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WJW Lawn
11-17-2006, 06:33 AM
Do you use 87, 89, or 93 Octane in your Lawn Equipment?

noseha
11-17-2006, 06:42 AM
all my stihl stuff I use 93 oct.. for my mowers and other stuff 87 oct. I use stable in all my gas! just because I do know when I uses them from time to time.

WJW Lawn
11-17-2006, 06:45 AM
I use 93 in my Stihl, Echo, and Redmax gear...and 89 in my mower.

kmann
11-17-2006, 08:02 AM
I use what the owner's manual recommends.

wriken
11-17-2006, 08:28 AM
I have been using 87 in everything, but recently went with 89 or 93 in the redmax's and trimmers.

jkingrph
11-17-2006, 08:51 AM
Have been using 87, old stihl blower was getting hard to start so switched to 93 for everything now.

tomo
11-17-2006, 06:31 PM
hello, always use octane rating provided by manufacturer as a minimum ,a higher octane number will give your engine increased resistance to internal detonation and in some cases better fuel economy .
In a older vehicle 4 example that originally used high octane leaded based fuel that is capable of using current low octane /unleaded and forced to by govt law the DECREASE in performance and fuel economy is HUGE.

tomo:waving:

Richard Martin
11-17-2006, 06:47 PM
I try to use 89 in everything.

Lugnut
11-17-2006, 08:51 PM
112 octane Sunoco at $8.75 a gallon is the way to go!!!!

Waterscapes By Design
11-17-2006, 08:59 PM
The guys down at my shop told me that I should just use 87 for the mowers, but I should AT LEAST use 89 with the small 2 stroke stuff. ESPECIALLY European or foreign made stuff, the gas they use over there and test all their equipment on is better stuff than ours is (his explanation he told me he learned when Stihl took them all over to Germany or somethin)....

WildWest
11-17-2006, 10:33 PM
The better the gas...the longer the life of the equipment! The high octane in the mix engines is the best thing you can do for them! 89 in the mower is 10 times better than the 87..... the higher the octane, the slower the gas burns, a slower burning gas means that if you develop a "hot spot" (usually carbon buildup) on a piston that caused PRE detonation the bulk of the explosion won't occur till AFTER top dead center... if it "bulk of the explosion" happens BEFORE TDC, then that is when you get your engine "knock" which is terror on bearings, journals, pistons, rods... and your wallet! ;)

DLG
11-17-2006, 10:57 PM
112 octane Sunoco at $8.75 a gallon is the way to go!!!!

ah!!!! racing gas got to love it.:weightlifter:

Jason Rose
11-17-2006, 11:00 PM
2 stroke stuff gets 93 becuse here it has no ethanol in it, everything else gets the cheap stuff.

Rons Rightway Lawncare
11-17-2006, 11:02 PM
You guys need to understand gasoline better, and once you do I am not so sure you would be spending extra money on the 89 or 93 Octane.....

If the engines compression and ignition timing is such that it is designed to run on 87 octane, there is absolutely no benifit to running a higher octane fuel. Believe it or not, 87 octane fuel is more powerful than 93 octane....

The one thing using a higher grade will help with is for the two stroke stuff. Not that the two strokes need the higher octane, but what happens is when you take a pint of oil and pour it in a jug of fuel, the oil degrades the octane level of that fuel, lowering it. The longer the jug sits, the lower the octane level becomes, and at some point the fuel is simply too low of octane to be safe for use. This is why most hard core Two cycle engine users - Motorcross bikers, Jet Ski racers, Snowmobile racers, ultralight airplane pilots, etc... - only mix oil in the fuel they plan to use that day and whatever is left over they don't save, they put it in their lawnmower or truck or whatever else they can use it in.

Most of the engines we use in this industry are somewhat low compression and the ignition is not advanced very far, chances of damage with 87 grade fuel is very little to none. There is really no good reason to spend more on higher grade fuel...

FATWEASEL
11-18-2006, 12:54 AM
The better the gas...the longer the life of the equipment! The high octane in the mix engines is the best thing you can do for them! 89 in the mower is 10 times better than the 87..... the higher the octane, the slower the gas burns, a slower burning gas means that if you develop a "hot spot" (usually carbon buildup) on a piston that caused PRE detonation the bulk of the explosion won't occur till AFTER top dead center... if it "bulk of the explosion" happens BEFORE TDC, then that is when you get your engine "knock" which is terror on bearings, journals, pistons, rods... and your wallet! ;)

I'm not sure that it burns slower. I think it just doesn't burn. If it doesn't burn, it's gonna do one of two things. 1. Exit the exhaust pipe or... 2. Wash down the cylinder walls. Number 1 is throwing money away every minute your mower runs. Number two is throwing money away when you waste unburned fuel, score the cylinder walls, lose compression and power, increase blowby, start burning oil, blah blah blah...........rebuild/replace engine.

The best thing is to put exactly what the manufacturer says to put in it. The ONLY exception I MIGHT would make would be in the dead heat of summer, say 95* plus for several days or weeks on air-cooled, carbed motors.

tomo
11-18-2006, 04:20 AM
hello, it is a known fact increase your octane increases power ,obvious dependant on application but at the end of the day itr still increases it even only a small amount .
For the people who did not read my prior post EG during the govts compulsory change 4 new vehicles from leaded/high octane fuel to low octane/unleaded from memory 1996 the lower octane fuel was gutless in performance and slightly higher fuel consumption . The same applies to vehicles made prior to this date the use of low octane fuel is any thing but exciting 4 performance and/or fuel economy .

The efects on a mower 4 eg would only be slight improvement and probaly not noticeable . Please be aware that air cooled engines operate at a higher level of stress and closer to absolute max .Another point is the larger the cylinder bore the less prone to detonation an engine is ,allthings being equal.This came from a mad keen volkswagon engine builder,apparently common knowledge in those circles.

tomo:waving:

John Gamba
11-18-2006, 06:12 AM
I try to use 89 in everything.


Same here:waving:

Rons Rightway Lawncare
11-18-2006, 09:05 PM
Tomo, do you have any proof of this fact? I bet you won't, but I am here waiting for it in case you do.

High performance engines use high compression, and advanced ignition timing.... Both of these things will tend to make detonation more possible in a engine. To avoid this, in these engines the manufactor reccomends using higher octane fuel, because higher octane fuel burns slower and more controlled and works better with the high compression and advanced ignition timing. It is not the fuel that makes these engines more powerful than their low compression counterparts....

Adding high octane fuel to a low compression engine, or a engine that has ignition timing set to allow for lower octane fuel, does NOTHING but drain you of more money from your wallet at the pump.

Most modern automobiles are computer controlled. The high performance ones in alot of cases require high octane fuel. This is because of the compression ratio and the high level of advance on the timing the computer is set to run at. You can use low octane fuel in these engines if you wanted to... The computer will detect the low octane fuel and will automatically ****** the ignition to avoid any chance of detonation. Doing this will result in less power than the engine would make on the high octane fuel, but typically only the very high performance vehicles require high test, and they usually have plenty of power to spare, and loosing 10-15 horsepower due to running low grade will not be missed.

If you wanted to put in high compression pistons and advance the timing on your Kohler or Kawasaki V-twin lawnmower engines, then running higher octane fuel would be needed to avoid engine damage, and overall the engine would produce more power, but not from the fuel, it would be from the pistons and ignition advance.

Like I said, alot of people don't understand fuel very well. Until I learned what I learned a few years ago, I would have and did assume that the higher the octane level the more power any given engine would make. I remember back when I was 18 and would go out on friday night to race friends, I would sometimes stop at Citgo and get a fill up of 100 octane " race " gas, I would have sworn it made my car faster, but knowing what I know now, it was all in my head.

saw man
11-19-2006, 12:32 AM
Ratings here are 85, 87 and 91. We are a little slow here in Utha! ;)


For mowers I dont care, for my handheld its always premium! I have equipment that goes over 15k RPM and the lower octane doesnt work as well in those machines.

tomo
11-19-2006, 04:42 AM
Tomo, do you have any proof of this fact? I bet you won't, but I am here waiting for it in case you do.

High performance engines use high compression, and advanced ignition timing.... Both of these things will tend to make detonation more possible in a engine. To avoid this, in these engines the manufactor reccomends using higher octane fuel, because higher octane fuel burns slower and more controlled and works better with the high compression and advanced ignition timing. It is not the fuel that makes these engines more powerful than their low compression counterparts....

Adding high octane fuel to a low compression engine, or a engine that has ignition timing set to allow for lower octane fuel, does NOTHING but drain you of more money from your wallet at the pump.

Most modern automobiles are computer controlled. The high performance ones in alot of cases require high octane fuel. This is because of the compression ratio and the high level of advance on the timing the computer is set to run at. You can use low octane fuel in these engines if you wanted to... The computer will detect the low octane fuel and will automatically ****** the ignition to avoid any chance of detonation. Doing this will result in less power than the engine would make on the high octane fuel, but typically only the very high performance vehicles require high test, and they usually have plenty of power to spare, and loosing 10-15 horsepower due to running low grade will not be missed.

If you wanted to put in high compression pistons and advance the timing on your Kohler or Kawasaki V-twin lawnmower engines, then running higher octane fuel would be needed to avoid engine damage, and overall the engine would produce more power, but not from the fuel, it would be from the pistons and ignition advance.

Like I said, alot of people don't understand fuel very well. Until I learned what I learned a few years ago, I would have and did assume that the higher the octane level the more power any given engine would make. I remember back when I was 18 and would go out on friday night to race friends, I would sometimes stop at Citgo and get a fill up of 100 octane " race " gas, I would have sworn it made my car faster, but knowing what I know now, it was all in my head.

hello,B4 u read this i do understand fuel basics that is why i use to run "100 oct" in my drag bike[high compression].
During 1986 when i had just finished my trainee ship as a mechanic [largest dealer in state for chrysler,mitsubishi,alfa romeo ,hyster fork lifts] ,there were many many unhappy customers when the unleaded/low octane fuel was released . An equal comparison was the on road performance comparison day and night difference of the same vehicle s.
The engines were 99.9% the same .!! That was on a engine that already had lower than desirable compression and spark advance that was pathetic .
To this day it still is one of the worst vehicles i have driven on low octane fuel'

Engine mechanics, engine management 101 engine detonation sensor .
Air cooled engines do run spark advance and reasonable compression on
some models .Combine this with high combustion temps and very uneven cooling and u would be approaching the border of the fuel being exceptable .Also add into that high ambient and high load .not good .
tomo

johnwon
11-19-2006, 07:22 AM
Tomo, do you have any proof of this fact? I bet you won't, but I am here waiting for it in case you do.

High performance engines use high compression, and advanced ignition timing.... Both of these things will tend to make detonation more possible in a engine. To avoid this, in these engines the manufactor reccomends using higher octane fuel, because higher octane fuel burns slower and more controlled and works better with the high compression and advanced ignition timing. It is not the fuel that makes these engines more powerful than their low compression counterparts....

Adding high octane fuel to a low compression engine, or a engine that has ignition timing set to allow for lower octane fuel, does NOTHING but drain you of more money from your wallet at the pump.

Most modern automobiles are computer controlled. The high performance ones in alot of cases require high octane fuel. This is because of the compression ratio and the high level of advance on the timing the computer is set to run at. You can use low octane fuel in these engines if you wanted to... The computer will detect the low octane fuel and will automatically ****** the ignition to avoid any chance of detonation. Doing this will result in less power than the engine would make on the high octane fuel, but typically only the very high performance vehicles require high test, and they usually have plenty of power to spare, and loosing 10-15 horsepower due to running low grade will not be missed.

If you wanted to put in high compression pistons and advance the timing on your Kohler or Kawasaki V-twin lawnmower engines, then running higher octane fuel would be needed to avoid engine damage, and overall the engine would produce more power, but not from the fuel, it would be from the pistons and ignition advance.

Like I said, alot of people don't understand fuel very well. Until I learned what I learned a few years ago, I would have and did assume that the higher the octane level the more power any given engine would make. I remember back when I was 18 and would go out on friday night to race friends, I would sometimes stop at Citgo and get a fill up of 100 octane " race " gas, I would have sworn it made my car faster, but knowing what I know now, it was all in my head.
Hi;From my reading on this subject...I agree with the above quoted post. One thing about those good old days of leaded gas cars/trucks, the timing could be adjusted by yourself "if you knew how" to get the added gain of power from your engine that can come with higher octane. Now days you can't do that unless you reprogram the computer or buy after market computer or other after market devise that will sort of trick the existing system to get the desired results. It looks to me like it can be done to these newer EFI mower engines if someone could make the changes to the computer program to run on 93 octane. If I remember right you have to program in a longer duration fuel shot and advance the ignition timing...should equal more HP & TORQUE
But if you use 93 octane instead of 87 where it was stated by the engine manufacture you could bring about a small resistance to the ignition which could have the same effect as ******ing the timing which would equal less HP & TORQUE. This may not hold true in some extreme conditions but should be about right in most conditions that a mower will encounter being that is what the intended use of the engine when manufactured. Now I'm only referring to 4 cycle engines...the 2 cycle is another story.

naturescape
11-19-2006, 09:38 AM
The guys down at my shop told me that I should just use 87 for the mowers, but I should AT LEAST use 89 with the small 2 stroke stuff. ESPECIALLY European or foreign made stuff, the gas they use over there and test all their equipment on is better stuff than ours is (his explanation he told me he learned when Stihl took them all over to Germany or somethin)....

I need to burn premium in my truck or it knocks, has 200K on it. I used it by mistake in my 2 cyc a couple weeks ago. I was wondering why the blower was running so much smoother, until I remembered the premium octane I used. That's what I'll use in 2 cycle from now on! Seems to make no difference in the mower....

John Gamba
11-19-2006, 09:48 AM
I need to burn premium in my truck or it knocks, has 200K on it. I used it by mistake in my 2 cyc a couple weeks ago. I was wondering why the blower was running so much smoother, until I remembered the premium octane I used. That's what I'll use in 2 cycle from now on! Seems to make no difference in the mower....




Same here. stuff just runs better and i guess the mower just doesn't care.

GravelyGuy
11-19-2006, 10:01 AM
What about gas made with ethanol blends? A lot of gas around here has like a 10% ethanol blend. For some reason this blend makes the 87, 89, 93 octane all the same price.;)

Rons Rightway Lawncare
11-19-2006, 10:27 AM
The octane in the gas in utah is lower due to the high altitude in that state. At high elevations the air is thinner and less dense, and the engine can not fill it's cylinders like it does at lower elevations. The end result is less power, from lower pressures in the cylinder. The need for high octane fuel at those elevations are very low, low enough that most stations don't even offer it.

Ethanol fuel also packs less power than straight gasoline. It simply makes a less explosive bang.....Octane is still octane so I wouldn't worry about it too much. To be honest I would use the fuel that most people use at those stations.... if everyone is buying 87 then that is what I would buy. Ethanol gas will absord some water, and chances are lower that you will find water in the tanks that are used the most rather than the tanks that are used less often.

GreenN'Clean
11-19-2006, 10:56 AM
I always use 87 and add some gum cutter into the gas before i put it in my mowers, it helps keep everything running smoothly with great performance and the machines start easier as well

topsites
11-19-2006, 12:35 PM
Run one kind for about a month, then the other...
Which one works best over time?

The cleaner fuel, Namebrand 93.

I always run 93, there is no question:
If an engine is tuned for 87, have it re-tuned for 93.

J&R Landscaping
11-19-2006, 01:24 PM
Mainly I run 87 octane but every now and then, I will put 89 octane in the everything if it isnt to expensive.

Dirty Water
11-19-2006, 02:15 PM
Theres a lot of confused people here, which is funny because every time this comes up I have to write a long post and people still don't believe me.

The Octane (in Gasoline) and Cetane (in Diesel) rating shows how hard it is to IGNITE the fuel.

The higher the rating, the harder it is to burn.

What does this mean to you? It means that a advanced fuel injected engine with computer controlled timing can detect the higher octane fuel (using a knock sensor) and advance the ignition timing, creating more power.

However, on your typical twin cylinder 4 stroke engine all that higher octane fuel does is NOT BURN COMPLETELY.

These simple engines have no way to tell they are burning high octane fuel, and are originally designed for low octane, so you end up with unburnt fuel in the combustion chamber.

This is bad for the cylinder walls, and the passed fuel can backfire in the exhaust.

So basically, you spend more money on high octane fuel, and you get worse economy on it because the engine is not able to use all of it. Sounds like a lose/lose situation doesn't it?

Well, there is one benefit of high octane fuel, and that is the detergents.

High Octane fuel usually carries cleaners in it that are beneficial to the fuel system, however, for much less than the cost of always running 93, you could buy a bottle of Fuel injector cleaner and dump it in every few tanks. Its the same thing.

So to sum it up:


Higher Octane allows an engine to have more compression and a radically advanced ignition curve, this is why racing fuel has such a high octane rating.

On an modern computer controlled engine (in a car) high octane lets the car advance the ignition timing creating more power and a complete burn.

On a simple engine seen in a lawn mower, the high octane fuel does not burn completely, causing excessive wear and fuel consumption.

If any of you doubters don't believe me, look up some articles on Octane and Detonation.

Charles
11-19-2006, 04:26 PM
I use 89 octane in everything. 87 ruined my echo stuff when I first got into business. Truck is a deisel

DLG
11-19-2006, 05:40 PM
The octane in the gas in utah is lower due to the high altitude in that state. At high elevations the air is thinner and less dense
:laugh:
sorry but the cooler the air the denser it get.:cool2:

WildWest
11-19-2006, 05:59 PM
:laugh:
sorry but the cooler the air the denser it get.:cool2:

Actually, you're BOTH right! Cooler air is more dense, but the air at higher altitude is less dense.;)

MartinsMowing
11-19-2006, 10:00 PM
well i dont believe our lawn equipment would produce detonation on 87. The engines dont have enough compression to require a higher octane. The only reason to use a higher octane should be higher compression. The only thing a higher octane rating does is increase the fuels resistance to ignition.

FATWEASEL
11-19-2006, 11:03 PM
Theres a lot of confused people here, which is funny because every time this comes up I have to write a long post and people still don't believe me.

The Octane (in Gasoline) and Cetane (in Diesel) rating shows how hard it is to IGNITE the fuel.

The higher the rating, the harder it is to burn.

What does this mean to you? It means that a advanced fuel injected engine with computer controlled timing can detect the higher octane fuel (using a knock sensor) and advance the ignition timing, creating more power.

However, on your typical twin cylinder 4 stroke engine all that higher octane fuel does is NOT BURN COMPLETELY.

These simple engines have no way to tell they are burning high octane fuel, and are originally designed for low octane, so you end up with unburnt fuel in the combustion chamber.

This is bad for the cylinder walls, and the passed fuel can backfire in the exhaust.

So basically, you spend more money on high octane fuel, and you get worse economy on it because the engine is not able to use all of it. Sounds like a lose/lose situation doesn't it?

Well, there is one benefit of high octane fuel, and that is the detergents.

High Octane fuel usually carries cleaners in it that are beneficial to the fuel system, however, for much less than the cost of always running 93, you could buy a bottle of Fuel injector cleaner and dump it in every few tanks. Its the same thing.

So to sum it up:


Higher Octane allows an engine to have more compression and a radically advanced ignition curve, this is why racing fuel has such a high octane rating.

On an modern computer controlled engine (in a car) high octane lets the car advance the ignition timing creating more power and a complete burn.

On a simple engine seen in a lawn mower, the high octane fuel does not burn completely, causing excessive wear and fuel consumption.

If any of you doubters don't believe me, look up some articles on Octane and Detonation.

Thanks for taking the time to write a long post but you really shouldn't. Knock sensors don't detect octane. They detect KNOCK. When they detect KNOCK, they generally ****** the timing.

Knock can be caused by several different things but the end result is that the fuel and air ignite too far in advance as the piston is moving towards top dead center and compressing the next charge. When the charge iginites too soon before TDC, it's basically an explosion that, in effect, is trying to force the piston in reverse. The knock sensors usually detect this "shudder" in the cylinder and ****** the timing of the spark to allow the piston to get closer to TDC before igniting the next charge. If all goes well, the ignition is advanced until it senses knock again or returns to its normal setting.

Also, using high octane for the detergents is no longer needed as all gasolines have detergents in the them now. Some may have more than others like Chevron vs Exxon vs Citgo. That's where the marketing department comes in.

Not really sure what you're trying to say in your list as some of those can be taken different ways but it doesn't really matter. If the manufacturer recommends 87 octane, there is no benefit to a higher octane unless you are experiencing knock. If the manufacturer recommends 93 octane, there IS a benefit to not using lower grade gas as you could induce knock.

Most of this is pointless since probably less than 5% of the members on here have a DFI engine on their mowers and don't worry about setting timing or power because after all, they have DFI and probably have 29 hp. And probably 90% or the other 95% will take their shtuff to the shop to get worked on if they have problems.

:)

Rons Rightway Lawncare
11-19-2006, 11:29 PM
Actually, you're BOTH right! Cooler air is more dense, but the air at higher altitude is less dense.;)


I never mentioned temp as a factor.... But bottom line is there is less air up there period, less dense air that is!

Rons Rightway Lawncare
11-19-2006, 11:34 PM
well i dont believe our lawn equipment would produce detonation on 87. The engines dont have enough compression to require a higher octane. The only reason to use a higher octane should be higher compression. The only thing a higher octane rating does is increase the fuels resistance to ignition.


And it blows my mind that there are still people out there that are just throwing money away thinking they are gaining something by using 89 or 93 Octane fuel in something that wasn't designed for it. It is totally nutz....


And by the way, the detergents in premium fuel.... they are also in 87 Octane fuel too! But just like the suckers who have that feel good feeling when they throw money away on 89 or 93 octane fuel - cause that is what the oil companies have always wanted us to believe, that the higher the octane the better the fuel is for any engine - they can do the same and buy a pint of STP to pour in the tank too.

Heck why not get some Slick 50 to put in it, that stuff is so good you don't even need motor oil in the engine!

John Gamba
11-20-2006, 05:38 AM
And it blows my mind that there are still people out there that are just throwing money away thinking they are gaining something by using 89 or 93 Octane fuel in something that wasn't designed for it. It is totally nutz....


!


There is a difference in power from 87 to 89 in my stihl 600 blower.

Richard Martin
11-20-2006, 06:01 AM
There is a difference in power from 87 to 89 in my stihl 600 blower.

Stihl recommends 89.

I use 89 for 3 reasons.

1: The majority of my 2 stroke equipment is Stihl. Stihl says to use 89 so I do.

2: I like to keep things simple and rather then carry a half dozen different cans with different mix ratios and octanes I use 89 mixed with Amsoil at 80:1 in all of my 2 strokes.

3: In keeping with the KISS principal I use 89 in my mowers so I don't have to go through the switching pumps and getting CC authorization each time I switch pumps routine.

Dirty Water
11-20-2006, 08:39 PM
Thanks for taking the time to write a long post but you really shouldn't. Knock sensors don't detect octane. They detect KNOCK. When they detect KNOCK, they generally ****** the timing.

I knew that. Modern engines will advance ignition timing until knock is detected. This way, you are always at the highest performance threshold for the fuel.



Knock can be caused by several different things but the end result is that the fuel and air ignite too far in advance as the piston is moving towards top dead center and compressing the next charge. When the charge iginites too soon before TDC, it's basically an explosion that, in effect, is trying to force the piston in reverse. The knock sensors usually detect this "shudder" in the cylinder and ****** the timing of the spark to allow the piston to get closer to TDC before igniting the next charge.

Thanks for elaborating, I didn't want to go into this much detail because most people on this site still think 93 = Bigger Boom. I know exactly how a knock sensor works and how to test them.


If all goes well, the ignition is advanced until it senses knock again or returns to its normal setting.

Which is why I said that only an engine with a knock sensor will be able to utilize any grade of fuel.


Most of this is pointless since probably less than 5% of the members on here have a DFI engine on their mowers and don't worry about setting timing or power because after all, they have DFI and probably have 29 hp. And probably 90% or the other 95% will take their shtuff to the shop to get worked on if they have problems.
:)

DFI eh? Unless they are running diesel engines, I don't think there is any member on this board that has direct fuel injection. Only a few cars have that, and I've never seen a direct fuel injected small engine.

However, I would bet a lot of them have EFI engines :)

Before you try to get smart with me, learn your acronyms :)

--Jon

Mic_bug
11-20-2006, 08:54 PM
91 or 92 ammoco ultra....it's like to be driven clean

Actually customers say it cuts better with 91+

Rons Rightway Lawncare
11-20-2006, 10:27 PM
Correction about knock sensors....

Most of the vehicles that suggest using premium, NEED the premium due to the default settings in the computer for spark advance and due to the compression and cylinder shape.

These engines will SURVIVE running on lower grade fuel because the knock sensor detects the knocking and tells the computer to ****** timing in a effort to save the engine from damage.

If the engine is to use 93 and you use 87, not only are you not getting the power you could be getting, but your running the risk of engine damage if the knock sensor malfunctions.


Using 93 in a engine made to run 87 on the other hand is just simply money thrown down the drain.

I can understand filling up the mixed gas jug with 89 or 93 and can understand being too much in a hurry or too lazy to use a separate pump so you can put 87 in the mowers.... as long as you do that knowing that it is not doing the mowers any extra good...

Richard Martin
11-21-2006, 06:02 AM
I knew that. Modern engines will advance ignition timing until knock is detected. This way, you are always at the highest performance threshold for the fuel.

This is wrong. Timing is predetermined by the spark maps stored in the computer. The computer only has the ability to ****** timing if it senses knock via the knock sensor. If you use 92 octane gas in a Chevy Cobalt the computer will not continue to advance timing until it senses knock. Advancing timing past a predetermined point will increase NOx emissions.

John Gamba
11-21-2006, 06:18 AM
DFI eh? Unless they are running diesel engines, I don't think there is any member on this board that has direct fuel injection. Only a few cars have that, and I've never seen a direct fuel injected small engine.

However, I would bet a lot of them have EFI engines :)

Before you try to get smart with me, learn your acronyms :)

--Jon


Joh E H.

DFI is what kaw uses for there Digital Fuel Injection on there 29 DFI.

John:)

johnwon
11-21-2006, 06:35 AM
This is wrong. Timing is predetermined by the spark maps stored in the computer. The computer only has the ability to ****** timing if it senses knock via the knock sensor. If you use 92 octane gas in a Chevy Cobalt the computer will not continue to advance timing until it senses knock. Advancing timing past a predetermined point will increase NOx emissions.
Yea...that has been my understanding of the ECM in todays cars, I wish it were the other way so we would not have to buy after market ECMs to get a power gain.

mowtech
11-21-2006, 01:46 PM
Octane facts:

knock occurs when engine pressures are high. Engine knock can result in serious damage to the engine.

High octane gasoline burns slower than low octane gasoline. The slow burn prevents engine knock when cylinder pressures are high.

If an engine knocks, it does not necessarily mean higher octane gasoline is required. It could be a problem with the engine's electronic control system, ignition timing, or exhaust recirculation.

Most cars today have fuel-injected engines that need gasoline with detergent additives. Low octane gasoline contains sufficient detergents as mandated by the government. Higher octane fuel does not have to have more or better additives.

Engines generally only need high octane gasoline if the manufacturer recommends it.

Octane myths

High octane gasoline improves mileage--if the engine is designed to run on 87 octane gasoline, high octane will not improve mileage. If switching does improve mileage, something is wrong with the engine.

High octane gasoline gives quicker starting--no, it does not.

High octane gasoline increases power--not if the engine is designed to run on 87 octane. If it makes a difference, there is something wrong with the engine.

High octane gasoline has been refined more and it is just a better product--nope, additional steps are used to increase the octane; however, these steps do not make the gasoline better. The steps just yield a different blend of hydrocarbons that burn more slowly. The additional steps add cost.


Source: Minnesota Department of Commerce, Weight and Measures Division.

http://www.state.mn.us/mn/externalDo...ctaneFacts.pdf

FATWEASEL
11-21-2006, 05:46 PM
Quote:
Originally Posted by FATWEASEL
Thanks for taking the time to write a long post but you really shouldn't. Knock sensors don't detect octane. They detect KNOCK. When they detect KNOCK, they generally ****** the timing.

I knew that. Modern engines will advance ignition timing until knock is detected. This way, you are always at the highest performance threshold for the fuel.

As stated by others, NO!


Quote:
Knock can be caused by several different things but the end result is that the fuel and air ignite too far in advance as the piston is moving towards top dead center and compressing the next charge. When the charge iginites too soon before TDC, it's basically an explosion that, in effect, is trying to force the piston in reverse. The knock sensors usually detect this "shudder" in the cylinder and ****** the timing of the spark to allow the piston to get closer to TDC before igniting the next charge.

Thanks for elaborating, I didn't want to go into this much detail because most people on this site still think 93 = Bigger Boom. I know exactly how a knock sensor works and how to test them.

Hammer?


Quote:
If all goes well, the ignition is advanced until it senses knock again or returns to its normal setting.

Which is why I said that only an engine with a knock sensor will be able to utilize any grade of fuel.

As stated, NO, again!


Quote:
Most of this is pointless since probably less than 5% of the members on here have a DFI engine on their mowers and don't worry about setting timing or power because after all, they have DFI and probably have 29 hp. And probably 90% or the other 95% will take their shtuff to the shop to get worked on if they have problems.

DFI eh? Unless they are running diesel engines, I don't think there is any member on this board that has direct fuel injection. Only a few cars have that, and I've never seen a direct fuel injected small engine.

However, I would bet a lot of them have EFI engines

Before you try to get smart with me, learn your acronyms.

Stop NOW, before it's too late. Save yourself while you can. :) :laugh:

j/k
Andy

walker/redmax
11-21-2006, 05:59 PM
One time I had a 25hp Kohler seize up on me when I was using 93oc. that I usually ran 87oc. in. I don't know if it had anything to do with the gas or not but since then I only run regular.:drinkup:

mowtech
11-21-2006, 06:23 PM
Quote:
Quote:
Most of this is pointless since probably less than 5% of the members on here have a DFI engine on their mowers and don't worry about setting timing or power because after all, they have DFI and probably have 29 hp. And probably 90% or the other 95% will take their shtuff to the shop to get worked on if they have problems.

DFI eh? Unless they are running diesel engines, I don't think there is any member on this board that has direct fuel injection. Only a few cars have that, and I've never seen a direct fuel injected small engine.

However, I would bet a lot of them have EFI engines

Before you try to get smart with me, learn your acronyms.

Stop NOW, before it's too late. Save yourself while you can. :) :laugh:

j/k
Andy



In the case of Kawasaki they use DFI to mean mult-port Digital Fuel Injection not Direct Fuel Injection. Which is what he was referring to. So who should learn their acronyms?

jpp
11-21-2006, 07:07 PM
Alot of responses here, but has anybody been told which gas to run in their equipment. Like use Shell,Marathon, or Sunoco 89? I been told that by the dealer that services my blowers and trimmers. Just curious.

JP

FATWEASEL
11-22-2006, 12:59 AM
Alot of responses here, but has anybody been told which gas to run in their equipment. Like use Shell,Marathon, or Sunoco 89? I been told that by the dealer that services my blowers and trimmers. Just curious.

JP

Sounds like personal preference to me. I'm sure there ARE differences from one distrubutor to another but they are probably minimal.

I usually pick 2 gas stations per area that I'm working that I'll go to on a consistant basis. I try to pick newer places that get alot of traffic. My reasoning is that the gas holding tanks are newer with hopefully less chance or leaks or cracks to pollute the fuel. The pumps are probably serviced more often and fresh fuel is brought in more often.

For the record. My Kawasaki manual that lists the FD671D (23hp), FD711D (25hp), FD750D (27hp), and FD791D-DFI (29hp), states:

"Fuel
Use only clean, fresh, unleaded regular grade gasoline.

Octane Rating
The octane rating of a gasoline is a measure of its reisistance to "knocking". Using a minimum of 87 octane by the antiknock index is recommended. The antiknock index is posted on service station pumps in the U.S.A.

NOTE
If "knocking or singing" occurs, use a different brand of gasoline or higher octane rating."

Andy:)

Dirty Water
11-22-2006, 01:35 AM
In the case of Kawasaki they use DFI to mean mult-port Digital Fuel Injection not Direct Fuel Injection. Which is what he was referring to. So who should learn their acronyms?

Every other manufacturer across the board refers to it as Electronic Fuel Injection, and DFI stands for Direct Fuel Injection. Kawasaki's marketing BS does not change what the acronym stands for.

As far ignition timing maps, fuel injected engines can run in two modes, open loop and closed loop.

In closed loop mode, the engine runs off precalculated ignition tables and ignores most sensors. In open loop, it ignores the fuel and ignition tables and runs directly off the sensors.

But what do I know, my experience is only in tuning EFI turbocharged vehicles, and equipping them with standalone control systems.

Richard Martin
11-22-2006, 04:06 AM
As far ignition timing maps, fuel injected engines can run in two modes, open loop and closed loop.

In closed loop mode, the engine runs off precalculated ignition tables and ignores most sensors. In open loop, it ignores the fuel and ignition tables and runs directly off the sensors.

But what do I know, my experience is only in tuning EFI turbocharged vehicles, and equipping them with standalone control systems.

B.S.

Quoted from www.fordfuelinjection.com...

====================================================
Full-Throttle Acceleration
Seat belts on please, this is the master plan, what is the quickest route from point A to point B? Wide-Open throttle assaults of course. The TPS signals wide open throttle to the EEC, this states that the driver doesn’t care about economy or emissions and want maximum power to the rear wheels. Fuel enriches to a preset level even further the colder the ACT is. The timing jumps up to a maximum preset level around 28°BTDC, and this is where the Knock plays a role. The Knock sensor acts as a safety net for the Ford. The factory does not want the EEC to bump the timing until we reach that edge. If you buy a new car and add timing with a chip or by twisting the dizzy you could cause detonation. People do this to get more timing and better performance. So the Knock sensor is there to stop the owner that twists the dizzy for more performance from blowing a ring or burning some valves.
=====================================================

Whether an engine is in closed loop or open loop has nothing to do with maximum timing. The max timing is preset from the factory and unless you alter the programming via a chip you will not exceed the preset limit.

Also from Fordfuelinjection.com is an explanation of open and closed loop...

=====================================================
Open-Loop

· Open loop defines the engine operation when the fuel ratio is calculated with consideration to only input signals from the main sensors in the program style (MAF / SD / VAF / AN).

Closed-Loop

· Closed loop defines the engine operation when the fuel ratio is calculated with consideration taken from the main sensors and feed back sensors like the exhaust oxygen sensor (HEGO). Closed loop operation is devoted to emissions, economy, and a Stoichmetric fuel ratio of 14.7:1.
=====================================================

Without the fuel and ignition tables the computer is useless. It wouldn't have a clue of what to do with the data it receives from the sensors regardless of loop status.

John Gamba
11-22-2006, 06:15 AM
Every other manufacturer across the board refers to it as Electronic Fuel Injection, and DFI stands for Direct Fuel Injection. Kawasaki's marketing BS does not change what the acronym stands for.

As far ignition timing maps, fuel injected engines can run in two modes, open loop and closed loop.

In closed loop mode, the engine runs off precalculated ignition tables and ignores most sensors. In open loop, it ignores the fuel and ignition tables and runs directly off the sensors.

But what do I know, my experience is only in tuning EFI turbocharged vehicles, and equipping them with standalone control systems.


Not cool to be a Turkey this time of the year:nono:

FATWEASEL
11-22-2006, 11:37 AM
Gobble Gobble

:laugh: j/k

jkingrph
11-22-2006, 12:52 PM
I had been using regular in my old Stihl hand held blower. After reading and checking, started using higher octane and it does seem to run smoother. As as sideline my wife's 2000 Mercury Marquis is supposed to run on regular, and in fact does quite well. To satisfy my curiosity, I tried a tank of 92 octane a few months ago and was amazed at the increase in mileage, gained almost 6mpg, but cannot tell any difference in smoothness or power. So, for a roughly 10% increase in fuel cost to get that kind of mileage increase is a no brainer.

Rons Rightway Lawncare
11-22-2006, 05:53 PM
You probably won't believe this, but often times when we do something to our vehicles in anticipation of getting better gas milage, often we do get it.

But the reason is often not what we did, but how we drove the vehicle during the " test phase "

What I am saying is most likely it is not the fuel that gave the better MPG, it was most likely you being more aware of how you drove during that test that resulted in the better mpg.

jkingrph
11-22-2006, 06:40 PM
You probably won't believe this, but often times when we do something to our vehicles in anticipation of getting better gas milage, often we do get it.

But the reason is often not what we did, but how we drove the vehicle during the " test phase "

What I am saying is most likely it is not the fuel that gave the better MPG, it was most likely you being more aware of how you drove during that test that resulted in the better mpg.
Nope, prior to higher octane was really driving carefully to get best mileage, running about 60 hwy. easy starts, coast down to stops ect. After fillup increased hwy speed to about 70 otherwise similar driving habits. I was making an effort for several days to watch driving habits for this test.

ha305
11-23-2006, 10:25 AM
I like to use rocket fuel it helps me get things done faster:clapping:

WJW Lawn
11-23-2006, 10:44 AM
Seems most people use 87....even in the 2 cycles???

jcb287
11-23-2006, 12:08 PM
I use 87 in everything.............