Lc3

[ProTouring442]

I recently picked up a '91 Thunderbird Supercoupe to become my daily good-weather driver. Naturally, I want to upgrade the thing.

I'll be doing all the "normal" upgrades, including 13" Mustang Cobra brakes, rebuilding the suspension with delrin bushings, 17" wheels, etc.

These cars came with a supercharged 3.8L V-6. Nice, but not quite what I want. Hence, I am thinking of a swap.

The supercharged Mustang 5.4 is a nice engine, but it's tall. It also doesn't make all that much power unless you modify it. There are some nice LS engines, but I think I'd like to stay with a supercharged motor, and the supercharged LS engines are pretty pricey.

But what about the Cadillac LC3, supercharged Northstar? It's a 4.4L that uses a different, sand cast block from the standard Northstar, and so does not suffer the head bolt and blown head gasket problems of the 4.6 Northstar. It also makes nice power in its stock form (469hp).

It uses the E67 ECU, so I would imagine I could get a harness for it, and a manual transmission flywheel and bell housing can be had. The engines themselves aren't so expensive (3K-4K for a good pull-out)....

Thoughts?

[ProTouring442]

Bueller? Bueller?

[DavidBoren]

Are you set on staying supercharged?

Are you hoping to find someone with experience swapping the engine out of a Cadillac sts-v (the most expensive Cadillac ever) into a Ford supercoupe? Because, you will probably be the first if you do this...

The idea is awesome. That xlr-v/sts-v motor is nice. If you do use it with the factory supercharger, add another heat exchanger between the reservoir and the blower. Still retain the main hx after the supercharger, as well.

As for wiring harnesses, make your own, don't be scared. Wire it up with megasquirt or the like, and perfect the tune. You are pretty much stuck with the stock cams and 9:1 compression ratio, unless you go into the custom market. So your only real room to grow is in the tune.

You mentioned a manual transmission option...? Did the xlr-v have a manual transmission available that I am not aware of?

[DavidBoren]

I tried to answer your question in my first response. You asked about swapping a Cadillac motor into your supercoupe, and I think it would be awesome.

However, I have to say, and I'm sure many people on here will agree, that an all aluminum 4.8/5.3 with a single 75mm-80mm turbo is actually exactly what you are looking for.

You specifically mentioned that $3-4000 wasn't too bad for a 400hp pull out motor. I think you would be pleasantly surprised to see what that same amount gets you as far as a turbo LS motor is concerned.

I love Cadillac. I do. But the best thing Cadillac ever did was stick an LS engine in the cts-v. The northstar just doesn't hold a candle to the cam in block LS motor in terms of reliability and upgradeability and user level maintenance.

[ProTouring442]

Originally Posted by DavidBoren

I tried to answer your question in my first response. You asked about swapping a Cadillac motor into your supercoupe, and I think it would be awesome.

However, I have to say, and I'm sure many people on here will agree, that an all aluminum 4.8/5.3 with a single 75mm-80mm turbo is actually exactly what you are looking for.

You specifically mentioned that $3-4000 wasn't too bad for a 400hp pull out motor. I think you would be pleasantly surprised to see what that same amount gets you as far as a turbo LS motor is concerned.

I love Cadillac. I do. But the best thing Cadillac ever did was stick an LS engine in the cts-v. The northstar just doesn't hold a candle to the cam in block LS motor in terms of reliability and upgradeability and user level maintenance.

Good and interesting points...

A turbocharged LS sounds good, but then we get into tuning an unknown quantity (meaning a non-production engine/cam/turbo package) to ensure I don't grenade the thing, whereas the LC3 would push 500hp (it's 469hp stock) with a simple aftermarket/non-emissions tune.

Still, interesting points...

[DavidBoren]

There are multiple proven recipes for ~600hp single turbo junkyard 4.8/5.3 motors. It's possible to put over 500hp to the tires with a factory sealed longblock, literally nothing more than afm/DoD delete, valve springs and injectors changed. Stock cam, truck intake, truck manifolds reversed, single 76mm hairdryer... Dyno tune and done.

You could probably find someone who has a turbo 4.8/5.3 and get an exact parts list, and their tune file. That would take out a lot of the guesswork.

If you really want some peace of mind, open up the longblock, gap the rings, and reassemble with ARP hardware.

It's literally just that easy. It's kind of disgusting, really. It's like cheating. Piece of crap, mass produced, light duty truck motor capable of withstanding 20psi of boost from the factory, capable of putting 1000hp to the ground... On sale now for $300 in your local craigslist auto section.

We live in good times to be car enthusiasts.