JJB

I see that in the P5 manual they call for 87 octane fuel (min) for the car... I have usually (in all my past cars) ignored that and run premium fuel in the car...

any opinions on what should/should not be run?

thanks!

Protege5chick

TTHANK YOU! Someone who agrees! BTW, I used Premium grade in my mercedes (because it asked for it in the owners manual) but it always has a rotten egg smell after driving it...i once accidentally fueled up on regular and the smell was gone...hmm...could it be...the car companies and gasoline companies just trying to make a buck?

Joe_Pro5

Yeah, thanks!
I always figured it wasn't worth it to get premium in my P5, and thanks to you I can justify not buying it

It's a shame more people don't know... a lot of my friends are hooked on premium because of the 'hype'

eeterp

I put in the highest available (91 or 93 octane) due to the higher compression of the fs-ze I swapped into my pro. So, any of you thinking about the swap may want to keep in mind that you'll need high octane gas too.

Sporin

Never put in more or less octane then the manual recommends... period.

My last car was a Passat 1.8T which required 91 or higher, so that's what she got. The P5 requires 87, so that's what she gets.

Don't let Exxon's marketing hype cost you.

turboge

I run 91.....but then again I run 30+ degrees timing under boost in hot weather =)

At the track I throw in 100 for safe measure due to 20psi...

130hp

i run 94 on my 2000 Acura 3.2TL (requires at least 91)
and i run 89 on my stock 2001 Protege ES
maybe im dumb. im use to it.

islandpro

87 here

MP3-Owner

Unless you are going to run Nitrous. Then you have to use 92 or better. Look here...http://photos.yahoo.com/bc/mp3owner/...c=ph%26.view=t

njaremka

oh boy, i guess we don't have any chemical engineers on the board, or at least they don't want to chime in.

Octane is a hydrocarbon. Octane is very explosive, but resists spontaneous combustion when it is compressed. this is why it is reccomended for high compression engines. the other component in gasoline is Heptane, which is also a hydrocarbon. Heptane does not like to be compressed, and has the tendency to ignite when compressed to much. Octane and Heptane are mixed to form gasoline. (among other ingredients) higher Octane will not give your car better performance, but it will lead to better combustion properties. if you have a dirty combustion chamber, there will be "hot spots" that will cause the gasoline mixture to ignite before the piston has reached the proper spot with respect to the crank rotation and cause the 'pinging' that every one talks about. with a higher Octane rating of gasoline, the mixture will not ignite untill the spark plug makes it ignite.

the reason for going with higher Octane is so that the gasoline will ONLY ingnite when the ignition system (spark plug) tells it to. just saying that Octane's only purpose for living is so your engine won't knock, really isn't telling the whole story.

so, in summary, Octane is highly combustable, but has a higher threshold for spontaneous combustion when subjected to higher pressures.

now, when it comes to what you should use in your car, i have a 2001 protege ES and the owners manual suggests using 91 or higher rated gasoline, and i use 93. the dealer i bought the car from, filled it up with 87 before i bought it and i got worse milage from the engine than when i started using 93. your results may be different, but that is what i noticed.

01esgt

In my manual on my Canadian spec Protege ES 2.0, the manual says to run 91 octane. I noticed the engine runs rougher with 87 and when it comes to racing i gain about a car length in the process. I may be stupid but its what the manual says. I usually run 87 but the car likes 91 better.

Net Seven

If you get a BPT or B6T and it says to run 91 or higher. I know there is someway they can change your ignition so that you can run 87 on it good. Would it be worth it, or would turbo engines run a lot worse from this downgrade?

P5Scott

Actually the Canadian Protege manual says to use 87 R+M/2 or 91 RON... typically gas pumps display the R+M/2 number, meaning the Protege only needs 87 octane...

P5Scott

If u get the rotten egg smell from higher octane you should either switch fuel companies or use a lower octane... the rotten egg smell means the engine isnt making any use of the extra potency of the fuel and dumping it into the exhaust system and ruining your catalytic converter.

ProtegeRider

Gasoline is mainly a mixture of hydrocarbon molecules, aromatic and nonaromatic, composed of five to ten carbons. It is important that these carbons vaporize and mix with oxygen and then undergo a smooth and controlled combustion so that the resultant energy can steadily and evenly push against the piston and turn the wheels. The nature of hydrocarbons in gasoline is important. They must be easily vaporized, but not so volatile as to boil out of the gas tank. Higher molecular weight components (higher boiling points) in the summer and lower molecular weight components (lower boiling points; more easily vaporized) in the winter enhance gasoline performance.
Octane numbers are used to describe gasoline performance. When the scale was first devised, isooctane, a branched alkane noted for its antiknock qualities, was assigned an octane number of 100. Heptane, a straight chained alkane and poor automotive fuel, was assigned 0. A gasoline that burns like a mixture of 90% isooctane and 10% heptane is assigned an octane number of 90, whether determined by the Research Octane Number (RON; laboratory conditions) or Motor Octane Number (MON; road conditions); the number posted on a gas pump is usually an average of the two.

This is from my notes in my Organic chemistry class. I'm in the last term of my chemical engineering program and i use low octane fuel (87) in the winter and high octane in the summer (92).