Maybe

The only way you can know without going on a dyno is going to the strip with your car and lookig at the trap speed.

 

iv been running 93octane since day one. It definately makes a little bit of a difference.

 

these cars are recommended to run premium fuel, not regular. By using the proper fuel that the car was desgined to run, it would more then likely put you over 150hp bone stock. Others have gone in the mid 150's bone stock without a tune.

 

I forget exactly the difference between the high and low octane tables...but it is 3-4 degrees of timing I believe

 

unlikely, the auto tranny robs a little bit of horsepower from these cars, probaby closer to 150

 

With an automatic on a dyno the horsepower will not show "real-world" street HP numbers. Having said that...running a dyno and driving on the street/track are 2 different "animals". On a dyno you have to bring the engine up to 2K RPM and then slowly floor it. On the street/strip I can "hammer" the throttle off idle -- I can assure you the HP and torque numbers would be completely different!!!

How about providing MPH from the 1/4 mile traps for both autos and manuals. That would be a better indicator of how close (or different) the horsepower numbers really are.

 

I believe that it will help to run higher octane, but most spec sheets that I have seen recommend regular for the 2.4.

 

Run 91+

/end that discussion

Lots of knock has to happen before the car switches to the low octane tables.

Everytime you start it

 

read the owners manual for the 2.4, the manufacture that made this car say to run premium gas in it.

There has been many discussions on this subject for a long time and it the same conclusion is reached, run what the manufacture tells you to, which is premium. Try it, u have the dyno numbers for ur 87 octane, now put 91 octane in, with the stock tune and see if the numbers go up. If the car is not meant to run with premium gas in it, ur dyno numbers wont go up on the stock tune.

Thats the expensive way to prove my theory right, but i just stick to the owners manual.

theres a 1/4 mile list available proving the auto robs hp.

 

Autos have more parasitic loss period.

Easing into flooring it on a dyno will not change peak numbers.

 

agreed. Auto's will have more drivetrain loss,which will always cause lower peak HP numbers. However, the tq converter allows for higher RPMs at lower sppeds, aka more power. I for example can be rolling 5mph at over 3,000RPMs. Therefore, all power below 3,000RPMs is not needed, because i will never be at those RPMs when the pwoer is needed.
These are just the pros and cons of an automatic. torque converters also make for good force multiplication in the midrange of the powerband.

 

u agree with him but he said autos will not change peak hp numbers on the dyno but then u said in the next sentence that it does cause lower peak hp numbers which is what I said

 

steddy is saying peak numbers will be lower...no matter what, and im agreeing. i think you're misunderstanding what he is saying.

 

I will get some premium in there and see what numbers it puts down. It's unfortunate that we're testing on winter blends, but thats what we have to work with for now.

I don't really expect to see a lot of gains on the stock tune with premium since there was very little KR. However, a few more degrees of timing and 91 octane might be worth 10 WHP.

As far as the manual trans vs. auto discussion, a fluid drive torque converter can never achieve 100% coupling efficiency without locking the converter clutch. At this power level, I'd expect a stock converter to be giving up about 5 or 6 whp at the peak.

 

...which doesn't even equate to a car length down a 1/4 mile. Would then depend on RT.

 

But the manual trans guys also have the advantage of closer gear ratios to stay in the heart of the power band.

 

this is the biggest advantage for the manuals. if the balts came with a 5sp auto with the exact same gearing, the auto would win no questions asked

 

Not sure what you mean here? The Auto tranny has a 1.0:1 difference between 1st and 2nd, and less then 0.5:1 ratio difference between 2nd and 3rd. Plus the torque curve is pretty nice on the 2.4 and both trannies keep the engine RPM inside that curve.

Both the manual and auto trannies behind the 2.4 have close final ratios too.

We could argue about this all night and into next month...I'm not going to convince you the auto is good enough and you're not going to convince me the manual is better.

 

you lose the ratio round....
3 underdrive gears in the manual vs 2 underdrive gears in the auto

 

What gear do manuals end the 1/4 mile in? 3rd or 4th. I bet it's the same as the auto -- 3rd. Not much of an advantage there...and if it is 4th I'd bet it's not in the high RPM/high HP area

 

redline of 3rd at the end of the 1/4 mile but if you seriously beleive the auto gearing is the same as the standard u got some specs to look over. An auto 2.4 on average is a high 15 to a very low 16 second car; a 2.4 manual is a mid 15 to a low 15 second car.

The 1/4 mile list for the 2.4 stock is a perfect example

2.4 SS, STOCK, THE WAY IT IS FROM THE FACTORY
1.)08sport1320,14.95@92.88 w/2.21 60'
2.)ProjectCobalt,15.46@86.69 w/2.35 60'
3.)UnLimiTed,15.66@88.64 w/2.27 60',coupe,5-speed,Timeslip Vid
4.)iLLmaTic3s, 15.824@@85.55 w/2.427 60', coupe, auto,VID Timeslip


premium is also healthier for these motors, these arent 2.2's they run on a higher compression, the manufacture doesnt just recommend premium for no reason. Thats usually a turn off for buyers to run an expensive fuel on a cheaper car.

Theres a reason why they do it, treat the car right. It has also been proven in tests for fuel economy that running the premium you receive better MPG then running the regular and you actually save money in the long run with premium because of the fuel you save. The reason being is because the car was designed to run on premium, not regular; cars that are meant to run on regular dont run as well with premium for the same reason.

 

A manual is better for acceleration in terms of gear ratios.

F23 weighs less than the auto trans.

Stock for stock, the manual walks the auto.

Both tuned, the auto picks up quite a bit but still is slower than the manual.

Longer gears+less power=a slower car.

Get over it.

 

get out of here u t/c owner..lol former le5 owner..lol

honestly...specs for specs..yes we know..but driver vs. driver..any cam happen..like personally i could of ran better stock than my 15.8 if traction was better and prolly ran low 15...but w/e its a cobalt, end of story.lol

 

yea...3rd is direct drive for the autos...whereas you're redlining in 3rd in the manual... that means throughout the entire time you were in 3rd, you were getting more power to the ground since you were at a higher RPM than the auto guy. just admit it dude...5 gears are better than 4...

 

We could argue about this all night and into next month...I'm not going to convince you the auto is good enough and you're not going to convince me the manual is better.