Allison behind 6.5

[Will L.]

Can a moderator please move this to a previously started thread if more appropriate there- my inability to properly search old threads is appalling, I know. Some men you just can't reach

Before I start:
I have no tie in to the company I mention here, and it will be a couple years at least before I send them my person Hummer. I have mentioned them to some buddy's in the DOD when they were looking for anyone that might tackle a problem they had with Hmmwvs...

Allison behind a 6.5 has been brought up here a few times and seemed to end in a don't bother feeling. I don't remember anyone from this forum having done it yet. If you are running fairly stock 6.5 and your transmission lasts you 150,000 miles the 4L80/85 is still the correct answer.

If you eat a tranny sooner, tow heavy, or are hopped up in power to a way above average level- this is being done elsewhere, quite successfully.

A bunch of people think the military or AM General as doing all upgrading of Hmmwvs, no.

http://www.uorva.com/ is one of many companies doing various upgrades.

One of them being putting Allison behind 6.5 with :
1. increase in longevity (obvious)
2. Quicker acceleration
3. Increased top speed

If you thinking knocking several seconds off an over 8ton truck, then pushing it over 100 mph interests you- we think alike.

One can assume accelerating quicker means reduced mpg, not improved. I have not spoken to Mark or John about that- have no interest in it for this type of application. However better top end gearing of the 4l80e over the th400 made an improvement on both ends.

Keep in mind they are use to dealing with 16,500 lbs hmmwv. They also do engine upgrades with a built up db2, "marine" injectors, and gm6 centermount with larger compressor housing and wheel, with cac, they come to a generic rating of 300 hp. (Idk if dyno numbers are there- not the point of this post) Not a big surprise most of us know what better fueling and turbos can do. Given as referance only, as to stop someone thinking minor upgrades get you there. 50% increase in power takes some doing.

Mark is a friendly & helpful guy- but don't waste his time or that is likely to change. They do installs / swaps for Hmmwvs that include wiring to run it components. Don't call to pick their brain how you can do a junkyard at home swap anymore than you would expect Leroy to give you the blue prints and engineering specs of his timing gears so you can make them at home. Aftermarket controllers for the trans is out there in the market for Allisons that can work with 6.5s.

If you're willing to cut a check for install, that is what they do. You might be able talk to them about buying some intelluctal info, idk what level it will go to.

I was on the phone earlier today over there and thought some people here might want to pay to play with them, and others might want to diy their own at a more affordable level once they knew it doesn't come out at a loss if you have the ponies to push.

There are still people saying adding a bigger turbo creates too much back pressure and head pressure to be worth it...others are just doing it.

 

[Twisted Steel Performance]

Interesting, I couldn't find much info on their site, but will investigate a little more.

I kinda like my clutch, but a ally might be good toooo, not sure about taking it to them tho...

 

[FellowTraveler]

Real estate for the Allison trans cooler maybe an issue, then there is the additional weight I think FERM mentioned in another thread however with the Allison an exhaust brake can be used too....

Does the Allison need to built to handle mods like the 4L80/T400 need, or?

 

[tanman_2006]

I don't think the trans cooler will be an issue and the weight isn't an issue when you have 10k or more behind you.

 

[tanman_2006]

A stock Allison can handle 300hp with out defuel, some minor upgrades can make it hold just fine. An lml converter would be a good upgrade also.

 

[THEFERMANATOR]

There is no aftermarket controller that has successfully shifted the ALLISON for any length of time that I am aware of(I'm not talking about the PCS controller supplying the J1850 data for a 5 speed TCM as even that setup has had NUMEROUS issues). So far all of the swaps I have seen that have worked, have all used the ALLISON TCM. There is PLENTY of info on the 4BT site on how to wire up a GEN IV ALLISON 6 speed TCM to make it work stand-alone. It's not that hard really as once the TCM doesn't see the CAN BUS engine data, it reverts back to it's base programming, and will accept a hard wired 3 wire TPS signal. As I've said before, it CAN be done, I just don't see the point for no more power and toirque than a 6.5L makes. I would bet the improvements they are seeing in acceleration are more so due to changes in power instead of changes from the ALLISON. I believe the DUMPSTER van is running in the 11's right now with a 4L85E behind his DURAMAX powered full size van with nitrous, and hasn't had any troubles all season. The added weight isn't a real issue. Yes it's more(just about double), but it can take it. It DOES require a MUCH larger cooler circuit though. The puny 3/8" cooler lines will NOT even begin to work with the ALLISON, and it's not reccomended to run just an air type cooler(it has been done, but it was 2 11X14 super coolers, both sporting high output electric fans.

It can be done, thats not the question. It's just do you need it, and are you prepared to LOSE HP from the swap. It has been proven that the ALLISON draws more HP due to many factors, and not to mention the parasitic loss from all the added mass you will be spinning(I'd almost be willing to bet there is more than double the amount of rotating mass in an ALLISON than there is a 4l80E).

 

[Will L.]

Yeah, I don't want to try to argue tranny with Ferm, he know his stuff, and I don't. I am just sharing info I have been talking to old work associates and a friend about.

In talking to them the reasons they went with the ally (I'm not sure which one) is all the upgrades in engine power had been done and they kept running the 4l80e, but were getting shorter life by a descent amount- probably the fact that the upfitted Hmmwvs weigh as much as 3 of the k3500 4 doors.

The extra 135 lbs of dead weight was worth it in acceleration, because it is faster than the 4l80e was. Why? The extra gear is major! Maybe they put in a wazoo TC? Jacked up or down pressure? Shift kits? I am far from a tranny guy. But I know guys that put a 4L80e behind a 6.2 fall in Love with it compared to the th400 3 speed. My old 69 Camaro when I first got it on the road with a near stock 305 had a used 2 speed power glide waiting for my th350 to get built. I ran 1/4 mile just for kicks- 23 seconds. 2 weeks later my new tranny took it to high 19. We threw in my buddy's old 700r4 when he took it out about 2 months later just to see. Flat 18. More gears gets you there quicker if you have time to shift. Yes weight in motion costs you power, but sometimes there is a net gain like loosing 1000 hp from a 3000 hp engine to drive a supercharger, but ending up with 8000 In a top fueler is an amazing net gain.

They do the engine upgrades without doing the trans upgrade if you want it that way. But if you want if FASTER, HIGHER TOP SPEED, and longer lasting, then you pay for the trans upgrade also. If your engine is already at 300hp that is where they say advantages start kickin in. Is it real 300 or marketed 300? Idk but look at what they say gets an optimizer to 300 and you tell me. If so there are a few trucks on this site in the 325-335 range.

Another thing that is HUGE is the engine braking capability. Running a tiny 7,000 lbs and you guys complain about braking. I would laugh my tail off if it didn't make me cry first. Hummer has a stupid jeep Cherokee or something caliper and pads. Then make it weight to 16,500lbs. Mine is less than 10,000 and I do front and rear brakes annually.

Why is the TCC lock up and engine braking argued against so hard by guys that towed heavy like WarWagon? Cuz the Tranny can't handle it. These do like a dream according to a friend driving an up armoured hmmwv towing a trailer that combos out over 22,000lbs. He is the one that keeps pushing me to do my hummer. I just can't get him to pay for it.

On the electronics- idk. More than this company has figured it out, because they are not the only one doing this to Hmmwvs, just reportedly the best. Not lasting long? True the military has been sold a bill of goods more than once, but having been an upfitter for the DOD, they do not except poor warranty treatment. Repeated problems and they force you into a repair. Think about it GM didn't produce the optimizer or p400, the just flipped the bill for AM Generals engineering costs- look it up. Hmmwvs have db2, engine speed sensor, and temp. The 4L80e has a TCM that works great without all the extra truck electronics, (what's an ECM? Haha) Appears they make it work with out too much input.

Transcooler placement problem in your verticle mounted cooling stack compared to my 30 degree angled stack that they have working in sandland? With a fan apparently 1/2"- 1" smaller diameter. I'm sure there is a solution. My 4L80e doesn't loop inside the radiator, it's a separate unit. They even run a separate little power steering cooling unit on the stack.

If some of you guys are willing to cut a check and buy electronic kit or something from them, they MIGHT sell it, idk.

 

[JayTheCPA]

Do like the idea of a more robust Allison and completely agree that the 4L80 is a weak link for towing applications (braking). But as Ferm mentioned, the things that held me back from an Allison were the reported extra weight and greater internal loss compared to the 4L80. And, Yes, I am one of those whiners with a mere 7K# on the hitch

Agree that the Allison's lower 1'st gear than the 4L80 is definitely nice for off-the-line response. Personally, I focus more on getting power to the wheels for getting the RV up the 5 % - 9% grades around me and this was why I stuck with the 4L80 when my last one wore out.


Perhaps the magic bullet to run an Allison is getting the 6.5 over the 300 hp mark (and I am presuming this is at the wheels) which in turn creates a heat management (shedding) challenge. UROVA's kits look like they are approaching the power upgrades with an intercooler, injection pump, injectors, and turbo master; the 300 hp kit adds a new turbo to the mix. Am curious about how UROVA is getting to the 300 hp mark when IIRC Banks peaked-out around 245 (or perhaps they are taking measurements at different places and are in fact at about the same power level). If it turns out that UROVA's sepecs are at the flywheel, then I am pretty much at the 300 hp mark with the Burb (last dyno was ~245 hp at the wheels) and personally would still have hesitations with the Allison were I given the option (on somebody else's dime).


If given an unlimited R&D budget, I'd look into either the ZF8 or GM's new 8L90 that IIRC are more internally efficient and weigh less than predecessors which (from a specs perspective) makes them good candidates over the Allison.


In the end, like any upgrade path, have high confidence the Allison is workable. The rest of the truck will need to get built around the Allison to balance it out and not result in less power to the wheels.

 

[tanman_2006]

If I wasn't towing then I'd stick with the 4l80 for a DD but I still have yet to see what downfall a fully modded 6.5 that tows hard (30k or more gross) would have with an Allison.

I'm not interested in an Allison in a DD or race truck. The 4l80 isn't a towing trans, GM didn't stick it behind any Duramax's that could gross 30k vans and race trucks aren't the same as a working truck in my opinion.

The trans cooler is a minor hurdle at that point. Using GM lines is a bad idea with a 4l80 let alone an Allison. Iirc, Ferm, you have said a LB7 radiator is the same dimensions as a 6.5 radiator (I'm sure inlets and outlets change some).

 

[WarWagon]

There are worse out there than the 4L80E. Like The 4l70E that blows the top off when a forward sprag fails on a TBSS. They make a kit to drop a 4L80E in the TrailBlazer SS. 395 HP and 400 FT LB at 6500 RPM is factory before you wake that LS2 up.

I posted a for sale on CL on here long ago of someone with a 6.2 NA and Allison behind it. Wish we had the old software where I could post the picture again.

Weak points are no compression braking as the over run clutch will burn up with the TCC locked, weak TCC clutch, 4th gear wear issues, oiling on early models, and ability to snap the input shaft off when shifting with the TCC locked.

I get them rebuilt for ~$1200 and add a ~$1100 Yank. More gears add a Gear Vendors over/underdrive. I don't think an Allison is worth it unless you also go "Alpha" and put a Duramax in place of the 6.5. Why spend the money on a 6.5 when a Duramax is also available? IMO the 4L80E is just fine for a extreme hopped up 6.5. Gear ratios are a compromise... But a high stall overcomes that some.

I have spent a lot of money getting a 6.5 to work hard. Flat lands it would have been different. Out here with the grades there are different platforms to start with that are cheaper total cost for the same result. I have eaten enough hard parts in the engine to seriously question why you would spend the money on a transmission swap and not a better engine - unless it's a P400 as well. And with the turbo fit issues on the deep pocket HUMMER owners I wonder if another engine is an easier choice?

 

[tanman_2006]

I keep saying p400, ATT or he351 (for the turbo brake), and Allison. Sure I could pony up for a Duramax and go through that wiring nightmare but I hate wiring and the 6.5 does fine for me. I've read enough anti 4l80 posts that I won't spend money on them.

All kinds of contradicting views here

 

[Will L.]

@JayTheCPA (that new @ thing is cool) I meant when your truck is 7,000 lbs, not towed weight. My Hummer weighs 9,000+ all the time. Over 10,000 when I go on a trip or to the boonies. I still have the small axles in mine. Hmmwv guys make fun of my light weight truck. So I'm just referring to brakes stopping the truck alone. Adding heavy trailers just takes it to a whole new level.

I have a few friends that had to get cdl for using their hummer towing trailers.


(For everyone). No idea on where they are measuring the hp, or if it's shoot from the hip (math only) that was used. The turbo upgrade is most likely the Switzer s300 s400 hybrid. I would relate it to better spool than hx35/hx40 hybrid with a bit more top end air volume. Iirc a venturied 16cm turbine housing side and a 19cm compressor housing. That seems to be the hot ticket item for centermounts at the moment.

I haven't ridden in or driven Them so I ant say,must going by a trusted friends years of experience driving uparmoured Hmmwvs.

 

[WarWagon]

I keep saying p400, ATT or he351 (for the turbo brake), and Allison. Sure I could pony up for a Duramax and go through that wiring nightmare but I hate wiring and the 6.5 does fine for me. I've read enough anti 4l80 posts that I won't spend money on them.

All kinds of contradicting views here

I would say it's more point of view.

I agree the lack of HD compression braking ability and no mods to 'make it so' cripple towing abilities.

 

[Will L.]

4L80 series is a great transmission, but like everything has places where we wish improvements were made. I would be happy with 4L80e 6 speed kit if it could handle compression braking. 4L85e even more so, plenty of them standing up to 800hp. They handle our power well with long life. And it's not like the 47re or 48re (forget which) huge costs to bring them to handle big power. It's a very affordable trans.

The thing about the Allison is it use to be very expensive, but now is becoming so common the affordability of them makes it much more of a consideration. No one in the world other than Eaton Fuller can even try to compete with that outfit.

It's like yeah my Caddy rides nice, but for a little more I can ride in this Rolls Royce Phantom. But now the price jump is not 4 times as much.

 

[n8in8or]

I've been drooling over those 6 speed kits, but between the hard parts and the proprietary programming it gets a bit spendy. If my drive shaft wasn't already only 30" long I'd love a gear vendor unit under there.

 

[GM Guy]

I do recall on one of the facebook groups, a guy that does lawn care has a yellow crew cab C3500 (might be a K3500) that he Allison swapped and liked it. no idea the specifics on it though.

I personally would be interested in one for Dad's 93 C3500HD, IMO the HD needs the lower first, and with the low rear end gears, it would likely benefit from the 6 speeds. I am sure on out of a topkick/ Kodiak would have the rear mounted parking brake too.

Its all what a guy wants to do with it. I think if i was building a trans for my burb (If I ever get the engine going...) I would stick with a 4L80E, but IMO for the HD chassis cab, the allison intrigues me.

 

[JayTheCPA]

@JayTheCPA (that new @ thing is cool) I meant when your truck is 7,000 lbs, not towed weight.

Ah, Ok. In that case, the shoe fits there too Although, braking is now acceptable while empty with the correct proportioning valve and larger rear wheel cylinders. For towing it is just Ok as I am sharing the same warping experience as Ferm, so I too am looking at moving up to the 1 ton rotors.

If my drive shaft wasn't already only 30" long I'd love a gear vendor unit under there.

Meh. Am leaning toward re-gearing to 3.42's. Rationale is that re-gearing both differentials it is probably lower in conversion cost than the GV install, lower TCO, and the end result is a *much* less complex system. But this is a little OT

 

[n8in8or]

Meh. Am leaning toward re-gearing to 3.42's. Rationale is that re-gearing both differentials it is probably lower in conversion cost than the GV install, lower TCO, and the end result is a *much* less complex system. But this is a little OT

What is OT? Yeah you're probably right about cost and definitely right about simplicity. I really like my first gear and gear ratio spread, I just wish I had one more gear to drop the RPM some more on the freeway.

 

[ak diesel driver]

OT =off topic

 

[n8in8or]

OT =off topic

Ah gotcha, thanks