Questions regarding Octane and fuel maps

[drzcharlie]

Ok, this admittedly is my first F1 bike. I am familiar with the premise and how it works. My buddy has a bike that allows him to flip a switch when he has to use non-premium fuel (below 91 Octane). Why then does the TR not have a similar device or remapping feature? Is this somehow done by the ECU? I have read reports that reduced octane fuel is really not a problem for this (engine except for some power loss).

First is that an accurate statement? Should I be leaning towards a power commander? Can someone explain how this all relates to our bike please?

Thanks in advance

 

[mag00]

What I have noticed so far is that the effect of octane affects the fuel economy of my bike. I don't have tons of miles on mine yet, so I don't have exact numbers. I have added small amounts of octane boost at times.

I do track my mileage at http://www.fuelly.com/motorcycle/husqvarna/tr650 And currently I am winning top mpg. I attribute it to altitude and I do not race down the freeway much. I get better mileage on the dirt than the highway, so keep it on the dirt is my advice.

It seems like altitude affects the mileage also. I would think this could affect horsepower.

As far as the power commander goes, I'm sure it should help some, and I think you are able to switch fuel maps easy enough, so if you had to use a poor grade fuel, you could switch. Having no experience with the power commander, I do not know if you would get any significant changes, but seems logical.

The ecu on our bikes are quite advanced and if not for the basic map installed being set to meet emission standards around the world, the average TR owner would not need the power commander or other gadgets.

 

[chris1261]

I think you also have to take compression ratio into account as well as spark advance. the PCV's for our bikes don't do spark advance programming (although some PCVs will for other bikes). Your friend's bike may have had a lower comp. ratio.

For the price difference between regular and premium, i'll just buy premium. excessive spark knock (pinging) can do lots of expensive damage.

 

[Zomby woof]

It has nothing to do with the fuel mapping, but the ignition timing map. More octane lets you run more timing advance, which gives you more power and better fuel economy. This is assuming the compression ratio, and cylinder head design are compatible. Older combustion chamber designs wanted more timing than newer designs, but I'm assuming you could probably still use more timing than the (safe) stock map allows.

My GM truck has 2 knock sensors, and two timing maps. It defaults to the advanced map on start up, and back to a standard timing map after it sees three knock events. If I run premium it stays on the advanced map all the time and makes much better power. This is the way it should be.

 

[Ignaciob]

O I have read reports that reduced octane fuel is really not a problem for this (engine except for some power loss).

First is that an accurate statement?

Unfortunately, those reports are probably anecdotal observations from places like forums....which are full of people with a variety of knowledge levels (or probably more accurately lack of knowledge and/or substitute in personal anecdotal observations as if they're empirical evidence).

One thing I do know for sure is octane does not have anything to do with how much power an engine produces. Octane is merily a measure of a resistance to the fuel mixture compressing and detonating prematurely. If an engine runs on 87 and doesn't ping....it produces the same amount of power as a fuel rated at 91 octane all other things being equal.

I've noticed (yes, that's me sharing a personal anecdote and not empirical evidence) that my bike doesn't seem to ping, knock, prematurely detonate or run differently on the few times only 87 octane was available. I *may* have noticed a bit of pinging in some low RPM/high load situations.

The complicating variable would be if there's a knock sensor in the Husky. I don't know if there is or not. If there is--then its conceivable with this other variable that its adjusting timing within a range they've designed for....and power and mileage *could* be reduced a small amount. I've noticed (yes, another anecdote...but with a bit more empirical foothold) I didn't notice a MPG difference because of octane. However, in the variety of road/non-road/low-speed/higher-speed/difference in elevation/difference in temperature variables that affect mileage with bigger X variables...it would probably be lost as noise.

In summation, I don't think a switch or PC has to be done. The bike seems fairly tolerant of various octane levels.

 

[drzcharlie]

Thanks for the incite Ignaciob and Zombie Wolf.

 

[bluegopher]

Just for the record, in the first 5 or 6 fuel ups I forgot to go with high (I'm used to putting the cheap stuff in my car) octane and I definitely noticed a difference in performance. Nothing at all as far as running performance but a bunch more hiccups, coughs and stalls. I made a conscious effort to always put highest octane available in the Terra after that. I also had the bike Mossed and installed a Wuka shortly after but I still avoid low octane like it's my job. A few low rev bunts since then but overall nothing I'm worried about.

 

[nev..]

Ok, this admittedly is my first F1 bike. I am familiar with the premise and how it works. My buddy has a bike that allows him to flip a switch when he has to use non-premium fuel (below 91 Octane). Why then does the TR not have a similar device or remapping feature? Is this somehow done by the ECU? I have read reports that reduced octane fuel is really not a problem for this (engine except for some power loss).

First is that an accurate statement? Should I be leaning towards a power commander? Can someone explain how this all relates to our bike please?

Thanks in advance

I'd be interested to know what model bike your friend has, and what that switch really does. I know some bikes - even the Husqvarna Nuda - that's why you have an M(ode) button on the TR650 Dash which does nothing - can let you switch between ECU maps, so that you can reduce wheelspin when it's wet for example, but I've never heard of one which has a switch for fuel). Surely if it had the capacity to adjust the timing when running low octane fuel they'd just do that automatically with a knock sensor.

 

[drzcharlie]

Nev, he has the switch on his WR250R. I asked about it tonight and he said he has the power commander on it. Hence the switch.

 

[Highfive]

Charlie, that switch is most likely to engage the AutoTune unit or turn it off. I put one on my own WRR. All it does is switch you from the fixed Fuel Map (which I established on a Dyno) to a variable map which is being adjusted in real time by the AT unit. The AT reads the oxygen sensor in the exhaust pipe (which has to be added as part of the deal), and makes fuel adjustments very fast to maintain the target AFRs plotted in the fuel table stored in the memory.

I found the AT unit to work best in steady state mode......i.e. Cruising down the highway, so I set the AFRs in my AT table for best fuel economy. Out on the trail, I didn't like running it in AT mode. The unit seemed to respond faster than the ECU. It was making so many fuel adjustments so fast, that the engine seemed a little rougher running. So, I ended up leaving my switch on my fixed Map (AutoTune unit turned off) most of the time.....all of the time offroad.

If I did it over again, I wouldn't buy the extra AT unit for a bike that is going to be ridden in dirt. Street bike....definitely! Just what I learned from my own experience. It's pretty well documented step by step at my website: WRRDUALSPORT.com if you're interested in digging further. Or, find it in my Athena Big Bore thread (linked in my signature).

Ask your friend more details about his switch to see if it is what I've described here. If so, then it has nothing to do with low octane versus high octane.....most likely. Whether or not he realizes that or believes that is another story. The change in fuel mapping might mask (band-aid) a low octane related problem for a bit, but only poorly.

IF he actually has an ignition map switch on his WRR, then I'm impressed and would like to know more about it. Send me a link to wherever he may have posted an expose' on this achievement. It would be most cool and I'd love to read about it....see how it was done. There are such systems out there, no doubt. I've just not seen one added to a WRR before. But I've also been out of that game for awhile too. Maybe some new developments have come down the pike. If so, they could be carried over to our TR650s......so please find out, for sure.

HF

 

[Xcuvator]

The KTM 950s had two wires under the seat that when hooked together the bike would run on the higher octane ignition curve and when disconnected a low octane curve.
I put a switch on my 2004 and could change it on the handle bar. Later 990 models came with a switch. I think they still have that switch on the newest model..

Charlie, that switch is most likely to engage the AutoTune unit or turn it off. I put one on my own WRR. All it does is switch you from the fixed Fuel Map (which I established on a Dyno) to a variable map which is being adjusted in real time by the AT unit. The AT reads the oxygen sensor in the exhaust pipe (which has to be added as part of the deal), and makes fuel adjustments very fast to maintain the target AFRs plotted in the fuel table stored in the memory.

I found the AT unit to work best in steady state mode......i.e. Cruising down the highway, so I set the AFRs in my AT table for best fuel economy. Out on the trail, I didn't like running it in AT mode. The unit seemed to respond faster than the ECU. It was making so many fuel adjustments so fast, that the engine seemed a little rougher running. So, I ended up leaving my switch on my fixed Map (AutoTune unit turned off) most of the time.....all of the time offroad.

If I did it over again, I wouldn't buy the extra AT unit for a bike that is going to be ridden in dirt. Street bike....definitely! Just what I learned from my own experience. It's pretty well documented step by step at my website: WRRDUALSPORT.com if you're interested in digging further. Or, find it in my Athena Big Bore thread (linked in my signature).

Ask your friend more details about his switch to see if it is what I've described here. If so, then it has nothing to do with low octane versus high octane.....most likely. Whether or not he realizes that or believes that is another story. The change in fuel mapping might mask (band-aid) a low octane related problem for a bit, but only poorly.

IF he actually has an ignition map switch on his WRR, then I'm impressed and would like to know more about it. Send me a link to wherever he may have posted an expose' on this achievement. It would be most cool and I'd love to read about it....see how it was done. There are such systems out there, no doubt. I've just not seen one added to a WRR before. But I've also been out of that game for awhile too. Maybe some new developments have come down the pike. If so, they could be carried over to our TR650s......so please find out, for sure.

HF

 

[nev..]

The KTM 950s had two wires under the seat that when hooked together the bike would run on the higher octane ignition curve and when disconnected a low octane curve.

These are bikes with lower compression engines than the Terra, so I'm guessing they are using the switch to take advantage of high octane fuel, rather than the other way around. Although my Terra has run fine on Low octane on the couple of occasions it's been all that was available, I'm guessing a switch for low octane fuel on this bike would need to mechanically reduce compression, rather than just electronically adjusting ignition timing.

 

[Xcuvator]

These are bikes with lower compression engines than the Terra, so I'm guessing they are using the switch to take advantage of high octane fuel, rather than the other way around. Although my Terra has run fine on Low octane on the couple of occasions it's been all that was available, I'm guessing a switch for low octane fuel on this bike would need to mechanically reduce compression, rather than just electronically adjusting ignition timing.

Yeah could be, but there is only .8-1 difference in the CRs. Not a big difference.
I wonder what the TR cylinder pressure is? The 950s run 200-210psi from what I remember.

 

[Zomby woof]

I'm guessing a switch for low octane fuel on this bike would need to mechanically reduce compression, rather than just electronically adjusting ignition timing.

No. Ignition timing alone will do it.