2.4L DI details
The new 2.4L DI engine delivers an estimated 180 horsepower (134 kW) @ 6700 rpm and 172 lb.-ft. of torque (232 Nm) @4900 rpm. It uses technology based on GM's other four-cylinder direct injection applications, but with unique features designed for its specific application.

This includes an 11.4:1 compression ratio that helps build power, slightly dished pistons that increase combustion efficiency and injectors with an application-specific flow rate.

http://www.gminsidenews.com/forums/f...3-0l-v6-72914/


I must confess that I am rather underwhelmed and disapointed at 180HP.

I guess the mileage will be good and you can use reg gasolione to get max hp. But I was hoping for 200HP.

I doubt the 2.4L will return to the Cobalt though

 

Thats cool in all but yeah 180 horse thats not quite wat id like to see either ya 200 or around there would be sweet thats what ive read too that the 2.4 is done

 

11.4 c/r and only 180 hp.... WTF??? GM = FAIL

and 11.4 is a lil high for pump gas...

 

According to the Autozone website:
06 SS/NA 2.4L was 4% of Cobalt production
07 SS/NA 2.4L was 2% of Cobalt production

Those numbers won't help to get the 2.4L back into the Cobalt.

Honda SI 2.0 has 12+ compression -- they don't have a problem with pump gas...

 

The DI allows for lower octane in a higher compression engine cause when the fuel is injected directly into the cylinder you don't have to worry about detonation.

 

And unlike the 2.4L in the old SS this new one makes a little more power while probably only requiring regular unleaded vice pump premium of the old 2.4L. The direct injection keeps combustion chamber charge temps better in check allowing the higher compression ratio which helps power and drivability. Just adding DI to an engine normally only gives a small boost in power. In the end this is still a smaller displacement, naturally aspirated four cylinder that makes a healthy amount of torque across a broad powerband. You could probably get 200hp but I'd rather have the 172 ft-lbs rather than say 130 you might get by changing the stroke and other characteristic to rev higher and produce that bigger peak horsepower number (just like a Honda since HP is based on torque and rpms).

Anyone also see the piece on the blog sites how this engine in the new Equinox is supposed to get 30 mpg on the highway? Considering the new modified version of the Theta platform that underpins it and the new Vue has put on weight I'd say that's pretty impressive. It also bodes well for the numbers this engine can produce in cars. Maybe they concentrated a little more on mileage than power. With gas prices what they were when it was in development I wouldn't blame them.

 

Do you have totals for Cobalt production for 06-07? I am wondering exactly what kind of number 2 and 4 % represent.

The 2.4L Acura TSX makes 172lb-ft.

You might give up a small amount of low end tq to hit 200hp---but it would not be catastrophic.

And its hard to believe that they just slapped on DI on the 2.4L and called it done. I bet there are host of changes. Just not many calling for more power.

My 2.4L has decent low end grunt but theres not much at high rpms. I hate that.

 

There's probably a lot of stuff done to the new engine. Just that direct injection alone isn't going to create a ton of power when added to a naturally aspirated engine. Honda does have a little more horsepower in that application but it would be interesting to compare the power curves.

If you really want more horsepower from GM in a naturally aspirated four then you're a decade or so behind. The Oldsmobile W-41 Quad 4's were putting out 190 hp and 160 ft-lbs in the early '90s. They were also very loud and rough in how they went about putting out that power. The new 2.4L is pretty close to the power numbers and should be an infinitely nicer engine to drive in most of the cars it will see duty compared to the old Quad, and it's also very competitive with what's currently available from every other manufacturer.

 

This new 2.4 is closer to the DI 3.6 than it is to the old 2.4, the new 3.0L 255 hp DI V6 looks promising as well. Also, in my opinion, we shouldn't be ready to call this engine a success or failure simply because its 180 peak hp isn't significantly more than the LE5. There's more to it than that.

 

With tuning and premium I bet it will hit 200 no problem.

 

Your suppose to put premium in it anyway or so it says in the drivers manual

 

We're talking about a new 2.4L engine that has direct injection, not the 2.4L in your car. I suppose we are in the LE5 section so you're forgiven.

 

true i wasnt thinking about that... brain fart lol but yea it would be nice to get some of those on here n see what they can do

i wouldnt doubt it one bit. with some bolt ons we could maybe see a big 4 cylinder do what it should be doing

 

Lol, dude... DI does not remove detonation. It just allows for a better fuel burn resulting in lower cylinder temps, which then lowers chances for detonation.

Also, you all who are comparing this to a honda K20/24... Do you realize those redline at 8k+ rpms? I bet this engine is only being taken to about 6500 max. You wouldnt be surprised if this engine pulls some nasty numbers on a nice full exhaust, intake, and tune.

 

it CAN in theory eliminate pre-detonation... what if you dont inject the fuel into the engine until the instant the spark plug fires? there wont be anything to detonate. With this method, cyl temperatures and the CR alone could probably ignite the fuel, removing the necessity of spark plugs, which would only cause a second flame front which WOULD destroy your engine. Of course this would only be under load. Im not saying this new engine does this, but the potential is there. Just eliminate spark during WOT and let the CR and cyl temps ignite the fuel, like in a diesel.

any takers? im sure its not a flawless idea, but hey, lets discuss this possibility

 

Already in motion: HCCI (Homogeneous Charge Compression Ignition)

http://media.gm.com/us/gm/en/technol...uels/hcci.html

http://www.gm.com/experience/fuel_ec...ogy-082707.jsp

http://www.popularmechanics.com/auto...html?series=19

http://www.motortrend.com/features/a...tem/index.html

The prototype engines running in the labs are supposedly based off production Ecotecs and they only operate in HCCI mode (i.e. diesel like) at idle up to a few thousand rpms then switch back over to conventional SI (spark ignition). Might want to search or start a new thread in another section if you want to discuss it more.

 

Isn't it a rule of thumb that higher compression is better for nitrous. These might be monsters with a 75 shot of juice