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Discussion Starter #1
ok so i was doing a lil researching and i noticed that the 2.4L has a 10:1 comp ratio and recomending 87 octain
well every other car i have ever heard of that has that high of a compression ratio has to run 91+
so
i filled up with 94 octain and unhooked the battery for about an hour to reset the PCM well i got 2 MPG better on this tank and it is noticably quicker
my friend just bought at cobalt sport and he would beat me pretty bad with 87 in mine
but i put 94 in and i actualy stayed with him for a while
it equals out to be teh same price
more $ on fillup= better mpg= enough to make the extra $5 at the pump wort filling up with a higher octain fuel

just thought i would let u know:D
 

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Wow. The 3.6 has a 10.2:1 compression ratio. I tried running 93 octane for a few tanks and noticed neither an increase in power or in fuel economy (actually, the MPG went down a touch). But then I never disconnected the battery to reset the ECM either. Doe not disconnecting it keep the ECU from recalibrating over a couple tanks (that's why I ran 3 tanks)?
 

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the cobalt sport is a horrible car, also its like 900-1000 lbs lighter than your car. I had to run 91+ when I have my Cobalt SS supercharged because thats what the recomended octane rating was. I loved my SS and the throw back in the seat feel, but I lost all respect when they got rid of the supercharger and went with a high output 2.4L. Then Chevy is like how bout a turbocharger.... I dont know how you guys are but I love superchargers more than a turbo any day... No turbo lag and instant power... Sorry I went in left field with that.. anyways they said with the 3.6L engine that we have if you put 89 octane (mid-grade) it will improve your performance and gas mileage a lil bit... But you should notice the performance..... after a year and half of putting nothing but 91+ in my cobalt I am glad I am putting 87 in the bu...... it doesnt hurt my bank account anymore lol
 

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ok so i was doing a lil researching and i noticed that the 2.4L has a 10:1 comp ratio and recomending 87 octain
well every other car i have ever heard of that has that high of a compression ratio has to run 91+
so
i filled up with 94 octain and unhooked the battery for about an hour to reset the PCM well i got 2 MPG better on this tank and it is noticably quicker
my friend just bought at cobalt sport and he would beat me pretty bad with 87 in mine
but i put 94 in and i actualy stayed with him for a while
it equals out to be teh same price
more $ on fillup= better mpg= enough to make the extra $5 at the pump wort filling up with a higher octain fuel

just thought i would let u know:D
I got the 2.4L also, though hate the thought of putting high test in my 4. I have a K&N drop in air filter ordered, also a set of V6 dual exhausts (well at least after the muffler), and will be going to Mobil 1 synthetic after 1000 miles. But I refuse to put hi test in her! Reserving that for my Z06!

So what kind of mpg are you getting? I have just been thru one tank of measured mpg hwy/city combined 27.4. That is before enough miles to have her broken in and without any mods yet. Bought the car for my wife to have a 4 door, smooth ride, and good mpg. Hopefully it will do all 3 without hesitation - pleased so far.
 

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Discussion Starter #5
i have a drop in k&n and got rid of the engine cover, im running mobil1 10w30 and with 94 im getting 25 in the city not sure on highway yet
 

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i have a drop in k&n and got rid of the engine cover, im running mobil1 10w30 and with 94 im getting 25 in the city not sure on highway yet
What did getting rid of the engine cover do? I did not think you could take it off with the air coming thru it from the air filter. Must be a hose under there? I am going to run the new Mobil 1 economy (selling it that way now) 0W30.
 

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Malibu Bob E - The one major gain to removing the engine cover is letting the heat out! I can't believe GM did this.....God they did it on their 3.8 Series III and it was maybe only a 1/3 cover of the engine....but on the Malibu it takes up WAY TOO MUCH. The cooler you can keep everything under the hood the better it will run.

However I am sure GTPMalibu can add more insight that I.
 

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Agree with DOA, the cover is supposed to suppress engine noise but all it really does is trap the heat :mad: I pulled mine off and just left the front piece on ;) also makes it easier to clean the engine when I wash it, another bad idea is the way they routed the intake tube over the front of the engine right over the exhaust manifold on the V6, that thing gets HOT !!!
 

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Agree with DOA, the cover is supposed to suppress engine noise but all it really does is trap the heat :mad: I pulled mine off and just left the front piece on ;) also makes it easier to clean the engine when I wash it, another bad idea is the way they routed the intake tube over the front of the engine right over the exhaust manifold on the V6, that thing gets HOT !!!

On the 4 it looks like the cover is part of the intake tube! I guess when I pull it off I will see how its on there. Thanks all. A photo of the 4 with the cover off would be helpful, if someone can post that.
 

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Discussion Starter #11
yeah all i did to remove the engine cover was go to murrays* ( autozone and advanced auto should also carry this) was buy a flex tube ( ricer parts section of the store) and a plastic t fitting looked of an elbow but i couldent find one then i just put it back together
the pictures should be all you need to do it very simple and the engine cover just lifts right off.

NOW does anyone know if doing that will void any kind of warrenty? i dont think it does but im not sure
 

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yeah all i did to remove the engine cover was go to murrays* ( autozone and advanced auto should also carry this) was buy a flex tube ( ricer parts section of the store) and a plastic t fitting looked of an elbow but i couldent find one then i just put it back together
the pictures should be all you need to do it very simple and the engine cover just lifts right off.

NOW does anyone know if doing that will void any kind of warrenty? i dont think it does but im not sure
Using corrugated pipe like that, don't you loose air flow and also create more turbulence?
 

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Discussion Starter #13
yes that is true. but honestly i like to be able to look at stuff under the engine and keep it clean so its a worthy trade off
i plan on taking a G6 or a coblat CAI and working it to fit on teh bu anyway so its just a temparary thing
 

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listen just find someone that can Tune it Thats what I did
 

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Some things about Octane. Ive been in the oil business with a major for 25 years and the octane thing gets misconstrued.

Octane is a flame RETARDANT. It does not make your gas more "potent". It is used to SLOW down the flame front in higher compression engines. It allows the use of HIGHER compression. That is what increases the power. This use of a higher compression - not the higher octane. You will NOT GAIN ANYTHING by putting in higher octane gas in an engine not designed to use it. And may lose some with a slower flame front.

Increasing the octane allows for higher compression by slowing the burn so the flame front wont slap the now closer/faster piston top and result in "pinging".
 

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My wife averaged 29.7 on her first tank (figured on paper no the car... 4 cyc, 6 spd). I'm sure the next tank will be better since it spent alot of time idleing and playing with the manual shifter, plus getting used to the car.
 

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Some things about Octane. Ive been in the oil business with a major for 25 years and the octane thing gets misconstrued.

Octane is a flame RETARDANT. It does not make your gas more "potent". It is used to SLOW down the flame front in higher compression engines. It allows the use of HIGHER compression. That is what increases the power. This use of a higher compression - not the higher octane. You will NOT GAIN ANYTHING by putting in higher octane gas in an engine not designed to use it. And may lose some with a slower flame front.

Increasing the octane allows for higher compression by slowing the burn so the flame front wont slap the now closer/faster piston top and result in "pinging".

People might notice a performance gain because if the knock sensor picsk up a ping on lower octane gas adjust spark, fuel/air etc resulting is a performance loss.

I did put in the Bosck Platinum Ir Fusion Spark plugs. About 2 months ago. I did notice faster starts, smoother ideal, and it seems more responsive. But that could be all in my head too. ;)
 

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The knock sensor only protects the enigne when 1.) using lower octane gas than specified, or 2.) the engine has lots of miles with excess deposit buildup.

The ECU in the Malibu 2.4 is tuned for 87 octane. It cannot take advantage of anything higher. It's a waste. Some of the other GM vehicles that use the 2.4 Ecotec are tuned to take advantage of 91 but run safely on 87 (read: knock sensor/spark adjust), but not the Malibu.

Mrbill is dead on in his statement. I wish more people would read and understand this. Octane does not equate to performance.
 
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