abdr500

iTrader: (1)

if a cosworth is mapped to run 98 ron fuel is ther any benifit in running 102 ron fuel if its not mapped for it will ther be any increas in preformance

GARETH T

nothing to gain

Big Will_

Maybe a bit of safety factor as i'm sure i'm right in saying the higher octane fuel is more 'knock resistant' - but no power to be gained in using 102 when mapped for 98

abdr500

iTrader: (1)

GARETH T
right so if it was mapped to run the 102 fuel ther would be gains if yes how .why does the ron make that much difference

abdr500

iTrader: (1)

'knock resistant' sounds about right

Anonymous

You would probably see an increase in EGT's that you wouldnt be happy with if you increased from 98 to 102, but it depends on other qualities of the fuel not just the RON rating.
You would also see a loss in power and a loss in economy.

markk

iTrader: (2)

alot of fuels you can buy now dont get rated in the same way as the old fuels did, i.e shell turbo rally iirc doesnt come with an octane rating, as they seam to be a bit useless really.

Big Will_

Do you mean using 102 in a 98 mapped car?

Anonymous

Yes

Big Will_

I'm just curious as to why there'd be a loss in power with using a higher octane fuel - i wouldn't have expected a gain particularly as the ignition would be the same etc. but i'm just struggling to get my head around a loss

Anonymous

Higher Ron rating (all other things being equal) means a slower movement of the flame front, which results in lower peak cylinder pressures if you dont advance the timing to utilise the slower burn.
The extra "energy" potential of the higher ron fuel would just be given off as heat not make any power.

Well based on the limited experience I have of people silly enough to use a higher CR fuel without a remap to use it properly.

Ive yet to see any car get quicker as a result of running the wrong fuel.