Octane Booster - anyone use one? - Page 1 - Boxster/Cayman - PistonHeads UK

Where I live I struggle to fine super unleaded petrol higher than 97 RON. I can get it, it’s just a 25 mile drive away. I have a Cayman GTS 4.0 I’m running in and wondered whether it would be sensible long term to use a fuel additive to boost octane. Hoping to hear what other folks use and would recommend or an alternate view.

Millers do a good one ... Petrol Power ECO MAX ... £13.49 at Wilco treats 500 litres increasing 2 octane numbers ... with a clever bottle to measure it out !

ChrisW. said: Millers do a good one ... Petrol Power ECO MAX ... £13.49 at Wilco treats 500 litres increasing 2 octane numbers ... with a clever bottle to measure it out ! So… that’s your secret! lol.

It’s a pain to get 99/98 around where I live as well which my GT4 requires. I have wondered about these, but are they any good? Do you just pour it into the tank? Or do you need to mix it in a Jerry can ?

ChrisW. said: Millers do a good one ... Petrol Power ECO MAX ... £13.49 at Wilco treats 500 litres increasing 2 octane numbers ... with a clever bottle to measure it out ! I use Millers VSPE in my classic...it's an Octane booster and has something in it to deal with Ethanol Corrosion. Obviously Ethanol not such an issue in modern cars https://motornuts.co.uk/millers-vspe-power-plus-mu...

anonymous said: [redacted] I had a 964 RS Clubsport with MOTEC ECU that had no knock sensing , so I had to use 98 + in that ... but I bought the Millers to help sort out a misfire I had in the 944 Cup .... we ended up replacing the HT leads, distributor cap and rotor arm which was the cause of the problem. But it is a very inexpensive way of compensating for fuel of an unknown quality. A question ... is it possible to over-boost ? Accepting that once there is no knock there is no benefit ...

ChrisW. said: I had a 964 RS Clubsport with MOTEC ECU that had no knock sensing , so I had to use 98 + in that ... but I bought the Millers to help sort out a misfire I had in the 944 Cup .... we ended up replacing the HT leads, distributor cap and rotor arm which was the cause of the problem. But it is a very inexpensive way of compensating for fuel of an unknown quality. A question ... is it possible to over-boost ? Accepting that once there is no knock there is no benefit ... Interesting. In another world long ago and far away, I was Technical Director of the original UK and European Motec importer. Can you remember which ECU you had? Knock sensing for Motec was long after I had moved on, and I'm not sure it was particularly well-developed when I last fitted and mapped a Motec ECU over 10 years ago. Back in that world, we did a lot of work on desert rally engines, mainly Rover V8. A lot of the development wok was on maximising power and minimising knock potential for running on "local" fuel. It was pretty bad back then (and we didn't have reliable knock detection in the ECUs, so thorough engine dyno testing was essential). I once got an engine specification extremely well developed for low octane petrol, and at the end of the process tried to recalibrate so we had a map available for 98 super, in case we could find some for the last couple of stages of a rally. There was nothing I could do with fuel or ignition maps to get as much power out of 98 super as we were getting with the "local" fuel we had simulated (supermarket basic unleaded with a dash of paraffin to make it knock a little more easily if I remember right...) So my gut feel is that you probably can "over-boost" the octane, but the worst that will happen is that you lose a tiny bit of power. And when I say tiny, I think the 3.9 V8 engines I was working on back then were making 220 bhp on "local" fuel, and the best I could get on 98 super was 218 bhp. Our engines built to run on 98 super made 235 bhp, but they really didn't like Egyptian / Moroccan / Tunisian brown and rusty looking petrol, and we'd have to back the ignition off so far that we lost all the low end torque that is vital to keep moving when you hit a big patch of soft sand. In short, agreed, my experience is that once knock is defeated, going further ends up lowering the calorific value of the fuel, and losing a bit of power. (All slightly dependent on how you boost the octane rating, and for turbo cars, you can always turn up the boost if you know you are not limited by detonation.) Liam

What ever you use make sure its compatible with your lambda sensors,esso super is still the best pump fuel out there.

Thanks. Very useful both ... P, how would you know if it is compatible with Lambda sensors ? I hope that the Millers is !! Regarding the Motec, it was fitted by Ninemeisters and then mapped by Chipwizards ... I believe to 340bhp and over 300 ft lbs (I can't now remember the actual figure) ... no cat, secondary exhaust bypass, Wills tip ... it just came in at 105db ...

ChrisW. said: Thanks. Very useful both ... P, how would you know if it is compatible with Lambda sensors ? I hope that the Millers is !! Regarding the Motec, it was fitted by Ninemeisters and then mapped by Chipwizards ... I believe to 340bhp and over 300 ft lbs (I can't now remember the actual figure) ... no cat, secondary exhaust bypass, Wills tip ... it just came in at 105db ... I guess you need to ask them,lambda does not like lead or some lead replacements.

Thanks ... neither do cats which I guess a current Millers product would therefore not have ... but certainly worth checking ... Particularly if there is some legacy octane boost in the garage ...