Turbo size help

[ssrogers]

Ok, I know this is one of the most common post in this section but I have to ask.

What turbo do you think I should run?

Ok, first off, I'm trying not to sink too much money into this car and I'd like to get me a turbo for $300 or less. I was looking around on ebay and found some T70s for 200 to 220, but felt that was slightly too big. No calculations have been done, I'm just going on feelings. After searching the site it looks like T61 or something closer to 60.

Anyway, 1980 Camaro, 2.73 gear, 4 speed manual. The engine I have for it is a 3970010 block 2 bolt main 355 (350, 30 over), with 3998993 heads (76cc, 1.94I, 1.50E), Cast crank, cast rods, hypereutectic aluminum pistons, dual plane intake, Cam from what he can remember is 112lsa, .481 lift, 280 adv dur, dur @.050 is unknown. I roughly calculated 9:1 compression. Blow thru carb and intercooler (thinking about an air-to-water), neither of which I have yet. Want to run no less than 5 no more than 7 and have the wastegates set to 6 or 7psi, probably 7 since I think I'll get a tad bit of bleed off with that cam. Oh and the wastegates will be hooked to the intake or right in front of the carb to make up for pressure drop in the intercooler. I'm going to try not to rev it past 5000, but it'll probably see 5500 every now and then, 6000 on a miss shift. Single turbo.

Umm, I think that's everything.

Goal: 400hp, 400+tq (I don't know that I'll get that, but I don't want to push a 2 bolt too far past that)

Thanks,
Steven

[flynbrian]

I have a 67mm Garrett on my 350 chevy and it falls into the range you want. Its got a .70 a/r compressor housing and a .68 a/r exhaust turbine.
It boosts right away and makes alot of power....Mine is a T4 flange set-up.
I also have a 76mm Precision T4 turbo with a .75 Compressor A/R and a .96 Turbine A/R It will be going on the car later on....

Right now my 350 is basically a stock 1974 L65 motor. Stock cam and compression anyway.

You will want more turbo than my 67mm

A 60-61mm turbo is too small for a 302 Ford let alone a 350 chevy.

A 67mm with a .81 exhaust turbine would work real well for you. My .68 turbine is creating boost just a few hundred RPM over idle...Its like a diesel truck.

I also run a 2.73 gear...

A Engineer at the office I work in calculated my combo at capable of 540 Horsepower. I doubt my stock cast pistons will go that far...But oh well its fun for now.

[flynbrian]

Also my car is a 1974 Chevy Monte Carlo and the Wastegate is a 38mm Tial, Blow off valve is a 50mm Tial, Carb is a 575cfm BG mighty demon Blo-Thru (I've had good luck so far with the carb) Torquer II single plane intake. Stock HEI welded up for static timing only...22 degrees
using stock exhaust manifolds flipped upside down.
Racepump mechanical fuel pump. Aeromotive 1.1 boost referenced FPR. and -8 fuel lines too and from the tank.

The car has been put together since November 07' and runs real strong. Still doing bodywork so it only gets driven around the block and up & down alleys....But its layed alot of rubber in the alley.

[jasonsnova]

go to theturboforums.com way more info there, if i remember right there is several guys running t70's on stock 350's and it works great ....make 550 + hp....

[gearheads78]

Since have not built it yet I would rethink the Hypereutectic slugs. Forged are cheap insurance. When a Hyper lets go because the tune is just not quite right they tend to turn to powder. If you hurt a forged usually you can throw another piston in and go.

[LS1NOVA]

Whatever you do dont buy a cheap turbo off Ebay like ssautochrome. Make sure what you getting is legit and not a china knockoff. Id say a 67-70 range would be good.

[ssrogers]

Thanks everybody.


flynbrian,

Thank you for your detailed reply, that's exactly the reply I was hoping for. I'm going with a 67mm, but I'll try to find one with the A/R that you recommended.


jasonsnova,

Thanks, I'll check it out. I'm pretty sure I don't need a T70 then. Because I'm only looking to build a mild 355 with mild boost, 400 to maybe 450 hp. 550+ might break things on this car.

gearheads78,

Cheap is relative to the budget. I know that forged is better for boost, but I got the long block from a friend fully assembled. He was going to make a V8 S10, but sold the truck for a Firebird. It's not built for turbo, I'm just turboing it anyway. That's why my power goals are 400 and not 500.

LS1NOVA,

Don't worry, It probably wont come from ebay. I'm not just looking for the cheapest one I can find. That being said I still believe that if I look hard enough, not ebay, I can find a good deal on one.

[Crossupbill]

Masterpower T-70 theyre like 580 shipped. That will do what you are looking for and be inexpensive and more reliable than the junkass ebay "super T-70"

[flynbrian]

I have bought good turbo's from Ebay but they came from "Real" stores. And they were name brand parts. I recently bought Precision GTQ76 for $1,000 its never been mounted on a car. I'm told its a $1,800 dollar turbo from Precision.
So Ebay saved me $800 bucks on that one....Just be careful.

Your welcome on the advice. Marty over at the theturboforums ran 9.37 @ 153 mph with a stock 76' shortblock-stock cast pistons and stock rods & bolts and all!!! SO its possible to do it....Sure he got lucky but that makes all us guys who only want to go 12's and have 400 horses alot less worried about making it go boom.

Eventually I want to build a great motor then I will turn the wick up on mine till it pop's. If I'm lucky it will be head gaskets and the block can be saved for another day.

Happy hunting for that Turbo! I paid $400 for my turbo used and rebuilt it myself with a $60 kit from Garrett and had the shaft balanced for like another $50 while I waited at a local diesel truck turbo and injector shop.