The right octane?

[jf13624]

Something seems strange to me. I have a 24 G70 2.5. The manual says 91 octane is recommended. Now.... the Hyundai Sonata N-Line has the same 2.5 liter turbo motor, both have a 10.5 to 1 compression ratio, yet the Sonata only requires 87 octane. Any thoughts on this contradiction? Do you think Genesis is recommending 91 to maintain the upscale image. Just curious, seems a little odd to me.

 

[Slip_Angle]

Something seems strange to me. I have a 24 G70 2.5. The manual says 91 octane is recommended. Now.... the Hyundai Sonata N-Line has the same 2.5 liter turbo motor, both have a 10.5 to 1 compression ratio, yet the Sonata only requires 87 octane. Any thoughts on this contradiction? Do you think Genesis is recommending 91 to maintain the upscale image. Just curious, seems a little odd to me.

G70 is making a bit more power, so the engine is possibly tuned different OR the G70 makes the same power as the Sonata running on 87.

 

[EdP]

Something seems strange to me. I have a 24 G70 2.5. The manual says 91 octane is recommended. Now.... the Hyundai Sonata N-Line has the same 2.5 liter turbo motor, both have a 10.5 to 1 compression ratio, yet the Sonata only requires 87 octane. Any thoughts on this contradiction? Do you think Genesis is recommending 91 to maintain the upscale image. Just curious, seems a little odd to me.

It is not 1960 any more where the compression ratio was the big factor determining octane. If you dig into the details you will find there may be some big differences. Computer controls, ignition timing, pollution controls, turbo response may differ to get that extra power. You pay for it with higher octane. The Genesis does have a 10 HP advantage.

It would be interesting to test both under the same circumstances with the different octanes. My Sonata with the 1.6 turbo requires 87, but I can easily feel the difference with 89. Better, smoother acceleration.

 

[Volfy]

Octane requirement is NOT a constant. What is the "right" octane depends on how you drive and under what conditions the car operates. If you gun the throttle going up a steep hill heavily loaded with passengers and cargo in 95F Texas Summer heat, what octane works well for that will be VERY different than steady 60mph cruising along I-25 in mile-high Denver with only driver onboard in 30F with a tailwind.

The best way to know is to pay attention to your car and gauge how it respond to driver input. The G70's ECU, like most cars these days, has enough feedback control to operate safely with regular gasoline, which could mean 87/86/85 depending on your locale. Worst that could happen is the ECU will dial in more spark ignition retard - trading less TQ/HP for lower threshold of pinging/detonation. ECU will not allow the engine to damage itself. If under some conditions, your car feel a bit sluggish with 87 compared to 93 octane, then you might feel inclined to spend a bit extra $$ for the better grade. And if you cannot tell the difference - or if the felt difference doesn't bother you enough to matter - then what is the point of pumping more $$ and getting no tangible benefit?

 

[Slip_Angle]

Octane requirement is NOT a constant. What is the "right" octane depends on how you drive and under what conditions the car operates. If you gun the throttle going up a steep hill heavily loaded with passengers and cargo in 95F Texas Summer heat, what octane works well for that will be VERY different than steady 60mph cruising along I-25 in mile-high Denver with only driver onboard in 30F with a tailwind.

The best way to know is to pay attention to your car and gauge how it respond to driver input. The G70's ECU, like most cars these days, has enough feedback control to operate safely with regular gasoline, which could mean 87/86/85 depending on your locale. Worst that could happen is the ECU will dial in more spark ignition retard - trading less TQ/HP for lower threshold of pinging/detonation. ECU will not allow the engine to damage itself. If under some conditions, your car feel a bit sluggish with 87 compared to 93 octane, then you might feel inclined to spend a bit extra $$ for the better grade. And if you cannot tell the difference - or if the felt difference doesn't bother you enough to matter - then what is the point of pumping more $$ and getting no tangible benefit?

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