can i switch to 85 or 91 octane?

[sh3pherdd]

87 octane seems to be such a pain for gas stations to carry in colorado. is there a handheld tuner i can buy to tune the car for 91? or is there something i could do to like the injectors or something to make it safe to use 85?

 

[aclos3]

Higher altitude areas sell 85 octane instead of 87. Due to the altitude, the 85 octane will function just like 87 would at sea level. That being said, these are fairly low compression engines that were purposefully designed to be tolerant of poor fuel. There is no need to put anything in other than the cheapest, lowest octane fuel you can buy.

Even though the LX450 manual states to use premium, it is utterly not needed. This has been discussed on these forums in pretty great detail, if you have doubts.

 

[Summiteer]

Run the lowest octane your engine can handle. From all the research I've done lower octane fuels theoretically produce more power than higher octane fuels do and they're not any cleaner from one to the next. 85 works great in my 80, the only reason to run a higher octane is if your engine is pre-detonating (pinging). This is an issue seen in higher compression engines, yours will be fine on 85.

 

[scrowley]

Wish they sold 85 in CT. It would be even cheaper.

 

[Timpanogos Slim]

Run the lowest octane your engine can handle. From all the research I've done lower octane fuels theoretically produce more power than higher octane fuels do and they're not any cleaner from one to the next. 85 works great in my 80, the only reason to run a higher octane is if your engine is pre-detonating (pinging). This is an issue seen in higher compression engines, yours will be fine on 85.

Right. higher octane fuels ignite later, which means more compression and timing advance is possible.

 

[Qball]

Keep your stock timing of 3 degrees and you probably can run 80 octane gas.

 

[blkprj80]

85 runs good in mine as long as it's from a decent station/chain.

 

[robertk61]

91 is the lowest we can get down here !!!!

 

[JCruse]

One other point would be that you don't need any special programming to run 91. I was using it this summer when my engine temps were high due to a coolant leak, which caused excessive pinging.

 

[Timpanogos Slim]

One other point would be that you don't need any special programming to run 91. I was using it this summer when my engine temps were high due to a coolant leak, which caused excessive pinging.

Right. Octane isn't a rating of power. It's a rating of how resistant the fuel is to ignition, and thus how resistant it is to pre-ignition.

It's not a bigger bang, it's a later bang. I'm also given to believe that it's a shorter, sharper bang, but the way that gas engines work, it's not important how sharp the bang is (within reason). I could be wrong about the shorter, sharper thing.

Watering the fuel, to an extent, also increases the effective octane rating by delaying the bang. There is a small quantity of water that can be absorbed by fuel (particularly fuel that has ethanol in it), or you can inject water droplets into the air stream.

For a variety of reasons, water + a water soluble fuel that increases the freezing temperature without enriching the fuel / air mixture too much is preferred. Say, a simple alcohol like ethanol. And nobody would be talking about methanol injection if it weren't for the taxes, tariffs, and regulatory headache that come with ethanol. The reason you don't see anyone talking about water+isopropanol injection is because isopropyl is too rich, and pre-ignites.

As compression increases, whether that is due to a smaller chamber or forced induction, pre-ignition (Due to the compression itself? I forget) is an increasing issue. So high compression and forced induction engines may require a higher octane rating.

1fz-fe is what, 9.0:1? Burn whatever is cheap (within reason).