M50TUB25 Gas/Octane Requirement

[Mushroom Stew]

Hello,

For such a simple piece of info Im having a hard time finding the answer- what is the octane requirement for a stock m50tub25?

Also, on a related note I live in Canada and normally get my gas at Shell which has 87, 89, and 91 available. Just wondering if there are differences in the Octane ratings btw the US and Canada that I might need to keep in mind. I'd like to get a chip and want to make sure the Octane I choose for the tune is correct.

Thanks

[wworm]

seems the same as what we have in most stations in the states. There are higher ratings at different pumps but the most commonly available ratings are 87,89 and 91.

[st.petebiodiesel]

My e36 325is gas cap says minimum 89 AKI but I used to run it on 87 all the time no problem. Never heard a single ping.



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[pazi88]

My e36 325is gas cap says minimum 89 AKI but I used to run it on 87 all the time no problem. Never heard a single ping.



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M50tu has active knock detection, so the engine won't break even how shitty fuel you drive it. Of course it will lose some power with low octane gas.

[st.petebiodiesel]

M50tu has active knock detection, so the engine won't break even how shitty fuel you drive it. Of course it will lose some power with low octane gas.

True, the knock sensors take awhile before they intervene. They won’t retard timing for several seconds, and even then they only temporarily retard the timing then it returns to its original setting.
I learned all this from my 12:1 M50B32 engine. Floor it below 3,500 rpm the engine pings for like 4 seconds, then it stops and it feels like you lost power.
But it’s just a little pinging, not full blown detonation.



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[Mushroom Stew]

My e36 325is gas cap says minimum 89 AKI but I used to run it on 87 all the time no problem. Never heard a single ping.



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Thanks. I'll stick with 89 to be safe. Since we are on topic, have any of you noticed a noticeable difference with a chip (say SSSquid) tuned for 91? Or is the stock tune on 89 pretty much engineered for best overall performance from the get go?

[raj]

A chip and injectors are worth it. I’m very happy with my TRM tune.