As some of you may know, I'm building the 400HP variant of the Cobalt straight out of the GM Tuner Build Book that was recently published. I have recieved many private messages about it, so I thought I would reprint one here for everyone. A lot of it is old info, but I still hope you find it helpful.


First, to answer your simple questions, yes, there are different pistons there. And yes, you need all of those parts, except of course that you don't need both kinds of pistons.

There are many things to consider. It is true no matter what car you work on. The Ecotec just so happens to provide a very easy and cost effective platform to work on.

You have to start with the limitations of the car. That means engine, trans, axles, wheels, anything that has a stress limit associated with operating the car. GM did a huge amount of testing on the Ecotec and found just about every fail point of every part. It was published in an article which is posted in a thread on this forum. Its a very good read.

When anyone builds a car, they make it stupid proof. Meaning, the car should be able to handle any kind of abuse you try to throw at it, and if you try to exceed any limit, the car just plain won't do it, hence protecting itself. For instance, they don't mate an engine capable of 300 ft/lbs of torque to a trans only capable of handling 250.

So, you wanna turbo? Ok, what can you do with a turbo without breaking the car? The stock Ecotec 2.2 (L61) can handle about 280 horse power before you destroy it. Most manufacturers limit the output of a turbo kit to 8 psi. which makes around 230 HP, to keep people from breaking their engines.

Take my car for instance. My goal is a street emissions legal, every day driver with the most possible power. I was actually surprised to learn during my research that I could get 400HP and still be street legal, which is making this whole project very exciting for me. I don't have to get into the engine to much because all that info is already been published in the Build Book, and discussed greatly right here in this forum.

So with the motor okay, you now have to ask yourself, "what will break next?" In my case, it was the transmission. The GM 4T45E automatic in the Cobalt has a torque limit of 220 ft/lbs. I would have torn it to shreads. So, I found a shop that does this very sort of job, IPT transmission. They will not only strengthen the trans, but also adjust the shift points to take advantage of my new 7500 RPM red line and give me a high stall torque converter for my turbo. I looked into Domestic Performance for this as well, but I was never able to get a reply to any of correspondence with them. Too bad for them.

Ok, what next? Reaching the 400 HP number, there was no other clear part that would fail under such a load. I could potentially break a drive shaft, but I would have to really wheel hop it badly, and an automatic trans usually prevents that problem.

So I'm not going to break anything, what other limits apply? With my set up, I'll be able to accelerate very quickly without limitations. Even the stock suspension can handle that. If I want better cornering control, then I have the upgrade suspension, but for going in a straight line, I'm fine there.

What about high speeds? Here is the next limit for me, tires. Stock tires can only go about 110 MPH before they start to come apart. So I would have to upgrade to some better rubber. And if I am going that fast, then I'm on a track, going in a circle, so now I'm back to the suspension stuff again.

I will be doing all that work. Not right away, but I will be.

Once you cross the 400HP threshold, things get harder. You need to replace the engine bolts with studs. You have to upgrade the valve train, port the head, and use different cam shafts. You have to bore and sleeve the cylinders. Its a lot more work.

The beautiful thing about this ecotec is you can get huge power gains WITHOUT doing any of those things. Don't let yourself be sold on a "headjob" for this engine. It just isn't worth it UNLESS you are planning on 400+HP.

So, there ya go. Hope that was informative.

 

Nice bit of information.

How's the project comming along?

 

thank you.. i cant wait til i get the funds for this. so exiting.

 

this will be one serious car when finished, once again good luck with the build, and please keep us posted on every stage.

 

Great information, thanks!
I was able to come up with two questions, and they will probably seem simple, but if you dont know you dont know right?

1: So, I buy a kit for 8 PSI, get well over 200 HP. My question is: Can I just have the kit bolted on and go? Or is there prep work I would need to have done first? This is based on me having a basically stock engine at the time.

2: You mention the auto tranny having a torque limit. Does this not apply to the 5-speed? I know manuals dont need Torque Converters, but will my stock trans be capable of handling the torque a turbo charged engine would provide?

Thanks!

 

you can run a turbo on a completely stock engine, but there are limits to psi that you can run. by upgrading internals; such as piston, connecting rods, etc. you can get more out of the turbo for more hp. and the stock transmission is perfectly fine to use with a turbo. however a new clutch is highly recommended.

 

Okay, new clutch, thanks!

So I guess my next question would be, just how much is it safe to boost through the stock engine. Ideally, I would like to run 8psi.

 

Any kit you buy is going to be an extensive project to install. Yes, the parts are mostly remove and replace, but still, there are a lot of parts.

Any kit you get should give you 8 psi, and that is a safe limit for a stock L61.

I know the stats on the auto tranny, I don't know the manual. I do know that the stock manual can handle more torque then the stock auto. I also know that 8psi won't break a stock auto, so logically, a manual will be fine.

 

GREAT info....thanks!

I'm going the supercharger route...I love the low end torque and when the funds come in will be doing that one, plus of course suspension upgrades, tire upgrades....that upgrade will be enough for me....it's a daily driver, and a sleeper in the making.

 

Sleeper! I am with you 100% on that one!

 

Even with all of his body mods etc. NO ONE is going to suspect a Cobalt of running that much HP hands down. I wish I could be there the first time he blows the doors off some unsuspecting car just to see the look on the other drivers face when they have to go back and pick up their doors .

I'm also seriously considering the S/C route but want to wait to see what GM offers up. I'm not looking to boost my HP anywhere near what Halfcent is going to be pusing but I'm always up for a little extra even if it is 35hp - 40hp that's still a significant increase for a daily driver .

Thanks for the info btw, seems you're the guinea pig on this build .

Permafried-

 

There arent going to be any doors left for them to go back and pick up. They are simply going to vaporize.

 

Not sure if this has been posted on this board or not, but here is a great manual put out by GM specifically for upgrading the 2.2 engine.

****dialup users beware, it's a 28 meg file*****

Someone was selling the same manual on cd on ebay.....I laughed since it is a free download and someone posted it on another cobalt board I am on!

http://www.gm.com/company/gmtunersou...build_book.pdf

 

That's actually what I was going by to come up with my appoximate horsepower numbers even though doing the math from the stock -> 250hp build book would look to be about 35hp if you take the nitrous into consideration. I'm being opimistic and keeping my fingers crossed the HP gains are larger than that when it's actually released, the one in the build book is actually for the Cavalier and Sunfire.

I posted the links to this a long time ago but it's always nice to have it kicking around for the newer members that join . Halfcent is actually going by these build books to overhal his 2.2L...looks like GM provided more than enough information in these (besdies of course what Halfcent provided us in this thread) to get the most out of our engines if someone was enthusiastic enough about it to go ahead with the project .

Permafried-

 

cant wait to hear about the finished project with some dyno stats and some track times

 

i know this post is a lil old but there is a lot of misinformation inhere and i gotta clear it up. ok where to start. gm said that the rods failed at 280 hp, that was on nitrous which is a sudden burst of pressure on the engine where as boost builds gradually. i know of a few eco guys that are running over 300 hp AT THE CRANK and there engines have held up for mutiple 12 sec quater mile times. next u can run upwards of 14 or 15 psi of boost ON A STCK ENGINE IF IT IS TUNED PROPERLY. dont expect to be able to run that from the get go IT MUST BE TUNED PROPERLY. lastly is gm's 4t40e can handle more than 220 ft/lbs of torque im almost postive that the 4t45e can do the same.

that is all.

 

maybe they were just being conservative in the build book instead of pushing thing to the limit...

 

Well, actually when they used nitrous to find the fail point of the stock L61 engine, they didn't jolt the engine with it as you would suggest. They had the engine on a test stand and slowly increased the nitrous pressure to the engine. This slowly built the pressure in the same way a forced induction would, so there was no sudden shock. After they upgraded the rotating assembly, they started again. I can't remember the exact number off hand, but they got to around 350 HP and the engine just wouldn't make any more power with nitrous alone. I remember the guys qoute, he said "the engine was really pissed off, but it held together". I thought that was funny.

As for the transmission stats, you are a little off. The 4T40 can only handle a maximum torque input of 190 ft/lbs while the 4T45 can handle 220. That data is published.

 

211 FT/LBS W/DYNO INSIDE, ENJOY

 

Okay, I can see you have some issue with this topic. I like a good debate, so here's what I got...

The car in your provided link is a 1998 Cavalier. It uses a 3T40 Automatic. And I don't even know that the car uses an automatic, his could be a manual, he never actually says. I don't know the limitations of the 3T40, but the point is that is a different trans then the 4T45. You are comparing apples to oranges.

Second, I am fully aware that you can put more torque into a trans then it is rated for. Doing so simply means that you are wearing it out faster and taking the inherant risk of breaking it. To tell people it "ok" to do so is irresponsible.

 

ahem....

the car linked is a 1998 z24 with the 2.4 twincam engine. all automatic z24 cavaliers with the 2.4L twin cam had the 4T40E transmission.

look here

if u click on his user name u can look at his profile and see that his car is an auto. (side note the dyno was only on 6 psi, hes already upped the boost a lil bit )

i made it easy for u

now back to the 4t40/45

"The 4T45-E is a variant of the 4T40-E, added in 1999 to handle higher engine torque. Most of the robust components developed for the 4T45-E are now incorporated in both transaxles."

taken from
here

so its actually red apples to green apples im comparing.

u said "As for the transmission stats, you are a little off. The 4T40 can only handle a maximum torque input of 190 ft/lbs while the 4T45 can handle 220. That data is published." i guess the publishings u were reading were a lil underrated.

just trying to clear up some of the misinformation ur spreading thru these forums. us jbody guys have been workin with the 4t40/45 for a while and the ecotec for about 3 years. we know a lil bit about them... so with that said im gonna be irresponsible and say that the 4t40 can handle more that 190 ft/lbs of torque, the stock eco can handle more than 280hp IF TUNED PROPERLY...

 

"Second, I am fully aware that you can put more torque into a trans then it is rated for. Doing so simply means that you are wearing it out faster and taking the inherant risk of breaking it."

adding boost to any n/a drivetrain wears it out quicker than intended and there is always a risk of breaking somthing. thats a risk u take with modifying imo.

 

Okay, a couple of things...

I don't make this stuff up. Here are two sources for you.

GM's 2005 Hydramatic data

GM's 2006 data

As you can see, even GM has a difference in the stats between the 05 and 06 years of 220 ft/lbs and 205 ft/lbs respectively. 220 is the highest number I've seen published.

Secondly, and more importantly...

Be careful pal. I've have never attacked you persoanlly. I have before now enjoyed what was a good argument. But if you are going to accuse me of spreading misinformation, you better be able be able to prove what I'm posting is inaccurate. And don't let your 3 years of J-Body experience let you think you can be cocky.

This thread was started for people that didn't know much at all about using the Build Book or what kind of limits exist on their powertrains. I'm going to help with them with the most conservative information available. I'm not going to advise them to put more power into their cars then it can safely handle.

You and I know that the car can handle more then the stats say it can when done correctly, just don't be a jerk about it.

 

wasnt tryng to attck u man. didnt mean to come off as a jerk, and its no being cocky, its just confidence in myu knowledge

i am learning as much from your posts as u are from mine. u have some good info.

after rereading my last post i can see how i came accross kinda rude but again i did not intend to attack u or make u mad its only the internet. im sure we will disagree again on these forums and i cant wait for our next debate.

oh and thanx for those links they will come in handy with my project.

 

where could i get ahold of the build book?