how bigg can you bore a 6 liter steel block? will it take a 4.100 bore with out getting too thin in the walls for n2o or would it be better to stay at 4.030. let me know. Rich

 

From my previous reading, many say start with 4.030 for nitrous. Then if you need to freshen it up, you have a little wall left to work with. Depending on the block, 4.060 isn't unheard of. PSJ has a 4.080 bore.

 

I have done alot of research on this as MTI is currently building me a 427 ironblock. If you plan on sig. N20 you should bore it out to 4.030 max, for N/A 4.060 is fine, but should sonic test (that's the size bore i am doing) and you could probably get away with 4.080 for all motor, but would be pushing the envelope a bit. 4.10 is out of the question, especially on spray.

Also, if you go much above 4.030, there would not be any cylinder wall thickness left if you had to rebuild motor. I am doing a 4.060 bore with 4.125 stroke for 427 cubes.

Prostock John only has a 4.060 bore also, matched with a 4.075 bore for 422 cubes.

MTI 427 C5 Roadster

 

thanks for the info it is a great help.

 

I have a 4.060 bore LQ4/6.0 iron block.

Rich, to answer your other question, the iron block is definitely going to add about 75 lbs to a car... perhaps 80 lbs.

I'd go 4.030 for most iron blocks, if you can find one with minimal coreshift you can go bigger like mine.