prof_dave

Just got an MY95 STi this afternoon - am still shaking and my face is aching from the smile!

Anyhoo, I was wondering if anyone out there could give me the definitive answer on octane booster - the cars an import so obviously I'm running it on Optimax, but should I be adding booster as well? The performance is more than adequate so I'm coming from a pure engine welfare kind of angle.

Also, can anyone tell me when I should be using the Intercooler Spray, if at all, and also, where the switch is (or would be, as I'm not sure if they're fitted) for the retractible mirrors.

Thanks in advance!!

The Prof.

kingofturds

iTrader: (1)

ive been running my 94 wrx on just optimax for nearly 10 months now never had any probs

GC8

I wouldnt run an STI2 on anything toher than Optimax and NF octane booster; Esso SUL at the very least. The engine will fail. Nitrous Formula is the best octane booster; without a doubt. I use the black 'Race Formula'; 50ml - 60ml per tank full; its the most economical as well as the best.

Simon

karl h

Im confused with all this. some say use it some dont which is it ?
Iv'e got a jdm 99 sti and just put optimax in it.
so maybe this is a stupid question but regardless of cost do i use
octane booster or not, is it good or bad for my engine.
and why do some say dont bother with it ???


karl.

GC8

Japanese (Premium) fuel has a RON of between 100 and 102; Optimax has a maximum RON of 98, other SUL is mostly 97; thats why you need to use an octane booster. Im afraid that 'I ran my WRX on SUL only for 6 months and its OK' wont be any comfort to you when youve run your big end bearings. If I were you I wouldnt consider driving an STI5 without using a good octane booster; in fact I wouldnt use anything other than NF.

Simon

RRH

The Jap ECU is optimised for 100 - 102 RON.

UK fuel is max 98 +-.5 (optimax).

Increase in Ron shows resistance to knock / det / pinking, which will damage your engine... an engine rebuild is circa £3000, whereas octane booster will probs work out about £3 per tank. Whilst I doubt anyone will say that your engine won't let go if you use ob, you are reducing the chances of a big bang, some may say significantly.

karl h

Thanks for the advice Simon

i sent a p.m. to you.


karl.

RRH

sorry, covered a certain amount of the same ground as GC8 as it took ages to type....

I picked up an STi5 the other day for track use, and got a total of about 6 miles before it let go

I had just filled her with Optimax plus ob, the previous owner had always done the same. howvere, at the start of her life, us UK citizens didn't know about ob, nor did we have optimax, and I reckon this was when the damage was done. Hoping to get her back from the engine man in the next week or so.....

G00ner

A friend of mine had a really tatty and well thrashed RA and through ignorance, never warmed up, never cooled down and never run on anything but supermarket fuel, he ran it for 12 months without incident...

Would I have brought his car... no chance, it will go bang one day.

prof_dave

Thanks for the advice guys - I'm going to get some NF ASAP - can anyone recommend an online retailer?

The Prof.

virgin

Dont suppose you know where to get NF cheap ?, or where do you buy it from ?

many thanks

prof_dave

lol - you read my mind!!

GC8

NF distributors are listed HERE; no one is especially cheap at nearly £15 per single bottle though. Still, NF is very effective at 1ml per litre of fuel, so a £15 bottle will stretch to six fill-ups on my WRX; at £2:50 a go this makes it substantially cheaper than Millers which is inferior in every respect.

Simon

GC8

Roger Clark Motorsport are probably the best bet btw; as theyre the importers.

Simon

RRH

I use Millers CVL (not a good plan if you have cats though) and have never noticed any difference between any of the octane boosters where knock-link activity is concerned.

redwrx

Ive got an my93wrx, i use optimax, and when its not available i use Normal unleaded ....ive never had a problem. (admittedly, i dont cane it as hard on normal)

i reckon im getting about 2km's more per gallon with optimax, than with normal.

If i had to use octane booster all the time, i wouldnt have kept the car as long as i have done ..... (4 years)

ive had full 3"decat exhaust, and ive got a (claimed) 300bhp modded ecu (from casmotorsport) ...and ive still never used octane booster....and 12months later it still runs fine.


If youre gonna cane it through every gear, everywhere you go, then yep, you could be inviting problems..

I guess its how you drive it....which detemines what fuel you'll need.


(sorry, if that contradicts any of the above posts, but thats the benefit of my experience.)


Frank



optimax 'is' 98.5 ron

MJW

Wouldn't it just be safer to get the ECU re-mapped to run on UK fuel ?

New_scooby_04

iTrader: (4)

Yep!