Which Block to Use
Turbo Mini Forums

Good morning guys,

I'm currently sourcing out a 1275cc block to be bored out to +20 for my 18cc forged omegas. I read some months ago that A+ blocks would be better for turbo'd engines, and I can see why. I have a gt block here at home, however I also read that such blocks tend to warp. What do you guys recommend ?

Also, should I consider relinering the block before boring, or the old liners should be fine for a turbocharged engine ?

Thanks in Advance

A+ blocks have the ribs on the outside of the block this meant to add strength. But i've also heard this was done because the quality of the castings was not as good so the ribs were added.

Does the block you intend to use already have liners? If i had the option i would go for a block without liners because then it'll be a fresh bore etc etc if you're going +20. Can your block with the liners be bored out?

check for a hole above the centre bearing cap of the GT block, f there is one its probably not the best block to use, that said I have run one of those blocks with the hole cleaned up at 20 PSI with a 7 port head.

I doubt it would warp, I have heard rumours the material was betrter grade on the oder blocks, but ruumers are rumours.

Is the hole a casting defect Joe ? or is it by design ?

design, the earlest blocks didnt have it bit it was introduced presumably to make them easier to cast.

What do you mean hazpalmer. Are there any A-series blocks running without any liners ? I thought all A-series blocks have liners.

To be honest I have an A+ std block and I was going to use it to bore it to +20. However it seems to have pitting holes in the liners, which I'm not sure they'll clear out to +20. So I might have to reliner the block or buy another one.

Thanks Joe, I'll check for that then.

only early A+ blocks had liners ( unless they have been fitted aftermarket) due to some boreing issues whent hey changed over.

Oh I see... so what would you recommend then. Linered or not linered ?

dosent really matter,

some will say the non linered is better some will say the linered is better!

general consensus is the linered ones are more wear resistant.

mm that's good..... Thanks for the good info chaps