I had read similar research on NASIOC a while back and was under the impression that our 93 was as good as their 98. They can't put Tetraethyl Lead in their gas if the cars have catalytic converters, since the lead gums up the cats... so I would think the answer is no lead in JDM gas. Lead only really prevents knock by upping the octane of the fuel. It was the cheapest way to increase octane, so that is why it was used. It also let the car manufacturers not have to harden the valve seats, since the lead would help seal the valves. The introduction of the emissions laws of 1975 and the catalytic converter ended the use of lead to boost octane.

Remember that the Japanese have 100RON available at their pumps also, but that doesn't seem to be a real big issue. I was under the impression that 100RON was about 94.5 octane by US standards (and 100+90/2=95 so I was probably real close)

As far as retuning? There shouldn't be an issue. I know several people who ran straight stock JDM motors without an issue. The factory ECU's may have to pull a little more timing to prevent knock, but nothing they can't handle. If you live in Cali and use that 91 crap, then its a different issue. I know Supermoose told me he has to pull several degrees of timing with his PowerFC to get his Ver2 RA JDM motor to run on the 91 "catpiss" fuel...

 

I will also be running a V2 STi RA motor and have access to 93 and sometimes 94 octane fuel. The information I was given by a fellow member, was that the JDM ECU's are tuned for 98 RON, which is 93/94 octane on US pumps.

Thank you for your thorough reply.

 

All I know is my EJ20G was knocking like a bitch on 91 and it seems to be OK now that I mixed in about 4.5 gallons of 100.

 

Wether it's RON or MON, the fuel is exactly the same. It's the testing methods that differ. So yes, 93 in the States is the same as 98 in Europe or Japan.

 

Wether it's RON or MON, the fuel is exactly the same. It's the testing methods that differ. So yes, 93 in the States is the same as 98 in Europe or Japan.

yeah exactly, i dont understand what the debating is all about

 

Yeah but since everything else JDM is better, then their gas is automatically better too!

 

yeah exactly, i dont understand what the debating is all about

Ok... I didn't title my thread very well.... I'm trying to see why people would have trouble running JDM motors on US 93 octane fuel.... Maybe they don't, but there seems to be some discussion on the US fuel being a main source of motor failure due to detonation... That was the purpose of this thread.

 

Answer to your problem is...Sell your car, and starting RONing MON. haha yes corny joke ftw.

 

if the gas is the equivalent octane here and over there why does everyone get colder plugs and want to run water/meth injection and get a tune for US 93 or 91

 

My stock JDM Motor knocked bad on 92 octane. Ver8 normal STi..

/shrugs

 

if the gas is the equivalent octane here and over there why does everyone get colder plugs and want to run water/meth injection and get a tune for US 93 or 91

because the equivalent fuel is not widely available in north america like in japan. i live in a big city, so i have access to 94 in some stations and 93 in others. but the second i live it, its 91 max.

 

93 is everywhere in the mid-atlantic region. People get water/meth and colder plugs so they can run insane boost, well above stock levels.

 

Gas in California at least it loaded up with additives so Cali 91 or Cali 93 isn't even close to Japanese 98 RON.

 

http://www.btinternet.com/~madmole/Reference/RONMONPON.html

 

There are a few 92 non-oxy stations in the Twin Cities here in MN. We do have 100oct pumps around, and a 110leaded pump too. The 92 non-oxy should run as good as the 93oct.

 

leaded is the best. smells so yummy,