High Octane Fuel.

[OmniCognateNeutronRangler]

Can someone explain to me the in's and out's of higher octane fuel? What I want to know is:

1. Why does it give you better performance (if it does)?
2. Does it give you better or worse fuel economy?
3. Does it have any impact on the life of your engine or any other components (CAT etc)?
4. Tesco sell 95 (normal) and 99 (high) octane fuel. - which would you recommend?
5. Is it worth the extra money?

 

[Myros]

here goes

it does
depends on what you do with the extra power
no damage to your engine, if it is meant to take high octane
tesco 99
hell yes

 

[OmniCognateNeutronRangler]

thanks Myros. You missed the "why" bit out though.

As for the "if it is meant to take high octane", how would I know? Also, engine aside what about the rest of the components (CAT etc).

 

[Hibbo]

How would an engine react to 130RON fuel?

 

[Blobcat]

Pls have read on the attached; http://forums.mercedesclub.org.uk/showthread.php?t=13593

 

[OmniCognateNeutronRangler]

Thanks Blobcat. There's a lot there. I looked at the first few and it seems to be saying it makes no difference. I'll have a look at the rest when I get a couple of hours free

 

[Myros]

if you have a high compression engine

usually anything over 9:1 ratio, then there is a downside to using 95, or 97 fuel. That's the burn time of the fuel at high piston speeds.( and therefore high revs).

A low octane fuel burns really quickly, which means you run the risk of pinking, ( predetonation), which is damaging to your engine.

Modern ignitions take care of this by knock -sensing and retarding the ignition so pinking doesn't take place, but the cost is, you don't get max oomph out of the fuel at high engine revs, and therefore, don't realise the full power output of the fuel.

They used to whack tetra-ethyl lead into it to slow down the burn, but now they just put in more heavy ends from the refining process. result= high power without the pinking, as the burn time is slower, and the ignition can be advanced to maximise power.

Check your compression figures to see if it is what you need. On older cars, like my SL, with no adaptive ignition, you just set the ignition timing manually to give the best advance for the mixture you are running. the rolling road and a sun analyser are calling......