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Can you put a 6L90E into a 4L80E '98 K2500 Suburban 6.5TD?

Husker6.5

Husker6.5

135' diagonal 16:9HD, 25KW sound!
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Like the title says, what would it take to put a 6L90E in place of the 4L80E in my '98 K2500 Suburban 6.5TD? I know the transmission will bolt up to the engine, standard GM bolt pattern, but what other mechanical mods would be necessary ie: cross member, front/rear drive shafts, adapting the mechanically actuated transfer case, etc? The motor would be mildly modified - ATT turbo, mild 40-80 HP tune, etc to be up around 250HP/500TQ running with either 3.73 or 3.42 gears front and rear.

More importantly, what would have to be done to the OBD-II ECM to make it so it would shift the new tranny?

The advantages are obvious to doing this - better gear ration spread with two overdrives and a final OD taller than the 4L80E to better take advantage of the torque band of the 6.5 and deliver about 20-30% better fuel mileage, especially on the highway.
 
Burning oil said:
Whats a 6L90E come in? Never heard of it.
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The 6L90E came in the new style HD trucks behind the 6.0L starting around 08-09. The 6L80E comes in the new 1500's and the CAMARO.

Husker6.5 said:
Like the title says, what would it take to put a 6L90E in place of the 4L80E in my '98 K2500 Suburban 6.5TD? I know the transmission will bolt up to the engine, standard GM bolt pattern, but what other mechanical mods would be necessary ie: cross member, front/rear drive shafts, adapting the mechanically actuated transfer case, etc? The motor would be mildly modified - ATT turbo, mild 40-80 HP tune, etc to be up around 250HP/500TQ running with either 3.73 or 3.42 gears front and rear.

More importantly, what would have to be done to the OBD-II ECM to make it so it would shift the new tranny?

The advantages are obvious to doing this - better gear ration spread with two overdrives and a final OD taller than the 4L80E to better take advantage of the torque band of the 6.5 and deliver about 20-30% better fuel mileage, especially on the highway.
Click to expand...

Bolting it up isn't the problem, the problem is it uses an integrated TCM to control it that works off of CAN BUS ONLY. CAN BUS didn't start until 06, and is a GM propriatary data protocol that works at VERY high speed(instant data transfer basically). I think theres a company out there working on an interface module to allow it to be used with stand-alone inputs, but I don't know if it was ever built or not. I'll try and look later on to see if I can find the company that was working on it.
 
You'd have a much easier time trying to fit the TCI 6X trans, basically a 4L80E with 2 more gears. It comes with its own TCM, but I'm sure it's not cheap. Basically you'd need the ECM programming for a manual trans, as the trans is a contained unit in and of itself. Not sure what that requires on the 6.5.
 
Dad's 05 LLY said:
You'd have a much easier time trying to fit the TCI 6X trans, basically a 4L80E with 2 more gears. It comes with its own TCM, but I'm sure it's not cheap. Basically you'd need the ECM programming for a manual trans, as the trans is a contained unit in and of itself. Not sure what that requires on the 6.5.
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The TCI 6X does not add any more gearing to the top end, it adds the two gears in between 1-2 and 2-3 so that 3rd (now 5th) is still direct 1:1 and OD (now 6th) is still .75:1. It is a racing tranny. The 6L90E's 4th is like 1.12:1 (a little under direct), 5th OD is like .82:1 and 6th OD is like a .63:1 ratio off the top of my head IIRC. With a 3:42 front and rear, it would drop the RPM's right onto the sweet fat spot of the torque curve at 82MPH out on the Interstate (Nebraska cruising speed on I-80 for residents, pulling over the out-of-state drug runners speed for everybody else)
 
THEFERMANATOR said:
The 6L90E came in the new style HD trucks behind the 6.0L starting around 08-09. The 6L80E comes in the new 1500's and the CAMARO.



Bolting it up isn't the problem, the problem is it uses an integrated TCM to control it that works off of CAN BUS ONLY. CAN BUS didn't start until 06, and is a GM propriatary data protocol that works at VERY high speed(instant data transfer basically). I think theres a company out there working on an interface module to allow it to be used with stand-alone inputs, but I don't know if it was ever built or not. I'll try and look later on to see if I can find the company that was working on it.
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Is this who you're thinking of, 'Fermanator? The thread is several (4-5) pages long and spans over two years, but this is what got me really thinking if the swap is feasible or not into out platforms. I found it on a Google search of 6L90E: http://www.performancetrucks.net/forums/gm-drivetrain-suspension-22/6l80-6l90-bolt-kit-462346/

If it's not practical or feasible due to either/or incompatibility of the two languages/computers to interface with each other or the overwhelming cost of a stand-alone TCM and reflashing a new program to delete most tranny control functions on the OBD-II 6.5 PCM to do the 6L90E-4L80E swap, how about what would swapping in a NV5600 for the 4L80E entail?
 
All of the kits I have seen to swap the 6L80E/6L90E trans require the use of a E38 ECM that talks in can bus protocol. They are swapping the ECM for the engine to the new one and integrating it into the old one to keep everything working like stock. I see no way at all to even begion to hook this type of set-up up to a 6.5. The real problem is that the TCM and valve body are 1 piece, and the TCM will ONLY work with a can bus controller. So it's not like you can remove the TCM and go with a stand-alone controller.
 
THEFERMANATOR said:
All of the kits I have seen to swap the 6L80E/6L90E trans require the use of a E38 ECM that talks in can bus protocol. They are swapping the ECM for the engine to the new one and integrating it into the old one to keep everything working like stock. I see no way at all to even begion to hook this type of set-up up to a 6.5. The real problem is that the TCM and valve body are 1 piece, and the TCM will ONLY work with a can bus controller. So it's not like you can remove the TCM and go with a stand-alone controller.
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Damn GM engineers! Looks like Plan B; NV5600 K2500 Suburban!! And I so do love the custom center console I have that extends all the way up to under the dash. On the other hand, the 4WD lever on the floor wouldn't be lonely any more!
 
OR, how about the feasibility of dropping in an '06 six-speed double OD Allison 1000 series out of a DMax?
 
Both of your above options look to be pretty costly. The NV5600 never came behind a GM, so you would have to find a way to get a GM bellhousing coupled up to the NV5600, and then run a DODGE transfer case(or custom drill the extension housing as GM and DODGE transfer cases are clocked 90 degrees different from each other). And the 6 speed ALLISON is an EXPENSIVE option, but is doable. I wouldn't do it myself as you would essentially lose about 15-20HP to the wheels just by adding the ALLISON in from the extra parasitic drag. The ZF6 would get my vote if your dead set on a 6 speed, but they are TOUGH to find.
 
What was the six speed manual ran behind the DMax the first years before they discontinued offering the option? I thought it was an NV5600. As far as the six speed Alison, if I was running the mods to the 6.5 listed at the beginning (intake, ATT, injectors, 40-80hp tune, 4" exhaust, taller gearing) wouldn't that more than make up for the parasitic losses and not hurt getting better MPG that much in the process?
 
The ZF6 as Ferman mentioned, was the manual trans used behind the Duramax till 06, when it was discontinued altogether.

It would make up for it, but you're now back to where you were power-wise. It's just 20 more HP being created into heat, instead of moving your rig forward.

Honestly, your best bet is probably going to be a Gear Vendors...
 
Doing the mods will make up for it, but look at it this way. you do them ods and up it from 190 to say 275 HP. With a 4L80E you'll be able to put about 220-230 to the wheels, with an ALLISON you'll be putting about 200-215 to the wheels with the SAME engine. The ALLISON has alot of rotational mass, and it's pump is HUGE compared to the 4L80E. theres a reason the 4L80E can get by with a 3/8" line whereas the ALLISON NEEDS a 5/8" line. the ALLISOn uses alot more fluid to operate, and that pump takes alot of HP to run and maintain 240 PSI(145 in lockup). And the ZF6 was the 6 speed manual used behind teh DMAX, only the 01-05 CUMMINS had the option of the NV5600, and even then not all manuals were the NV5600 as you could get the NV4500 up to early 03.
 
Great info Ferm, just one question? I thought the Ram got the NV5600 in late 1998? I was under the impression that there was a rare-as-hen's-teeth configuration in 1998 with a P-pumped 12-Valve and the NV5600.

I enjoy learning about the new GM drivetrains, I am glad you share such knowledge with us.
 
Gotta agree on the 'gear vendors' option for a second overdrive.

Good to know a out the canbus systems, makes all the latest auto trans very difficult to adapt
 
There was a rumored 98 12 valve with a NV5600, but no one has a picture or anything else on it other than yeah I seen one. And I remember working for DODGE, and all the hub bub in 00 about the all new 6 speed coming out for 01 behind the 245HP HO engine. I think the rumor started because somebody swapped an NV5600 into a 98 12 valve when there NV4500 spun the 5th gear nut.
 
What about those 2 speed gearboxes they made for TH400 transmissions? You could either have it to gear up or down.
 
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