Have asked around but never get a definate answer...

Am running a full de-cat system and want to know what will/would happen if I ran "normal" 4 star fuel as opposed to Optimax. Assume it'll give it a little more kick.....

open to views and suggestions !?

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[Edited by NACRO - 10/28/2003 2:55:02 PM]

Normal 4 * only contains lead addative which is of no "real" importance to modern engines which do not require the lubrication by such.
Optimax however is a 99.9 ron fuel which is about the highest octane rating you can by as a "pump fuel" at present. yes I know you can pour in addatives and get higher but I am simply talking pump fuels here and not "add ons".
BP "Ultimate" is only 97 ron rated but does have some added performance options and also worth a try.

I thought that Optimax was 98 Ron as against Superunleaded which is 97 Ron? .

LeMans,
Optimax is 98 ron & superunleaded is 97 ron.

This is what I meant. Still no definate answer. I've always assumed that the 4* was a better "quality" fuel.

In the past have heard a 22B owner saying that having put 4* "oneday", "it went like F**K".....

leaded fuel will eventually lead to Lambda sensor failure. The lead contaminates the reactive surface of the probe.

Where is the lambda sensor located ? I assumed with the full decat it was blanked off.... or is this just my wild imagination taking over.

The lambda sensor is in the downpipe and even with a full decat is required by the ECU.

DaveW.

what does it do 'cos it's not on mine ?!

On certain MYs, the "blank off" you're referring to is for the COF (cat-on-fire ;)) sensor. The lambda is at the top of the downpipe, not long after the turbo. However, on other MYs, the lambda is in the exhaust header, I believe.

Gari, The Lambda (or oxygen sensor) Is the sensor for detecting the fuel mixture of the engine. ALL petrol cars manufactured after 1992 have them. On UK cars it should right after the turbo, but it may vary depending on the model year

Running with leaded fuel will contaminate the sensor and it will fail, as the sensor contains similar materials to those found in the cat.

I believe the same may apply for LRP

Thought I'd add the lead in the 4* does give better anti-knock properties. I'm not sure how that compares to Optimax, would be interesting to find out.

for the ultimate RON use AVGAS :D

[Edited by ALi-B - 10/30/2003 1:43:22 AM]

Yup I would concur, LRP is more than likely to have the same effect.
Watch out for octance boosters as well, if they are not cat friendly, then they too will eventually screw the Lambda sensor.

cannot find this sensor. Right after the turbo on the down pipe there is a "blanking plug".

You sure it's not in the exhaust headers? Near the O/S of the front bumper IIRC...

nope

ALi-B,

Can you use AVGAS in your import scooby, is it safe? is it worth looking into?

Where can I get hold of some AVGAS ???

AVGAS is 110LL - 110 octane low lead , the low lead term is relative . About 4 X normal leaded if I remember correctly.

It is taxed as an aviation fuel not a road fuel so it is only available at airfields for aircraft , find a friendly cessena pilot if you want some.

Decat exhausts only !