scud8

iTrader: (1)

I filled up my STI5 at the Shell SS in Porthmadog at the weekend and the nice lady behind the counter told me that I'd actually filled it with a new Shell fuel "for performance cars" (they'd received a delivery into the SUL tank, but hadn't relabeled the pumps yet).

She gave me a leaflet (which I can't find now - doh!) which I seem to remember indicated this will be released nationwide soon. She also told me it is guaranteed to be at least 98RON, but since the leaflet didn't say anything about octane rating, I'm a little sceptical.

Has anyone else heard about this? Any other experience using it? To be honest I didn't really notice any difference from the tank of Esso SUL I had been driving on for the previous couple of days.

mutant_matt

It's also being discussed in General :

LEE P

Well i dont know about anyone else but if ive had a tank of super then 95 ron un leaded i can tell the differance, super is more responsive and the engine note sounds smoother, plus the turbo sounds more aggresive. roll on the 98 ron fuel! Lee

coyote

Yep, they "learn up" a lot slower than running for safety.

coyote

I wouldn't expect you to notice a difference when putting in 98RON after 95RON. In engines without a knock sensor, things need to be retuned. Engines with a knock sensor require an ecu reset. I find that doing the reset and then driving it like you just stole it works really well. The fuel will not give you any more power or efficiency by itself. It will give you the ability to change (or let the ecu change) other things which can give these benefits.

charliecossie

I wonder why Optimax is 98 RON in the UK and 99 here in Germany?

MorayMackenzie

Funny, we used to have 98 ron fuel, called something silly like "super unleaded". We then had leaded fuels withdrawn and LRP brought in which used the same base as this "new age" super unleaded that was degraded to 97 ron in the process. Now, (just as many forecourts have only recently bothered to put 97ron labels on their pumps and hence stop breaking the Trades descriptions act), Shell is giving us back the 98ron Super we used to have anyway. ho hum.

Oh, and IIRC, higher octane fuels are harder to ignite and burn more slowly than lower octane variants... so even in cars without knock sensors fitted, super can make a significant difference to perceived smooooooootheness if nothing else... certainly makes a difference in my M3.

Moray

[This message has been edited by MorayMackenzie (edited 18 August 2001).]

pat

Lee,

the knock control algorith is dependant on age and manufacturer....

For example, the old Subaru JECS engine management retarded quickly and advanced slowly and hence the ECU reset has a big effect on these cars. Later cars such as the MY99/00 had more sophisticated knock control, and it pulled the timing forward reasonably quickly again, hence no need for a reset.

The current MY01 unit uses dynamic timing control whereby it pretty much runs continually on the limit of knock... the display on a Select Monitor gives you a pretty good indication of the fuel quality

Out of interest, Toyota and Bosch engine management systems have been doing this since the dawn of time, Subaru is just catching up.... indeed some of the Bosch systems maintain a retard table for each cylinder

Any vehicle with dynamic timing control system will immediately benefit from better octane rating (unless the knock limit is beyond MBT timing anyway, then they are equal). Also, higher octane can improve fuel economy, since the greater ignition advance can place the peak cylinder pressure closer to the "magic" place of about 16 degrees ATDC where the maximum amount of useful work can be extracted from the cylinder; hence more miles to the tank, you get the same power with less right foot

FWIW, and don't try this at home, LRP actually appears to have higher knock tolerance than Super Unleaded. There was some mention of oil companies using MMT as an addiive to help reduce Valve Seat Recession (VSR), however it has the other side-effect of being an octane improver. It will not do your catalytic converter or lambda sensor any favours though, and is I would not recommend that people use it....

Cheers,

Pat.

ikinder

Shell have now put more detail on their web page:http://www.shell.com/uk-en/content/0,4011,44847-69442,00.html#12

Though I'm not totally convinced at their proof. The 1-3 car length improvement on overtaking surely need a few more details adding to make it more scientific such as car tested, speed of vehicle being overtaken etc.

Worth a look though.

Regards,

Ian

p.s. The list of stations published that have the fuel isn't too large. It's better to rely on older technology and ring them up for details of when your local shell will have it available.

Andy W

for the lazy folks

James_Harvey

Probably the same reason why our Super Unleaded and LRP are 97 RON, when it is 98 RON in the rest of western Europe.....

James

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:<HR>Originally posted by charliecossie:
<B>I wonder why Optimax is 98 RON in the UK and 99 here in Germany?
[/quote]

Doogsy

Says at least 98 RON in the leaflet I got
Doug

rollerskate

Filled MY01 this morning excellent improvement!!! Pulls stronger and no hesitation at 6k what a cheap mod.