Question about Optimax and red rose

[gazm]

Was wondering what (if anything) the difference between running a standard 4.5 on Optimax and a Red Rose is and if Optimax is a sufficient alternative to 98?

[J_S_G]

gazm said:

Was wondering what (if anything) the difference between running a standard 4.5 on Optimax and a Red Rose is and if Optimax is a sufficient alternative to 98?

Optimax is 98 RON. All other UK "supers" that I'm aware of are 97.

Not sure what the other part of the question you're asking is about...

[kojak69]

J_S_G said:

gazm said: Was wondering what (if anything) the difference between running a standard 4.5 on Optimax and a Red Rose is and if Optimax is a sufficient alternative to 98? Optimax is 98 RON. All other UK "supers" that I'm aware of are 97. Not sure what the other part of the question you're asking is about...

I think you are right JS about optimax being 98, and the others 97.
I too am not sure what the other part of the question is asking.

[maxbison]

Hi Gareth,

Ok, think I know what you mean.
Not sure about a standard 4.5, but the red rose apart from the extra hp, allows you maximise the cars performance so it will run perfectly on both 95 & 97RON fuel. This is done by pressing a switch to select what fuel is in the tank.
Having said all that, I'm not sure how it compares as I always make sure it's full of Optimax, so haven't needed to use it yet!

Hope that helps.
Phil

[daver]

gazm said:

Was wondering what (if anything) the difference between running a standard 4.5 on Optimax and a Red Rose is?

I’m not the best person to answer this. But I believe the situation is something along the following lines:

The AJP has no knock sensor so the ignition timing is set with a margin of safety (retarded) to prevent pre-ignition. The resultant timing is actually such that you can use ordinary unleaded perfectly safely and, indeed, there is no benefit in increased power to be gained by using Optimax.

The Red Rose on the other hand uses a higher compression ration to begin with and has 2 timing maps with the ‘super’ map designed to optimally use higher octane fuels – so the RR should produce higher output with 97/98 compared with 95 RON.

I believe a knock sensor based system continually adjusts the timing to enable the engine to ‘sail closer to the wind’ without risk of damage as the timing can be backed off if knock is detected.

If I’m talking bollocks, will somebody please jump in and correct me. Hopefully I’ll be slightly better informed after Al Melling’s presentation in Henley next month.

[dannylt]

Sounds perfect Dave! Much simpler for a big manufacturer to fit a knock sensor. Pretty expensive mistake for someone to put 95 in and leave the switch at 98.

Trivia - apparently the new BMW V10 engine (in the new M5) can detect detonation before it actually happens, via the spark plug in each cylinder. Sounds better than a microphone for each bank.

[gazm]

sorry for not getting back sooner - i've been away.

You have pretty much answered my question - sorry when I read it back just now it did seem confusing.




cheers