Gas Octane

^^ x2 in regards to suffer = less MPGs.

On a modern ECU setup like my 03 IS300, the MPGs and perfomance increases with higher octane as the ECU's closed loop ignition probing and knock sensing advances the timing to use it. On the flip side its not dangerous to run the lower octane, the mapping adapts- to an extent. If you have an old engine with build-up and/or pushing it really hard, retarding timing can only go so far but can't prevent pre-ignition.

On my 5vzfe, I get better mileage using 87. The ECU is 'dumber' to knock feedback and the OE compression and ECU's ignition curve is more suited for 87 and doesn't benifit from higher octane. So if I'm not boosting (road trip), I'll fill up on that. Once I revamp the water/meth to be more accurate, I may always run 87. Boost on the other hand- I have a ping happy 5vz, 91 without water/meth barely does the job even with a piggy that keeps good a/fs and retards timing. E85 tells ping to f*ck off and I can run the OE ECU's N/A timing curve, and could probably advance it if I had the ability.

 

Changing octane from a vehicle that calls for 91 and you put in 87 will hurt performance. Tacoma running 87 236HP 266 FPT, 91 gets you 239HP and 278 FPT. No much improvement except torque. 91 and 93 oct, has advantages over 87 except cost. Running higher oct does little for your vehicle but I have read nurmerous posting on here and in articles and seen little where it MAY harm your vehicle and none hurting performance.

 

I've noticed a difference from 87 to 93. Its not just the butt dyno either. I've had a friend of mine put gas in my taco, and id get my truck back, and definitely notice its not 93...

 

Where did you get those numbers?

 

Huh???

I know we are in a Tacoma forum, but I am going to use the new 5.0 engine in the Mustang as an example. The Copperhead ECU found in the 5.0 can adjust for different octane. I have no clue if the Tacoma's ECU is like this.

Anyways, the 5.0 is designed to run on 91 octane but can also run 87. The CR in the 5.0 is 11:1 FYI. If you run 91, the knock sensors should not detect any knock in the engine, thus advancing the timing in the engine and allowing for maximum horsepower.

If you run 87, the engine will probably detect some knock and retard the timing, which equals to less HP and tq.

I am new to the Tacoma scene, but I would imagine it also detects knock. If there is knock present the ecu backs off timing and saving your engine from continuous detonation. If the Tacoma ecu does not detect knock, I'm sure the ecu advances the timing and will allow a minimal HP bump.

Higher octane will advance timing if no knock is detected, not retard it. This is of course, if the ecu in the Tacoma is this sophisticated.

 

You misread, the fuel itself (higher octane) is slower burning which retards or slows down the ignition of the fuel. This is a fuel characteristic, I was not talking about engine timing.

 

One thing I noticed at some stations in our locale is a decal on the pump stating that 87 octane contains 10% ethanol 89 octane contains 5% ethanol and 92 octane contains no ethanol.Most pumps only say gas may contain up to 10% ethanol.Now this could account In itself for better gas mileage using premium gas would it not.What I am not understanding is if all the gas in our locale comes from the same refinery would the same ethanol content not apply at every station?

 

^

E0 vs E10 is what makes the biggest difference.

Use E0 87 and you will get better mpg than E10 91.

 

Several posting on this forum. Here is one.
http://www.tacomaworld.com/forum/2nd-gen-tacomas/138552-85-87-91-octane-e85.html

Here is more info.
http://en.wikipedia.org/wiki/Toyota_GR_engine

 

Here is the quote from Wikipedia:

The 1GR-FE is the 4.0 L (3956 cc) version, designed for longitudinal mounting in RWD and 4WD pickup applications. It has a 94 mm bore and a stroke of 95 mm. Output is 236 hp (176 kW) at 5200 rpm with 266 lb·ft (361 N·m) of torque at 4000 rpm on 87 octane, and 239 hp (178 kW) at 5200 rpm with 278 lb·ft (377 N·m) at 3700 rpm on 91 octane. This engine features Toyota's VVT-i, variable valve timing system on the intake cam and a compression ratio of 10.0:1. An updated version of this engine features Dual VVT-i, increasing output to 254 hp (189 kW) and 270 lb·ft (366 N·m) on 87 octane and 285 hp (213 kW) and 289 lb·ft (392 N·m) on 91 octane.

 

The additives, detergents, etc., (or lack thereof) are the same across the range and not just added to that which has higher octane levels. There was a link in one of these many fuel threads showing which stations had "better" gas due to added detergents, etc., but I can't find it.

 

There was a guy on the Texas Fishing Forum that works for a gas distributor. He said there are 2 octane levels delivered to the gas station. Midgrade is a blend of high and low. I cannot confirm this but there are a lot of guys on this forum running high performance outboards. Some of these guys go as far as to carry test kits to the gas station.

 

With 87, I averaged 18.6mpg combined
Now running 89 non ethanol! Not filled up since, but judging by the gas gauge/odometer I'm going further and needles moving slower will repost with mpg

 

non-ethanol will raise your MPGs regardless of octane. One of many reasons why ethanol is crap. With all our oil we do not need it. Ethanol producers have top much clout now so I guess we are stuck with it.

 

via XRU

 

Got gas today after using 89 ethanol free, 21.3 with some city driving, compared to 18.6 87.

 

Will run 87 unless I'm towing or seriously working the engine. Only Then would I run the higher octaine!

 

I think people are getting better MPGs from the ethanol free and thinking it is the octane. It is like doing 2 performance mods at the same time. How do you know which one was responsible for the result. I would like to see the effects of running 87 ethanol free versus 91 or 93 ethanol free.

 

Just filled up with 89. I got 280 on my last tank with another 20 dollars more of 87. I'll see if it's worth the extra $ to fill up.

 

Yeah, i dont think its the Octane, just the Ethanol, but the gas station where i fill up only has it in 89. So thats what i get, there is a place that sells 87 but im not driving out of my way to get it. . . .