Any difference between 91 and 94 Octane?
02-06-2009, 07:50 AM
#31
Audi Forum - Posts like an S4
Join Date: May 2008
Location: Calgary
Posts: 211
Re: Any difference between 91 and 94 Octane?
this isn't true UNLESS u either remap the fuel line (chipping it or flashing the ecu to make the car perform better).
higher the octane, the better the stroke of combustion will be for the spark plug to ignite. You make it sound like the higher the octane, the worse it is for the car rusty. Better fuel = better performance, why else would u not put 87 than 91? like u said, higher octane = higher temp.. so lower ur oct = much higher temp = weaker performance. think, the shittier fuel you put into your engine, the shittier the combustion output it'll give u because it'll ignite before it even reaches the spark plug which ****s ur engine up real bad. This is a GERMAN car bud, not a freaken honda civic where u can put even water and it'll still run.
higher pressure is when u chip it, or really aggressively step on the pedal (and this u do NOT want to do if u fill 87-89 octane), yes the timing will change, but if u keep it pretty low, your engine will eventually give u more downtime later on down the road.
yes your car runs great on 91 because it requires you to put it. Point is do u want to keep your car for a long time or are you a dumb enough to disagree with that?
difference between 91 and 94 isnt a big difference ill admit to that, but its cleaner none the less and gives the engine a better fuel to run with. if you dont clean your fuel injectors at all, putting 94 oct will help u reduce clogging and better emissions.. studies even show that.. dont tell me your smarter than those who invested billions of dollars to prove that this is a factual result.
idl: back to your question about why dont audi recommend you 94 octane is because not all areas provide 94 octane.. at best they only provide 91, 93, and 94 in rare locations.. thats why they made it standard at 91.
higher the octane, the better the stroke of combustion will be for the spark plug to ignite. You make it sound like the higher the octane, the worse it is for the car rusty. Better fuel = better performance, why else would u not put 87 than 91? like u said, higher octane = higher temp.. so lower ur oct = much higher temp = weaker performance. think, the shittier fuel you put into your engine, the shittier the combustion output it'll give u because it'll ignite before it even reaches the spark plug which ****s ur engine up real bad. This is a GERMAN car bud, not a freaken honda civic where u can put even water and it'll still run.
higher pressure is when u chip it, or really aggressively step on the pedal (and this u do NOT want to do if u fill 87-89 octane), yes the timing will change, but if u keep it pretty low, your engine will eventually give u more downtime later on down the road.
yes your car runs great on 91 because it requires you to put it. Point is do u want to keep your car for a long time or are you a dumb enough to disagree with that?
difference between 91 and 94 isnt a big difference ill admit to that, but its cleaner none the less and gives the engine a better fuel to run with. if you dont clean your fuel injectors at all, putting 94 oct will help u reduce clogging and better emissions.. studies even show that.. dont tell me your smarter than those who invested billions of dollars to prove that this is a factual result.
idl: back to your question about why dont audi recommend you 94 octane is because not all areas provide 94 octane.. at best they only provide 91, 93, and 94 in rare locations.. thats why they made it standard at 91.
Rusty is correct in his comments.
02-06-2009, 11:29 AM
#32
Audi Forum - Posts like an A1
Thread Starter
Join Date: Jan 2009
Location: Victoria
Posts: 12
Re: Any difference between 91 and 94 Octane?
like i said before, my car hasn't cost me anything yet in terms of parts like replacement. been running 94 everytime.
if u love your car u give it the best, if you dont ull give it less. gas difference compared from cheap gas to good gas is 5 bucks difference, so u save 5 bucks... on a tank.. want a high five?
w/e, its your car.. your problem.
if u love your car u give it the best, if you dont ull give it less. gas difference compared from cheap gas to good gas is 5 bucks difference, so u save 5 bucks... on a tank.. want a high five?
w/e, its your car.. your problem.
Maybe 91 is better than or maybe equal to 94 for our car.
02-07-2009, 08:24 AM
#33
Audi Forum - Posts like an A1
Join Date: Jan 2009
Location: Montreal
Posts: 13
Re: Any difference between 91 and 94 Octane?
I can attest to that, I'm chipped GIAC though, but my car seems to run better on 94. Not to boast, but I was averaging 670 km (highway driving) a tank without any respect for speed limits. Averages to about 8.96L/100KM or 26.25 MPG.
02-11-2009, 10:55 AM
#34
Re: Any difference between 91 and 94 Octane?
so wantthema i'd just like to ask, when the last time you took a course in thermodynamics or fluid mechanics?? It might be an idea before writing off my opinion, and especially assuming that I'm ignorant. You are taking things the wrong way, I never said it do any harm to run a higher octane, there is just a point where it doesn't help any or much.
I did not disagree with the fact that it would help clean your engine (companies put more additives in the higher octane fuel, eg. more techron at chevron) , but I do believe you would get better bang for your buck with a good fuel injector/system cleaner.
I'll just leave it at that, just remember this is a place to post your opinion on the subject not the users.
I did not disagree with the fact that it would help clean your engine (companies put more additives in the higher octane fuel, eg. more techron at chevron) , but I do believe you would get better bang for your buck with a good fuel injector/system cleaner.
I'll just leave it at that, just remember this is a place to post your opinion on the subject not the users.
02-11-2009, 11:08 AM
#35
Re: Any difference between 91 and 94 Octane?
just to clear up the whole high temp high octane thing.
a lower octane fuel has a lower combustion temperature and vise versa. Adding more combustion pressure (ie. more boost or higher static CR), ups the temperature inside the cylinder. If the fuel your running can't handle the temperature before the piston reaches top dead center, detonation will occur. This is the reason for running higher octanes. Our cars do have sensors and will avoid this, but this is when you start to lose performance
a lower octane fuel has a lower combustion temperature and vise versa. Adding more combustion pressure (ie. more boost or higher static CR), ups the temperature inside the cylinder. If the fuel your running can't handle the temperature before the piston reaches top dead center, detonation will occur. This is the reason for running higher octanes. Our cars do have sensors and will avoid this, but this is when you start to lose performance
02-12-2009, 10:37 AM
#37
Audi Forum - Posts like an A4
Join Date: Dec 2007
Posts: 126
Re: Any difference between 91 and 94 Octane?
Rusty, sorry but you are about to get a Nobel Prize in thermodynamics.
Guys, I’d pay attention to Espritman99 as his explanation reflects the reality closely.
You might believe the higher is the better but that’s through up to certain level => beyond the optimal octane rate for YOUR particular engine (state of combustion chambers specific) one will get high unburned hydrocarbons – the result is failed Air Care or Clean Air.
Is well known fact that with age any engine requires higher octane (due to mostly carbon deposits).
Just stick a gas analyzator in your exhaust and read with different grades.
(This topic is appreciated as much as the oil topic)
Guys, I’d pay attention to Espritman99 as his explanation reflects the reality closely.
You might believe the higher is the better but that’s through up to certain level => beyond the optimal octane rate for YOUR particular engine (state of combustion chambers specific) one will get high unburned hydrocarbons – the result is failed Air Care or Clean Air.
Is well known fact that with age any engine requires higher octane (due to mostly carbon deposits).
Just stick a gas analyzator in your exhaust and read with different grades.
(This topic is appreciated as much as the oil topic)
12-15-2010, 12:22 PM
#38
Audi Forum - Posts like an HORCH
Join Date: Dec 2009
Location: Burlington, Ontario
Posts: 2,719
Re: Any difference between 91 and 94 Octane?
Here a link to a discussion on gas differences.
https://www.audiforum.ca/general-aud...o-you-use.html
https://www.audiforum.ca/general-aud...o-you-use.html
12-15-2010, 07:56 PM
#39
Audi Forum - Posts like a Q5
Join Date: Aug 2010
Location: Calgary
Posts: 531
Re: Any difference between 91 and 94 Octane?
I bought 94 at Chevron and I found the car sluggish afterwards. I had to wait untill it would gain momentum and start accelerating. Never again. 91 or 92 is better.
It is not true that high octane is more power. High Octane is only highly resistant to detonation this is all.
Gas has so called Cetane number and this is what describes temperature, but they will not tell you about it.
Higher Cetane = more power.
I increase cetane by using diesel fuel conditioner or nitromethane or ether.
Nothing equals addition of 100ml of nitro, bang for my buck!
It is not true that high octane is more power. High Octane is only highly resistant to detonation this is all.
Gas has so called Cetane number and this is what describes temperature, but they will not tell you about it.
Higher Cetane = more power.
I increase cetane by using diesel fuel conditioner or nitromethane or ether.
Nothing equals addition of 100ml of nitro, bang for my buck!
Last edited by adamstasiak; 12-15-2010 at 08:00 PM.
