S2000 Under The Hood S2000 Technical and Mechanical discussions.

Minimum Octane Requirement?

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Old 10-21-2005, 04:13 PM
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Thumbs up Minimum Octane Requirement?

Wondering if anyone can tell me what the minimum octane requirement is for the JDM spec engine?

My engine is being replaced, potentially with a JDM engine, however I'm concerned as most gas stations here (with the exception of Sunoco) don't have 91+ octane fuel.

Any input is appreciated.
Old 10-21-2005, 06:14 PM
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on my MR2 it was 94 octane vs. 91 octane.
Old 10-22-2005, 03:46 AM
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Old 10-22-2005, 04:51 AM
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It has been reported that the JDM engine is tuned for Japanese gasoline which is rated at 100 RON. I would expect that 93 AKI sold in North America which is approximately equal to 98 RON would be the minimum required and still not ideal.
Old 10-22-2005, 08:51 AM
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So for argument sake, Canadian 91 octane is definitely not going to fly
Old 10-22-2005, 09:01 AM
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The next question will be if the US spec PCM will keep it from detonating.
Old 10-23-2005, 03:13 PM
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We have many JDM S2000 running in my country and the only fuel found in our stations is $hit. roomers say its between 88 and 90 octane, am not sure if US fuel has different rating then Europe.

Most of the JDM owners add NOS black formula Octane booster to the fuel, without it they claim to have a very bad flat spot (loss in power) between 3500 and 5000rpm.

Probably XXX240 can be of help as he has a JDM
Old 10-24-2005, 08:24 AM
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JDM cars need a min of 100ron fuel.

I'm running my car with a Mugen N1 ECU, and I really need to put some high octane fuel in my tank..

Currently I'm using 93ron fuel with 4 cups of Nos Black Formula and car seems to run fine.. No detonation of knocks.

I'm also thinking of buying a full drum of VP Street Blaze, which is around 104 octane, and mixing it 50/50 with our 93ron pump gas.

Thats another option. But for the time being, the car is running fine.
Old 10-24-2005, 11:23 AM
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FYI...a local has been running a JDM engine on 91 for well more than a year. Engine runs fine.

Octane boosters are questionable at best they don't do much if anything to raise octane.

Also just to remind, make sure that if you are running a cat you only run unleaded, usually anything over 100 Octane is leaded which will eventually destroy your cat.

Around here we can get 100Oct which I've been running for 5weeks or so ever since the gas 'crisis'
Old 10-24-2005, 12:09 PM
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My car is JDM,

When i run EU 91, i dont know what US octane that is, i have problems, (konocking, loss of power, hesitation etc) when i run 98 i still have problems but i couldn not run 98 over and over again to see what's gonna happen yet, the station which sells 98 is far away and my work and school hours wont let me go there often. I will somehow do that and post in the other threads aswell i started.

My point is, the engine being EU, US or JDM does not matter i think. They have the same inlets, injectors, fuel rail and everything right? the point is the ECU. If you have a JDM ecu, it's programmed for Japan standards, if you have a US one, it's programmed to US standards.

So if you have a JDM engine and a US ECU, no problem, JDM engine with JDM ecu in US or EU, yes, u have a problem. If you have a JDM car in US and you can afford, go for a different brand ECU like Mugen.

Am i right?


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