Octane and performance

[Peter Westling]

Hi all.
I think the normal gas in US is 87 - 89 octanes, right? We have unleaded 95 96 and 98 here in Swe. How does that affect the engine in a hp view? Is it noticable? Can I adjust the computer for a specific octane and make the engine more efficient?

 

[glfredrick]

Typically, unless you have one of the Crane adjustable plug in jobs, there is no other way to adjust your computer except to change the chip.

There isn't really a HP difference from running higher octane gas, except that you can run a bit more advance on the timing without detonation. Your Ex should have a knock sensor that automatically backs off the timing if it hears detonation (pre-igniton of the gasoline mixture while the piston is still on the upstroke), which will cut a tad of the hp out of an engine, but nothing really serious.

BTW, You can get a higher grade of gasoline at most stations - you just have to pay for it... Most pumps feature 3 grades - 87 - 89 - 93 or some combination like that. Some even have more - but they are sort of hard to find while traveling - sort of luck of the draw. You can also run an octane booster if needed... I do that when I wheel my truck so that it has what it needs when it gets lugged sometimes. I want all the power I can get in certain circumstances.

 

[Maniak]

Don't forget.. Octane is measured (displayed at the pump) differently in different countries... I haven't been able to find a good link explaining it..

It the states we use the average of the 2 types of octane measurements (RON + MON)/2 The way I understand it, some countries only show one of the octane numbers ( I can't remember which)...

~Mark