Xc40 at 7000-10000 above sea level

pvegrietas · Post by **pvegrietas** » 26 Jun 2019, 05:22

Hi,

I’m headed for a cross country trip in our new XC40 where we will climb to 10,000 feet above sea level. I’ve heard I should use a different octane of fuel at this altitude. Is this also applicable to my car? We will be there for about two weeks.

Thanks for any advice!

Post by **Rattnalle** » 26 Jun 2019, 05:41

I haven't been above 2100 m in my own car or ~2400 in any car but at those altitudes I didn't notice too much on regular European RON95 at least.

pvegrietas · Post by **pvegrietas** » 26 Jun 2019, 06:08

Thanks Rattnalle

Post by **Rattnalle** » 26 Jun 2019, 06:54

A smaller modern engine with higher boost might be more sensitive though, I'm not sure. Those newer engines aren't supposed to be run on US regular regardless afaik, unless they've got a different engine software over there to compensate.

Post by **jimmy57** » 26 Jun 2019, 08:44

When you get to any point of high altitude in the US you will find octane 2 points lower across the grades. Use the highest grade and it will be all good. For instance: you going west from Denver over Eisenhower pass. The octane you can buy in Denver will be 89 for premium unless you drive all over and find that place that has 90. Even though it is turbo charged the engine will be at a reduced boost level and the need for octane is reduced for that reason and the reduced oxygen content will make it richer if you are at high throttle where it goes open loop and the A/F ratio correction is more relaxed and richer.

pvegrietas · Post by **pvegrietas** » 26 Jun 2019, 11:41

Thanks so much jimmy57! This is very helpful!

Post by **matthew1** » 26 Jun 2019, 12:42

I always wondered why the premium octane rating at stations here in Denver was, like Jimmy said, two points lower than other cities I've lived (Baltimore, Seattle). Then I did a Google search and got the answer, years ago.

https://www.denverpost.com/2006/10/16/s ... ne-levels/

Research several years ago from the American Petroleum Institute showed that lower air pressure at higher altitudes allows vehicles to perform as well with 85 octane as they would with 87 at lower altitudes.

I would have guessed it would be the reverse, i.e.: cars would need more octane at higher altitudes. But science is science.

So, pvegrietas, you'll be fine with whatever you put in, down to 87.

http://volvo.custhelp.com/app/answers/d ... quirements

Fuel Requirements. Volvo recommends premium, 91 unleaded octane or higher for optimum performance, but your Volvo can run on regular 87 unleaded octane without affecting engine reliability. It is safe to use fuel containing up to 10% Ethanol in your Volvo.

pvegrietas · Post by **pvegrietas** » 26 Jun 2019, 13:49

Thanks everyone!!!