Angel VW Club

im no expert but i was always under the assumption that the octane was the figure giving to illustrate the engines resistance to knocking i e pre ignition so the lower the octane the more the engine will knock. lead is shown to slow down the burnin process and create a smoother burn so increases the octane because the knock or pre ignition has been reduced!detonation or pre ignition dramatically increases chamber temperatures thats why a turbod car runnin high boost with no intercooler will very quickly melt a piston or a valve because its pre igniting the fuel because boost pressure raises the inlet temperatures! thats why we have intercoolers. so it stands to reason to me that lower octane fuel will increase combustion temperatures so does this mean unleaded runs hotter well it does if the octane rating is lower! thats only my understanding tho im not a particle physicist im a welder!

Exactly!

Yes the lead had a lubricating effect, so yes with out any sort of replacement for that then you will get friction and thus increased heat - but i've yet to find figures that will give any real qualititive evidence of how much difference.

Just cos a bloke in the pub told you doesn't make it true.

That said lots of customers at work seem to think so.

Anyway i am now going to end my involvement in this thread cos i'm bored with it - let it die a natural death.

higher octane lower cylinder temperatures! run two identical engines one with leaded one with unleaded and the one with the higher octane will run cooler simple as that! when combusted lead leaves particles and sulfates in the combustion chamber and on the valve seats which stops metal to metal contact i e acts as a lubricant which stops the two metalic surfaces welding together and pulling particles of each other off when forced apart again! which is the cause of the erosion it has nothing to do with raised temperatures

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If you have any servicing needs or any technical queries dont fail to contact me on nic.b_c@btinternet.com 01915208556 or 07773203551

Why lock it, whos sick of it etc etc etc , I see people posting on it!

Flange, spongle, gravy flaps, barse, ooh smack 'da helmet.

_________________
If you have any servicing needs or any technical queries dont fail to contact me on nic.b_c@btinternet.com 01915208556 or 07773203551

_________________
If you have any servicing needs or any technical queries dont fail to contact me on nic.b_c@btinternet.com 01915208556 or 07773203551

_________________
If you have any servicing needs or any technical queries dont fail to contact me on nic.b_c@btinternet.com 01915208556 or 07773203551