Ok, so I just scored a FREE good running 98 vortec 5.7L engine with transmission. The old L03 in my RS is getting pretty tired (200,000+ miles) and I'm thinking of swapping in the L31. I have everything needed for a tpi swap. I also have an Lt1 intake that's already been modified to fit on a SBC, although it won't work with vortec heads. I'm thinking of selling the vortecs and picking up a set of LT1 heads to modify for use on the L31. That way I can run a larger cam than with the vortecs, save a few pounds of weight, and most importantly not be stuck with the restrictive factory TPI. Now I know LT1 heads will work on L98s because my cousin did the swap on his formula, but can they be used on an L31. According to everything I've read, the blocks are pretty much the same. Does anyone know of a reason why it wouldn't work. Any help is appreciated.
Brad

 

There may not be reasons why it wouldn't work, but there are plenty of reasons not to do it.

 

Such as...

 

The Vortec heads are very good heads. Very good heads, you'd be better off going for an aftermarket EFI setup for the Vortec heads.

If you dont have the money for that, sell the Vortecs (a week ago I would have offered to buy them from you, but I got a set on the way now) and put that money into getting a good set of 083's or corvette 113's and you can make those work with the LT1 intake you have. Of course, you'd make a lot of power by just making the vortecs work to begin with...

Also, remember the LT1 heads were designed for reverse flow cooling so I think they have smaller chambers than Vortecs or other heads. So your compression could be higher than you'd want. Not sure on that, though.

 

figure out what your power goals are.

Either a tpi setup with the edelbrock vortec tpi base or a vortec based ramjet intake (much more expensive) would work great with those heads.

Those heads are descent, better then stock for sure, but dont outflow my stock dart 180cc iron eagles which i think are garbage, good for 300rwhp max.

however stock lt1 heads arent really much better so if thats what your power goals are id just keep the l31 motor intact with the edelbrock high flow tpi base, high flow runners from your company of choice, and youd have one hell of a torque monster.

that combo should be good for id say 275 rwhp and 340 rwtq, with the right cam of course...the xe268 with 1.5 rockers comes to mind (i think its the 268, whatever the step below the 276 is)

 

Well, since all of my money is going into my trans am I'm trying to do this build as cheap as I can, using parts I already have. I'd like to use the vortec heads but I just can't justify spending the money for the intake manifold, only to be stuck with TPI. I see what you mean about the compression, according to what I just read on cz28.com stock Lt1 heads have 54cc chambers. I might just put some stock L98 heads on it. I'm really just trying to get it running so I can drive it while I work on my trans am. Once I swap the new motor into the trans am I'll have an LS1 to put in the RS, which is my longterm goal for the car.

 

Vortec heads are HEAVILY based on the LT1 aluminum heads, but with more improvements made. IMO, you would be money AND power head to use the Vortec heads. They have the same chamber design as the LT1 cylinder heads, just a bit bigger (64cc VS 55cc for the LT1 aluminum). The LT1 heads also require quite a bit of cutting, grinding, welding and machining to make them work on a Gen 1 small block - whereas the Vortecs just bolt right up. In the end, the cost of making the LT1 heads work on a Gen 1 small block is going to cost more than getting a Vortec style intake manifold is going to, and the Vortecs flow better "out of the box" than the LT1 heads anyway (around 230cfm on the intake side VS around 210cfm for the LT1... both around 170cfm on the exhaust side).

I say keep the Vortecs and get a matching intake, but thats just my 0.02... Holley makes a Stealth Ram manifold now for Vortec heads, for what its worth.