I have my LT1 down to the bare block, everything cleaned. I plan on to bore the motor to 4.060. My goal is to be the fastest I can in the 1/4 mile using as carburated plate system on the LT1. I would like the spray to be pretty moderate 200+. I would like the biggest crank I can get, what do you all suggest? should I do low compression pistons for nitrous? or high compression and only spray a little? has anyone had experience? I would like to go high 9's in the 1/4.. I weigh under 3000 lbs. My "roller" is all taken care of suspension, tire, brakes, so I am just focusing on getting this motor done. Any suggestions, setups, help, is appreciated, thanks in advance..
Dave

 

Nitorus does not "like" low compression. Do not bore 60 over for a high-po forced induction or nitrous buildup. The largest practical stroke for an LT1 is 3.875". At 30 over the displacment would be 396ci. Many people prefer a 383 (3.75" stroke) for a variety of reasons. I am one of them.

Rich

 

so if I bore 30 over and store it at 3.75 what would the displacement be? so if I went 60 over I should not spray or blow the motor? This motor is going to run ONE season, then rebuild... I will have two motors so I can alternate between seasons while one is being rebuilt. for 30 over, high compression pistons would be my best bet? I am running this motor to go fast, blow it up, and rebuild it.. of course I dont want to blow it up in one run.... Id like a year out of it.

 

There's so few cubic inches with the larger overbore that it makes no sense at all. Bore it 0.060" over and you aren't going to be able to rebuild it every year. You'll end up with thin cylinder walls that will be stressed by the high cylinder pressures of a big shot of nitrous or high boost. I limited my overbore to 0.020" for exactly those reasons.

With a 3.75" stroke:
4.020 = 380.8 ci
4.030 = 382.7 ci
4.040 = 384.6 ci
4.060 = 388.4 ci

With a 3,000# race weight, a well built 381 with a decent shot of juice will easilly put you in the high 9's.

Your questions are fairly basic.... not really Advanced Tech. I'll move this to "LT1/LT4 Engine Tech".

 

You could always pour the block like I did and stroke it 3.875 like the above post said with a .030 overbore for 395 and some change inches. You need to modify the stock pan, or get a stroker pan to clear the added stroke. If you went this way, I would probably go with a set of converted gen 1 heads to supply the air for the cubes. Then you can run any sbc intake manifold without drilling new holes. Of course, you will have to plug up the dist hole unless you use a low profile dist instead of the opti. It might really be easier/better to get a gen 1 block and go from there. If you threw away the computer, and went all carbed with a built turbo 350, you wouldn't be limited by the 7200 rpm the pcm is good to.

 

The info in the above post is accurate, however, it is a major step up in complexity/cost and I, for one, would never go back to a carb. In fact, over last winter I converted my BBC alcohol race car to EFI and got rid of that nasty carb! Starts and runs better and goes quicker and faster. Tuning took about an hour, vs. a carb where I have spent weeks getting them right.

My LT1 blower + nitrous combo is 0.010" over.

Rich

 

EEK! Blower, nitrous, EFI, and brains. Scary combo!

 

I often scare myself

Rich

 

It is scary isn't it...