here's a question:-

Why do the earlier cars require 98ron while the later 95ron?

Did Honda make changes to the engine to allow the car to produce the same power using 95 ron as when using 98ron

Are in fact the older cars more powerful

Surely to enable the car to no need 98ron would mean they were detuned? No?

 

Are you sure? My car is an 03 and it specifies in the fuel filler bit 98RON. It only drinks 97RON and Optimax because there is no 98. IIRC the manual also says 98RON.

 

Many ECU's as with Audi's are intelligent and can adapt to the octane level of fuel being used (apparently), maybe the S' ECU does the same?

 

I thought the later cars were designed to run on 95ron

 

No,

I believe the later cars could run on 95, but were recomended to be run on 98. The pre 02 cars should not be run on anything less than 98. All in the tech faq

 

What happens if I run on 95 for a couple of tankfuls, like I had to in Italy where it seems 98 is not very common?

 

The inside of my fuel filler cap ( 02 car ) says 95-98 ron, the 98 is in larger type so I presume that is the preference, but obviously 95 is o.k. Round here I have difficulty getting s.u.p. or optimax so most of the time it has to be 95.

 

They're all only going to give there best when running on 98+

The ECU isn't intelligent really. All it does is retard the timing a lot after in senses knock with the knock sensor. Then it'll gradually bring it back, until it gets back to the base maps, or gets knock again. So if you run low octane fuel, the ECU will compensate, but only after it's heard the knock. And it doesn't really do so in an 'intelligent' manner. Not a good idea to run an S2000 on low octane fuel for any length of time. If you're going overseas and not sure, take some octane booster.

-Brian.

 

Mine is an 02 and says

95-98RON

 

The 03s say it has to be at least 95 RON but you will not make peak power unless you use 98 RON. It's exactly the same with the BMW M3 engine.