I am gonna build a budget 355 stock crank, stock rods with arp bolts and forged dished pistons. My question is how much boost will be safe on pumpgas with each of the following intercooled?

Max boost on pump gas?

8.5 = how much #s

9.5 = how much #s

10.1 = how much #s

 

It depends on about a million things such as. . . ignition timing, A/F ratio, chamber geometry, cam IVC timing, compressor efficiency, intercooler effectiveness, etc. . .

But, for TRULY safe, I'd say the following:

8.5/1: 12-14 psi (though it can be run up to 18 psi in not-as-safe trim)
9.5/1: 8-9 psi
10/1: 6 psi

Take a quick look at the FACTORY FI setups, what boost they run, and what the compression ratio is. The SC Fords run 8-10 psi at 8.5/1, the Buick GN's run 12 psi at 8.5/1, and the SC Sea-Doo's run 9 psi at 8.5/1. These engines all have tough pistons and you can beat on them all day long without breaking anything. Also note that they all run very conservative timing curves, rich A/F ratio's, and have very effective intercoolers. You CAN raise the boost on any of them, but reliability suffers in most cases.

Mike

 

after you re condition the rods and buy ARP bolts some scat forged I beams would only be another 100-150. Id pop for them, also stud the mains. I am in the process of do a budget build and after much research and advice I am throwing extra loot in the shortblock. Ive maxed out my CC's and such but I wont be building a motor twice which is much cheaper in the long run.


As for the compression id shoot for 8.5.1-9.1

 

I did not see if any major work has been done such as heads, cam, valve train etc. I agree with slomarao on the rods and studs. You are looking at around $279 for the rods and $70 for the studs. Which would be around $150-200 extra but well worth it in the end. I would shoot for 8.5:1, you can run low boost and have the option to turn it up if you would like. A good wide band kit will do you well also and will help with tuning and keep you up to speed on you AFR.

 

My experience, though 4 supercharged and 3 turbocharged combo's is that piston failures occur at least 10 times more often than con rod, main, or crank failures. Don't get me wrong, my Z28 had 4340 crank, 4340 rods, ARP 2000 bolts, and billet 4-bolt mains, but I lost pistons more often than I changed the oil.

 

I don't think there is any magic formula. A big part in determining if it lives is the tune and the driver. If I were building a combo like that I would go for the lower compression, use water injection, and 10-12 psi of boost. Headers and a little head work would really heklp the power with a setup like that.

Rich