RON octane Options

[CoSo]

In the manual, it says that the Celica should run on 91 or higher RON octane.

I was wondering if there's any benefit to running 98 RON (as per BP Ultimate) consistently, and most importantly, whether it has any side effects or detriments to the car in the long or short term? Sorry if this has been asked before, search didn't come up with much.

[popstar]

as i understand 98 could burn to hot and there fore 'coke' the engin....
i could be tolally way off, it's just the info i have...

i run on 95, but the petrol is so bag over here, i wouldn't trust what the pumps say and go for the best they have in .........
(most petrol stations stock '80' over here) !!!!!!!!!! even in the city !!!!!!

[Supersprynt]

The US doesnt use RON. It uses MON, I believe.

[Silvan]

RON98 is quite common here, but expensive. I fill her up with it once in a while, just to burn the engine clean, but doesn't matter in performance.

[popstar]

i found no noticable difference usinf 95 or 98 (apart from price) in my GT-4.....
but i'm not a hard driver.... so.....

but that's just me, someone else may have some facts for you when they wake up

[Supersprynt]

You wont notice a difference, the higher octane simply is used to fight off preignition. Everyone who notices a difference well, its psychological.

[97GTinKC]

You wont notice a difference, the higher octane simply is used to fight off preignition. Everyone who notices a difference well, its psychological.
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Actually, you can notice a slight difference, (in a GT or other engine with a higher compression ratio, an 8:1 low compression ST wont notice anything), the premium allows the computer to NOT retard the timing in response to the knock sensor, if you ever hear the pinging sound under load, you could benefit from a premium fuel, and I get approx 1.5mpg better on the premium over the lowest octane

The U.S. uses RON + MON divided by 2, which is why our numbers are lower.

This post has been edited by 97GTinKC: Feb 8, 2005 - 11:07 AM

[Mr_E]

You wont notice a difference, the higher octane simply is used to fight off preignition. Everyone who notices a difference well, its psychological.
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Want a bet? My car is supposed to run on 100 octane jap fuel. On standard 95, it retards the ignition to prevent detonation. It's noticeably less rapid.

i found no noticable difference usinf 95 or 98 (apart from price) in my GT-4.....
but i'm not a hard driver.... so.....

    but that's just me, someone else may have some facts for you when they wake up
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My four will run on 95, but it much prefers 98.

[_rz_]

well I can tell that if I use 92 the fuel consumtion rises compared to 95 or 98

[Supersprynt]

Mr. E. if you have a JDM ECu in your UK car, there will be a difference but thats ONLY because your Ecu is tuned for the normal Jap gas and not the gas thats commonly used in UK. Same thing with my car, I have a JDM ecu so I HAVE to use 93 in my car all the time. But the US uses an average of the Jap system and the UK system so your system is FAR below the Jap system, thats why you feel the difference.

I'm talking about the US, KC I have to disagree with you. What kind of slight difference are you noticing? If its so slight, you wouldnt be noticing it. Now wouldnt your fuel economy decrease if your car is advancing timing on a higher octane gas? The only reason its doing that is because its nto detecting knock, which is what higher octane gas does, deter detonation.

This post has been edited by Supersprynt: Feb 8, 2005 - 12:45 PM

[popstar]

i only notice any differents when i switch brands of petrol.....

and i don't believe what any of the pumps say over here, i just go for the highest available......

some petrol i got 300km from the city last summer, was ment to be 95 but felt more like 85 !!!!

so i would suggest that with out hard and fast information try some different brands and test between 95 and 98....

what was you car run on before ?
has it been tuned to that fuel ????

[Supersprynt]

Different countries have different standards, I dont have a clue what Russias would be.

Here in the states, I've used everything in the 5s, and whether its Mobil, Sunoco (used to have 94 but dropped it) or Hess they all felt the same. The 3s gets 93 only but thats due to the ecu.

[Chrobis]

I only get to use 91 in my 3s... and I have the group A ecu.... seems to run fine to me, ruff idel but I think that cause of my AFM being messed up. Still drives like crazy.

But if 93 was available here I would definitly pump it, and I know I would run into problems if I crank up the boost at all.

[97GTinKC]

Mr. E. if you have a JDM ECu in your UK car, there will be a difference but thats ONLY because your Ecu is tuned for the normal Jap gas and not the gas thats commonly used in UK. Same thing with my car, I have a JDM ecu so I HAVE to use 93 in my car all the time. But the US uses an average of the Jap system and the UK system so your system is FAR below the Jap system, thats why you feel the difference.

I'm talking about the US, KC I have to disagree with you. What kind of slight difference are you noticing? If its so slight, you wouldnt be noticing it. Now wouldnt your fuel economy decrease if your car is advancing timing on a higher octane gas? The only reason its doing that is because its nto detecting knock, which is what higher octane gas does, deter detonation.
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Other than a seat-of-the-pants power improvement feeling, it does seem to get about 1-1.5 mpg better on the good stuff, and I do keep pretty good track of that, I set the trip meter every time I fill up. average 29.7mpg on the premium. a little better if on the open road at a steady 65-70mph. My reasoning is that if its making more power at the same throttle setting, I need less throttle to move the car at the same speed, so the fuel mileage also improves when driven normally. its not a magical 20% gain or anything like that, but when you drive a 4-cylinder every little bit helps. (These cars need a wider spread on the tranny gear ratios. )

This post has been edited by 97GTinKC: Feb 10, 2005 - 2:54 AM