Hey I have been doing a lot of research and I just wanted to ask a few quick questions.

First off, I think I have a basic understanding of how the turbocharger gets spooled and its interactions with the exhaust system. If I have a stock exhaust on my 08 Cobalt SS, will I see significant improvements in spool time, and also increased acceleration times because of faster spooling times?

Secondly, is it worth it performance-wise to look into replacing the stock turbo with a bigger one? I understand that I don't need a massive turbo because it could take longer to spool. I assume there must be improvements that can be made to the turbo though?

Thanks for your time : )

By the way, the Cobalt has had the front mounted intercooler replaced with a larger all aluminum one. This stretches across the entire front grill of the vehicle. The plastic charge pipes have also been replaced with stainless steel charge pipes. I *think* the stainless steel charge pipes have been welded onto the pipes for the front mounted intercooler... So I think these are things that can help with cooling if the turbo is replaced at all? Please forgive me, I'm trying to learn more about under the hood. I really don't know very much about cars, but I'm trying to learn!

 

Oh there is also a blow off valve installed on the charge pipes :>

 

First of all, I am glad you are new to the engine bay and want to learn. It can intimidate some people.
The K04 turbo in itself is a pretty quick spooling turbo. Opening up the intake and exhaust is always a plus with performance. Faster the air can get in and leave, the better. Turbo cars like our 08's dont need exhausts, technically, because they do not require the back pressure naturally aspirated cars do. The stock exhaust is pretty restrictive.

The intercooler piping being welded straight on is probably unlikely because it would really restrict being able to replace specific parts in the event of a failure. Large ass intercoolers are a double edged sword to me and are not really required unless you're running crazy ass levels of boost. The intercooler only cools the air that has been compressed by the turbo, as the compression process heats the air up. If you replace the turbo with a bigger one, then yes, a larger intercooler setup would be beneficial in cooling charged air. Just think of it this way, when you increase the amount of area in the intercooler and piping, the spool times could INCREASE because now the turbo has to pressurize more air than it did before.

Hope this helps, and if I am not correct on some things, I am sure other members will chime in lol

 

OP does your car have any type of a tune on it yet? If not I'd look into that and a downpipe before thinking of a turbo upgrade. A lot of people are happy with the power ylu can make from the stock k04

 

Hey guys thanks for posting. As for RyBread, I actually ended up reading "The Ultimate ECOTEC Related Turbo FAQ!" right after making this post (maybe I should have read it beforehand >.>) and I have an understanding of the point you make about the intercooler. I can take pictures and post them of the parts that were replaced.

There is one thing that I am certain of. This car no longer has a catalytic converter. I am probably totally off on what parts are welded where. I hope that the pictures I provide will bring some light to that.

As per KM043 -

The person I purchased the vehicle from said that it was tuned for winter weather. He handed me a red Trifecta ODBII tuning cable with the vehicle...However, when I first met him, the guy from the performance shop met with me and at some point in the conversation he said something like, "It's too bad we didn't get around to tuning it." So I don't really know if it has a tune on it yet. Can I use the cable to somehow see if it was tuned already? I don't have the program for my laptop though.

 

honestly you wont gain much horsepower from exhaust on the LNF. its not a huge restriction, and will just gain noise.

Downpipe is the number one mod on our cars. A catless downpipe will net you more horsepower once you are tuned. Intakes are really just for sound and dont have that much gain.

it all depends on your goals with your car. a k04 will usually net you around 320 whp max on gas, and around 350 on E85. A bigger turbo will obviously gain you more power.

A k04 at 24 psi is about 310 to 320 whp with supporting mods like downpipe.

A Hahn s20g, or ZZP EFR 6758 at 15 psi will be around 350 whp. give or take.

The bigger turbo will be easier on the motor even though its bigger, at the same power range because of turbo efficiency.

now these are just estimates and can range and vary depending on car, tune, mods, etc.

 

Here are some pictures I took. I hope they are good enough to make some sense out of them.

 

I really don't know what parts are what if you could tell me what they are though, I would greatly appreciate it!

 

Can you take a pic of the whole engine bay. Those are custom intercooler pipes that I have never seen before. I'm interested in the one that's welded into the intake is that from a bypass valve??

 

Wtf kinda intercooler piping is that?

 

Looks like it just goes to an aftermarket BOV.

 

The thing should be called Frankenstein. OP, the car has to be tuned for all of those mods, no cat, relocated BPV. When you give it the beans, what boost PSI is displayed?

 

Hahahaha alright. I'm at work now however. I will get the picture of the whole engine bay uploaded around 5:30 CST. So...do you think this custom intercooler pipes actually hurt the perfomance of the vehicle? Hahaha.

@RyBread
At full throttle she pushes 15 PSI of boost

 

Oy, maybe it isnt tuned then lol

 

No, those pipes probably have little effect if any on performance.

If the previous owner said it was tuned for winter then 15psi doesn't mean its stock tune

 

Very true

 

So I should probably look into getting some pipes to replace these then?

Also, even if it was tuned for winter, it probably isn't tuned for performance is it? It needs to be tuned for warmer weather right? I will *never* be driving this car in the winter time. It will be stored somewhere away from snow/salt/cold

 

Another question -

I should be able to push ~22 PSI theoretically shouldn't I? Do you think this could be tuned to not provide much performance as far as acceleration/torque goes? I feel like the car should be much faster than it is. I mean don't get me wrong, it's definitely faster than my Cobalt LT, but I was thinking it would be like a lot more considering it has almost twice the HP of my Cobalt LT.

 

Yes you can run 22psi on the stock turbo. It's also possible to turn down the power for a winter tune or whatever you need. I've never driven a LT before just a SS/NA but now that I'm tuned if I ever put the stock tune back in my car feels really slow. Even tho it's still 90hp more than the SS/NA

 

Well KM043, just imagine flooring it and taking a solid 10 or so seconds to get to 60 haha. That's about what my LT does.

 

I loved my SS/NA and would love to build a autoX short road course car from one but it takes so much $$$ to build a powerful NA and I know I won't be happy with it afterwards.

You really enjoy the are when the boost is turned up it totally wakes up the car!

 

I may sound like a noob here, but what is an SS/NA?

So is there a night and day difference between 15 PSI and 22ish PSI? I really love when you feel the torque pulling when you're accelerating, and it puts you back in your seat. However, it's not very consistent. Sometimes it puts me in my seat, and sometime it doesn't. I'd really love to have that power *all* the time, whenever I give it enough to go, if you know what I mean

 

Cobalt SS Naturally Aspirated

And yes more boost always makes a difference.

I think you should focus on getting a nice baseline tune from somewhere or someone and then start doing revisions to get it where you want it. I bet you will be very happy with the end result

 

Thank you for informing me sir!

Do you think it would be wise to look at replacing the custom intercooler piping before I get the tune done? Or should I get a tune done with the current setup?

 

Oh ya 15 vs 22 you'll really notice the guy I tuned on Sunday could tell between 20 vs 23psi. At 22psi you'll have lots more torque it'll put you back into your seat