[QUOTE]Originally posted by Luis:
[B] Actually, from 91 to 100 octane fuel you have a 90 point spread not 9.

 

[QUOTE]Originally posted by stocks2k:
[B]I remember reading in the manual that we can use any unleaded gas without harm to the engine.

 

I'll reiterate what Stocks2K said - It is my understanding that the S2K engine has knock detectors that will retard the timing of the engine to compensate for lower than recommended octane. Thus, if you use 87 RON gasoline the engine will run fine (no knock) but the retarded timing will decrease performance. I haven't run anything other than 91 or 92 RON gasoline in my car, so I can't report actual data.

As was stated by Luis, the use of gasoline with higher than recommended octane will not improve performance. Indeed, it may be detrimental if it doesn't have the same additives as automotive fuel (e.g. Aviation gasoline).

 

A quick point- with todays electronic ignitions, even though the engine will retard the timing for lower octane fuel, it needs to sense the knock prior to retarding and this will go on ...knock-retard..knock-retard so there can be some pre ignition damage but it should be limited...best bet if you need to run low octane, limit it to a small amount and top off with higher octane asap...

 

I would not use anything but premium. If you can afford the car, you can pay the extra $0.20 a gallon. It barely even adds $100 to your annual fuel cost. I remember this same thing coming up when my Dad got his M3. I finally convinced him that if he's going to buy a performance car, he should give it the fuel it was designed for. Why buy an S2000 and then get cheap on the gas and lose power?

Mark

 

Higher compression needs higher octane. Some engines will change timing if you put in lower octane, I know someone who did this to test and then dyno'd on his Acura, and he lost like 6hp.

Since my 4Runner is supercharged and has higher compression than stock, it runs like crap if I put anything lower than Premium (93 around here) and runs great on 100 octane racing gas I accidently put in 87 once, won't make that mistake again.

 

Please explain "pre-ignition" damage. When I do own an S2000, it will likely be nothing but premium. But I'm curious, why Honda would print a manual saying the engine can operate on regular unleaded gasoline, if in the end 87 octane would cause damage over time. The compression is nearly the same on the new MR-2 Spyder and it's manual recommends regular 87 octane???