Chris'sHHR

Dont throw your money away. use the proper fuel for your HHR. In the 2.2 you only need 87 octane and in the 2.4 you need 91 octane. Using a higher octane fuel in your HHR doesnt make it have more power. On another forum someone said to me that they used a racing fuel in a bike they had and it dynoed with more hp than with a 93 octane fuel, they wanted an explination. For you guys and gals wondering the same thing... Pump gas (in Chicago at least) contains 10% ethanol. Ethanol doesnt produce as much power as gasoline. So a race fuel with zero Ethanol will make 10% more power per gallon as a pump gas with the Ethanol (im no mathmatecian so my number may be off).
Enjoy the article


Here's an explination of Octane and its relation to your car:

Higher octane ratings correlate to higher activation energies. Activation energy is the amount of energy necessary to start a chemical reaction. Since higher octane fuels have higher activation energies, it is less likely that a given compression will cause knocking. (Note that it is the absolute pressure (compression) in the combustion chamber which is important - not the compression ratio. The compression ratio only governs the maximum compression that can be achieved).

Octane rating has no direct impact on the deflagration (burn) of the air/fuel mixture in the combustion chamber. Other properties of gasoline and engine design account for the manner at which deflagration takes place. In other words, the flame speed of a normally iginted mixture is not directly connected to octane rating. Deflagration is the type of combustion that constitues the normal burn. Detonation is a different type of combustion and this is to be avoided in spark ignited gasoline engines. Octane rating is a measure of detonation resistance, not deflagration characteristics.

It might seem odd that fuels with higher octane ratings explode less easily, yet are popularly thought of as more powerful. The misunderstanding is caused by confusing the ability of the fuel to resist compression detonation as opposed to the ability of the fuel to burn (combustion). However, premium grades of petrol often contain more energy per litre due to the composition of the fuel as well as increased octane.

Source: Octane ratings

solman98

Good read,

Bottom line, if yours call for 87 use 87. If it calls for 91, use 91. Modern computer controlled vehicles burn better at the recommended levels. Using higher, and you are only wasing your own money. Using lower, and you could delevope a "pinging". If it does not run right with the facoty recommended octane, you have a different problem. Only time you should use higher octain is with a PCM reprogram. The computer will adjust the timing if you use other grades.

krishaynes

I'm surprised more about the fact that most pump fuel in Chicago contains Ethanol! When I had my Motorcycle it said in the owner's manual that no quantity of ethanol should ever go in the fuel tank (1999 Suzuki GS500).

I have noticed a difference in fuel economy when using 10% ethanol as it does reduce the amount of energy in a litre of fuel.

I've always wondered why people use "higher grades" of fuel in their cars. If it asks for 87 give it 87!

Snoopy

Kris, Solman, and Chris....

Good read. And almost exactly what someone else said...not in entirety, but in context. But, you will have people argue this point still, because their "butt dynos" say they can feel ..maybe 2 HP.

krishaynes

Maybe my butt-dyno needs to be recalibrated. Wait a tic. That sounds painful!

JoeR

I'm convinced that quite a few people here have been secretly buying THIS and not telling anyone!

HillsdaleHHR

GCarp

I'm going for the dual exhaust... and maybe the oil bypass...