Okay, so, prepare for a quick novel.

I'm here to ask a few questions regarding turboing my buddies tC. I'm an active member on the Cobalt Forums (ya, I said Cobalt, lets just be friends lol), so I'm highly familiar with the whole "forum world" lol.

My Background: I have a Cobalt SS Supercharged, that I converted to supercharged on 18psi on e85 fuel. (still working on the e85 tune lol) I'm very familiar/comfterble with cars, I cracked a piston on my cobalt about a year ago, replaced them with forged pistons, (our stock rods are forged and tested up to over 450), and some other engine support goodies.

Enough about me. Here is the quick jist of my buddies part list:

t3/t4 57 Trim turbo
550cc Injectors
Turbonetics Wastegate
HKS SSQV BOV
3" exhaust
As for the turbo piping, I just planned on welding up the piping for him, and using V-band clamps almost everywhere needed (except going on to the turbo outlet and throttle body, obviously)

I did some searching around, and had alot of questions answered, but here are some of the ones that I still have.

1. For the turbo piping, obviously we are going to run 2.5" piping for the hot side, but for the cold side, can we get away with 2.5" piping without over loading the MAF or will we have to size up to 3" piping? I'm a little unsure because on my cobalt, I have to run 3" piping, cold side, because our MAF's are really sensitive, granted i'm running 18psi.

2. We planned on running 550cc injectors. My concern is will they be too big? Right now he's only planning on running 8psi, but the 57 trim is a good sized turbo. I'm trying to tell him to go smaller, but he's sold because he eventually wants to go more boost.

3. Will we have to run a bigger/additional inline fuel pump to support the larger injectors? My concern: Bigger injectors demand more fuel, can the stock pump support it?

4. Is there any other "little" things that need to be addressed when converting to turbo?

and I'll see if I can find a cracked piston picture.

 

1. 2.5" will be fine
2. 550s are fine for around 10psi. I personally dont see how your injectors could be "too big" considering they are controllable
3. Upgrade the oem fuel pump to a walbro/dw300

 

Well heres my 2 cents:

1.) 2.5" piping will do the job. Im running that right now so i would know.
2.) If you think 550's are too big your crazzy lmao. Im running 850's and they dont seem to give me any trouble. I promise 550's are just fine for the boost hell be running.
3.) Stock fuel pump will be ok for the boost level. Im currently running 10psi on a larger 60-1 turbo and my stock pump is doing just fine. If hes planing on more than yea an upgraded pump would be a good idea.
4.) Youll definently want to upgrade the clutch asap. Stock clutches burn up real quick with a turbo setup on a tC.

 

My opinion:

1) From my experience, most short ram/cold air intakes are 2.75" ID and the MAF plate is elevated about an inch or an inch and a half from the outside edge of the pipe. The key is to get the tip of the MAF in the dead center of the inside of the pipe.

2) UMS Tuning (guys that tuned my kit) informed me that 550cc injectors are good for up to 12 psi (provided that there is sufficient fuel pressure and volume), so 8 psi should be simple for them.

3) I would strongly advise replacing the stock fuel pump with a Walboro 255 or the new Deatschwerks 300. UMS actually replaced my 8 psi wastegate spring with the 4 psi spring since the stock fuel pump on my tC could not supply enough fuel for 8 psi (AFRs leaning out too much for their liking).

4) Goes without saying, but some sort of additional engine management software (AEM F/IC or GReddy eManage and related PNP harness), appropriate guages (vacuum/boost, wideband, oil pressure, etc.). Also, I would suggest a vacuum block.

I also bought 2 14mm spark plug anti-foulers and drilled out the bottom part of one of them and then screwed them together (to spoof the 2nd O2 sensor CEL).

Are going for a blow-through MAF setup (easier for atmospheric BOV dump) or are you doing a recirculated BOV?

And that is my 2¢

 

Thanks for the great responses guys!

The plan is for a blow through setup.

Because I'd perfer to do it right the first time, we'll get an upgraded fuel pump, then its there for when he wants to up the boost, and we can be sure not to burn out the stock fuel pump.

I'm with ya on the vaccum block. Good tip! Probably wouldn't have thought of it until we started putting it all together lol.

As for tuning, I thought that the AEM EMS seemed like the best setup, because you can control the most fuel paremeters ect with it (if i'm not mistaken) plus he can buy the plug and play kit for it as well.

One last question that I can think of, do these motors have an oil sending fitting on the block anywhere?

 

yes, the oil sensor is threaded into the head just below the crankcase vent bung on the driver's side of the engine. most kits just use a T for the feed and the oil pressure sensor.

i have my oil pressure gauge running off of a oil filter sandwich adapter.

 

Recomend getting a Engine mangement system, AEM F/IC or Greddy E-manage Ultimate (Witch I am curently selling one with a 05-06 pnp harness and greddy pressure sensor classified section Engine/powertrain) Boost and Wideband gauges would be a good idea also.

 

There is no need to replace the pump for 8lbs of boost but for the sake of making plans for more boost later then fine.

57 trim is not to big for a tC, it's the size commonly used in the off the shelf kits.

 

Bluescion I think we helped you and your friend out. So you guys should be fine.
Just my opinion-
-Go Blo-thru better for driveability than draw-tru and utilizes the BOV more effectively trust me.
-550cc's will get small real quick with higher boost levels. I'm on 700cc right now with stock pump
-2.5' is optimum piping. Any bigger and you might increase lag on spool time
-50 trims are common for our car and will get you about 350 and up with higher boost and full 3' exhaust.

-Well again when does he want to hit boost at the low-end or mid-range?

-I'm sure you know already but acquire a proper wastegate(no fakes) and run open dump it's so sexxxi,lol
Post the details of the build and keep us updated.