911/Q45

Never wrestle with a pig. You can't win, you get covered with poop and the pig enjoys it.

Nordschleife

Look Tiny Tim -

Don't tell me what I said - you may need reminding, I don't.

You are flying in the face of the knowledge and experience of thousands of people. The Bosch Motronic units are designed to cope with a range of fuels. Go away and read up on throttle body adaptation. This feature is most important on forced induction engines, and not as noticable on normally aspirated engines. Most of the better quality vehicles sold in Europe are designed to work with a range of fuels. If a manufacturer wishes to cut corners, then this is an aspect of engine management they may scrimp on.

What you are maintaining was true in the days of carburettors and early injection managment systems.

Your statement - "the ECU determines the maximum advancement of timing, NOT the octane level" is meaninglesss and irrelevant in this context. You haven't read what I wrote.

and then your final statement -
what drugs are you on? send them this way, the dog looks like it needs a good laugh.

R+C

Nordschleife

You are quite correct ;-)

R+C

1999Porsche911

In response to the question: Has anyone had experience using 100 octane fuel in their GT 3 RS? If so, any noticeable performance improvements? Did[or does] the ECU automatically adjust itself for the higher octane gas?

Here is your quote: "the Bosch ECU is a fairly clever bit of kit. It does adjust, as anybody who has driven Turbo cars at high speeds will know. The gains in horsepower being most notcable at high speed. The adapation process is not instant. There are various 'tricks' for speeding it up."


So I guess all of us should simply increase our octane rating from 93 to 100 and we'll reap all these performance benefits?


This statement is wrong. The ECU cannot, will not and does not adjust upwards above the predetermined, manually set maximum performance settings, including timing. Try to back track all you want, facts are facts. Keep referencing Bosch Documentation all you want. It does not exist.

Octane will not provide any increase in performance on an engine that is not knocking or experiencing a condition that is retarding the timing. The only way to benefit from a higher octane is change the ECU. I realize that not all of us have formal education, but I would think more of us would have common sense.

You can continue debating this subject with yourself, as I have already stated the facts and you continue to stick with your fantasy.

dasams

This is the RON (research octane rating) which is used in the EU. Pumps in the US are regulated by the ave of the research and motor octane numbers. You'll notice [RON + MON]/2 on the pumps. The spead is typically 8-10 numbers so our fuel is commonly 98 RON and 88 MON (or it could also be 97 & 89) for pump gas that is 93. In CA, it's more likely 96 RON and 86 MON for an average of 91 (and those stuck with this fuel are probably down a few ponies).

I've never seen any documentation that the Porsche ECU will increase power to take advantage of fuels with an octane rating above 93. And I don't think this would make sense from a warranty perspective. After all, where would it end? Would Porsche tune for 100 octane and retard timing for street gas? I don't think so. And you can be sure they wouldn't do this for the track guys (track use and Porsche warranties are another can of worms).

My understanding is that 93 octane fuel gets the most out of the Porsche ECU. To take advantage of higher octane fuel, you'll have to go aftermarket and mod the ECU.

dave

gweedo911

Entertaining

pdxjim

I am not sure if I am learning anything here, but it is good entertainment! Going to nuke some more popcorn!!

tiger 6

The reason I asked this question is that I am running 100 octane in my GT 3 RS because Chuck Goldsborough[The Baron] said to do this.

pole position

LOL, 1999P is correct.

The ECU is set for perimeters which the factory considers safe with adequate common pump fuel, ideally Super in Germany or Premium in the US, both fuels (except the better part of the w-coast) are in the 93-94 octane range. The ECU will retard timing when knock is detected due to inferior fuel and advance again once proper fuel is in the tank. There are more factors involved in this process (like heatsoak, temps etc) but those are the main reasons the ECU pulls/advances timing. However at no circumstances will the ECU adapt to a higher octane what is was designed for...........that is where all those chip jockeys come into play and on a normally aspirated engine they crank the timing, lean it out , remember you of using the best fuel and off you go. If this magic pixieedust Motronic according to Schleifennord would exist then there would be no need for various aftermarket tuners, ecpecially on forced induction cars offer their "chipselector", pump/race/valet......

Short story : some aftermarket enhanced ECU's will adapt to higher octane up to around 97/98 but that is it. Higher octane being it leaded or unleaded you need a specific tune for it otherwise you are just supporting the oil companies and not your performance portfolio. On aircooled turbocharged cars you will add a safetyfactor but , again, no performance gain.

Maybe die Schleife des Nordens sollte sich weniger an der Lambo/VAG Leder innenausstattung aufgeilen und mal nachhilfe stunden im electronischen motorenbau machen oder seine demutigung und lektion in sachen ECU mit ein paar bier und mehr Schnapsen runter zu schutten.

MarekN

MVD, I know about the difference in US and EU designations, but thanks for pointing it out.
Just to get back to my little comment on the Impreza, as picked up on by 1999P, we were resetting the ECU because it was the quickest way to clean the table. If we put in quality gas and then something with toluene (to spike up octanes), the two running characteristics would average out in time and it would never run as well as when you reset it and start directly with the high octane fuel.

This was on a 1998 car, almost ten years ago. What Porsche must have now in terms of ECU must be two or three generations more advanced.

I also want to add that I can only confirm the above with my butt-meter, but no dyno sheets, and that this approach is and was the general consensus on all current and previous turbocharged boards.

I wonder what the large BMW 335i US tuning community would have to say on the subject we are just discussing.

Nordschleife

actually I wouldn't make that assumption. The tuner I know who has the most intimate understanding of what is achievable with the Motronic unit (and other big name tuners buy his firm's expertise) made his name on Audis. His guys regard tuners who switch to the motorsports ecu as sloppy workers who haven't finished the job. (its easier to use the motorsportds unit because it doesn't get so cross when exceptions arent handled properly, so good for quick and dirty jobs, but it doesn't stop the engine handgrenading itself).

PAG has spent a lot of time borrowing diesel technology to control variable vane turbochargers, Bosch being wizzo chaps when it comes to stinky motors. so some of the other clever stuff hasn't been explored as much as might be expected.

there are all sorts of parameters in the motronic unit (orders of magnitude more sophisticated than what is found in Japanese turbo engines), many of these are ignored, particularly by Mercedes/AMG. these parameters can be set and altered and often define ranges rather than absolute values. The limits of these ranges define the ability of the ecu to adapt to different situations and grades of fuel (and its not all octane). So the ecu will try to prevent the engine from damaging itself as a result of poor fuel, or overheating for example. Similarly, when the situation improves, the ecu allows the engine to make more torque. In fact, you may consider the Motronic unit as a torque gratifier. It constantly to measures/estimates the amount of torque being demanded by the driver's actions and then controlling and configuring the engine to deliver that amount of torque.

this means that the parameters are set to allow for efficient operations using a range of gasolines. There is no need to set the ecu to handle only the worst fuel available in a particular market, it can be set to work with good and bad fuel. A car raised on a diet of cruddy stuff will adapt when presented with tankfuls of decent fuel. Put the engine on a brake and you will discover that the car does, indeed generate more torque when running on high octane fuel than it does when running on poor grade fuel. However, the adaptation is not instantaneous and takes time. Various tuners and drivers have learned techniques to speed this process. Many VAG group drivers have invested in Uwe Ross' VAG tool simply to be able to run a throttle body adaptation on a regular basis as they change their grades of fuel.

the dealer and the factory have no interest in explaining this to customers. Otherwise the dealer would be inundated with requests for the parms to be tweaked to allow the car to work with ever more extreme fuels.

It is no accident that BP, the most 'green' of the petroleum companies, has launched a premium fuel with a 102 RON rating.

Now if your car cannot benefit from such fuels, its because the various parms have been set that way. these values can be altered by somebody who understands what is going on. Unless somebody is living in an area where the available fuel is as good as the manufacturer envisaged when setting these parameters, there will be an improvement in performance as the ecu adapts to the better quality fuel when it is used. I don't know what the situation is now, but when I lived in the US, Southern Cal had terrible fuel and some of the other areas had much better fuel.

The improvments as a result of using higher grade fuel are hard to measure in normal driving. In my experience, the buttometer can pick up the improvement in top speed, but not acceleration.

I know quite a few people who habitually drive long distances in fast cars in Europe, they all make a point of filling with 100+ octane fuel, despite the punative additional costs. They aren't fools, or spendthrifts, they have learned that it is worth using higher octane fuel in their cars.

there are facts, and then there is religion, I have no interest in discussing religion, but if anybody cares to examine the facts, thats fine.

R+C