Hello all, I have a 1988 IROC with the L98, 700R4, 9 bolt rearend. I'm looking to eventually upgrade the motor and I've boiled it down to two main ideas, which I am flexible on. I'm looking for any advice, suggestions, alternatives, or tips. Although, I am not interested in swapping an LT1/LS1, mainly because I do not want to deal with the new computer. Also, the car is going to remain in California, so I'm screwed when it comes to swapping in a carburetor or removing the emissions equipment.

1. My first idea is ripping the L98 out, tearing it down to a bare block and taking it to a machine shop. At this point, I would want them to bore/stroke the block, I'm open to any size 383ci or larger. Either I would go with a separate kit for the rotating assembly and give it to them to install or buy the parts from them. This was my first idea because I wanted to retain the original motor to some degree.
2. Second, I could buy a long/short block, pull the L98 out and transplant the intake manifold, oil pan, Vcs, etc. If I buy a built/complete shortblock of a given size (383, or whatever the next side up is) I would then buy aftermarket heads and matching cam, since the stock L98 stuff wouldn't work well with a larger displacement engine. The analog to this is just buying a built/complete longblock of 383 or bigger; either way I would re-use the stock intake and everything and sell my stock L98 longblock which I imagine would be easier than selling everything piecemeal. This was attractive to me because at the end of the day, I work full time and tearing down the L98 to a bare block is going to take some time.
   

The big questions I'm still working on are the following:

1. If I rebuild/stroke and bore the L98, what cubic inch should I try for, what heads and cam?
2. If I go with a short/long block, what would be the best motor/heads/cam/intake combination?
   

I hope this establishes my thought process and where I am tryingto go. I am open to suggestions and alternatives as I said, so pleasefeel free to throw them out there! My basic goal is to rebuild themotor or drop a new one in, put out between 350-450hp and retain allemissions equipment to pass California smog inspection. Money is not a huge deal, but it's not unlimited. I would like to stay under $5,000 total. Thanks foryour time in advance!


Nate

 

Even after market LTR's on a 383 yield a great tow truck motor but little else. I'm a bit disappointed with my build as the torque is great but you leave a lot of HP on the table with a TPI. A stock intake would be even more biased towards torque. Either go to a different intake, (HSR, miniram, etc.), on a stroker or stay with your 350.

 

Can't use HSR or MiniRam in California. Not emissions legal.

Best route to go out there would be, LS1. (or similar, something from the same series, such as a 6.0L) If for whatever reason that's not attractive to you, best thing to do is "eventually" sell the car with the weak TPI motor and get a newer car. While some of the CA guys claim very impressive power #s for emissions-compliant L98s, they're NOT CHEAP to get there; and require a level of tuning skill, attention to detail, knowledge of electronics, electronic (computer) equipment, etc. that sounds to be beyond your scope.