daves12secV6

iTrader: (3)

ok well i started with a 3.1 motor.with an t04e turbo .63 hot side.now im gonna build a 3.4 with aluminum canted valve heads.the heads flow aprox 40 cfm better @ .500 lift stock then my fully ported iron heads.

now with the increased displacement and the better flowing heads do u think the .63 hotside will be to small,and also would the cold side possibly be to small for this new engine with this much of a flow increase.

right now the turbo has done 19 psi on my 3.1

Naft

go bigger. t-60. i think doward is running a t-60 on his 3.1. a bigger turbo will generally make more hp at the same boost level as a smaller turbo(assuming they are both made with the same technology) because it will be more efficient. from what i remember looking at turbos for a 3.4 a t-60 was just a tad on the big side for a 7k rpm motor, but that was with iron heads.

bottom line is do the math and plot stuff on compressor maps, but id start looking in the t-60 range size wise.

TTA850

I dont think you'll have a problem with a .63 exhaust housing, lots of guys with the turbo buicks run .63 housings with no issues. What kind of housing are currently running and which are you considering? Also what wheel are you running?

To give a few examples of what a .63 housing can do, the best times my car has run are 11.20 @ 120mph(19psi street trim)and 10.69 @ 125(25psi racegas)with a TE64-1(64mm compressor .55 cold side, p-trim .63 hot side). I curently run a CCH-70(70mm .75 cold side, p-trim .63 hot side)and while I have not been able to make any full passes due to other problems the same turbo has gone 9.79 in a friends turbo buick so I'd say is has the potential for alot of power even through the .63 housing.

For the cold side Naft is right, your gonna have to do the math and figure out how much power/airflow/pressure your gonna need and pick a compressor that will work within that range.

daves12secV6

iTrader: (3)

thnx guys
naft on my 3.1 the t04e is at 74-75% efficency on the 3.4 it drops a bit and quite a bit at higher boost levels
yeah it looks like ill be going to a t61 or t70 but not right away.if i figured out everything right the turbo i have now should be good for 12-14 psi on the new motor,and should make decently more power then im making now at 19psi on a slightly smaller engine with less free flowing heads/intake.
once i get it together ill decide on a turbo the t-61 will make a nice street strip turbo/but the t70 will make one helluva drag turbo @ the boost levels im looking to run.though wont be as much fun on the streets

Naft

tt850, a/r ratio is generally only useful in comparing turbines of the same exducer bore(trim). if you are on the upper limits of a certain size bore you will need to run a high a/r ratio to avoid restriction, but if your turbine is a little to big then running a low a/r ratio essentially makes it smaller.

i dont know though if its better to have a large exducer bore & small a/r ratio or the other way around, or if they essentially add up to the same thing.

dave, you will definitly at least make as much power as you are now(with the same turbo). the thing to remember too is that psi is just a representation of the restriction of the engine . . . 12 psi boost on an engine that flows really well can make more power than 19 psi on a totally crappy flowing engine of the same displacement. its like putting a restrictor on the return line of a fuel tank, the psi generated reflects only the restriction to the amount of fluid trying to get through, if the hole gets bigger, pressure goes down, but more fluid is actually flowing through(fuel flows more at higher psi only through the injectors, the pump's gph rating actually goes down).

props anyway on doing what most other 6'ers here(myself included) dont have the determination/guts/money/interest/whatever to do.

daves12secV6

iTrader: (3)

yeah i know that the better flowing engine wont need the same amount of boost to make the same power.the turbo i have now will actually be at its limit im quessing around 12 psi(due to what it can flow) on the new engine just based on how much better the new heads should flow.im looking at prolly a 80cfm increase or more after there ported.as far as doing this ive had plenty of v8 cars,its a nice change of pace for once.i never planed on takling it this far though.but after being able to get dam good performance out of a half hearted build i figured **** it why not go all the way with it.That and i like the fact that th ecar gets alot of attention at car shows/racetrack

TTA850

Your right, my mistake for assuming we were talking about either a 69-trim or p-trim T04 wheel in a .63 housing, either of which should flow enough for this application.