95 vs 98 and 99 petrol benefits?

[Kregiel]

Hi Guys,

Had an interesting conversation about petrol recently and though would get guys opinions here. Apparently apart from obvious more power on 98 and 99 petrol than 95, higher octane also lowers the cylinder and pistons temperature. Can somebody shed some light on it? In Ireland we only have 95 petrol and when car pushed hard 95 petrol is not a good idea compared to higher octane ones. Some advise installing WMI if running on 95 on track not to get more power but to keep temperature low which would normally be the case with high octane

Do you all guys use high octane fuel?

Thanks
Paul

[GrayMK5GTI]

There's loads of benefits from using higher octane, the power benefits were shown when R-Tech did a test on Fifth Gear with a mk6 GTI.

Higher octane reduces knock and burns more cleanly too 

The benefits are huge on direct injection engines in particular

[Steviedubs]

Basically an octane rating is the petrols resistance to combustion and you want it to be resistant to combusting so the burn is controlled and therefore less pre-detonation. Think of it as getting one big bang rather than a lot of smaller bangs, which is why the engine will be more efficient mpg wise aswell as the power gains. For diesels it's a cetane rating and basically is the opposite way around because the diesel needs to combust more easily due to the volume of air compared to diesel in the cylinder.

Steve

[MC71]

Have only ever used the Power of V.

Plus my fuel flap tell me too.  Do you know the reason why you don't have the high octane juice over there?

[Kregiel]

Have only ever used the Power of V.

Plus my fuel flap tell me too.  Do you know the reason why you don't have the high octane juice over there?

Higher tax on higher octane fuel coupled with size of market made it not viable for petrol companies

However there is one fuel made by Maxol with 5% of ethanol and this is rated at 99 RON which is great news! See below. It has negligibly lower energy...

If this is coupled with a proper map than the higher power benefits will be seen? It will also mean that my car can only run this fuel going forward or ECU will adapt in i put in 95 RON?

http://www.maxol.ie/index.php?option=com_content&view=article&id=144&Itemid=292#What%20is%20the%20Octane%20Rating%20of%20E5%20compared%20to%20ordinary%20Unleaded

Thanks
Paul