What makes you think running a higher octane will give you better performance. It might, it might not. I'll give you an example. I know someone who a few years ago got a brand new stock Honda CRF250 mx bike, not fuel injected. He put it on the dyno and tested every fuel mix they could think of. From 91, 95, 98, straight avgas, various avgas mixes, and a race fuel. Which fuel gave the best overall performance, thats right, it was 91.
I would think an expert would tell you, the octane you should use would be governed by the compression ratio of your motor. The higher the compression, the higher the octane required. I beleive higher octane fuels burn cooler than low octane, ie they have a lower detonation level.
I've learnt this shit the expensive way by having to rebuild motors due to running the wrong fuel. There are quite a few misconceptions out there and I'm sure some will say I'm wrong here. All that really matters is that you know what works for you.
ralphdog1,
Jun 4, 12:42am
That cool, you therefore should have qualified your previous advice with what you have just said there. I have done extensive comparisons (30,000k+) on my two recent vehicles, one there was virtually difference in l/100km, the other there was, to the point 96/98 was cheaper per km. So to say "The fuel economy will be the same." is rubbish.
00sub,
Jun 4, 12:52am
if you have a high compression engine or turbo you should be running a higher octane as these engines will not runn aswell on the likes of 91, and some cases 95 is still to low. keep in mind jap cars are usually designed to run a high grade fuel which we dont really have over here except for some 98 fuels. my car has a 11.5:1 compression ratio and runs very well on 98 and also getmore economy than on 95 as engine is getting a better burn. will never run 91 its just crap
zirconium,
Jun 4, 12:55am
Op is just talking about the colour of the handles at the pumps. Green is low octane, red is higher octane. Fuel for cars is not allowed to have lead in it in NZ, hasn't been allowed for about 15 years.
95 is the better fuel for your car, as well as mine
theknightz,
Jun 4, 6:27am
Blue is 98 octane
s.c,
Jun 4, 6:45am
So I'm lost which one doesmy BMW need!
unbeatabull,
Jun 4, 7:20am
95 Or Higher.
mgmad,
Jun 4, 7:31am
That's not a particularly scientific method, but it's better than having no evidence at all. With my wife's old Nissan AD 1300 injected, she used to run it on 91, so I did a few brim to brim tests (quite a few) then compared to the same with 95 - on 95 it used just under 10% less fuel than on 91 - result is obvious, way cheaper to run on 95. And that car ran fine on 91, no pinking, and no appreciable gain in performance on 95 (not that it had any performance anyway), just cheaper to run on 95.
mgmad,
Jun 4, 7:32am
And I would agree with this as well.
horsepower7,
Jun 4, 10:29am
red 95
bellky,
Jun 4, 8:57pm
You have quite an annoying tone. I don't have to qualify myself at all should I choose not to. 'The fuel economy will be the same' is not rubbish.
bellky,
Jun 4, 8:59pm
Oh right, my method is not particularly scientific. Well yours is no better Einstein.
the_chooky,
Jun 5, 1:57am
100LL is also blue.
bellky,
Jun 5, 4:06am
Yes that's right, but don't forget about turbo/supercharging etc. Compression ratios around 9:1 are ok for 91 octane I think.
mgmad,
Jun 5, 5:27am
Well, yes it is. The amount of fuel you were putting in would have varied significantly with the cost in fuel, so you put in "about the same amount" of petrol each time, then drove "about the same distance". Not partiucarly scientific. I did multiple back to back tests were I filled the tank to the top, and recorded the mileage. This will still have some error, but it will be very small and much lower than your method, and it's about as accurate as you can get for real-life testing without some really expensive equipment.
dvince,
Jun 5, 11:38am
Because that's what the Australian market wanted.
ralphdog1,
Jun 5, 11:47am
Careful with the tone there MG, Belky will tick you off for being annoying.
bellky,
Jun 5, 8:38pm
No. I put in a certain amount every working day over 4 years. The pertrol price didn't change every day obviously, but it did change. And I drove exactly the same distance. So there.
tonyrockyhorror,
Jun 6, 12:57am
95 min.
If you use 91 in pretty much any engine with a knock sensor, the ignition timing will always be retarded back on engine load, and not to a point that just stops the detonation, but to a preset safe setpoint in the ECU. That is usually a lot more retarded than actually necessary and thus engine power will be down on what it should be for that throttle opening.
The only way to prevent this occuruing is to use fuel that doesn't cause detonation in that engine in the first instance.
tonyrockyhorror,
Jun 6, 1:00am
Exactly.
He's trying to claim that for 4 years $25 worth every day was always the right amount of fuel to last for just that day. The tank was never any higher or lower after each dose and trip. The fuel at the beginning and the ead of each trip didn't gradually increase or decrease over time.
Yeah, right.
bellky,
Jun 6, 1:13am
You duds are too dumb to understand.
bellky,
Jun 6, 1:13am
It is proof.
bellky,
Jun 6, 1:14am
Complete rubbish.
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