1992 Civic VX: Does it use premium fuel?

[mochabuzz]

I was wondering. Does the 1992-5 civic VX use premium (91octane) fuel? It has a VTEC, so i'm a little scared that i would have to use premium gas. The VTEC is called the VTEC E. Does anyone know if i can just use regular fuel in this type of civic? THanks

[R.I.D.E.]

Nothing but cheap regular in mine, no problem. Miles, carbon, and EGR issues could cause it to ping on regular, but it does not require premium to my knowledge.

Mine is a 94 (Federal emissions) that just turned 49k actual miles.

regards
Gary

[GasSavers_TomO]

The owners manual calls for a minimum of 87 Octane.

[IndyFetch]

I would expect the car would actually not run well on premium. A fuel's octane rating it its resistance to combustion. A fuel with a rating of 93 octane will be harder to ignite than a fuel with an 87 rating. Since the engine has such a lean air/fuel mixture in lean-burn mode, Honda actually designed it so that one of the intake valves will only open a smidge to let fuel "dribble" in and ignite near the spark plug. Otherwise, the mixture would be too hard to ignite. I am unsure if the car would run well in lean-burn mode with a higher-octane fuel.

[i-DSi]

Originally Posted by Fetch

I would expect the car would actually not run well on premium. A fuel's octane rating it its resistance to combustion. A fuel with a rating of 93 octane will be harder to ignite than a fuel with an 87 rating. Since the engine has such a lean air/fuel mixture in lean-burn mode, Honda actually designed it so that one of the intake valves will only open a smidge to let fuel "dribble" in and ignite near the spark plug. Otherwise, the mixture would be too hard to ignite. I am unsure if the car would run well in lean-burn mode with a higher-octane fuel.

Hi Fetch,
I would like to correct this. The octane numbers mentioned in this thread are extremely low. In Europe 95 octane is the LOWEST octane rate you can buy. 98 is also available. The Vtec-e engines were also sold in Europe, without any problem to ignite the lean mixture.
The octane rate is indeed as you mention the resistance to self combustion, but it does not mean a spark plug wil have any problem with a very high, or even extremely high octane rate (>100 is used in racing). The octane rate is resistance to heat and pressure caused ignition, not to spark-ignition.
Of course, a spark will have difficulties with igniting an extremely lean mixture, but this is independant of the octane rate.
By the way: I filled (and still fill) all my cars and motorcycles with the lowest availabel octane rate (95 in Europe). No problem at all.
If Honda says it runs on 87: i would buy this fuel for my car.

[theholycow]

The octane rating system is different in Europe, so the numbers don't directly compare.
http://en.wikipedia.org/wiki/Octane_rating

[IndyFetch]

Originally Posted by i-DSi

Hi Fetch,
I would like to correct this. The octane numbers mentioned in this thread are extremely low. In Europe 95 octane is the LOWEST octane rate you can buy. 98 is also available. The Vtec-e engines were also sold in Europe, without any problem to ignite the lean mixture.
The octane rate is indeed as you mention the resistance to self combustion, but it does not mean a spark plug wil have any problem with a very high, or even extremely high octane rate (>100 is used in racing). The octane rate is resistance to heat and pressure caused ignition, not to spark-ignition.
Of course, a spark will have difficulties with igniting an extremely lean mixture, but this is independant of the octane rate.
By the way: I filled (and still fill) all my cars and motorcycles with the lowest availabel octane rate (95 in Europe). No problem at all.
If Honda says it runs on 87: i would buy this fuel for my car.

Indeed, the octane rating is the resistance to combustion or "flash" ignition. I figure that if Honda went out of the way to create a new valve timing setup so that fuel ignites close to the plug, they must have had reason to believe that the mixture would be more difficult to ignite. Perhaps I'm wrong; I'll be the first to admit I'm not an engineer.

[i-DSi]

Originally Posted by Fetch

Indeed, the octane rating is the resistance to combustion or "flash" ignition. I figure that if Honda went out of the way to create a new valve timing setup so that fuel ignites close to the plug, they must have had reason to believe that the mixture would be more difficult to ignite. Perhaps I'm wrong; I'll be the first to admit I'm not an engineer.

Hi Fetch, the whole idea for the e-Vtec is to burn a lean mixture. Lean mixtures are extremely difficult to ignite and they burn relatively slow. The e-Vtec creates a rather rich spot just around the spark plug. Once the mixture around the spark plug catches fire, the rest is piece of cake!
This is the same e-vtec as in Europe.
I didn't do any research, but the resistance against spark ignition was in my understanding independant of the resistance against self combustion because of heat and pressure.
What I do know for sure: the most important factor for a spark to ignite the mixture is an 'ideal' mixture (not too lean and not too rich). High pressure makes it also more difficult to ignite (minimum tension needed becomes higher to create a spark). And some other factors (spark gap, temperature, humidity, dirt on sparkplug...).
But octane rate...? Not that I knew of.

[i-DSi]

Originally Posted by theholycow

The octane rating system is different in Europe, so the numbers don't directly compare.
http://en.wikipedia.org/wiki/Octane_rating

Hi Fetch and Holy Cow,
Just as I thought: also in this link there's nowher a relationship between octane rating and resistance to spark ignition. They explain that octane rating is a number to tell how much energy is needed to burn the fuel.
'Energy' is heat and pressure.
But thanks for the link. My fuel is also mentioned: 'Eurosuper 95'.
Hear you later!

[rgathright]

Could you run a few tanks of both fuel types for us and update your gas logs?