x-3.5 ratio.

90% of the transmissions we build are for 800+ RWHP, with many being in the 1200-1500 range. That's just the nature of many of the forced induction setups these days.

The 4L80E ratios simply work better at that power range, and in some cases even the stock 2.48 ratio low is too much starting ratio or a closer ratio gearset works better such as the 2.10 gearsets.

The argument about shift extension being covered up by a looser converter that some 4L60E advocates argue is weak at best. The 4L60E ratios require that the converter be loose enough to provide that shift extension, a properly setup combo will have ratios that work, and the converter can be built for ideal stall speed, not covering up poor ratios.

When the power levels get even higher, we're dealing with 2nd gear launches on the TH400s and 4L80Es. Even less starting line ratio.

In a typical bolt on car with 400 RWHP the 4L60E ratios will make the car FEEL faster, and the transmissions will be approximately equal at the track.
Anything much faster and the closer ratio with less launch ratio starts to shine.

ez2cdave

I found this chart, comparing ratio's in the 4L60E Vs. 4L80E on a website . . .

http://www.gearvendors.com/hrgm4s.html

ez2cdave

4L80E Transmission Specs

Gear Ratio
First 2.48
Second 1.48
Third 1.00
Fourth 0.75

Trans Weight w/o converter
4L80E 187 pounds
TH400 130 pounds
4L60E 160 pounds
TH350 125 pounds

http://www.carcraft.com/techarticles..._transmission/

ez2cdave

How about a "5-Speed or 6-Speed" 4L80E ???

http://www.powertraincontrolsolution...ed-Valve-Body/

thunderstruck507

iTrader: (18)

For what it's worth I was not trying to argue for or against anything just pointing out the detail from the other thread I had noticed. I had not considered the weight of the converter so good point there.

One of these days I wouldn't mind a 4l80 in mine but it will require floor cutting as the ribs on a 4l60e case come into contact with my floor as is.

ez2cdave

I've been searching for more dyno comparisons . . . Please post them up, if you find them!