I am thinking of trying to swap in a 8.1 vortec truck engine into my '91 firebird. Are the mounts the same as the 5.3/6.0 vortec? What can I do with the added weight of the 760 lb engine to keep the car cornering good, besides stiffer springs and larger sway bar? Is the bellhousing the same as an ls1, or do i need to stay with the automatic that is in the truck i am wanting to get for parts? It would be different, but that's what makes it fun...

Search a bit, its been discussed some. The 8.1 is a BBC. BBC's have the same mount location as SBC, same with the bellhousing, You could use the trucks 4L80E if you are staying automatic, which may require some clearancing of the transmission tunnel, and fabricate a trans crossmember. Go with a 4L60E which is a direct bolt in. Or you could go with a 94-97 T56 from a LT1 4th gen.

I would strongly suggest getting the engine complete with an uncut wiring harness, all front driven accessories, exhaust manifolds, etc.
A tubular K member would help a great deal with the swap also.

I am looking at buying the whole truck.... it's been wrecked but still drivable. My concerns stem from the fact that the 8.1 vortec isn't a regular BBC, it's a light truck/RV engine and doesn't match up to a regular BBC's motormounts, bellhousing or anything else. It's an ls style engine, but I'm not sure what parts I would be able to use and which I would have to make.

I like the idea of the K member, it might let me lower the engine an inch or to, and give more room for the oil pan. And god knows i will need all the weight loss possible.

I dont know where you are getting any info that its an "LS" style engine, its nowhere even close, unless by "LS style" you mean "has coils near the plugs, fuel injection, and 8 cylinders" Its a BBC, look for the marine 496's, its the same stuff. Im quite sure its still got the normal engine mount locations.

OK, I stand corrected. Even though it is a newer ls style engine, it shares the motor mounts and bellhousing with older chevys. The heads and intake from a typical BBC don't fit though.

To share new found info for those interested..... custom headers are a must, along with a tubular k member. An oil pan needs to be fabbed, or modded. Electrical is all basic re-wiring, which the schematics are good for. The 6.0 vortec throttle body can be swapped if you don't want drive-by-wire (same size). Trans choices are the same as any regular small block.... t-56, 700r4, th-350, and so on.

Now I am down to 2 questions remaining. What else i can do for the added weight? And what can i do for hood clearance?

For the weight, can i just treat it like a regular BBC swap? It seems like it should work. Where can I get a custom intake made for hood clearance, or another route to try?

Thank you for the help. I did find a lot of what I needed in other posts.

Seriously, stop calling it an "LS style engine" is has about NOTHING interchangable with an LSx, it is a new gen BIG BLOCK CHEVY. Simply a BBC with some modern pieces. Yes the heads are different to match the intake manifold. Take the heads and manifold off and you could bolt older bbc heads and matching intake manifold right on.

I would attempt to use the stock exhaust manifolds and build a Y pipe for them. The oil pan im sure you can get an aftermarket BBC oil pan to work. The tubular K member isnt needed, I just suggest it due to a/c compressor location and the weight savings. Not to mention extra space when you do go to headers.

Hood clearance shouldnt be an issue i wouldnt think, the intake manifold is pretty low profile, though until someone does an actual test fit this is just speculation.

Weight, you can go to aluminum heads (raylar makes them for it) though they arent cheap. Tubular K member, Tubular A arms, and Coilovers up front all remove weight, a rack and pinion setup will remove additional weight, several of the aftermarket K members can be had with mounts for a 4th gen rack allowing you to retain PS. One makes proper spindles for the reduced rack throw so you dont lose turning radius. A fiberglass hood of course will help remove the weight up front. Lightweight battery and/or relocation to the rear. Light aluminum rims (16" GTA rims are quite lightweight).

Z28***** you are right. It is a tall deck block with a 4.00 inch stroke. GM actually sells oil pans to retrofit it in musclecars. I can't find the website but it is COPO division that sells the pan.

OK, newer style, not ls style. The heads have 2 more bolts then a typical 454. There is a thread about the possibility of converting the heads cause they are so close. There are some minor difference like that, but I want to try keeping it fuel injected anyways. It looks like I can use the manifolds to save money and switch later. I am thinking I can shave a lot of weight with the ideas you guys have given me too. By measuring, hood clearance will be close, but I have a stock hood still. It should clear with a 3" cowl. I am going to try match an older BBC oil pan to this when i get the chance.

Z28*****, I am sorry about getting you frustrated like that. I really appreciate all the help. I am used to carbs, points and HEI. This is a new game for me here, but live and learn. I will get here eventually on the newer motors.

a stock 700 or 4l60 wont live behind that motor if you plan to beat on it.

Hi! I have a complete 8.1 (496) motor. Complete wiring harness with computer. It's all there, plug and play. Only 8000 documented miles. $2000.00. steve@superiordj.com or 269 876 7454

Do these engines have better valve angles like the ls1? I havent read good things about these engines. They don't seem to support hardly any power in stock form.

I have the engine. Now it's a matter of getting home from Iraq to put it in. As for the power.... it is more torque, 450 lbs stock. Up to 800 hp modified, maybe more. I think 450-500 hp is plenty (start stock and work up). I am just trying to pull off something completely new to me. I have almost no experience with FI.... unless you include removing it and replacing with a carb. It would really be unique. I have a parts truck that runs, and should be getting the T-56 real soon. I am going to get custom exhaust, and a friend of mine is going to help me with all the wiring. I think i will try running it with the engine stock for a while to get used to it.

Only thing so far is I am still looking for the oil pan.... Maybe I can get one fabbed.

Is it any better than a traditional 454? You can easily make that much power and tq with a 6.0.

I was pretty excited to hear about the 8.1, but I dont think it shares the same tech as the LS1 or 6.0.

what it lacks in tech it makes up in grunt.
you can make good power out of both.

I just want to do it to be different then everyone else around where I live. I have a stout 400 horse 350, but that is always done. It would be docile on the street, and have enough torque to go sideways any time..... enough to make me happy. The LS1 would be a wiser choice, but this will be a learning experience for me and something new.

It would be awesome, to have more tq than tpi, and some good hp.

Not cheap motors though.