[ALAP]

I have a Seltos with 30K on it. Never had an issue with mountains (Blue Ridge and Smoky Mountains) The turbo model has all the pep I need. Note on octane. With this type of vehicle (and others) the system is programed and tuned for 87 octane. What many don't realize is the higher the octane the quicker the burn. The PCU doesn't know what octane is burning and in fact, the vehicle may run like crap with a higher octane. Missfires, knock, skips, lower power. I assure you that these facts are true and the car is designed/engineered for a certain octane level for performance, mileage, and power. I am a retired Molecular Chemist and have actually did some research on this exact subject. If you'd like, and I can find it, I can send some papers I co-authored on the subject. Thanks

 

[ALAP]

My understanding is that while there are a lot of caveats, high octane fuels burn more evenly/slowly which helps prevent pre-ignition.

Combustion Basics: How Does Fuel Make a Difference?

We expose the truth behind whether or not the quality of fuel you use can make a difference in how your car performs.

www.motortrend.com

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which says:

"Fuel with an 87 octane rating burns more quickly while higher-octane fuels burn more slowly. In engines designed for standard unleaded fuel, efficiency and performance is optimized for 87 octane and could actually perform worse with higher-octane fuel since the burn rate is slower."

As long as the base chemistry in the fuel is the same, the differences which cause higher octane numbers typically make the fuel harder to ignite and to burn more evenly. This helps especially at low RPMs and high load, which is when pinging/preignition typically occurs. I believe that once you get into race fuels, with an extreme example being alcohol or nitro based fuels like dragsters use, burn rates aren't comparable to gas.

But be that as it may, it's good to know that you've had good experiences in the Blue Ridge and Smoky Mountains. We've never been there but am hoping to get there soon. I know that out here in the Rockies, there's a take-no-prisoners attitude on a lot of the mountain passes and we're fans of just following along. There have been many times we've experienced 80-90 MPH traffic on 6% uphill gradients, but making that kind of power out of a 1.6 liter means a lot of heat to dissipate through the oil and coolant.

The article is correct and so are you. I really need to read what I typed before submitting. Should have said higher octane burns less quickly....................................THIS is what retirement did to me!!! LOL. I will admit, winter of 2021, there was a fair amount of snow in the Smokies. I locked the AWD, displayed the transmission temp on the dash, and slipped it into "manual" and drove up a section in 2nd gear. Everything went fine. Since there no highways so to speak through these mountains, I didn't experience "high" speeds.