kingchrissyp

After a slight debate in another thread i thought it best to use this thread!So as title basically want to know whether it s safe to run on 95 RON and if so how much difference in performance you should notice?
Cheers Chris

kingchrissyp

Cheers mate

nick172sport

iTrader: (6)

super unleaded only on the inside off fuel cap seen it on at least four scoobys you can run with it but you will cause early detonation off engine be warned

ALi-B

iTrader: (1)

95RON is safe on a unmodified UK wrx bugeye (not PPP'd, mapped or modified).

Note always go by octane number, not by "premium" or "super" " branding, as these terms are too vague and non-specific.

The RON value is the measurement to rely on - and thats found printed in the user manual

kingchrissyp

This is the reason i asked the question as it gets mixed responses,as if the cars mapped to run on 95 RON then surely it won t benefit from any higher grade of fuel unless mapped to it? But then does it cause harm to the engine and if it does why would they map the car on fuel thats no good for it???
I m as confused as when i began

nick172sport

iTrader: (6)

all ive been told by many members on here previous posts about this and by meeting people with same model it causes early engine failure

bluenose172

iTrader: (2)

It won't cause engine failure, the ECU will more than likely pull timing in certain areas of the load/rev range to accomodate the lower octane fuel, hence the dip in performance.

cossie-nutter

iTrader: (45)

I know this may not be of any help But I only use Shell V Power just to be on the safe side!

Abit of course here I know but in the Rs Cosworth Tesco's 99 is fantastic stuff and can be noticed! (354bhp)

danog

I ran my unmodified 2004 wrx on 95 ron for two years with no problem. as stated earlier the ecu picks up any detintation an adjusts the timing to compansate. but if you fill it up with super you wont feel any difference as the ecu has chaged the timing. if you want to start running on super you need to reset the ecu so it relearns to run on super. Ive fitted a ppp on mine now so it has to run on super.

s c o o b y

i ran a standard 2000 turbo on 95 ron for years and with no probs. but now have it mapped so will be using something a little better now, was mapped on v power . it says super on the fuel cap aswell but never hurt it or my other one either.

kingchrissyp

Thanks for the info everyone

nick172sport

iTrader: (6)

well ive bin told otherwise on here and have been runnin mine on 99 ron because i dont want engine det these people whouve advised me then are puddled dont think so

ALi-B

iTrader: (1)

Its confusing because some Subarus can run 95Ron, others can't.

Then people take advice and warnings of other people who suffered the consequence of running a car mapped for 100RON on lower octane fuel. They then assume their car is the same, when its not always the case - as not all Subarus are the same

The main rules go:

Anything imported from Japan: WRX 98RON minimum, STi usually 100RON (depending on year, or if its been mapped for UK fuel).

For UK cars:

UK Turbo 2000: 95RON
UK WRX: 95RON
UK STi 98RON
UK WRX PPP 98RON (PPP=prodrive performance pack)

Anything modified; ask the tuner (usually 98RON minimum).

EU cars: as UK equivelent.

LAG

i always run my WRX on V-Power, after watching Top Gear a fee years back they proved that it made a difference on the Subaru, however on cars with less power such as clio 182 etc it did make a difference but not as noticable as a Subaru.

When I open my petrol cap it says run on super unleaded and as stated earlier in this thread super unleaded is not always high octain in some stations, i think Subaru were suggesting that you use high octain.

Midlife......

iTrader: (2)

For an unmodified UK Bugeye WRX the Denso ECU is a pretty fast learner and can cope with 95 RON

You will lose a litle of the (215 BHP) performance but won't have a problem with det and engine longevity as the ECU will modify the Closed loop map.

Any other performance mods will eat into the ECU's ability to cope (like the PPP) and 98 octane will be preferred but the ECU will still cope and degrade performance of the TD04 turbo output.

TBH it's difficult to break a TD04 turbo WRX bugeye as the performance is so crippled from the factory as not to encroach on the STi sibling .

Shaun

kingchrissyp

Cheers for all the replies
I ll run it on Super to begin with at least and then maybe try some 95 and see if i notice any difference?I don t mind paying the extra for Super as long as i know it actually worth it!And the car is benefiting from it.
You say it might actually be down on the standard power figures if ran on 95,but somebody said they were mapped on 95 fuel so surely it should make standard power on standard fuel?

ALi-B

iTrader: (1)

Put it this way, for some reason most (if not all) UK cars appear to put out more than standard power when run on RR dynos. (usually around 230bhp).

So on 95Ron a UK WRX should give AT LEAST 215bhp minimum IMO (unless there is something wrong with it).

Now it could be the dynos being favourable, or the rated figures are intentionally conservative (i.e absolute minimum power output on a hot stuffy day on 95RON at 3000ft altitude, or the official figures were fudged to make the UK cars more insurance freindly, speculate as much as you like ).

Tidgy

for the cost difference then id only ever run mine on vpower standard or not (classic uk turbo), tesco 99 is starting to get a bad rep for poor batch quality so wouldn't use that anyway.

would you feed a race horse mouldy old hay, or decent food?

kingchrissyp

Good point

s70rjw

iTrader: (2)

Much of the cost would be offset by the improved MPG 99 RON will give you.
However, the car will run just fine on 95 RON. I found all my UK cars were fine on it, but more responsive and thrifty on 99 RON

pmarch bugeye

I now run my standard WRX Bugeye on V Power all the time - as someone else has said it's better to err on the safe side - but the extra cost per litre does seem to be offset by better MPG than when using 95RON, so I think its all equal.

kingchrissyp

I ll give both a try and see what differences i notice performance,MPG etc as long as i know it s not doing any harm