I'm wanting to replace the 180k mile LB9 in my '88 convertible with a healthy 350. I'm looking to eventually make somewhere between 350 and 400HP. Here are my block options:

'87 L98 (stock)

'97 Vortec bare block (2-bolt, no heads, pistons, etc.) casting #10243880

'80 long block (4-bolt) casting #3970010

My question is, which of these two are going to give me the most power for the least amount of machine work, and for a reasonable price. I'd like to start out with the stock TPI setup, eventually move up to a larger intake and runner setup, and maybe, if money allows in the future, end up with DFI, mini-ram, and a supercharger.

This much is known - I will be boring .030 over, adding forged pistons and rods, a decent cam, and headers.

Most important - I need to remain emissions legal, and get relatively good gas mileage (18+ MPG).

Anyone have any suggestions? My initial budget for this motor is somewhere around $1500. But as I mentioned before, I'd like to eventually see a supercharger (with appropriate cam), a mini-ram, and DFI setup. Keep in mind that I'd like to keep as much as possible through the transitions. Thanks ahead of time. - John'89L98

 

unless your revvin up real high, I would skip the 4 bolt.

the advantages of the other 2, is for sure, the 97 block is set up for a roler cam.
I think the 87 is a roller.

disadvantage or a roller block, is a roller cam is about 300$$

a minor problem with the 80block, it will have a drivers side dipstick, this will not clear the stock exaust manifolds, headers required.
the older style block will also require a new flexplate and oil pan, as the newer blocks are 1 peace rearmain seal blocks.

the block wont have much effect on emmisions.

the roller cam will give you about 20hp over a flat tappet cam, of the same size/grind.

 

go with the 87 roller block! it is a roller block so you can use factory roller lifters. if you chose to use that type of cam. you pretty much can use any cam you want. if you use a retro fit roller cam or a reg. hyd one you will need a differant timming chain gears but, those are even cheaper that the factory roller cam ones. that block in my opinion is the best for the buck you can use old or new stuff with them. the 97 block is almost the same thing with a few minor differances like the timming cover being plastic and having a crank sensor hole ect. but, why when the 87 block is there. the 80 4 bolt is nothing special and I would not even bother with it. 4 bolt mains are more than you need if you ever need the extra bottom you can have the roller block made stronger than the 80 block and put splayed main caps on it.

 

Would a 1991 305TBI be a long or short block? Just curious.

 

I've decided to go with the L98 block, and keep it in the N/A 325-350HP range since it's my first attempt at an engine build. Thanks to everyone. Now on to what I'm gonna do with it... - John '89 L98