chewyboy

i got an import and the engine has blown does using 95 or 98 octain fuel blow the engine up melt pistons or big end bearings go ive been told just wanted to see if any one else has had this problem
any help would be thank full.....

scoobyDAZZA

yes

japanese fuel is 100 ron
so import owners tend to use V-power with a splash of octane booster

Simon 69

Depends on the age of the car. Earlier Imprezas will run happily enough on Super Unleaded, but cars built for the 1998 model year and beyond need something a little more fruity than 97/98/99 RON fuel.....

StickyMicky

my 97 wrx has ran on mainly optimax/v-power without octane booster for 4 years now @ 1.45bar on the standard ecu



i have also ran 95ron without issues (although not at full throttle) infact i do belive my tank is full of 95 ron ta the minuite (it was filled up for free, be rude to say no LOL)

AndyC_772

iTrader: (2)

Are you sure it's that way round? I thought it was the later ECUs that are more adaptable when it comes to detecting knocking and making corrections. Or do the older cars run a lower compression ratio so it's not such a problem in the first place?

Andy
(about to be STI v2 owner )

Daft Lad

Not sure which way round it is regarding earlier / later ECU's, but I run my STi2 on V Power and a bit of octane boost just to be safe, the car certainly seems to run better with the octane boost added!

Shark Man

It depends on the year and model which also relates to the power output of the car.

Early classic shape 240ps cars are ok on 95rom, 260ps iffy, 280ps a big no unless it been remapped for uk Fuel.

Newage cars have better knock correction, but still should be used on their intended fuel or remapped for the fuel they will use.

mozzaITA

Ive just bought a sti 98reg - It has been in the uk since new and always run on 97-98-99 ron according to the former keeper.

Would my car suffer from not using super unleaded as its never been in japan anyway? NOT that im gunna put normal UL in her anyway.

James Neill

iTrader: (1)

You need to run it on Super (Shell V-Power or Tesco super at 99RON is best). BP super is not so good. Personally, I'd get it mapped to be on the safe side.

AlexJReid

I heard somewhere that 100RON wasn't available in Japan until around '98, so cars before then should be OK on 98/99RON.
I run my MY97 STI3 with V-Power and OB just to be sure, however...

StickyMicky

the reason why my 97wrx (280bhp model) has been fine

LEUVEN

How does the power output have an affect on what fuel is required?

hux309

When i first bought my 94 wrx it ran like a pos on sul/bp ultimate, so the first thing i did was fill her up with vpower, been running fine ever since.

However i do put in the odd splash of millers cvl turbo, engine definitely runs smoother and a bit faster.

Simon 69

Certain Andy. MY99 onward cars do have a better ECU, although its still quite poor (New Age cars do have a decent ECU though). 100RON fuel wasnt available when A; B & C-Series cars were built, so they dont need it. The power hike to 280PS came with the introduction of the higher octane fuel, hence the requirement. Even thought the ECU can be flashed, theyre still ****-poor at dealing with detonation and have little ability to retard the ignition.

Simon

Simon 69

Thatll probably be me: Ive been saying this on SN for a number of years (with a different user-name though). I was 1997 mind -or thereabouts-, when the D-Series cars were introduced.

Simon

Shark Man

Quite simple, the high output versions basically were designed to run on higher octane fuel.

The 280ps WRX only became available in Japan when 100RON fuel was available; the engine is essentially the same as the 260ps WRX, but the Engine ECU has been programmed to take advantage of the higher octane fuel which allows for the power increase.

However, the downside is it will be less tolerant to low octane fuel where it cannot compensate as well when knock and detonation is detected. The result of which is as mentioned, detonation, which in extreme cases will melt piston and overload big end bearings.

Shark Man

I thought you left Simon...that is if you are the Simon I think you are

dan83590

Let me get this clear. On a 'standard' ECU. So you have no remap, a dawes or bleed valve and a Fuel Cut Defender??

BigBez

i got my 95 import wrx (260PS) last NoV

i thad 100,000 KMS (60,000 miles) on clock from import, so assumed its been on 100 ron most of her life.

I ve always just used Shell V-Power nothing else seems to work fine....its standard engine atm

AlexJReid

That makes sense as that series saw the power go up, as you say.
My D-series is a December 1996, so luckily I hadn't assumed it'd be OK on ordinary super unleaded.

diehardbruce

always use high octane fuel

jaytc2003

iTrader: (1)

always a can of worms this type of thread. I used to run my my92 on supermarket unleaded (quite often as supermarket a few mins away from work so convienient) with a full decat and turned up boost with little knock activity, that was on a U8 ecu with a bleed valve, ran fine like that.

Now have an apexi pfc and that was mapped for 97ron, however I still use a mixture of normal supermarket 95ron and tesco 99ron (moved house so not to far away from a tesco), funnily enough never 97 ron but still get little knock activity (thought I had some issues recently but found out thats a water pump on its way out)

James Neill

iTrader: (1)

The higher power engines are more highly tuned. Tuning the engine includes advancing the ignition further. Basically, you can imagine this as the piston traveling further up the cylinder before the spark plug fires. The net result is a "more powerful bang", creating more force.

The problem with lower octane petrol is that it is (bizarrely) more flammable and under load can actually cause pre-ignition. So with the above explanation in mind, this means the "bang" is caused before the spark plug fires. This can damage the engine as the explosive forces work against the timing of the engine.

So, higher octane petrol burns more smoothly and the explosive nature of its ignition is more reliable under pressure.

So there you go, hope that helps.

Simon 69

Ali, I thought that you knew?

Andy S.

My JDM Sti has been remapped for UK fuels, now produced more power and torque than the origional set up, and as it has been remapped by Richard Bulmer it is as smoth as they come

I run the car on V power all the time

johnnywrx

I thought the early ones could'nt be mapped due to the ecu they run?
i run a 94 import and would like to have it mapped for uk fuel if it can be done?

Simon 69

The ECU cant be 're-mapped', but a daughterboard can be fitted which carries a new IC (which in turn carries the new parameters).

Simon

myblackwrx

iTrader: (1)

PolarPerformance
JollyGreenMonster.co.uk

Bob Rawle

Early cars ccan be live mapped now, did one today in fact

cheers

bob

Moley

iTrader: (9)

Is that the new ESL package?