Allison truck tranny

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Dec 7, 2014 | 11:12 AM

waxenate

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Allison truck tranny

Anyone have an idea what to expect from putting an Allison out of a 3500 gmc behind a 6.0 in something small like a miata? Overkill? Power robber? Planning on a tb upgrade, head porting and a cam swap. Looking for atleast 450hp.

I have swapped an ls1 into a 95 z28. About the event of my knowledge. That was for my son and now dad wants a toy.

Dec 7, 2014 | 11:16 AM

ls1nova71

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Are you serious? ! You want to put an Allison in a Miata? That is probably the most overkill thing ive ever heard, not to mention it probably wont fit very easily. Would also likely rob a lot of power. If youre only going for 450hp in a small car a 4l80e would be a good choice and still probably be overkill, but that's what I would do.

Dec 7, 2014 | 01:37 PM

tfi racing

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From: Cedar,BC

Nothing to it.Cut away firewall,dash,tunnel,most of floor and that huge Allison tranny will slide right in...

Dec 7, 2014 | 01:56 PM

Jimbo1367

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Sounds like a smart swap. N_E_V_E_R have any tranny problems.

Dec 7, 2014 | 08:28 PM

66Chevellelq4

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From: Torrance Ca

Thats plain overkill. Plan on cutting up your entire floor

Dec 7, 2014 | 08:47 PM

truckdoug

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From: Portlandia

make it a structural member and skip the cage!

Dec 7, 2014 | 11:12 PM

jmd

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It is the reason the 3/4 and 1 ton trucks have elevated bodies off the frame. Probably not the hot point for a Miata. However I am willing to review pics of you cutting one up and provide critique.

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Dec 8, 2014 | 04:33 AM

waxenate

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That's what I love about this forum! Ask and ye shall receive! I kind of thought it might be overkill. Just had a chance to pick up a 2005 Sierra with the 6.0 and tranny.

It would be a sick though wouldn't it! Lol

Thanks guys!

Dec 8, 2014 | 06:03 AM

#10

etijsma

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I don't know how much bigger they are compared to another but if you have to cut think about how much you may have to cut out. On my project I had to move the pedals over and my tunnel is 1/4 away from my seats.

Dec 8, 2014 | 06:07 AM

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MrJuanderful

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Allison is for diesel only.Even if you could somehow couple it to a gasoline engine,the gear ratios are tailored for the narrow diesel power band.It never came with the 6.0

Dec 8, 2014 | 07:13 AM

#12

1964SS

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Quote:

Originally Posted by MrJuanderful

Allison is for diesel only.Even if you could somehow couple it to a gasoline engine,the gear ratios are tailored for the narrow diesel power band.It never came with the 6.0

You are partially correct. The Allison did come behind one gasoline engine, but it was 8.1 BBC.

Dec 8, 2014 | 02:30 PM

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01cherryreds10

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If the truck had a 6.0 it had a 4L80 and I would say yes buy it if the price is right

Dec 8, 2014 | 09:15 PM

#14

MrJuanderful

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Quote:

Originally Posted by 1964SS

You are partially correct. The Allison did come behind one gasoline engine, but it was 8.1 BBC.

I stand corrected.Probably not the best combo of all time.

Dec 9, 2014 | 08:27 PM

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waxenate

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Update..... It's a 6L90 transmission. I saw the six speed and assumed allison. So what about a 6L90 in a miata???? Lol

Dec 9, 2014 | 09:17 PM

#16

pdsq98gt

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A 6l90 would be great. But it wouldn't be from an 05 truck

Dec 15, 2014 | 10:05 PM

#17

Manic Mechanic

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Quote:

Originally Posted by MrJuanderful

I stand corrected.Probably not the best combo of all time.

This sounds argumentative but the best way to say this is stick to what you actually know about when dolling out assumptions. I own one and it's the best combo I've ever driven in a truck, the ratios are wide and fine for any type of fuel. The 8.1 leaves hard and shifts out at about 4800-5200 stock then falls back to the torque peak, what more do you want?

The Allison is not well suited for a light weight performance application. Also gear changes require release of the current gear before the next can engage. This makes shifts take more time. The ratios are not the problem as the six speed auto has similar gear spreads.

Vernon