Didn't know

[BHarvey]

my Sonata has an 11.3-1 compression ratio!

Sweet huh?

[pounsfos]

its amazing what modern technology can do these days, my starlets CR is only 9:1, imagine what would happen if i planned my head to get 11:1 on that thing, i would have to run 100ron gas,

sometimes i have always wondered what would happen if they took all this modern technology and put it into an old car like mine,

[JasonG]

Amazing, and it runs OK on 85 octane?
I would love to have the fuel / timing map to look at !

[Old Mechanic]

If the engine is direct fuel injection then you have to cooling effect of the fuel being directly injected into the combustion chamber to allow higher compression. Using heat energy otherwise wasted is the real secret to higher efficiency.

Mazda is developing their SkyActive engines to run on compression ratios of 14 to 1 and higher using advanced injection and EGR strategies. That's diesel compression territory.

regards
Mech

[BHarvey]

87 octane is fine as the timing will range from -5 to +50 degrees. Not sure on the fuel map but have seen fuel trim from -10 to +10 on the UG.

From what I hear you can safely run lots more compression with Ethanol.

[redpoint5]

My bike is recommended to run 87 PON and it has a 12:1 CR. Of course, the engine is only 0.6L

Originally Posted by BHarvey

87 octane is fine as the timing will range from -5 to +50 degrees.

Is that 87 PON?

What kind of mpgs are you seeing in that Sonata and what year is it? The Sonata was on my radar when I was looking to buy a car last year.

[some_other_dave]

In the US, it would be "AKI", which averages the "MON" and "RON" ratings of the fuel. The AKI is 4-5 points lower than the RON rating for any given batch of gasoline.

-soD

[Old Tele man]

AKI = AntiKnock Index.

[Diesel_Dave]

Originally Posted by BHarvey

my Sonata has an 11.3-1 compression ratio!

Sweet huh?

Oh, my poor spark plug saddled friends! How on earth do you manage to be satisfied with a compression ratio of only 11.3:1?

[Big Dave]

One does wonder.