6.5TD / Alison

[CareyWeber]

Would an Alison (Duramax version) help or hurt a 6.5's performance?

Is there a stand alone trany control unit for the Alison?

Carey

[AndyL]

A 4L80E is plenty for most 6.5 applications, and can be built very strong if you need more. The Allison behind the D-Maxes is huge, and I bet it sacrifices a bunch more efficiency!

I have never seen an aftermaret controller for it. Seening the 60/80Es selling for $700, I bet the Ally version would break a Grand easy if they made one.

[moondoggie]

Good Day!

I think the 4L80-E is factory-rated for 440 lb-ft; I vaguely remember reading somewhere that a company named Jet produced rebuilt 4L80-E's they guarantee to 700 lb-ft. (I'm counting on folks who might know better to correct these numbers, if wrong.)

If this is so, who needs an Allison? :D

Blessings!

Brian Johnson, #5044

[CareyWeber]

I'm not look for more strength.

I'm wondering if having five gears would help with towing and is there a stand alone controller for the Alison trany.

Carey

[Cowracer]

You would probably save money/time/headaches if you just went with a gearvendors unit.

I cant imagine anyone making an Allison work on a 6.5 for less than $1600, even if someone GAVE you the allison in the first place.

Tim

[grape]

call www.compushift.com (http://www.compushift.com) he makes controllers for various electronic transmissions.

[Keith Richards]

Definately an extremly costly and skill required conversion.Makes that gear vendors sound like a bargain.I want one.If anyone who has one reads this,how much did it cost,labor included.

[More Power]

There's a 2004 Allison for sale in the classified ad page, listed for $1950 O.B.O. This includes TCM, wiring harness, and Torque Converter.

http://www.thedieselpage.com/classad.htm

This was removed from a 4x4 truck, but doesn't include the transfer case. However, an NP-241 (used with all 6.5 trucks/Subs) has the same trans adapter bolt pattern. I don't know about input/output shaft differences or whether its adaptable.

I would imagine someone with some time and technical skills could make it work.

The Allison has been run behind the 6.5 before. In 1999, a Powertrain engineer told me they built a number of 300 HP 6.5 trucks to test the Allison (before Duramax test engines were available). They wouldn't give me any details about how they got to 300 with the 6.5, except to say they were concerned about durability during that time frame (~1998).

MP

[MartyB]

The low end should be better with an Allison vs the 4L80E, as the Ally has a 3.1 first gear ratio vs 2.48 for the 4L80E. The one thing that may kill this tho, is the torque convertor ratio, IIRC it is about 2-1 for the 4L80E, and only 1.73 for the allison, with 20% loss for slippage/heat, the Ally has an effective ratio of about 4.3-1, vs the 4L80E at 4-1, so a bit more low end, but not as good as a manual NV4500 at 5.64 or the ZF at 5.79-1

Marty

[CareyWeber]

Do you think a Alison itself require more power than a 4L80E?

I seem to remember a post the said the 4L80E took more power than the 4L60E, so I would guess that the same would hold true for the alison.

Carey

[grape]

that's cool for future reference about the 241 transfer case. The 208 in the old bodystyle trucks has the same pattern as the 241. This could be interesting.

[rjschoolcraft]

The Allison will take more power to run than the 4L80E. There's a little discussion of this in one of my posts in the thread, 6.5 Performance (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=006650).

[moondoggie]

Good Day!

Keith Richards said,

[More Power]

David Kennedy, writer for 4 Wheel & Offroad is a member of The Diesel Page, and he & I discussed installing an Allison in a Baja Suburban he was building some time ago. At the time, I had not studied the various manuals, and wasn't much help. I haven't talked to him lately, and don't know if he was successful. He was planning to use one of GM's big block power monsters with EFI.

Maybe I should send him a followup email....

MP

[MartyB]

Moondoggies comment re the 700R4 instead of the 4L80E is a common transplant into rigs with TH400's and 4L80E's, as the 1st gear is the same....well a bit off, 3.08-1 as the Allison. You can have 3.73's in the pumpkins with a 700R4, and have the same starting power as a 4.33 gear'd 4L80E/TH400 tranny combo.

The other option, is to put the 1st and 2nd gear from the 700R4/4l60e into the 4L80E. This is doable, but not as common as yanking out the 4L80 for a 700R4.

Same idea as putting in the 1st and 2nd gear from the earliest NV4500's, onto the later models, giving you a 6.34 vs a 5.64 1st gear in those rigs.

Marty