4l60e To 6l80e Almost......

FREAKENHYE · July 4, 2008

Well after talking to someone on other threads, and one person on PT.Net looks like all im gonna need for this is a

6 speed from a 07 Denali

Transmission harness

Crossmember of the 07 Denali/Esca

New Drive Shaft

And reprogrammin of he bcm and ECM to control it.

Everything is plug and play from the hardware part.

Well i started my search for a 6speed, harness, and cross member.

Got the Magnuses mp112 ordered, just need a tranny to put all that power onto the ground.

Oh also gonna drop the gears from 3.73 in the rear to 3.42's or 3.08's

since the gear ratio for the tranny is

1st Gear Ratio 4.027

2nd Gear Ratio 2.364

3rd Gear Ratio 1.532

4th Gear Ratio 1.152

Service Information

5th Gear Ratio 0.852

6th Gear Ratio 0.667

3.42s should feel like 4.56s should get a kick ass MPG with this setup.

Already getting 23.9mpg now on the highway at 65mph cruise control.

Should see a nice improvement once done. Hoping

BigJayDogg3 · July 4, 2008

I don't think so. IIRC the final drive of the 6l and the 4l are reeely close to each other.

I could be, and wouldn't mind being wrong, but I don't think that I am.

FREAKENHYE · July 4, 2008

I don't think so. IIRC the final drive of the 6l and the 4l are reeely close to each other.

I could be, and wouldn't mind being wrong, but I don't think that I am.

True, but dropping from 3.73's to 3.08s and still having it feel like its 3.73s in the back because of the first gear ratio of the tranny, it will help me get about 25mpg on the highway im good.

svensk · July 4, 2008

I don't think so. IIRC the final drive of the 6l and the 4l are reeely close to each other.

I could be, and wouldn't mind being wrong, but I don't think that I am.

True, but dropping from 3.73's to 3.08s and still having it feel like its 3.73s in the back because of the first gear ratio of the tranny, it will help me get about 25mpg on the highway im good.

yes that first gear is crazy low.

slomo007 · July 4, 2008

Already getting 23.9mpg now on the highway at 65mph cruise control.

Not with the 3.73 rear end, there's just no way. Sorry.

Maybe downhill over 20 miles, but not consistently.

BigJayDogg3 · July 4, 2008

FREAKENHYE · July 4, 2008

Already getting 23.9mpg now on the highway at 65mph cruise control.

Not with the 3.73 rear end, there's just no way. Sorry.

Maybe downhill over 20 miles, but not consistently.

Actually got the vids to prove it. 80 mile trip from Riverside, CA to Northridge, CA

I was on cruise control at 65 mph the whole trip.

VMax2007 · July 4, 2008

Already getting 23.9mpg now on the highway at 65mph cruise control.

Not with the 3.73 rear end, there's just no way. Sorry.

Maybe downhill over 20 miles, but not consistently.

Actually got the vids to prove it. 80 mile trip from Riverside, CA to Northridge, CA

I was on cruise control at 65 mph the whole trip.

yeah, but how "real world" is that? I suppose you reset the DIC after getting up to 65 and then documented it as you were slowing down on the offramp. Right?

redvett · July 4, 2008

The 4L60E has a different ECM than the 6L60E and requires a faster ECM along with a TCM switching from the 4spd to a 6spd is very costly, ECM,TCM,gearing,drive shaft & other parts along with wiring and programming. You will never re coupe the costs.

slimjim2525 · July 5, 2008

Already getting 23.9mpg now on the highway at 65mph cruise control.

Not with the 3.73 rear end, there's just no way. Sorry.

Maybe downhill over 20 miles, but not consistently.

I agree with ya, it's just not possible. 4l60 to a 6l60, I don't see the point, and the cost will be tremendous.

svensk · July 5, 2008

If this was a race truck there would be benefits to the cost. I've seen a guy on pt.net who did this swap to a 6.0L in a reg cab truck and after a tune he was in the 13's quarter mile.

BigJayDogg3 · July 5, 2008

If this was a race truck there would be benefits to the cost. I've seen a guy on pt.net who did this swap to a 6.0L in a reg cab truck and after a tune he was in the 13's quarter mile.

And the fact that he has a supercharger on the way makes me say that is what he want it for.

FREAKENHYE · July 5, 2008

Already getting 23.9mpg now on the highway at 65mph cruise control.

Not with the 3.73 rear end, there's just no way. Sorry.

Maybe downhill over 20 miles, but not consistently.

Actually got the vids to prove it. 80 mile trip from Riverside, CA to Northridge, CA

I was on cruise control at 65 mph the whole trip.

yeah, but how "real world" is that? I suppose you reset the DIC after getting up to 65 and then documented it as you were slowing down on the offramp. Right?

Rpm was at or about 1850 or 1900 at 65mph. 3.73 gears with stock 20's. Rear cover, nerf bars, 3/4 tank gas and passanger.

Also mods where done to the truck, like intake, exhaust, headers, and a minor tune.

I think ill do the whole trip with a camera and see if i can duplicate it again, also this time instead of having 3 sep vids, ill have one long one.

FREAKENHYE · July 5, 2008

The 4L60E has a different ECM than the 6L60E and requires a faster ECM along with a TCM switching from the 4spd to a 6spd is very costly, ECM,TCM,gearing,drive shaft & other parts along with wiring and programming. You will never re coupe the costs.

If im not mistaken the E38 ecm whitch controls the Tranny on the Denalis is also on the silverados. only thing left is programming the BCM and ECM, and im gonna have to look into that one. Everything else is plug and play since all you have to do is buy the parts and put it on.

Tranny cost 2k rest of the materials just about 2k plus or minus 200 bucks. Speartech will the reprogramming of the ECM and gotta find out exactly whats needed in the BCM

FREAKENHYE · July 7, 2008

i gotta say this, one guy has already done this just found out, he is only having problems with the fual pump, and cluster not displaying 321 only displays PRND

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