For those who reads the article (4 PDF sections available also on a CD) from GMPP, they explained how to build a 2.0 LSJ Ecotec up to 315 BHP (engine crankshaft power) and 250 engine TQ. These numbers are shown in the 4th section.

Part #1: http://www.gmperformancedivision.com.../23/ecotec.pdf
Part #2: http://www.gmperformancedivision.com...tec_Part_2.pdf
Part #3: http://www.gmperformancedivision.com...tec_Part_3.pdf
Part #4 : http://www.gmperformancedivision.com...tec_Part_4.pdf

We all know GM underated the stock LSJ power (205 BHP) from the factory, since the Cobalt SS seems to dyno an average of 210 WHP (4th gear on a dyno jet). 210 WHP equals to 245 BHP (engine power).

Here are the parts used to achieve the increase in performance. Numbers in parenthesis are estimated to get the 245 stock BHP to the 315 modded BHP. I think they use a midly modded "conservative" setup ...

1 : Forged aluminium pistons
2 : More agressive Comp Cams camshafts (15 BHP) and higher spring rate valve springs
3 : Replaced balance shafts (5 BHP)
4 : Bigger injectors 44 lb/hr
5 : New calibration and controller (15 BHP)
6 : Shorty header and opened exhaust (15 BHP)
7 : Air filter seems a Donaldson like the stock one
8 : 3 pass coolant intake manifold (minmal gains according to the article)
9 : Stock supercharger WITH a 73 mm (2.87") pulley @ 16 PSI (15 BHP)
10 : CNC ported cylinder head (only 5 BHP gained at the 315 BHP level since the stock head has been said to cause no loss up to 275 BHP).

One thing isn't sure : Did they underated the 315 BHP result ???

 

kinda old cheif but thanx for the effort

 

Isn't rasing the boost 4lbs going to yield more than 15hp?

 

Every pound of boost

1lb = 10whp for our displacement.

It's more like 40whp. To be more conservative would be between 25-40whp for all the haters.

 

the article actually says that they made "real power gains" going from single pass to double pass so u wrong there. while the 1psi=10hp equation is a good guideline, there is nothing scientific about it and it doesnt work like that on all engines.

 

and also im pretty sure there would be more than a 5hp gain with a pnp head just because its not a restriction up to 300 hp, there is always room for more flow. granted u can overport (?) a head and actually lose power but i dont think gm would have done that

 

Well one its never been broken down and put into one post like this before so relax and kick your feet back you may actually learn something by the time this is done. And by Sneaky's rule anyone running the 3.0 pully should be at just about 250 whp with just throwing on a smaller pulley and thats it, when thats hardly the case.

 

If you break it down 1psi equates to about 8.6hp on our cars.

red - he was saying that going from a 2 pass to 3 pass leaves minimal power gains not going from 1pass to 2 pass which obviously gives lower intake air temps.

 

6 : Shorty header

Not to beat a dead horse, but I think GM knows what their doing with this motor. And they think a shorty style header is best. Ok I'm done....

 

Trying to be honest, the main purpose I post this is to get the people realize that (as an example) just replacing a muffler or installing a cold air intake won't give you 300 TRUE WHEEL horsepower, since the engine is only a 2.0 liters, and since ALL the bolt-ons gives GMPP a result of "only" 315 BHP (engine brake horsepower) thus resulting in 270 WHP.

Also, what is not good for the Cobalt SS owners reputation, is all the kidders who claims that their cars makes 250 WHP bone stock, but drive their car to a 14.8 or 15 second quarter mile. Ok I tried to help, period.

 

With this "wrong" formula, only throwing a 2,8" pulley (giving 5 PSI more than stock) would give 50 WHP ! Aahah maybe in our dreams ....

 

Here is a copy of the fourth part. http://www.megaupload.com/?d=FL38QU4V It is a shitty host though, and **** may pop up so I wouldn't view it at work. I didn't have anywhere to host it though.

I can email it to someone if they want to host it.

 

Stick to the man Jmc!

 

I would put money that a full length race header will out perform a shorty header.

 

Anyone have any idea how much it would cost to have all the things in the build book done to the engine?

 

man i def know thats for sure. i got a CAI, magnaflow, and a 3" pulley and on a dynojet im only pulling like 239 whp! also the 90 deg weather kinda hurts lol

 

Yes I believe the article states there were significant increases when going from single to double pass... but not from double to triple...
I keep wimping out but I would love to see someone take off there intercooler and figure out how this modification is done.. I think it would net some good gains... especially with a pulley.

 

I"ll be damned if I don't put down at least 240+ on a dyno jet. I'll will the horsepower on to the chart. Or Throw race gas at the bitch and also run it lean. I want 250 wheel hp now!. But since I haven't been to a dyno yet who knows?

 

whats this 1pass and 2pass stuff???/

thanks for any info

 

How many times the compressed are goes around the cores in the aftercooler before going into the intake manifold

 

These upgrades are fairly simple if you know your way around the engine bay. As soon as I save up the money I will be doing this build up. I'd conservatively say this build should run you about 2 grand plus...If you do everything yourself...

 

Yup, I know a lot of guys with moddified quad 4 grand ams who run 14.7-15.0 and can't understand how the SS S/C aren't much faster if they are making 210WHP.

 

what is meant by opened exhaust? are they talking about their GMPP exhaust, or no exhaust

 

RWD...

 

they welded a plate to reroute the coolant back into the manifold and back around again
the pics i have of it suck, i printed the book in the library, but have all four save on a disk

i would think it would be easy but cant see how they get it to only loop twice