89 octane no go with a turbo?

[Philip2]

Found a Facebook G70 site. These guys are basically amateurs that talk about cosmetically customizing their cars and showing pictures of their cars in action..

They were discussing choice of octane and said that if you have the 3.3T you have to use at least 91 octane. I never heard of this before and like I said these guys are amateurs. With the price crunch here in California I am now using 89. I do not to extreme turbo boost often. Will 89 damage the engine?

 

[EdP]

Found a Facebook G70 site. These guys are basically amateurs that talk about cosmetically customizing their cars and showing pictures of their cars in action..

They were discussing choice of octane and said that if you have the 3.3T you have to use at least 91 octane. I never heard of this before and like I said these guys are amateurs. With the price crunch here in California I am now using 89. I do not to extreme turbo boost often. Will 89 damage the engine?

There are two or three threads about octane requirements. Do a search and you will find enough information to make your brain swell.
Start here

Premium Gas

This is my first time owning a vehicle that requires premium gas. I was curious if someone could explain to me the reason for premium vs. regular and the impact it has on the engine. Thanks so much!

genesisowners.com

Meantime, read the manual.

 

[Philip2]

Yeah- I remember those topics but the wrinkle here is that these guys say having a turbo requires 91. the compression will be higher during turbo boost so maybe.

 

[JCtx]

The compression is LOWER on a turbo (10.5), compared to a NA engine, which nowadays is 13 with direct injection. With a turbo you have higher pressures when under boost. The manual says premium is RECOMMENDED, not required. But manual actually recommends MID GRADE, since it says 89 octane or better. And in some places, regular is actually 89. So regular definitely doesn't damage the engine, but it'd obviously make less power. How much is anyone's guess, but my guess is about 20HP/TQ less.

 

[Volfy]

Long story short... your engine's octane requirement varies depending on how you drive (engine load) and the environmental conditions (altitude, temp, RH%, etc.) at the time you drive. Cruising along lightly loaded in cool weather will be very different than climbing a steep hill WOT in 102F Summer heat.

Most direct parameter that influences whether your engine will reach impending knock is peak cylinder pressure. If your PCP doesn't get anywhere close to impending knock, burning premium gas is just throwing money down the drain. It is no different than buying flood insurance if you live above the 100yr flood plan. Still nice to have in case you get hit with 500yr flood, but most likely you won't ever use it.

I say impending knock because your ECU will not allow your engine to damage itself. It'll advance timing right up to where the knock sensor(s) detect the onset of knock. This maximizes power output. But the ECU will not let it go past that point, so there is no danger of engine damage if you drive with 87 under conditions where the ECU might need to retard ignition timing to protect itself, at the expense of some power loss.

This is why 91 is "recommended", not required.

If you are okay with spending money on 91/93 regardless, then by all means fill up with nothing but. You'll know you'd be fine come hell or high water. Otherwise, just pay attention to how your car reacts to different octane fuels. It will tell you if it "needs" higher octane. Over time, you'll learn the pattern and gas up accord to the driving conditions you'll encounter in that tankful. And if you cannot tell the difference... well, that too is informative - not to spend money on things with which you reap no perceivable benefit.

 

[Philip2]

Thanks

That facebok G70 group should stick to photos of their paint jobs and the bling they add to their rides.