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

:thumbsup:

[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.

[SHIFTY]

ethanol is bad for our motors... so the v-power racing (100 octane which uses ethanol i beleave) is not good for our cars (there is a list here on honda aus website with cars that can use ethanol http://www.honda.com.au/wps/wcm/connect/internet/Honda.com.au/Home/Owners/Ethanol/)

[dahon]

nah cos i saw on their advertisement that shells unleaded is 95... was just wondering if it was true...

[teh_mechanic]

nah cos i saw on their advertisement that shells unleaded is 95... was just wondering if it was true...

its getting complicated these days.
unleaded is 92/91 octane and nowadays has 10% ethanol in it.this is sometimes called eco unleaded or some other crap because it has ethanol in it which is a more sustainable fuel source than old school petrol,so then what they call the regular unleaded is 95 octane,then the premium is 98....every manufacturer has a different version of naming though

[dahon]

yeh its really weird...
and i reckon that shell is just saying its 95, but its actually just 92... noone can really check anyway... bah

[Brash22]

Ignore all these stories about impending doom. The H22 ECU is equipped with a bunch of sensors so will retard the ignition timing if it notices sub-par fuel in the sytem. This will cause the engine to underperform, but won't do any damage to it.

Run 95 as a minimum, or if you're overly pedantic like me, run 95 only when 98 isn't available.

And if you don't want to spend the extra $3 or $5 at the pump, then a Prelude isn't the car for you.

[aaronng]

Ignore all these stories about impending doom. The H22 ECU is equipped with a bunch of sensors so will retard the ignition timing if it notices sub-par fuel in the sytem. This will cause the engine to underperform, but won't do any damage to it.

Run 95 as a minimum, or if you're overly pedantic like me, run 95 only when 98 isn't available.

And if you don't want to spend the extra $3 or $5 at the pump, then a Prelude isn't the car for you.

But if it is self-igniting before the ignition even fires, what protection will retarding the ignition give?

[teh_mechanic]

But if it is self-igniting before the ignition even fires, what protection will retarding the ignition give?

indeed,when you get really low quality fuel it can self ignite just from the compression alone withouth the need for a spark at all,so retarding the timing will not help....this is with quite low quality fuel though

[Terry_GT-R34]

QUOTE=SHIFTY;1543979]ethanol is bad for our motors... so the v-power racing (100 octane which uses ethanol i beleave) is not good for our cars (there is a list here on honda aus website with cars that can use ethanol http://www.honda.com.au/wps/wcm/connect/internet/Honda.com.au/Home/Owners/Ethanol/)[/QUOTE]

Hiya,

I looked up this site because I've been running my 4th Gen Prelude on E10 95 RON for 14 months now without any pinging or other adverse effects.

I noticed that all research recommendations referred to Hondas manufactured since 2002, which didn't really impress me being a Prelude owner. So I called up the Honda Hot Line on that site Ph: 1800-804954 and talked to a technician who said to-day (on 18/08/08) that officially, no research has been done on Honda Preludes running on E10 fuel; but he can't see why they shouldn't so long as the RON is equal or greater than '95'.

I've been reluctant to use V-Power Racing (soon to be phased out of Oz) on the GTR because of the ethanol content, although I know that some guys do use that fuel (despite the ethanol).

End Result: I'll continue to use E10 '95' on the Lude!

Cheers,
Terry

[port3s]

all you guys are saying higher octane wont do anything, but have you tried putting a lil nitro in your fuel tank or autogas i think it is.. WOW gives it a kick

[Petronas]

all you guys are saying higher octane wont do anything, but have you tried putting a lil nitro in your fuel tank or autogas i think it is.. WOW gives it a kick

I don't really know what you're talking about but it doesn't sound too good for our ludes... (Well my H22A anyway)

[Vti-Arh]

dont use anythin under 95, i dont know why u wouldnt. you want whats best for your car dont you?

[Stevo77]

dont use anythin under 95, i dont know why u wouldnt. you want whats best for your car dont you?

TRUE. i wouldnt ever use anything under the specified reccomendations.. 95 is reccomended for my teg but i still always put 98.. car runs much better.

[kelviN]

using 91 on a 95tuned car - one result is VERY poor fuel consumption. drinks like 16L-17L/100km haha. One previous long weekend there was only 91 around =(

[Terry_GT-R34]

^^^ Good point.

But even after putting some 91 in, the next fill will be with 98 will it not?

I would... Sweet as....:honda::wave: