turbo sizing

[speedracer95v6]

Okay, would a turbo this size:

http://cgi.ebay.com/ebaymotors/ws/eB...tem=7988177187

be a decent type for the 3.4L.

What I am looking for is a decent turbo (price : performance) and what ratios, etc. would be the best for this size of engine and the list of possible modifications (balanced bottom end, 8.5:1 compression, ported heads, intake, cam, roller rockers, headers, 3in exhaust, etc).

I want to run 5psi daily and up to 10-12psi at the track. Suggestions are welcome.

[camaroman1181]

personally, id say that turbo is a bit on the small side. it'd spool super quick, but wouldnt be that good for overall power.
as far as mods go, it all depends how much you wanna spend. i've seen some decent numbers put down with mildly modded motors. But if you want to realize teh true potential of the engine, redo teh entire valvetrain, p&p the heads adn intake, probably get some forged pistons, a rebuild wouldnt hurt. you got lots of options to consider really. do some searching really.. i konw i've posted a bunch of questions bout turboing a 3.4 in the past few months myself. so there is good info out there...

[T-Punk]

That is an acceptable turbo for the 3.4 it just depends on where you want your power band to be. I cant say that such and such a turbo will be perfect for you because i dont know what your goal is. Is it quick spool you want with decent power, a slower spool with big top end #s or a more middle of the road turbo. Will it be used for everyday driving or as a track car? Do you want to leave in some spool up time so you can drive on the street without being in boost so you dont get worse mileage? There is a lot to consider. Also i wouldnt buy that brand, I would recomend spending a little more and getting a garrett.

[oil pan 4]

Not them.
Members hear have gotten some real shady deals from them.
That is a good choise. It is the size range you want to be in.

[speedracer95v6]

Well I talked to a friend at a machine shop today. Here is the list:

P&Pd heads and matched intake
oversized valves
stiffer springs
roller rockers
balanced rotating assembly
bored and honed block
stronger rod bolts
slightly bigger cam
8.5:1 compression ratio
decent efficiency intercooler
7-10psi daily (with boost controller)
appropriate fuel system modifications


I want something with a decent spool, great volume, and something that will let me get decent gas mileage on the street (not too far from stock). My goal is to be able to run 87 on the street and just bump up the octane when I run higher boost.

The damn lt1 deal fell through and I decided to build a real nice L32 instead of a halfass l36.

Maybe that will give everyone an idea of what I am needing.

[oil pan 4]

You will want more then a slightly bigger cam.

[speedracer95v6]

Nothing crazy though. I want to keep some gas mileage as long as I don't keep my foot in the throttle.

This is my daily driver. The vette is the race car ;)

but really, I don't want to go too crazy with the cam cause that would make it hit me in the wallet on gas. I want to be able to doddle this around all the time and not worry about it drinking like my friends do on the weekends.

[T-Punk]

have you bought all those parts yet? there are some things you really dont need. Roller rockers is deffinately one of them. If you are camming I'm guessing you are getting the same ratio as stock. You really dont need to do this. The stock rockers are pretty efficient, they have a roller pivit just not a roller tip so you wont see much of a gain at all. There is a wheight difference but the gains you will see are not enough to worry about. Unless you plan on changing shift points to over 6500 you dont need roller rockers. Also i think you need to do some more research as to what makes a good turbo cam. They are very different than other cams (mainly on the seperation). Take a look at the turbo cams on intense to get an idea as to what makes them different (you dont have to buy from them just take a look at the specs to get some ideas). As for stiffer springs if you dont plan on getting a crazy cam you wont need more than 105# and you might even be able to get away with 90#. Also for what you described as to what you want out of a turbo the specs of the turbo you found are probably what you want... just not from them. Keep us posted.

[speedracer95v6]

He wants stiffer springs partially because of the cam and partially because we should be able to boost it pretty high (well, maybe less boost, just more volume).

Just best not to have bouncing valves.

[T-Punk]

I understand why you want stiffer springs but you shouldnt spend more than you have too. Since you said you dont want a huge cam I was just suggesting that you dont have to go higher than 105# springs. Anything over that is really only needed for very agressive high lift cams.

[speedracer95v6]

Ah, well I'll prolly go for the first or second stage cam from comp or crane. It won't be very radical. I won't need too much spring.