Agreed.

And it might improve performance in our Z. Unfortunately, we'd need to talk to the guy that programmed the ECU to learn if the mapping goes far enought to advance timing to take advantage of the high octane properties.

I've heard reports of high octane fuel leading to over heating exhaust valves and manifolds from improper combustion. If combustion is so slow (not enough advance) that it keeps on burning during the exhaust phase, it won't make the engine happy.

As a side note. With my Impreza 2.5RS (NA engine, built to run on regular), I'd get on average 50km more out of a tank of premium than regular.

It's a case by case thing. Dependent of the car, the driving style and environnement.

 

I guess it could depend on the conditions? With a stock Z I would think under conditions where the ECU pulls timing even with 91-93 octane that a higher octane would help prevent that from happening. Not so much that a super advanced timing could be run.

I didn't think the octane rating had anything to do with the rate of burn, just the amount of energy needed to initiate the burn??

 

I have a Bimmer friend who pluged his M3's cats with 2 tanks of race fuel...

 

It was most likely leaded then... they make unleaded 100octane that will not do that...

 

Unleaded

 

1) There is no advantage to using a higher octane rating than the manufacturer specifies. Octane rating is only a measure of knock resistance. Higher octane does NOT have greater energy content.

2) All commercially available automotive fuel is unleaded, regardless of octane rating. Higher octane has no effect on the cat, the O2 sensor, etc.

3) Actually lead was good for valves. It formed a deposit on the valve seat and the underside of the valve that both cushioned the valve, and impsroved sealing. This was one of the auto industries complaints when the US switched to unleaded, tht it would cause premature valve failure.

4) Higher octane is more resistant to ignition (Thats why it is knock resistant). And the burn rate is slightly slower.

bill

 

Ah yes I used to drive by it everytime I went to the mall. I miss San Diego! I wish Id get IA'd sometimes so I can drive my car over there to my Dad's house!

 

I'd say that would be an advantage.

We're not even talking of the additives...

 

"Are you tempted to buy a high octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner's manual."


http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

bill

 

I’ll trust my own fuel consumption calculations thank you very much. Running premium in my Impreza, with my driving style, was cheaper than running regular. Period.

Now, if it’s stuff written on the web by people we don’t know that you need. Have a look at this:

http://www.toptiergas.com/

And put whatever you want in your car. It’s yours!