Stock 350 block w/ twin turbos?

[Mike Davis]

Can this be done? Is the block strong enough to handle 14-18 psi from twins? I will do everything i can to strengthen the valvetrain , but unfortunately i cant strengthen the actual block,

[Turbo67camaro]

Blown engines need a beefy bottom end mainly - stout rods and pistons, preferably a forged steel crank, and a compression ratio in the vicinity of 8.5:1 with 4 bolt mains or studded 2 bolt mains preferably.

Valve springs need to be stiffer to avoid valve float on a turbo engine due to increased cylinder pressure, but you don't need to get too fancy with the top end to make power.

Plus a very capable cooling system.

Avoid detonation and it should handle it imo.

[shmoov69]

Boost is not really saying everything. 8psi from a properly designed engine/turbo combo will make more power than a poorly designed system at 14psi. Ask me how I know!! Lol!
But to your question. The first turbo engine I had was a stock 2 bolt block with a stock cast crank with stock rods (AND BOLTS!!) with factory replacement cheapie hyper pistons in honed only holes! Lasted 2 1/2 years, 17,000 miles of hard beating on it before the cyl wall split from the skirt being broke off. And whoknows how long it was off, because the pieces were mashed in the pan and the car still ripped (was actually at the strip when it started puking water). Car ran low 11's high 10's at 125ish.

So will it work? Yes. Is it best? No. Just keep it out of rattle!

[DeltaT]

You can also do a short fill of Hard Blok (up to the bottom of the freeze plugs) which will stiffen the cylinder walls by having about 1/3 of them anchored in (effectively) concrete. I have run my 383 for 5 years like this with no problems on the street, making up to ~800 at the crank. All the other advice above is top notch.

Jim

[TheRev]

http://www.theturboforums.com/smf/index.php?topic=61219.0

This guys Trans Am was in car craft a few years ago.

[DButler]

Hey guys I am new to the turbo world and I am currently putting twins on my 67 camaro. i have two 57mm turbos with an intercooler. I have a carb shop carburetor, bg 400 pump, and aerospace boost ref. regulator and etc. I am trying to do this with the motor I have now which is a pretty much stock 350 that.040 over with a 480 lift camshaft. It has hyper pistons. I have a 383 in the works that has forged dishtops, forged crank, h beam rods and ect. but I am trying to make the one thats there now last as long as possible. I know that this motor is not a turbo motor, but my question is what is the most boost I can run to get the most life out of this motor while still making decent horsepower?

[shmoov69]

If you can keep it out of detonation, you can run a bunch for quite awhile!
But the main q is what is the compression ratio? If it is 9:1 or lower, you should be fine with 8-10psi on pump gas and a bit more on race gas if you are conservitave with the timing and a bit rich on fuel. That is just my experience.

[LSx_88_Ciera]

Actually there are some things you can do to strengthen the block.
Splayed 4 bolt mains (Billet) provided you have a 2 bolt
Main stud girdle
Remove all sharp edges and casting flash (stress risers)
Partially fill with hard block.

[DButler]

I have 9:1 compression and I was wanting to run 10 psi on pump gas. I was going to carry it to a performance shop and let them do the fine tuning and everything on it. So with turning the timing down and running the fuel a little rich I should be able to accomplish this? I am hoping to get 500 horsepower out of this motor. With your experience is this possible where the motor will last a bit or is that hoping for a little too much?

[shmoov69]

With what you are saying, 500 should be no problem at all. With longevity also. Detonation will be the killer with hyper pistons, they tend to pop the top ring land off if they either get too hot or if the rings are not gapped wide enough for the higher cyl pressure. If you keep the boost moderate for awhile and "work your way up" while you are learning the tune, you should be fine.
The turbos are a different animal for sure and you WILL be in love! The way they come on with the TQ curve is amazing.......and addictive! Lol.

[DButler]

I bet! I am almost finished with all the fab work. Yeah on this motor I am going to stay pretty moderate. One reason I haven't finished the 383 for it is because I want to learn the tuning on a cheaper motor lol or at least that's what was recommended to me. I am hoping to have the 383 in there maybe next spring if all goes well. I have never drove a turbo car, I have been in a procharged car, but like you just said and everyone else that turbos are a different world. All of your help has been very helpful. Thanks Also what size cam would you recommend for the 383? I am wanting a good streetable cam.

[shmoov69]

Well mine is a 350 and I put a roller in it this time. I don't know for sure on the specs off hand, but I believe it is around a....well nevermind, I will have to look!

[4086D9]

Jimmy are you running an intercooler or just meth???

[shmoov69]

Air to air intercooler.
I think there are pics in my garage or in my FQuick account.

[4086D9]

Thanks Jimmy! I checked out your Fquick pics and am really digging your set up. A budget twin turbo set up would be really cool.

[shmoov69]

Thank you. I did mine in 2000 I believe, and it was a budget with lots of used junk! Lol.

[4086D9]

Thank you. I did mine in 2000 I believe, and it was a budget with lots of used junk! Lol.

Right on man. im gonna send a PM so I dont hijack the thread..lol

[mnm99]

It could be done with no problems. My setup is set up with twin 44mm wastegates and a .2 spring. It should net around 4-5psi. Plenty safe with the right tune.PM sent

[turbo kid]

It's all in the tune!!!