what size snails do i require

i think i am going to take the leap to forced induction on the belair this winter.

the engine is a mild 330ish hp 350 with 9:1CR and vortec heads. not i am not sure whether i plan to blow through a modified carb or go FI. right now i am curious as to what i should be looking for as far as a matched pair of turbos.

my headers have t3 flanges so that is my only real limitation on suggestions. i do not wish to go nuts and make 800hp. i don't even want 600. i would be totally happy with 450. some people tell me that is a silly low goal for a twin turbo 350, but nobody says i need to run lots of boost.

the only limits i've ever encountered with this engine is valve float at 6500. i shift at 6k at the track but i don't have to run it that high. it has about 4,000 miles and i built it myself with good solid internal parts and have pushed 100hp bottle shots through it on multiple occasions. the nitrous is coming off and going to the impala.

transmission will be a manual if that matters.

i'm at the point now where i am not ready to buy unless i have a crazy deal fall into my lap, but i want to know that it is the right deal if it does happen.

With that low of a power goal and that high of a starting power you are looking at a really really torquey motor with appropriately small turbos.

yay, something i know something about. BOOST!

ok, so 9:1 CR and 350 cubes, divide by two equals about 2.8 liters per turbo. im assuming your going with 4 cylinder per turbo, divided setup, A.K.A. two 4 cylinder setups? i only ask cause some guys SWEAR by a stacked/inline setup on V8, but i think its a waste.

anyways, for that setup and 5-7psi minimum, and 14-18 psi max (thats a guess please correct me if im wrong), id go for a pair of SC60Rs from precision. 60 trim compressor, either .63 or .85 hot side with at LEAST a stg 3 wheel (id go for stg 5 if the money was there), and go ball bearing for longevity and smoother response. also uses FAR less oil and cokes oil far slower, allowing normal 3-5k oil changes. intercool it at LEAST some, even a crap intercooler is better than nothing cause it evens air temp across a wide range of boost levels, but if it were me id get a monster from like a powerstroke or something, cause i love making 20PSI and still having ambient air temps at my intake valve...

dont forget the ancillary stuff: bigger radiator, oil cooler, braided lines for oil and returns, water cooling if desired (specify this when ordering the snails cause running a wet turbo 'dry' isnt real great. i know its been done, but its not designed for it).

i hope you picked the right rods, rod bolts, head gaskets, head bolts, pistons and rings for this... :P

-J0N

This should get you started doing the calcs. (you will have to know how to read turbo maps) http://www.squirrelpf.com/turbocalc/

This should help you find cars with appropriate sized turbos.
http://www.dieselevante.it/index.asp It is also a great source of info when you have a turbo and want to figure out what it is and what it came off of.

Possible turbos to look at

TD06 17C

or

GT2860R-2

Are you looking for cheap JY pulls, cheap online deals, or cheap new stuff?

Shave heads, cam, tune and have the HP without the added hassle of boost?

I understand what you want to do, I just don't see adding all the complexity/fittings/lines under the hood with what can be very easily accomplished without.

Here's another one: 1nzfe (scion xA) motor, 1.5L, 11:1 compression, intercooler and turbo from a SR20DET (T25, I'm told, but I don't see "T25" listed in the sites linked to above). Stock HP: 115-ish. Goal: 160-175 HP. I'm thinking that about .6BAR should do it. The turbo I have needs a rebuild, so wheels are open. What should I get?

z31maniac wrote: Shave heads, cam, tune and have the HP without the added hassle of boost? I understand what you want to do, I just don't see adding all the complexity/fittings/lines under the hood with what can be very easily accomplished without.

because i want to. plus 450-500hp on a 350 with forced induction is going to be a ton more street friendly than that power level n/a. i know i could go junkyard up a 6.0 and throw a cam at it and some L92 heads and make gobs of LS power, but i don't want to replace my own well built engine with very low miles for one of questionable origin. it's not about making the power any way possible as it is about making the power the way i want to. plus who has ever popped the hood on a 4 door 54 chevy and seen a twin turbo setup? nobody is who.

i'd be looking for cheap local deals on non chinese parts. worst case this does not get done for a while, doesn't hurt my feelings if i have to wait 1-5 years for the right deal, i've had my turbo headers on the shelf for 4 years already. it would be 1 feeding off of each bank.

it is definitely not priority #1 and other stuff is getting done this winter to the car first. i may even not want more power after the other stuff i do.

You shouldn't be floating the valves at 6500 with a 350. If that's what's really happening, you should fix that problem before you go any further.

for that low of boost/power goals on a turbo v8 you could get away with a t25 series... but I think a t3 would prob be best suited... something abouts what volvo used stock, or even better two t3's from the manual turbo fords... so you'll have the nice 60trim t3 compressor with the larger .63 a/r exhaust housing...

either way on a budget in that power range i'd go t3.... they are plentiful and if/when you want to up the anti you have a lot of options

I'll just add that carbs + boost = giant PITA.