Better to run higher octane fuel on an older acccord?
 

I have a 94 Accord. Its starting to get sloppy at times possibly engine knock. Would higher octane fuel make the car run better and smoother since its older and has less compression than what it began with.....

I would not run anything much higher then what its rated at. It will run too hot and possibily cause damage. Higher Octane = Higher Burning Temps.

less compression = less octane also.

Re: Better to run higher octane fuel on an older acccord? (hondaracin24)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SPEED FoRCE &raquo;</TD></TR><TR><TD CLASS="quote">less compression = less octane also.</TD></TR></TABLE>
what he said

Re: (BryonC17)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BryonC17 &raquo;</TD></TR><TR><TD CLASS="quote">I would not run anything much higher then what its rated at. It will run too hot and possibily cause damage. Higher Octane = Higher Burning Temps. </TD></TR></TABLE>

This is not true. Octane is an anti-detonant, which in laymans terms means that it helps to keep the air-fuel mixture from combusting before it is supposed to. You don't necessarily have less compression. I have seen cases where an older engine has more compression due to a lot of carbon buildup(which can also cause detonation because it can stay red hot, acting similar to a glow plug). You can't tell your compression without using a compression tester. Using higher octane fuel will help "knock", but you will be basically bandaging a underlying problem. It won't hurt.

OK it may not overheat, but there is potential problems with doing it. The following explains it.

I THOUGHT GASOLINE WITH HIGHER OCTANE REDUCED ENGINE KNOCK?

It did in older engines using carburetors to regulate air/gas mix They cannot as accurately regulate the air/fuel mix going into the engine as a computerized fuel injector. Carburetors need adjustment, as a part of regular maintenance, to keep the air/fuel mix as accurate as possible. So many times, these adjustments were not made regularly causing too much fuel to be mixed with the air. When this happened the gasoline would not burn completely soaking into carbon deposits. This would cause a premature ignition of the gasoline due to the intense heat in the engine cylinder creating "engine knock." When this happened, people would change to the higher octane/slower burning gasoline to resist the premature burn, thus minimizing the knocking problem. And it worked. Good solution.

However, since the middle to late 80’s, engines are designed to use fuel injectors with computers to accurately control the air/fuel mix under all types of temperature and environment concerns. However the accuracy of the fuel injectors and computers is based on using the recommended gasoline for that engine.

Most cars are designed to burn regular unleaded fuels with an octane rating of 87. If the vehicle needs a higher octane rating of 89-93, there is documentation in the owner’s manual, as well as possibly under the fuel gauge and by the fuel fill hole. Usually you will see this rating for high performance engines only.

WHAT IF I PREFER TO USE GASOLINE WITH HIGHER OCTANE RATINGS?

You can, but there are no real benefits, other than the gasoline manufacturers making more money off of you. When you use a fuel with a higher octane rating than your vehicle requires, you can send this unburned fuel into the emissions system. It can also collect in the catalytic converter. When you over stress any system, it can malfunction or not do what it was designed to do properly.

Re: (BryonC17)
 

I had to run premium in my 87 Accord because of engine knock. It would ping pretty bad on regualr 87. With 93 it ran great. I would assume it was a problem with the timing or a build-up in the combustion chamber bumping up compression but i was too lazy to fix it. I just used premium nad it ran great. I thought what a relief when I bought a new car to not have to run premium and then I bought a Legend which requires premium https://honda-tech.com/forums/images/smilies/emsad.gif

Edit: Most premium fuels have higher detergent content in them to keep your engine cleaner. I would run a tank of premium through a regular engine on occasion to help keep it clean but unless you have knock or your vehicle requires it, you do not gain any advantage from using premium fuel. (not including nitrous or modified engines of course)

wtf... i run 91 everyday. it does run smoother than 87. you know how i know? go put in energy suspension mounts in your car and try driving around on 87. you'll rattle your teeth out. and it is an anti-detonant...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BryonC17 &raquo;</TD></TR><TR><TD CLASS="quote"> When you over stress any system, it can malfunction or not do what it was designed to do properly. </TD></TR></TABLE>

then lets all just put our cars back to stock... we're adding stress to just about everything. oh and dont drive over 3000 rpm.

Re: (s.cali alan)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by s.cali alan &raquo;</TD></TR><TR><TD CLASS="quote">wtf... i run 91 everyday. it does run smoother than 87. you know how i know? go put in energy suspension mounts in your car and try driving around on 87. you'll rattle your teeth out. and it is an anti-detonant...

then lets all just put our cars back to stock... we're adding stress to just about everything. oh and dont drive over 3000 rpm.</TD></TR></TABLE>

So what are you trying to say? That is funny. My teeth don't rattle when I used regular gas. Sounds like your car is jacked up. Might not want to drive it over 3000 rpm.....

Re: Better to run higher octane fuel on an older acccord? (hondaracin24)
 

According to the owners manual for a 1994 accord, it says to use gasoline with an octane rating of "87 or higher" so Honda doesn't seem to think it would be a problem...

sohc

Re: Better to run higher octane fuel on an older acccord? (SOHCMAN)
 

it wont be a problem at all to run higher octane. maybe some places dont offer 87? or offer stuff lower than 87. I dont know about all that, all I know is, with less compression you can use less octane, its not as stable but since it aint as hot, it will run fine.

Threads like this are why I come back to honda-tech all the time.

Good thread... Im trying to learn something here.... but we've got 2 sides.... keep posting https://honda-tech.com/forums/images/smilies/emthup.gif

Re: (Nicknyce)
 

run the lowest octane needed... if you feel that your car runs better on a higher octane, and doesn't get lower mpg, then fine... run higher octane. i know for a fact that my car, '99 4cyl at ~150,000 miles, gets the best gas mileage on 87. (3-4 mpg better to be exact.) f-series motors tend to run better on lower octanes...

Re: Better to run higher octane fuel on an older acccord? (hondaracin24)
 

I notice a big difference when I run 93 in my 95 Accord. It seems to start faster and also run smother. I don't know if it burns quicker but it seems that I fill up a little more. http://images.honda-tech.com/set1//smile/emcrook.gif It is only 20 cent more than 87 so I figure it is worth it. $1.50 or so more if you fill up the tank.

Re: Better to run higher octane fuel on an older acccord? (Hybrid95Accord)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hybrid95Accord &raquo;</TD></TR><TR><TD CLASS="quote">I notice a big difference when I run 93 in my 95 Accord. It seems to start faster and also run smother. I don't know if it burns quicker but it seems that I fill up a little more. http://images.honda-tech.com/set1//smile/emcrook.gif It is only 20 cent more than 87 so I figure it is worth it. $1.50 or so more if you fill up the tank.</TD></TR></TABLE>

You're an idiot. Your car is not faster....period. Putting higher octane in a car that does not require it, will actually HURT performance. Dynos have proven it. Stop using you butt dyno to spread pompous information like the above.

Re: Better to run higher octane fuel on an older acccord? (Justin Klemgold)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Justin Klemgold &raquo;</TD></TR><TR><TD CLASS="quote">

You're an idiot. Your car is not faster....period. Putting higher octane in a car that does not require it, will actually HURT performance. Dynos have proven it. Stop using you butt dyno to spread pompous information like the above.</TD></TR></TABLE>

Agreed, using higher octane in a fuel injected car can actually cause a more rapid carbon build up in the engine. Especially in the EGR system on 6th gen and 4th gen Accords. I don't know why but for some reason I don't see as many EGR problems on the 5th gen Accords. But the 6th gen V6 cars carbon up really bad on 92/93 octane.
(See the same thing in all 98 and newer Honda V6 cars.)


Besides the fact that the original post is most likely referring to piston slap as a knock which has nothing to do with octane of the fuel you run.