Octane rating of fuel

[iket]

Hey guys..
did a quick search of the forum and didn't come up with anything.

I've got a H22a prelude and the manufacturer recommends 95 octane or greater right?

My question is what would happen if less than 95 was used? ie. 90 octane.

My mate told me it was only a performance issue and that the car would be a bit sluggish from it, but I beg to differ. I belive it wouldn't be so forgiving.

Can anyone confirm this? cheers

[DLO01]

You should never use anything less than what the manufacturer recomends. Not only will performance suffer, but you can damage your engine.

Please research RON:
http://en.wikipedia.org/wiki/Octane_rating

[Luder88]

I believe the best fuel we all must use in order to maintain good fuel efficiency plus performance is '98ron' fuel.
Something like Vortex 98 or Shell V-Power is sweet.

[dahon]

i always heard you could go 1 level up or down on recommended octane ratings... depending on what u wanted...

[teh_mechanic]

going up is not going to hurt your car (say if it recommended 91 octane,using 98 octane will still benefit your car,most of the time these petrols are the premium unleaded and are slightly more refined).

However using a lower octane rating than is recommended can cause damage to your engine.a manufacturer will usually recommend 95 or 98 (premium unleaded) on engine with higher compression ratios....the higher octane fuels burn more smoothly and evenly in these 'high performance engines' wheres 91 octane fuel could cause an engine condition known as pinging,this is very bad for your engine,will shorten its life and in extremes can melt holes in the top of your pistons....off topic,but another cause of pinging is timing being too far advanced. If your car pings,checking your timing,or going up an octane rating in fuel can fix it

[EuroDude]

For a 95RON tuned engine:

91RON - only use it in an emergency, when 95RON or higher isnt available. Drive gently to avoid pinging.
95RON - use this fuel as normal
98RON - use this fuel to gain fuel efficiency, possibly more power, and to keep the engine clean (it contains additives that clean the engine).

[[NAV]]

have you guys seen the 100octane vpower racin they sell at shell petrol stations?? is that any good? or are they just adding ethanol to it

[teh_mechanic]

shell vpower 100 octane is good,if your running high compression,very advanced timing etc etc.

the thing people dont realise is that higher octane fuel does not actually make your car faster (bp say it will make it a bit faster but thats because the bp ultimate has slight cleansing agents,which make the engine gunk up less,increasing performance....thats their claim anyway).
Higher octane fuel allows you to run higher compression,which is associated with faster cars....but running shell v power 100 octane in your stock motor (no internal work) is pretty much a waste of money,but if you feel it makes a difference,and you can tell the differene,then go for it,why not

[SHIFTY]

we often get cars in that use shit fuel (below the specified octane rating) it can really harm ur engine so u got 2 be careful...

last case scenario if there is no 98 just get 95 and throw in some octane booster....

[dahon]

isnt regular shell unleaded 95 anyways?

[teh_mechanic]

isnt regular shell unleaded 95 anyways?

regular unleaded these days is normally 92 octan (and with 10 percent ethanol these days
Premium unleaded is normally 95 octane.
BP Ultimate and Shell V Power etc is 98 octane.
Shell V power racing is 100 octane

[aaronng]

isnt regular shell unleaded 95 anyways?

It is 91.