LY6 and 6L90e swap for my Cutlass. Any and All information is appreciated.

[Calvin Babineau-Crane]

Hey guys. Picked up a 2008 GMC Sierra 2500hd the other day that was missing some front end parts for a really good deal. Has a LY6 and 6L903 with 76k miles that I'll be keeping for my '85 Cutlass Salon. Hoping that once I sell all the remaining parts I'll be pretty close to breaking even if not making a profit so fingers crossed. I haven't been able to find much info on this type of swap. Seems like more people just stick with a 4 speed but i'm stubborn.

Anyways what I'm hoping to get out of this post is a parts list of different parts that may work best, any advice on what changes I will have to make etc. If you've done this swap and have first hand tips and advice that would be great.

I keep hearing mixed opinions about the truck pans working or not working along with the intakes fitting under the hood.

 

[MrSony]

You'll never know until you try. Kickass cutlass btw

 

[Calvin Babineau-Crane]

Thanks MrSony! I will be trying regardless.

You'll never know until you try. Kickass cutlass btw

It's happening one way or the other lol. Just hoping to get some pointers before I dig into it.

 

[Texas82GP]

I know you don't want to hear it but I would ditch the 6 speed trans. We run those trucks at work. I'm the guy who buys them new and rigs them out for our crews. That trans will make it drive like a truck. If you drive it normally it is in 4th by 25 mph.

If it was me I would put in a cam, an LS3 intake and headers. I would run the Holley setup for mounts, pan, headers, crossmember. I would run the Corvette accessory drive. I would go with a T56 magnum myself but a beefed up 4L70E or a 4L80 would be fine. Obviously it would be less expensive to use the truck accessories, pan and intake and there are folks on here who have done it. I don't like how the truck stuff fits the g body chassis or how it looks in a car. I don't like how the oil pan hangs down and I don't like how close the alternator is to the hood. That's just me.

I would sell the truck truck stuff and part out the truck to fund the project. My brother and I did a 6.0 (L96) swap into his 78 Z28 and we ditched the truck stuff. To me it fits like it belongs in there.

 

[Calvin Babineau-Crane]

That looks pretty awesome! And I understand what you mean about the truck stuff but all in all I already have this one, and I really like the idea of a six speed. I'm not to picky with how things look, I'm not building this car for shows or anything, it's more of a budget build and it's also going to be my daily driver. Also like the idea of having something that not many other people have.

 

[Texas82GP]

After thinking about it more it might run pretty well with a fairly high (numerically low) rear gear like the 2.73. I'll have to look up the 6L90's gear ratios.

 

[MrSony]

I know you don't want to hear it but I would ditch the 6 speed trans. We run those trucks at work. I'm the guy who buys them new and rigs them out for our crews. That trans will make it drive like a truck. If you drive it normally it is in 4th by 25 mph.

If it was me I would put in a cam, an LS3 intake and headers. I would run the Holley setup for mounts, pan, headers, crossmember. I would run the Corvette accessory drive. I would go with a T56 magnum myself but a beefed up 4L70E or a 4L80 would be fine. Obviously it would be less expensive to use the truck accessories, pan and intake and there are folks on here who have done it. I don't like how the truck stuff fits the g body chassis or how it looks in a car. I don't like how the oil pan hangs down and I don't like how close the alternator is to the hood. That's just me.

I would sell the truck truck stuff and part out the truck to fund the project. My brother and I did a 6.0 (L96) swap into his 78 Z28 and we ditched the truck stuff. To me it fits like it belongs in there.
View attachment 55575

love the gm blue on it too. Makes me with BOP were still around and gave a sh*t and had their own version of a distributorless FI ls based enigne.

 

[Calvin Babineau-Crane]

After thinking about it more it might run pretty well with a fairly high (numerically low) rear gear like the 2.73. I'll have to look up the 6L90's gear ratios.

I'm hoping it works out well. I have 3.73 gears in the car now. we'll see how it goes I guess.

 

[GBodyscuffle]

I haven't looked into those transmissions very much so I can't help you there. But with any type of build especially LS, spend your money wisely when choosing parts. Do your best to do research on every aspect of it you can. There are plenty of wiring sites for the harness stuff. I have a 5.3 in my 87 cutlass, truck intake fits but barely. I used the weld in universal motor mounts from ebay. And I used the summit muscle car oil pan kit, which is just a hummer H3 alpha pan.

 

[Texas82GP]

I'm hoping it works out well. I have 3.73 gears in the car now. we'll see how it goes I guess.

The first gear is 4:1. The truck has a 3.73 in it as well. With a 3.73 in the car it will jump right out of first just like it does in the truck. The problem is it has a 0.67 overdrive so if you go too high (numerically low) with the rear gear then 6th will be useless. I think the 6l90 is a bad choice for a car but I wish you good luck.