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502 mpi 95 octane

Old 05-12-2018, 09:18 PM
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Default 502 mpi 95 octane

Hi. Hope some of you guys can help me. Here in Norway we only got 95 octane fuel and with a little Google search I read that my engine should only run on 87 octane. Does anyone have some advice how the I can run my engine safe and what kind of timing i should run. Today I have 8 deegre advance timing. Should I change this to earlier timing and should I remap the mefi 3. This is s 2000 mod with coolfuel system.

Regards Dan

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Old 05-12-2018, 09:55 PM
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Always ran 93 in mine with no issue. If anything, advance the timing 2 more degrees to 10 initial and leave the mefi tune stock. Retarding the timing would be a mistake with higher octane.
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Old 05-12-2018, 11:02 PM
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Originally Posted by CJSYD View Post
If anything, advance the timing 2 more degrees to 10 initial and leave the mefi tune stock. Retarding the timing would be a mistake with higher octane.
I would not recommend this.
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Old 05-12-2018, 11:04 PM
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Originally Posted by danse78 View Post
little Google search I read that my engine should only run on 87 octane. Does anyone have some advice how the I can run my engine safe and what kind of timing i should run.
You likely ran across some very dated information regarding running 87 octane only. That was for VERY early MEFI 1 big blocks and was resolved with a MerCruiser Service Bulletin. Not an issue with your MEFI 3. Leave the tune alone. You will be fine.
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Old 05-12-2018, 11:49 PM
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Originally Posted by danse78 View Post
Hi. Hope some of you guys can help me. Here in Norway we only got 95 octane fuel and with a little Google search I read that my engine should only run on 87 octane. Does anyone have some advice how the I can run my engine safe and what kind of timing i should run. Today I have 8 deegre advance timing. Should I change this to earlier timing and should I remap the mefi 3. This is s 2000 mod with coolfuel system.

Regards Dan
Ran 87 to 89 in mine for years without any issue at all. Never needed to make a timing adjustment.
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Old 05-13-2018, 01:49 AM
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The octane rating system in Europe is different from the US.
The US uses the AKI and the EU uses RON. https://en.wikipedia.org/wiki/Octane_rating

Just run your lower octane fuel. It will be about the same as 89 octane US and will be fine without doing any additional tuning.
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Old 05-13-2018, 10:37 AM
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Trash, ran mine like that on 87 as well without issue. That being said, his safe bet is what others stated... leave as is and he will be fine.
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Old 05-13-2018, 01:53 PM
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Ok, thanks guys for good info 👍 Then I can smile all the way to the gas pump with no worries 😜
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Old 05-13-2018, 03:29 PM
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there is Merc OEM SB about issues caused with the higher octane and why not to use it for early and mid 1990 s big blocks EFI and 350 small block EFI

I ll see if I can find it rather than me typing it all out. Do not feel like typing a book a today.

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Old 05-13-2018, 03:45 PM
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http://www.boatfix.com/merc/bullet/94/94_12.PDF
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