I've watched the OBDII output for timming. I've logged the timming data for WOT conditions through the whole RPM range. Then I've changed gas to a lower 87 octane rating gas. Purged the system and logged again.

Surprise......

no knock.. and no timming change ..

Maybe the 87 they were selling was actually 92.. Ha.. when does that happen..

Maybe the atmosphere in Calgary, Alberta is thinner... So I could get a couple degrees of advance and still be ok?

Honda uses speed density to calculate the air but does it have a altitude sensor?

Does anybody have any ideas on this?

 

Eugene, I've seen a few posts on this subject, where someone has put in "regular" fuel by mistake. The car seems to run fine. I cannot explain the technical reasons why, but the engine management system on this car is able to run quite adequately on low octane fuel. I don't believe the engine will output the same as if it had high octane, but it still runs quite comfortably.

 

In my previous car I was forced to get gas in a bad area in the middle of no where upstate N.Y. I asked for 93 at the pump. This station must have 87 under ground in all their tanks because the next day my RPM's were going crazy. They were going up and down in idle. It was a 99 Civic Si with fairly high compression.

 

I doubt that the erratic idling was octane related - you probaly got some bad gas. Or, a gas blended for a different season. Fuels are blended differently for summer, fall, winter, etc. Sometimes the cheesy distributors will "dump" out of season gas to discount gas outlets, so the low price can sometimes buy you bad driveability, or worse. I drive out into Powhatan County (same tribe as Pocahontas) because they are not subject to Richmond's oxygenated fuel in Winter, and the extra 10 miles is worth it to me for my "good" cars, and the back roads icing.

Some of the 2003 Cobra guys have posted that the gas in NYC area in winter is absolutely shiznit, and kmesses up their custom tunes - most are very careful of running 25 psi of Kenne Bell boost without race fuel.

I posted once before, and have here in my paper files somewhere, Honda Engineering reports on the NSX that showed that the diff in HP between 97 and 91 was <10, closer to 8 as I recall. Torque a bit more. I believe Honda engines are very well designed and less suceptible to octane effects bu nature of that engineering.

 

lower grade gas tends to have different detonation points that a higher octane gas would during high compression, ie the s2000 motor.i have noticed that under harsh compression cheaper gas, ie 87-89, tends to detonate slightly earlier, and the dyno proved it as well, it shows in the torque curve, for instance on a 93 octane the torque curve is pretty constant throughout the rpm range. with a lower grade fuel, ie 87, the torque curve tends to be slightly irregular towards the higher rpm range and doesn't show a consistent build up, the car only begins to have the right amount of avance at a certain rpm. i would say that if u put it in once or twice, it wont kill u, but if u use it alot, it takes a toll on ur o2 sensor, on the plugs, and it begins to deposit residue onto the valves.

 

Doesn't heat have something to do with detonation too? I've heard the higher octane is more important in the heat of summer than in winter for high compression engines.

 

yup. heat plays a great factor during detonation. that is why all FI cars use intercoolers, out of wich most are air to water to achieve the lowest intake temps possible

 

OK, so it's hard to gather much from a test done in December in Alberta. It's usually pretty cold up there this time of year, eh?

 

haha, i wish it was colder here all the time, my car loves it althou not an s2000, but nevertheless the supercharger is screaming away.

 

[QUOTE]Mee