Whats the most amount of boost that you guys that are running the high HP motors putting into a inline 6? I remember the old days of turbos in road racing and some of those guys were putting around 50-60 ponds in. I am working on a project and would like to know what is the maximum amount of boost I can get away with before the block starts to come apart.

to help answer your question, i ran 50 psi boost into a calculator for a turbo system.
it would need 120 lb/hr injectors x 6 running @ about 90 psi
hp would be around 1050.0
tq around 850 ft lbs
i think the block would need some serious prepping and added bracing to achieve that, even with that it would need replacing continuously.
i have run up to 12-14 lb boost on a relatively stock block, no problems yet on the 292. some others are pushing more, but i will let them answer how much. i bet a 250 could take 25 lbs with out to much for issues(be reliable). tom

Thanks, thats the kind of info I was looking for. If any others would like to add to this and let me know what they think.

How about a practical limit for the 4 main bearing engine blocks (GMC in particular)?

I have built a 302 GMC for the salt flats. It has a compression ratio of 8.2 to 1, was also wanting to know what boost it will hold. The block is "O" ringed with copper gasket and ARP head studs, no receiver grooves in the head.

Turbo Boost
I think what you heard was 30-60 inches of mercury, 60 inches is about 30 psi.

Actually we were running a IMSA GTO car in the mid 80's an we were a support race for the GTP cars. At that time I was talking to one of the mechanics on a GTP turbo car and they said that they were running 50 pounds at the time. The turbo was a monster in that it had almost a 8" exducer wheel and a about a 4 1/2 inducer wheel. Never saw such a big turbo on a car.

Thanks GH.

Wow 50 PSI, was that Toyota, or Nissan?