100 Octane Fuel - Does it hurt anything

[tissimo]

If you put this 100 octane in your 2jz car you probably picked up power. The 2jz has a timing modifier based on knock that adds or subtracts timing from the basemap. So with more octane its seeing less knock and advancing the timing till knock point again.

 

[BlackDevilSupra]

^^^^
Hmmm, the "archaic" 7M's ECU does that too, , along with just about any other EFI automobile with knock sensor feedback. Basis of all EFI with O2 sensor and knock sensor feedback is to continuously update the base maps based on the sensor feedback and engine's operation and condition. This is the reason why to negate previous feedback influence on current engine operation whenever using higher octane (such as race fuel), the ECU is manually reset.
As IJ and others have mentioned before, higher octane by itself does not net you higher HP, just the ability to adjust timing / boost, etc. to make more power. And if there is any observable gain, then attribute that to the use of crappy fuel.

 

[selfinfliction]

As IJ and others have mentioned before, higher octane by itself does not net you higher HP, just the ability to adjust timing / boost, etc. to make more power. And if there is any observable gain, then attribute that to the use of crappy fuel.

i will have to disagree... this vehicle makes more power with fuel than with gas, without changing any map or timing settings.

 

[supraturbotimmy]

Octane rating is a measure of detonation resistance, we over in the uk have a minimum of 95 and most higher end fuels are 99, using higher octane fuels youre more able to take advantage of higher boost, with lower octane the knock sensors will tell the ecu to pull back timing to keep the engine from "pinking" this will limit hp.

 

[DaleH]

i will have to disagree... this vehicle makes more power with fuel than with gas, without changing any map or timing settings.

:rofl:, now thats a mean Tricycle.

I once heard running High Octane Race Fuel could burn a hole in your pistons? Fact or Myth?

 

[OneJoeZee]

I once heard running High Octane Race Fuel could burn a hole in your pistons? Fact or Myth?

I don't see how. Unless you were running too much boost/timing/compression for that fuel.

 

[tissimo]

^^^^
Hmmm, the "archaic" 7M's ECU does that too, , along with just about any other EFI automobile with knock sensor feedback. Basis of all EFI with O2 sensor and knock sensor feedback is to continuously update the base maps based on the sensor feedback and engine's operation and condition. This is the reason why to negate previous feedback influence on current engine operation whenever using higher octane (such as race fuel), the ECU is manually reset.
As IJ and others have mentioned before, higher octane by itself does not net you higher HP, just the ability to adjust timing / boost, etc. to make more power. And if there is any observable gain, then attribute that to the use of crappy fuel.

Based on my experiences the 7m and even jza70 1jz ecus are different. They have a timing modifier but not in the same way. The 7m ecus have a base timing map, Then will retard timing if knock is present. The 2jz ecus have a more advanced timing system (i think Soarer 1jz ecus as well). They have a base timing map then a modifier based on the knock noise. It will advanced (or retard) the timing from the base timing map until knock is heard. So it can actually run more timing over the base timing curve if no knock is detected. The stock 2jz ecu can run up to 22-23* of timing if no knock is present.

 

[selfinfliction]

I once heard running High Octane Race Fuel could burn a hole in your pistons? Fact or Myth?

it is possible if they were running oxygenated fuels. you are required to run (generally) 5% more fuel if using oxygenated than regular fuel. so, if that was the case, they burnt pistons because it was running lean, not because of the higher octane.

some of the guys at my uncle's dirt track have $30k+ motors that run on oxygenated fuel only, but IMHO it's pretty stupid cause the guys running alky are putting down the same power and it's ALOT cheaper.

 

[Dan_Gyoba]

Octane ratings is basically a measure of when octane starts to detonate. The higher the number, the less prone it is to pre-ignition, ie knocking. Therefore the higher the number, the less likely the fuel is to detonate, and damage your motor.

There are 2 different ratings that have to be done. Research Octane and Motor Octane. Motor octane is rated with a pre-heated fuel mixture, and is therefore a lower number. I can't speak for everywhere, but fuel in Canada is rated at (R+M)/2, or the average between the Research Octane and Motor Octane numbers. Some plaves rate fuel my the research number alone, but I don't know where those places are.

Avaition fuel generally lists both numbers. A common aviation fuel is 100/130, which has a Motor Octane number of 100 and a Research Octane number of 130. If this were sold in the pumps at the gas station, it would have a 115 octane rating.

This fuel would take a lot more compression/cylinder pressure before it would preignite, and therefore you could run more boost before running into problems. The basic makeup of the fuel determines how much potential energy the fuel has. Gasoline has a certain amount of potential energy per litre, so the only way to make more power is to either use it more efficiently (higher compression) or simply burn more of it.

So higher octane fuel doesn't make more power. It allows your engine to make more power by allowing higher cylinder pressure, which generally means higher boost, which also translates to more air/fuel mixture.

If you run lean, it's just as bad, if not worse, because you are dealing with more potential energy. However, if you are running high octane fuel at an appropriate mixture, the worst case is that you won't make any more power because your engine isn't set up to make use of the higher octane fuel. (This is the same as running premium fuel in a car that isn't set up to need it. You get no power benefits, though you are safer in the event of an unexpected issue.)

 

[quake]

keep in mind that you do not have access to toyota timing maps. They are kept secret, even from us that work there. Also the timing values are not in real time, as there is a delay in the time span of the data with a scan tool. The newer scan tool we have is a lap top and is much faster though.

The last time we had a car with problems that could not be fixed without looking at all the data toyota actually sent 2 design engineers from japan to our dealership to check the car. They took some readings and fixed the problem in short order. They would not let us know what they did.