6.2/6.5 Allison

[afgunn]

In a couple of years, I hope to rebuild my 6.5 and do a lot of the power and reliability improvements including a transmission upgrade. I have searched this forum for info on connecting an allison to a 6.5. I have seen that there is interest. The Truck Trend Magazine article on your Duramax/Allison Project for our trucks http://www.trucktrend.com/features/t...nes/index.html is helpful. On page 2 you will see a picture with the 4L80 and Allison side-by-side. In the caption it states, the allison can be installed with "minor adjustments and NO cutting. Also, that the bolt patterns are the same for the TH400, 4L80 and Allison! For me the Duramax conversion is just too much but, I really would like to do the trans conversion.

Sooooo, the only problem would be interfacing the TCM!? There is also the 6L80/90 but, I think there would be the same problems with interfacing the TCM. Possibly with these they may would bolt in without driveshaft mods and possibly the TCM would interface easier?!

Comments?? I am VERY interested in an Allison conversion!


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[john8662]

I think this will work if you get a standalone controller for the transmission and replace the harness for your truck and computer for that of the same truck and options with a standard transmission.

Which Allison?

If it's the one behind the Duramax, this is a worthy swap because of the 5 forward gears. The latest Allison would be awesome with 6 gears, giving you an awesome overdrive.

But...

The Allison will take more HP to run, so you'll be getting less to the rear wheels, you'll need that 6.5 running pretty stout.

If wanting more gears, a gearvendor would probably cost you less to adapt in, and would be neat to drive still too.

I understand the want a little bit, I'm in a love-hate relationship with my 4L80E in my '96 right now...

J

[DmaxMaverick]

Welcome to the Forums!

Points to ponder....

An Allison will cost you more than twice that of a 4L80E (which you already have, so big $ difference).

The Allison has a greater parasitic loss (takes more power to turn, like John said).

Although the Allison has 5 gears, direct is direct (3 for the 4L80, 4 for the Allison) and the overdrive gear is about the same between them. The only advantage would be shorter gears between 1 and direct with the Allison, if that's an advantage for your application. It may be a disadvantage. The Allison reverse is very deep, though.

The 4L80E can be built, rather cheap, comparitively, to handle about all the power a 6.5 can put out.

You already have computer control and ABS/PCM interface for the 4L80E.

There's nothing wrong with the Allison, but I think it would be way overkill for your application. It would peg the cool meter, though.

[moondoggie]

Good Day!

I edited my post. I started out trying to convince you a 4L80-E would work fine, but it's your truck - all you asked for was advice on how to do an Allison. Glad I caught it B4 it was too late for me to be able to edit.

However you go, best of luck &...

Blessings!

[More Power]

afgunn, I couldn't view the entire link you posted, but a 2-part article did appear in Truck Trend (http://trucktrend.com/features/tech/163_0412_duramaxpart1/) that I wrote for them in late 2004 and early 2005. You are correct in that the Allison will bolt right onto the 6.5, and the Allison torque converter will bolt to the 6.5 flexplate. The photo I used in one of the articles was of an Allison and a TH700R4 sitting side by side. During the process of fitting the engine into the truck, I used a TH400 to check fit. It bolted right up to the Duramax. :)

AM General has also experimented with using the Allison behind their Optimizer 6500 (6.5L TD), and they offer that combination as part of their mil-spec HMMWV as an option.

The company Powertrain Control Solutions (http://www.powertraincontrolsolutions.com) offers a stand-alone Allison computer.

I've seen new take-out Allisons offered for $1800. :)



Jim

[afgunn]

Sorry about the link here it is again:
http://trucktrend.com/features/tech/163_0412_duramax_allison_diesel_engines/

Thanks Jim for the informative help and encouragement! That was great info! And thanks moondoggie for not being critical. After all, what does practically and cost ratio have to do with our hobbies and toys!? I understand if you are talking about a work or tow truck that is work/business but, my truck is more of a hobby and I look forward to rebuilding and improving it. And a 5 or 6 speed allison would be wayyyyy cooool!

I hope to build my 6.5 according to the "Power Project" in a couple of years, with 18:1 cr etc. and would like to get it all done then including the trans. I am planning to have the truck 10 to 20 years to enjoy all the work (and coolness!). To me the allison has a lot of benefits: durability, ease of filter/fluid change, 5 or 6 gears, gear ratio, 2nd OD with 6 speed. And then I can sell the perfectly good 4L80 that I no longer need.

Jim, I too have seen the allisons for about $1500 and up. That makes it very doable! Thanks again! I will definitely be checking that link you gave me. And the 6.5 repair has been very helpful - just repaired my wiper motor! Very helpful with Ernesto bearing down!

OK, I see my link has been truncated again! Anyone know how to overcome that?

Ok, here is a link to the link:
http://www.thedieselpage.com/features/project2-16.htm
Click on the word "here" near the end of the article.

[afgunn]

WOW! Great link Jim. And the controller will also control the 6L80 which leads me into my next post!

[afgunn]

Ok, thanks to all who posted - a lot of good helpful info! I am about 99% sure that I will go with an Allison 6 speed for the strength (360hp and 520 ft-lbs), durability, it bolts to the 6.2/6.5, fits in the trans tunnel and the fact that is is made and geared for a diesel! And, for the final reason:

RPM = MPH x Final Gear Ratio x 336 / tire diameter
= 70 x (3.73 x 0.61) x 336 / 30.6
= 70 x 2.28 x 336 / 30.6
= 1749 RPM

And yes you would need a stand-alone controller because the TCM of the Allison is not made to communicate with the 6.5 PCM. And this one looks like a good one:
http://www.powertraincontrolsolutions.com/content-4.html

[JohnC]

I don't think it'll fit the tunnel unless you lift the body. IIRC, the HD trucks come stock with a 2" body lift.

[afgunn]

On page 2 of the link below they put a Duramax/Allison in an '89 with "minor adjustments (no cutting)" to the tunnel and, to me, it does not look lifted - no lift mentioned IIRC.
http://www.trucktrend.com/features/tech/163_0412_duramax_allison_diesel_engines/index.html

[DmaxMaverick]

On page 2 of the link below they put a Duramax/Allison in an '89 with "minor adjustments (no cutting)" to the tunnel and, to me, it does not look lifted - no lift mentioned IIRC.
http://www.trucktrend.com/features/tech/163_0412_duramax_allison_diesel_engines/index.html

Hehehe.....

That's Lil' Red. The Duramax project truck Jim Bigley did (you know, the owner of TheDieselPage). Nice article, but all the poop is here, on TDP.

The project is well documented HERE (http://www.thedieselpage.com/duramax6600.htm), as well as other places on TDP.

[afgunn]

Exactly!!!!!

[More Power]

Here's a pic of a TH400 bolted onto a Duramax.
http://www.thedieselpageforums.com/photopost/data/500/jimbigley09.jpg

GM Powertrain actually experimented with 300 horsepower 6.5's equipped with the Allison sometime during the 1999 time frame. :)

Jim

[Dale S]

This is exactly what I need to do for my 98 3500HD cab and chassis. Just think, I already have a raised cab truck from the factory, so I have lots of room. I can not afford a Duramax box truck but could do it this way. There are used 96- 98 cab and chassis like mine available for about $1500 to $2000 or so that I could buy one and do all the conversion's and then put my 16 foot box on it and sell both 6.5's and 4l80E's or put one F engine in my 95. I sell parts at car shows and pull a camper with the truck too, so I could stay in business and change the box out after everything is checked out and running great with the Duramax and Allison. Man, I am sure glad I stopped by here today! I probably won't sleep tonight!!!!!!!!!!

[afgunn]

WOW! Great info Jim! Thanks again!

For all, FYI:
The bolt patterns for the bell housing and flexplate for the Allison are the same as the TH400 and 4L80-E. Use the flexplate, bell housing and torque converter for the Allison on the 6.5. Seems like the Allison would be about one of the most cost effective routes to go for the power stated above. And even if not, then you still end up with more, 6 speeds, strength, durability, etc.

[moondoggie]

Good Day!

"And thanks moondoggie for not being critical." I had no intention of being critical, but still needed to not try to sell you against your idea.

Blessings!
(signature in previous post)

[afgunn]

Alan,
The Allison 1000 swaps are a very popular request. We have spent a great deal of time working with this transmission. However at this time we are not selling the Allison 1000 control due to the difficulty level in tuning the transmission correctly. My recommendation would be to get a factory controller and retune the shift points using HPtuners software. We expect to release the Allison 1000 control at a later time after we refine the software to make the transmission more understandable to the average user.

Russell Turner
Powertrain Control Solutions LLC
11139 Air Park Rd. Suite 2
Ashland, Va. 23005
804-752-6025 ext. 202
Russ@ptcs.us

[moondoggie]

Good Day!

"...due to the difficulty level in tuning the transmission correctly." Interesting! I've only ridden in a D/A truck a few times, but I find the shifting of the Allison to be, well, weird. Don't get me wrong, I'd have one in a heartbeat if I could, but my 4L80-E is MUCH less busy - shift points seem to make sense. I think at least some of this is due to the D/A PCM messing with engine power output during shifts, in effect taking over your footfeed at those times; my 4L80-E just shifts, firmer under greater load, softer if driven easy. Perhaps this company is having similar difficulties.

Blessings!
(signature in previous post)