Could I safely bore the lb9 5.0 to a 5.2? more? less?
How much wall is there?

 

D Stroy,

You can always bore 0.040" oversize, and usually bore 0.060" oversize depending on the quality of the case casting and amount of core shift. Going 0.060" oversize with a standard stroke would yeild about 310 cubic inches, or 5.1L. 5.2 could be done with cylinder sleeves or changing the stroke, but if you're going that far you may want to consider a 350 case to start with, simply for the cost. Whether you remove your 305 and machine it, or machine a 350 for installation, an engine comes out an an engine goes back in anyway.

 

as far as i can recall from my calculations, a .030 305 is 310, .040 is a 312, and .060 is 315 cubic inches. at 315 it may be classified as a 5.2, but i can't find my metric conversion chart off hand.

 

315 Cubic Inches = 5.16285 Liters
I guess if you wanna round it, its 5.2

.060 over on a 305 may or may not work, depends on the block. I would not by any means bore the block to gain cubes, too little gain for making your block basically unrebuildable in the future.

 

yeah, that is kinda an inbetween number. i'd only go .060 over if you have a spare block available or are just going for everything out of it you can like class racing or street racing for money and still want to use the 305 block.

 

Well, the thing is, is wanted a 350 for all the power, but the carb board guys told me tpi would restrict the 350, and is made for the smaller block. And theyre right, the 305 w/ tpi is 230hp and the 350 w tpi is only 15 more. So to save money, and still replace my sloooow *** 3.1 with a nice punchy powerhouse, i was going to get the lb9 b/c its the highest powered 5.0 in the third generation. And if i had a 350 with a 4bbl, id spend soooo much money on gas. So i was wondering if boring the 5.0 to a 5.1 would give me a little extra umph with the tpi.
=P <takes breath>

 

anyone know the stock quarter mile and zero to sixty for the 1991 firebirds with the 230hp LB9s?

 

yeah, i do.

 

lol. so what are they?

 

depending on the options as far as weight is concerned, they run from 14.6 to 14.9 and 0-60 in around 6.5 to 6.7.

 

awesome. I figured low 15's and bout mid 7's

im definitely getting the lb9 then