Low octone (87-89 RON) will NOT cause detonation in the S2000. The ECU will retard timing to prevent knock.

And yes, detonation is bad, just not applicatble in this analysis.

 

wrong. just because you drive like an old lady and even shift at say 4000rpm, that doesn't change the fact that the compression ratio is still 11:1.

grandma or mario andretti, doesn't matter. either way, if you put regular in, you are losing power and getting worse gas mileage. and actually, you could even cause damage over the long run. while you have detonation/knock sensors to prevent damage, this requires you to actually have detonation before it dials back the timing.

 

yes it will. as i said. in order for the ECU to retard the timing, it must FIRST DETECT PHYSCIAL DETONATION/KNOCK! so yes, it will cause some detonation. hence the danger of using it in the first place.

and of course, your ECU will continue to try to advance the timing, so you will keep getting moments where your engine knocks/detonates as it tries to bring your timing back to normal.

 

I used regular in '94 LS400, premium was recoomended, for about 2-3 years in late 1990's. In city streets and on local highways, I could not feel the differencs between regular and premium gas. Only when I went to Vegas in summer of 1999 or 2000, then the Lexus showed the missing power of the premium gas while it climbing the hills of the death valley. Since then I switched back to use only premium gas in cars that recommended it. That Lexus LS400 has more than 160k miles now, and shows no sign of engine damaged after two or three years of using regular gasoline.

There is no data about using gasoline with octane rating less than recoomended will increase fuel consumption either. Yes, there was some data about losing power if you are using gasoline at octane level less than the car was designed for.

 

i dont know anything about the LS400.

but yes, often you will get worse gas mileage than if you are not using the premium in an engine that requires it. if you retard the timing (as happens when the car detonates) it doesn't make as much power. the car is not burning fuel as efficiently as it could, which can lead to poorer gas mileage.

think of it like this. let's say you normally accelerate from 0-50mph in a given circumstance on a given stretch of road. since you are making less power, it will require either more time, or a heavier foot on the gas, in order to accelerate to 50mph in that circumstance.

and when the ECU does try to test by advancing the timing, detonation occurs, and then you're DEFINITELY not burning fuel efficiently, and you lose gas mileage there. i'm not talking 10mpg less. I'm talking maybe 1-3mpg worse than normal.

as for "feeling" a difference. you may not feel the difference, but the human body often cannot tell the difference. our senses simply aren't sensitive enough to really tell in this particular example.

 

When I would race my Civic, I would splurge on 106 - 116 octane gas. I could feel the difference very easily, even on the drive home under "normal conditions".

Even if you don't do any type of competiton with your S, I would highly suggest to anyone to splurge a little- just once. Buy some really expensive gas one weekend and feel new life injected in to your S2K. You'll never buy the cheap crap again.

C'mon, like you've never taken a woman to an overpriced resturant for a little

 

Just think of it this way: The car manufacturer knows that people don't like paying for premium gas. Therefore, they wouldn't say it is required unless it really made a difference.

Just go with the grade of gas that is recommended by the manufacturer.

 

Ditto to what everyone said here. If there was ever a car that needed premium, it's one with a compression ratio like ours.

Just a little side discussion. It was a common thought in the Celica community that using 91+ in the GT (which only requires 87) actually hurt gas mileage and power a bit. The theory was that not all of the gasoline was being burned off, and some of it was just passing through and also clogging the cat. Anyone believe this could be the case in some lower-performance cars?

 

[QUOTE=Spaceman Spiff,Jul 18 2005, 04:27 PM]

When I would race my Civic, I would splurge on 106 - 116 octane gas.

 

I come from the same Celica community and that is where I got the information from.

Another source that proves my point...

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

I highly doubt this unless your Civic is modified. Having your fuel be less able to ignite does not help a car that is not designed for it.