Petrol comparison

[digifish]

I was referring to petrol only :P

We are going to hunt you down on this one!

Petrol has the same MJoule/litre content regardless of RON

digifish

[bornwild]

We are going to hunt you down on this one!

Petrol has the same MJoule/litre content regardless of RON

digifish

For the general populace, it is a roughly accurate thing to say that, the higher the RON, the higher the energy content. Technically this may not be correct, but in the end the results are the same, hence I didn't really bother to look it up into detail

[digifish]

For the general populace, it is a roughly accurate thing to say that, the higher the RON, the higher the energy content. Technically this may not be correct, but in the end the results are the same, hence I didn't really bother to look it up into detail

Hmmm.... my 'reality distortion field' is stronger than yours...in my version of reality you have just claimed that aliens stranded on Earth when their ship crashed here in 1951 are stealing RONS from petrol in order to power a faster-than-light-drive for a ship they have constructed from old beer cans. This is the main reason petrol dropped from 98 RON to 91 with the introduction of unleaded as they needed to hide what they were doing and so brain washed the population to think lead was bad...when infact it's a brain food.

[dunko]

i got a braina 94 gsi if u run it on any less the 96 it is a dog have to run it on 96 98 or 100 100 is the best and its cheaper as it is 10% ethanol.

[stevedee3]

Here's what I thought the story was:

1. Thermal efficiency of an ideal Otto cycle engine is a function only of compression ratio - higher compression ratio = higher efficiency
2. Higher octane fuel allows for higher compression without unwanted pre-ignition

Put these two together and higher octane fuel allows for greater efficiency => more power out from the same amount of petrol in

[rjastra]

So they choose a control vehicle from a market where 100RON fuel is common place and the MR2 is most likely designed for it.
And the other car is a highly modified M3 that is designed to produce max power on 98+ROn fuel.

Then they fill both of them up with regular (in the EU) unleaded of 95RON and wonder why they get a power drop.

What they prove is nothing more than engines designed to run optimally on 98RON will see a power drop when you run them on a lower octane fuel.

It does not mean that a car designed to run on 95RON efficiently will see a power hike when run on 98,99,100RON fuel.

[gman]

Any increase in power from the change in the octane of a fuel will depend on the ability of either:
a) the ECU,
b) the tuner,
c) the engine builder or
d) a combination of the affore mentioned three points.

If the standard ECU doesn't run closed loop O2 fuelling control and/or knock sensor ignition control then it will not be able to take advantage of the increased octane.

You would then have to either:
a) mechnically increase the compression/boost (effective compression increase) of the engine or
b) re-calibrate the ECU to take advantage of the different characteristics of the fuel.....

The Motronic 1.5.1 in the SRi-T does both so can "learn" the new fuel advantages by altering the fine tune fuel and ignition maps that overlay with the base map from the factory or from a re-mapped tuner.

[GreyRex]

Any increase in power from the change in the octane of a fuel will depend on the ability of either:
a) the ECU,
b) the tuner,
c) the engine builder or
d) a combination of the affore mentioned three points.

If the standard ECU doesn't run closed loop O2 fuelling control and/or knock sensor ignition control then it will not be able to take advantage of the increased octane.

You would then have to either:
a) mechnically increase the compression/boost (effective compression increase) of the engine or
b) re-calibrate the ECU to take advantage of the different characteristics of the fuel.....

The Motronic 1.5.1 in the SRi-T does both so can "learn" the new fuel advantages by altering the fine tune fuel and ignition maps that overlay with the base map from the factory or from a re-mapped tuner.

Awesome, so with the SRi-T (TS and AH) it'll learn your fuel type and you'll have some benefits? Because that was basically the point of my post lol

[rjastra]

Awesome, so with the SRi-T (TS and AH) it'll learn your fuel type and you'll have some benefits? Because that was basically the point of my post lol

It depends if it has any maps for fuel greater than 98RON I suppose.

So, you will get a difference 95 vs 98RON but not feel get any significant difference for 98 vs 100RON.

This all goes out the window for modified ecu cars with maps for 100RON fuel.

[gman]

Awesome, so with the SRi-T (TS and AH) it'll learn your fuel type and you'll have some benefits? Because that was basically the point of my post lol

Yep, you will if you let the ECU learn the fuel by pushing the fine tune timing and fuelling maps..

It depends if it has any maps for fuel greater than 98RON I suppose.

No, the ECU will keep moving the timing and fuelling thereshold until it has reached the max values of the fine tuning tables regardles of the fuel used.

These tables have enough "headroom" to easily accomodate the extra timing and fuelling needed to take advantage of a 100 ron / 5% Ethanol fuel over standard 98ron.

Example: a Standard ECU Map can learn the fuelling difference between the standard and VXR injectors and compensate...Fit the larger VXR injectors and the car initially runs very rich...After about 100km's the ECU reduces the fuelling through ther closed loop O2 sensor and the car runs perfectly..

These tables allow the car to use lower ron fuels like 95ron in a pinch or run more efficiently on 100ron if available...

The only time it will be "lazy" is if you drive it like a grandma so it never gets to reach the current fine map timing and fuelling tables..

So put it in, drive it hard and you should see it pick up some performance after 2 or 3 tanks...

My car has the re-flashed ECU & certainly notices the difference..I only use the 100 RON stuff now, sometimes for hard driving I've used a nitromethane additive and it responds nicely to that too....