ok long story short i had a 383 ls1 that was at 3.903 lost a set of rings and am rebuilding now, my engine builder said i now need to go to atleast a 3.907 or 8 and get custom pistons made i have never heard of a ls1 being bored this much i wouldn't think there would be anything left to the walls and i plan i spraying a 250 shot through a direct port kit this year. now for the price difference of buying custom pistons it would prob be about the same as getting a used block and standard wesico. also is it true you can bore a 5.3 aluminum block to 3.903 without any issues and basically make it a ls1 block? any help would be great

 

You can get iron 5.3 blocks brand new for really cheap and bore them to stock ls1 bore size and still have them be able to handle lots of power. With a 250 shot an iron block would handle that much better than aluminum.

 

Your cheapest route is a used block that's not wore as bad as the one you have. Have you ever sprayed a 250 shot before?

 

never had a nitrous car in my life, this year my car should dyno around 520 on motor last year it was at 490, im getting a DP kit this summer and spraying a 100-150 shot off the rail with the 255 and hot wire kit, then getting a progressive controller and standalone with c16 then spray 200-250 then ill have a real street

 

what year is your block? If its 99-up you can safely take it out to an overbore of .010 over stock which would put you at 3.908. They also make replacement pitons for this size so its not hard to find them however idk if I would feel comfortable running a 250 shot on a stock ls1 block let alone an overbored one

 

I saw a guy in Jacksonville, FL spray 200-250 direct port on a completely stock internals in a 99 T/A for 2 years almost every weekend, over and over and over. It finally got to smoking pretty bad and he rebuilt with forged pistons and rods and stepped it up to 300 shot and had very good success with it. I do not know however what size bore he had.

 

it is a 98 ls1 blockso can you not bore it to 3.908, its gonna have a forged lunati crank and rods, and forged wesicos's

 

yup, you can bore it out to 3.910 which is the max.

 

I have a '00 ls1 block im considering parting with, bare block with main caps, has cam bearings in it but I would replace them. Casting number 12559378

 

ya if its a 98 your already maxxed out. I'd start looking or either another ls1 block or perhaps you could find a 6 liter iron block and use that if you dont already have the lunati pieces

 

so can you please confirm what the safe max bore for a 98 ls1 block

 

Your machinst should be able to tell you max.

Stock bore is 99mm or 3.898 with a "safe" hone up to 0.0040" which puts you to 3.902" and I have heard people push it but you should be cutting through the sleeved or be paper thin.

- As per HP Boks CHevy LS1/LS6 High perf. which is older info but still relevant.

You could choose to bore out the sleeves and put Darton Sleeves in and go big bore, or pony for a LS2/3 block. Or take on some nose weight on a 5.3 IMO I would look for a LS2 used/new as you will get a 4" bore and open up cyl head choices.

*Note* Later LS1's (1999+) did allow for a 0.010" BORE for max vs the 0.0040" HONE.

I would really research what the cost of doing sleeves vs a new LS2 type block. Going aftermarket on the sleeve would make the block better and give you room to bore in the future if you have another engine issue.

 

The Will Handzel book "How to Build High-Performance Chevy LS1/LS6 V-8s" states that 3.903" is the max for 98 and 3.908" is the max for later LS1s.