High Altitude Octane Requirement

[dtech]

Hi just picked up a Sport with 2.0L turbo - manual says regular us grade, I think 87 octane rating. So I didn't ask the dealer but assume it's ok to use 85 in Colorado as that's what most cars that run on regular grade use here.

I have a couple of Saabs that can run on regular gas but cannot use 85 rated gas here in CO, it must be 87 or higher, the Saabs use a different type of combustion and knock detection and the engine can produce more power with premium fuel.

Just a comment on engine performance - I'd agree with a couple of the reviews I read saying that in certain conditions the engine seems to be uneven with respect to smooth power output and throttle response, but overall it's pretty potent for a 2 liter.

[knzshrk]

Hi dtech, Small world. I live in Westminster as well. I have been running 87 due to the turbo. The turbo and its nature sort of makes the altitude a moot point (within reason) as the boost stays relatively constant no matter the altitude and thus the cylinder pressures are relatively constant which is definitely not the case on a NA engine. During the winter I think its probably safer to run lower octane due to the lower intake temp reducing the chance of ping. During the summer I would say 87-89 minimum.

[Big Kahuna]

I agree its a small world.......I use 87 Octane and have had no problems so far at 3,500 miles. That extra $1.50 in the added cost is well worth it for the octane.

[peachferrari]

Should be ok with 85. Almost all Hyundais recommend 87 including my Tiburon and Santa Fe, but I've run both on 85 here in Utah with no issues whatsoever.

[dtech]

yeah but are your cars turbo charged ? As pointed out the turbo will compensate for less dense air at higher altitudes, different from a na engine so I will feed it 87 as recommended.

[peachferrari]

Originally Posted by dtech

yeah but are your cars turbo charged ? As pointed out the turbo will compensate for less dense air at higher altitudes, different from a na engine so I will feed it 87 as recommended.

No they're not. In fact I usually run mid-grade in my Tiburon anyway since I like to drive it hard sometimes. Mid-grade here is 88 octane. Does your manual say anything specifically about the turbo engine?

In any case, it can't hurt to run higher octane and you'll probably see a little more power too, though it may not be enough to notice.