I've been thinking of putting a 5.3 out of a truck into my '86 Firebird. Was wondering if there were any disadvantages of that instead of using an LS1 (other than just cubes, of course).

 

it basically is an LS1....

aren't the valves smaller on the heads?

and the intake is different, if nothing else taller so it may hit the hood.

 

I figured they were about the same. Since the bore is smaller, would there be any problems putting bigger valves in it?

 

A 5.3 would be a large improvement over what is in an '86 Firbird, if you can get one cheap. Just get a LS1/6 intake to replace the truck one if cowl height is an issue. Add a small cam, some headers, and you will have a nice running machine. It would probably make 350+ rwhp and rwtq. Call it a 327 and enjoy.

 

Thats exactly what I was thinking. From what I've seen, the 5.3 are much cheaper than the ls1's. I saw a running motor on ebay for $750 buy it now with the wiring harness, coils, maf, and all the goodies. If I do decide to go that route, I'll probably keep the truck intake and run it without a hood if need be, since I hear the ls1 intakes require different injectors for some reason.

Does anyone know of a good web site with details of a 3rd gen/ls1 swap?

 

I see no reason why you couldn't bore out a 5.3 to a 5.7. However the Joe Gibbs trucks proved the 5.3 is no slacker either. I believe they make ~425hp.

 

IDK if the 5.3 intake is the same as the LQ4 intake. The LQ4 intake flows like an LS6 and is cheaper. Just an FYI.

Get the trans and ECU while you're at it.

 

LS series motors are less bore acceptable than older designs. I seriously doubt you can punch out a 5.3 to 5.7. I believe the newer 5.3 motors are aluminum with iron liners just like the 5.7's. Then you definately can not.

 

You COULD re-sleeve it.

 

By the time you did all that you'd be $ ahead by just getting an LS1.

 

Yea, I know that......thats why I emphasized the *could*.

 

Depends on your horsepower goals. It would be fine for a streetable hot rod, but I would reject it for any serious performance application as the bore size is too small to get any real valve size in there. Resleeving would cost more than the motor is worth. Besides, if you have the choice, why give up 19 extra perfectly good cubic inches that the LS1 would provide?