Ok, I know the Premium requirement argument has been done to death. But
I do have one question.
From what I understand, Our cars run the best on 91 octane fuel, Should they
have a lower grade fuel put in, they retard the Timing to avoid knocking, I assume with a knock sensor that many new cars these days have.
So, would it be possible to fill up with 94 octane, Reset your ECU and have the same ECU that retards the timing advance it to make the best use of 94? I know the gains would be small But I have heard that retarded timing can knock HP and TQ down by as much as 22/25 Respectively.
Maybe it would require some Stand alone Engine Management to accomodate this?
94 Is just Pump gas, and Might aswell make use of it. Or, if 91 is as advanced as the ECU will allow then I won't bother using it.
( Y2K SE Manual )
Any Input would be great !

Markus.

 

My input..... dont waste your time messing with gas....

 

94 isnt high enough of an octane to make your motor retard on it's own. Thats what a J&S safeguard electronic module does.

Every car runs at it's prime with premium fuel. End of story.

 

i run 93 all the time. if you want to use higher octane maybe get a PCM or somthing

 

......but a lot of cars also run at their prime at less than premium, so why waste the money?

 

That's true. My truck runs fine on 87 octane and would not benefit from using anything higher. It's just a 2.4 liter 4 banger.

 

stick to normal premium. I highly doubt you'll see any difference with 94.

 

Well here in Ontario, Sunoco offers 94 octane and its not much more than 91 octane, so you might as well use it. It's only a couple of pennies more per liter.

 

i run with 93, would use 94 but it isnt sold much anywhere

 

here in jersy u could buy 94 at some places but i would think u would need to have some serious mods and maybe boost to make use of the extra octane.

 

Nope. Absolutely untrue, although that's what the advertising from the oil companies wants to brainwash you into thinking. So all you've proven is that you're able to be brainwashed.

 

It's not that simple. The timing advance maps in engines only advance to a certain point. Sometimes their maximum advance is set for 87 octane, and on higher end cars where manufacturers can get away with premium fuel requirements, they set them for 91 octane. If the user puts in 87, no problemo, that's what the knock sensor is for. Some cars even have multiple maps.

Example. The 2.4L I-4 in the Honda Accord has a knock sensor, but putting anything higher than 87 in it has proven on the dyno to show no substantial gains. So max advance in the ECU is set for whatever the best performance the engine can achieve is on 87 octane fuel. The 9.7:1 compression ratio is regular grade friendly also. Now take the 2.4L I-4 in the Acura TSX, which is a very tuned up engine of the same displacement. It gets its 200hp vs 160hp with a combo of many different things, but one of them is a higher 10.5:1 compression ratio (not really 87 octane friendly) and a premium fuel requirement.

Same displacement from the same engine block, but two completely different applications and with different fuel requirements.

 

That's only when the knock sensor is blown and the engine is on the safe map setting. With an operable knock sensor but just 87 octane in the tank the difference was around 7 whp and 9wtq on a 4th gen as I recall. More powerful engines tuned for premium would see a bigger difference.

 

Actually here in S.Florida there's Gas stations called VP Racing and they have 94, 97, and 102... errr 103 one of those two. Anyways I notice alot of people with boost uses them. A friend of mine used 97 octane with his Civic which only had intake, header, piping, and exhaust and ended up losing horsepower, he only drove it when he needed to and that lasted him almost 2 weeks lol.

 

I do too.
But we have modded ECU's which may benifit more from it.
I think 93 is high enough for me.

 

Plain and simple.....

Unless your boosted or built, your wasting your $$ putting in a higher grade fuel than the manufacture recommends.

 

and as it says on our fuel doors "Premium fuel recommended for maximum performance." Too bad while the Max was w/ my brother, it fell victim to his fill-ups w/ 89 octane, and there was a notable difference in the way it drove w/ 89 octane compared to how it drives w/ what I always put, 93 .. really noticed it when I got it back from him last spring. I only stick w/ whats good for our Max's, 93. I'll have to try a tankful of Sunoco Ultra 94 to see if there's a noticable diff. w/ just a slightly higher octane

89 octane works just fine in my GC, but that's my preference

Here's what I put in my cars & works for me:

89 octane - GC
93 octane - Max

 

I use 93 here in Birmingham, but only becuase I can't find a place that sells 91. I'm afraid to use lower than 91 because I might screw something up. I paid $1.84 for 93 today.

Mooney

 

I am guessing that Sunoco sells them since i remember the commercials w/ the quote "Ultra 94."

 

I wish people knew what octane really means...........

 

The output of an engine is positively proportional (when one goes up, so does the other, and vice versa) to the amount of air and fuel it can get in and out of the combustion chamber. On a four stroke engine with multiport fuel injection (and not direct injection), one stroke, called the intake stroke, has the intake valve(s) open, and the piston near or at the top, and drawing air in, as well as fuel from the injectors. Then the intake valves close, and the piston moves upwards (the compression stroke), compressing the air and fuel mixture. Pressure can be calculated by mass / volume. After the air and fuel enter the combustion chamber assuming perfect conditions, mass remains entirely constant until the exhaust stroke. However, the volume changes. That volume change is the compression ratio. With the VQ30, it has a compression ratio of 10:1. So the mass of air and fuel that enters the combustion chamber now sits in a volume 10 times smaller. Ergo pressure rises, and accordingly, temperature as well.

Octane is a measure of the fuel's resistance to combustion or volatility. The higher the octane, the greater pressure and temperature the fuel can withstand before ignition. When you run a lower octane, the limit of fuel and air that can be compressed is less than that of higher octane fuels. And because the amount of air and fuel that an engine can get in and out of the combustion chamber is positively proportional to output, this means if you use a higher octane, you can cram more fuel and air into the combustion chamber because it won't detonate too early (causing knock, and why octane is really another form of the anti-knock index).

What is the range of adjustment on timing, fuel delivery, etc, that the ECU can fudge with? Many, many Hondas have shown small but consistent gains to be had with going with high octanes, i.e. 98+. Not all Honda engines do, but many have shown consistent gains in the 7-10hp range at the wheels between minimum recommended octane and a 98+ octane gasoline. I don't know about you, but that's pretty noticeable gains considering it's only a switch in fuel, and no other mods, and on a stock ECU.

Which begs the question, how much range does the VQ30 ECU have? I would say lots. Why? Because I've fooled around with 98 octane fuel. I run a wet nitrous setup. I run up to a 50shot on 91 octane. After 50, I run 98. When I run 98 octane NA, there is a noticeable difference in the output, and the tone/volume of the engine. Just how much? I can't say. But I'd say somewhere in the range of 5-10hp. Nothing crazy, but noticeable.

However, one large factor that no one has addressed yet is the amount of boom you get for a given mass. Not all fuels expand at the same rate or ratio, nor do they produce the same amount of heat per given mass. Alcohols are generally used to increase octane. Back before the change from leaded fuel to unleaded fuel, lead was used to raise the octane of gasoline. Now, it's usually MMT. However, some gasoline suppliers use ethanol. MMT was touted as the great safe replacement for lead. It has its pros and cons. One, MMT is about as harmful as lead. It is primarily propaganda that allowed MMT to become the major replacement for lead as an octane raising gasoline additive. But as an octane-increasing additive, it gives more bang for the given mass of fuel compared to alcohol. Alcohol is a great octane-increasing additive from an environmental standpoint as the by-product of alcohol combustion is significantly “cleaner” than those of gasoline alone or gasoline with MMT. MMT is added is much smaller quantities, so you're getting a lot of gas, a little MMT. Gasolines with octanes raised by alcohol require quite a deal of alcohol, which is as discussed, produces less energy.

Generally, most 94+ gasolines have those higher octanes because of high amounts of alcohol. So, though your ECU may allow you to cram more fuel and air into the engine because no knock is detected by the knock sensor, and the oxygen content in the exhaust stream by the O2 sensors, that greater amount of fuel and air may not necessarily create a bigger boom, because alcohol does not produce as much energy as gasoline does when burned. Try soaking a bill of money in rubbing alcohol. Then light it. It burns with a blue flame, but not hot enough to burn the paper (actually, it's cotton) soaked in the alcohol (it will burn if dry and held above the flame). Try that with gasoline. It will burn orange, and hot enough to burn the paper.

One great additive for increasing octane is toluene. The only problem is, toluene has a way of eating plastics/rubber, of which part of the fuel system is composed. So long as the concentration is low enough, it’s plenty safe. The concentration and the amount of time it sits in the tank is critical. The higher the concentration, the quicker you should go through the tank. Also, the stuff is kinda on the toxic side. I mean, so is gasoline, but toluene is a little on the carcinogenic side, not that gasoline isn’t, but toluene much more so. It produces more power than alcohol per given mass though.

***Disclaimer*** I thought I would also mention that although performance seemed noticeably better while on the 98, I must also mention that after I finished off the 98, and went back to 91, the car ran like ****. My mileage was total ***, my power output was less than normal. I figured the ECU just needs to relearn. Hell no, I gave it like 2 months, and finally decided to reset the ECU. And voila, ran much better again on the 91. Also, the 98 octane I was mixing was done so by starting off with 91 octane, non ethanol anti-knock index rating aided gasoline, to which I mixed two different anti-knock index raising additives to it, as well as an upper combustion chamber lubricating additive for the oil that is consumed with the much higher cylinder pressures and temperatures of running 100 wet shot of nitrous.

 

My Honda was dyno proven to get 7-10 LESS horsepower on premium vs regular.

 

That definetly happens on a number of cars. The problem in that case is, the ECU is not capable or atleast is not taking advantage of the higher octane. In that case, the higher octane, lower volatility gasoline is not burned as thoroughly. Also, many premium gasolines have ethanol in them. When ethanol is burned it produces a smaller bang compared to gasoline.

 

I use super 93 all the time.

 

Alright lets make this easier on everyone, which Gas Station is more legit?... Has the "good" quality gas that we dont have worry about having poor performance and MPG. Chevron? Shell? Hess? Mobile? Texaco?
I only use Chevron, sometimes I'll use Mobile.