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ZF 8 SPEED TRANSMISSION CONVERSION CONSIDERATIONS

tanman_2006 said:
I am not completely sold that an Allison is too big for a 6.5 . . .
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From a size perspective, from what I can tell it kind of depends. Some bodies will either need a 2" lift or banging out the tunnel. So the size issue is workable. But at 300+ lbs, it does make for a heavy beast.

From a power delivery perspective, am reading where its internal drag actually gets less power to the wheels than the 4L80E. Not so much of a factor for a DI motor (like the Dmax), but definitely a consideration for the 6.5.
 
Cannot see the testimonials (something about their site and my firewall are not playing well), but can see on the homepage where it looks like they have a 6.2 ready to pull a semi.

Definitely, agree that the Allison is physicall possible. Only comment is that it seems like a step backward for the 6.5 as the Allison has regular notations of internally consuming more power than the 4L80E.
 
That burb has a Cummins swap and I've deemed that post worthless. I pulled loaded semis with my K1500 6.5l when we had a starter quit one harvest.
 
Can itbe made to work, yes. The problem is the parasitic draw. The 4L80E is perfectly suited to a 6.5's output(even when modofied), so why put a trans behind it that is going to INSTANTLY ROB ANOTHER 10% or so of your power? The question isn't can it work, the question is should it be done.
 
I'd run this and maybe an lml converter since its higher stall (maybe go custom).

Its a 6 speed Allison from an 06 in case the link goes dead.

http://oklahomacity.craigslist.org/pts/5438665357.html

Its not that I think the 6.5 will over power a 4l80, and I don't think anyone is saying that.

I think an Allison with grade braking and manual shift capabilities would be a good next step for 6.5's its dang near bolt in. We have proven a 6.5 can make more power so parasitic loss isnt a big concern since we are seeing around 300hp crank on modded trucks. Add in the beefy p400 I'd be tempted to stick it in a gmt800 to get the Allison in easier.
 
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Thats a good point.

Gear it for the Rpm's you plan to use towing. I never towed in 6th and rarely towed in 5 heavy. So with 33's (255/85R16) and 4.10's you should be able to tow good at 70 in 5th and 4th shouldn't be out of power band with a large or vgt turbo.
 
Lets say your making 300HP at the crank. With a 4L80E you should be able to put down say 250 or so to the wheels, wit hthe ALLISOn that same 300HP will put down about 225-230HP to the wheels(stock LB7's from 02-04 put down 225-230 at the wheels, 01's seem to put down about 230-240). So at 300 flywheel HP, that is 30 HP pissed straight dow nthe drain because of nothing more than parasitic loss. With an ALLISON all that extra weight is primarily in rotating mass. Once you've held the C1/C2 drum in your hands, you understand why these things have a MAX RPM input rating of 5K RPM's, and where all that weight is. Secondly a LARGE portion of the parasitic loss is due to the pump. The ALLISON uses a LARGE pump in it that moves ALOT of oil. It needs 5/8" cooler lines for a reason, and that is just the fluid that is bypassed from the pressure regulator(the ALLISSON flows the oil that the pressure regulator dumps out through the cooler circuit to lubricate teh rotating assembly, so when the pressure is low at low RPM's, theres little to no cooler flow). Then your up against the problem that the 6.5L isn't a high torque diesel, and torque is what you need for all that drag, all that mass, and all that internal loss. Like I said, can it be done, sure, I just don't see the reason. And in a swap situation, grade braking would NOT work, you would have to manually downshuft it for it to work as grade braking will lok for feedback over the data bus from the engine in regards to fuel delivery.
 
On grade braking it should work because they have it on the standalone controllers behind a 12 valve.

IMO a 6.5 rivals an 8.1l in power and they run an Allison.

What I'm reading is low Rpm's are bad with the Allison (same is true for the 6.5) and don't rev past 5k (same goes for 6.5).

I'm in the same group as @Will L. that power loss can't be linear. 300hp at the crank is possible from a stock db2 and att. There are a lot of trucks that should hit the rollers.
 
Without knowing the internal penalty of the 6L80E / 6L90E and if limited to just a 6 speed, if I had to go with a 6 speed and could not wait for the 8 speed conversions to come out, I'd go with a built 6L90E prior to the Allison simply due to weight advantage and wider gear range.
 
Possibly, my 2 biggest concerns on a 6l90 are the standalone performance and its not proven behind a diesel. Otherwise it makes a good bolt in choice and newer 6.0's have put some respectable power numbers through them.
 
JayTheCPA said:
Without knowing the internal penalty of the 6L80E / 6L90E and if limited to just a 6 speed, if I had to go with a 6 speed and could not wait for the 8 speed conversions to come out, I'd go with a built 6L90E prior to the Allison simply due to weight advantage and wider gear range.
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As it stands now the 6L90 would be the best choice.
 
No definite report on grade braking abilities but can't be worse than a 4l80 surely.

I like the Allison gear ratios better but the 6l90 isn't terrible.

Allison builds and sets up their transmissions for standalone operation all the time, I have a feeling their TCM might be superior to some aftermarket controls.
 
tanman_2006 said:
Possibly, my 2 biggest concerns on a 6l90 are the standalone performance and its not proven behind a diesel. Otherwise it makes a good bolt in choice and newer 6.0's have put some respectable power numbers through them.
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GM puts the 6L90E behind the DURAMAX in the vans, has been for years now.

tanman_2006 said:
On grade braking it should work because they have it on the standalone controllers behind a 12 valve.

IMO a 6.5 rivals an 8.1l in power and they run an Allison.

What I'm reading is low Rpm's are bad with the Allison (same is true for the 6.5) and don't rev past 5k (same goes for 6.5).

I'm in the same group as @Will L. that power loss can't be linear. 300hp at the crank is possible from a stock db2 and att. There are a lot of trucks that should hit the rollers.
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I haven't towed with a 8.1L, but I doubt the 6.5L is going to out pull one head to head. Most will argue and say teh 454 will outpull a 6.5L under most conditions, and a 454 can't hold a candle to a 8.1L. I know many here are die hard 6.5ers, and nothing against it, but it isn't really known as a power house. Power loss will be more so a percentage based loss. And if stock, it will lose more power with the trans unlocked as pressures are higher out of lockup. The ALLISON has NO problems with low RPM's, it's high RPM's where it has problems(hence the 5K RPM limit). As to grade braking, mine barely kicks in, and is often times disabled because of no ABS input to the TCM(have logged it with my V2 and verified this), and mine is still running a DURAMAX engine in front of it but it doesn't have any ABS or other inputs over the J1850 data bus. I know several CUMMINS guys have complained that grade braking does NOT work with there swaps using the PCS box(don't know about the ones who did 6 speeds with the true stand-alone swaps as the PCS only worked with the 5 speeds). And the 6L90E hasn't been proven that well in stand-alone apps with it's internal TCM. It works ENTIRELY off of high speed GM LAN communications to the internal TCM. I know theres a company making an analog conversion interface to send the required signals to it, but last I heard was it was hit or miss wether it woudl work or not.
 
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