i'm using the expansive premium stuff but would not mind using the cheap stuff. any reason i should not? worse milage? more frequent injector cleaning? less power?

 

I think 22re is like 9:5:1 compression so i would say 89 octane which is mid grade around here. no need for premium although its good to run once in a while.

 

i run 87 most of the time and 91 once every couple on months

 

I found that I get about a 10% improvement on premium (tweaked EFI mind you).. so if the spread between low grade and preimum is less than 20 cents (with gas over $3 it often is) I go with the premium..

But I have a tweaked engine.

YMMV

 

Mobil 87

Rob

 

I use 87 octane in my Runner. Any station except AM/PM

I average 15-17 MPG depending on how I drive.

John

 

Probably depends a lot on the elevation you are at. I live in colorado and actually get better gas mileage with lower octane. I can get 21 city with 85, but if I use 87 or 91 I usually get around 18.

 

i use 87 in mine and it works just fine

 

higher octane is going to prevent pre-ignition due to high pressure or high heat, or both. I would think that our 22R's and 22RE's are not making enough power to warrant the use of higher than 86 octane, especially at higher altitudes like in the western states.

Oh yeah, I buy 86 octane for both of my vehicles.

I've also experienced the same thing as 90RunnerRed. I've put 100 octane in the 4runner mixed in with 86 and the gas mileage goes down quite a bit.

 

ok, so we got the milage covered. how bout power on the lower octane? and how does the lower octane effect injectors and the overall cleanliness of the fuel delivery system?

 

87 (pump octane) per my Owner's Manual:
http://www.4crawler.com/4x4/4R_TechInfo.shtml#Fluids

I've run 85 up in the mountains with no issues.

 

I run 85, cheapest I can find. (I'm in Colorado, higher altitude so 85 is most common) When I go out of state to lower altitudes, 87 is the lowest. Like others have said, higher octaine prevents pre-ignition. It's for higher compression engines. They need it to prevent spark-knock as well. My suggestion is just to use the cheapest stuff you can find. Sure, people claim "Well if it's not <x> brand then it's horrible gas for your motor!" I find that to be a bunch of BS, besides, it's a Toyota, it'll survive anything!

 

85 for me and that's with a head shaved 20 thou

Like Pest said, these motors will run on anything.

 

The over all cleanliness of your fuel system is going to be reliant on the overall cleanliness of your gasoline. A higher octane gas is not going to give you any more power than a lower octane. Your engine is not capable of making enough power to need the higher octane fuels.

The air in the cylinder thats mixed with unburned gas will heat up due to compression (lots of molecules that are excited, getting pushed closer together causing friction and heat Kind of like a dance party in a small room). A lower octane gasoline will detonate when the heat and/or compression gets to be too much. This is called Photo-detonation. Higher octane resists photo-detonation to higher tolerances. Thus, higher octane doesn't mean the gas has more power, it means the engine can compress it harder which in turn generates more power when the gas is ignited and the cylinder is moving through the power stroke because all of that compressed air is now expanding.

Diesel engines work on photo detonation. They don't have spark plugs, instead they compress the diesel fuel until it detonates. This is why they make such efficient power. All of the fuel gets burned.



Please feel free to add on or correct me if I'm wrong about anything.

 

I would think you're dead on. Just in my own mind, I would be lead to believe that if you don't have a high compression motor, higher octane might not get completely burned up before being pushed out the exhaust, which would generate less power, fuel economy, and maybe backfiring if the remaining fuel ignited in the hot exhaust pipe. But I have no evidence of this, just what my mind generates. Any thoughts?

 

my 84 (with 85- up block) 22r carb with weber 38 runs better on 93 octane than on the 87. when i run 87 it pings under load and i lose power slightly it also diesels when i shut it off with 87 but not with 93. i have my timing bumped up a tad at about 8deg btdc and its got oversized valves,261crawler cam and my compression is slightly higher dude to decking the block .002" more than the aftermarket pistons are destroked, my quench is set at .009" which boosts compression, i still need to get an lc adjustable cam gear. i think my timing could use a bump back but i just put in 93 octane or run 104+ octane boost when i use 87 octane , acceleration is alot better off idle that way. my carb also is jetted rich so i have some tinkering to do.

 

I get best results with 93 or better octane.

 

I run 87 In mine. No problem for me

 

87 octane since June of 1984

 

you are close. a diesel is a compression ignition engine, yes. but it actually compresses the air, then once it's near TDC it injects the fuel and almost instantly combusts.