10 replies to this topic

[dcs]

Hello all,

Was going through the net to understand the stoichiometric air-fuel ratio, I found out that the ideal ratio for clean combustion is 14.7.

Source Stiochiometric Air-Fuel Ratio

Simplifying it, it simply means we need 14.7 parts of air for every 1 part of Petrol for clean combustion. And this is how a fuel injected vehicle scores over a carbed vehicle, as the former calculates (on the basis of data provided by sensors) how much fuel should be delivered for ideal burning. A Carbs can not calculate and hence can not regulate the amount of fuel going in the cylinder.

It generally doesnt bother me much, as long as I am in plains, but as soon as I hit the hills, the thinner air starts playing its game and hence, I see a drop in the power of my Karizma.  While going through the topic, it stated that different fuels would have different stoichiometric air-fuel ratio. which is as under:

Gasoline: 14.7

Natural gas: 17.2

Propane: 15.5

Ethanol: 9

Methanol: 6.4

Hydrogen: 34

Diesel: 14.6

I was just wondering, would using or adding Ethanol or Methanol to our fuel tanks at Higher altitudes do any difference, for they seem to need less amount of air for clean burning.

I am looking forward for some serious information.

All cheers
dcs

[rahul_rn]

well i ain't a genius about this but ill tell whatever i know(could be wrong), the theory says it should burn and maybe it will.. but we have to understand that here the amount of air isn't dropped but just its density.. if the amount of air is dropped then it would mean the engine is running rich.. so we need something that burns at lesser air density then normal..

now lets say that ethanol burns at lesser air density, then we just cannot throw in ethanol and run the bikes.. have to see what's the power output of ethanol.. because if i ain't wrong then ethanol isn't as powerful nor efficient as pure petrol(again i could be wrong here)..so no use of adding ethanol as you want power itself..

hydrogen has a higher power output rating.. which is what is needed but as you have shown that it requires the highest amount of air.. and even if we hydrogen was usable then we need engines which can withstand that power.. none of the newer generations are designed to take some beating.. they are designed to be light-weight and perfect for petrol and not for anything else..
so if hydrogen is working then we have to give a really small amount of hydrogen as input and accordingly required amount of air..
i.e. in a 150cc engine we may have to input hydrogen in the same quantity as much as the amount of petrol required for 100cc bike.. then maybe the engine can withstand it..

so for doing this you would have to have a separate hydrogen tank fitted on your bike and feed it to the engine, have to alter crab which again might be useless in this case because the amount of air requires is way higher, so have to think of something else..
on top of that this theory is based upon something which is impossible.. i.e. hydrogen to burn in thinner air..
better solution then this is selling your zma and getting a zmr..

[arn]

Serious answer:

The power drop is there but hardly as much as you think. At 12000ft, on a flat road your ZMA will touch 95, you will run out of road before you run out of power. One up, with luggage, you will easily be able to climb most terrain, without slipping the clutch.

You can have a local mech set your carb lean for SLIGHTLY better performance, just remember to reverse the change when you descend.

Whatever you do, and even if you do run stoich or near, less A/F mixture will enter the engine (primarily because of less air by weight), so you will not have sea level power levels. Thats why high altitude piston engined aircraft have forced induction to increase the amount of explosive mixture being fed into the cylinders at altitude.

Dont bother to force feed this bike. IMO it's not worth the bother. And don't even think of ethanol. Gasohol has a lot of very annoying problems (absorbs water, does not like to vaporize, etc), you can google for the complete list.

[rahul_rn]

now you got an answer from an genius..

[Keith]

Sorry, not an expert. However simply buy a bigger engined bike and rider skill, not engine power, will be the limiting factor to how fast you can go. Undoubtly will also be much cheaper than messing with your bike. Rey

[pulsurge]

Aaah nice thread! The subject made me think that everything'll go over my head But understood! Thanks!

[rash]

Also, ethanol is corrosive to rubber and plastic parts. Most duel fuel vehicles have all plastic components that come in contact with fuel made from special rubber/plastic.

Methyl Alcohol (Methanol) is poisonous, you could die inhaling the fumes. Have you heard of folks who die/fall sick after consuming country liquor? More often than not its Methyl Alcohol thats not been distilled out fully!

[Silver Phantom]

me no expert, but heres my 2paisa...
when on a flat road (read level, and less curves, and less traffic), you may be able to rip the bike. here the power is required in the last gear
whereas on a hilly / mountainous regions, especially the ghats, or rugged regions like that of the Leh, power is required in the lower gears.
here the A+F mixture may play a huge part, but the drawbacks will be rather insignificant..
A weird solution (weird coz i am suggesting it, from the depts of my Metal workshop).. Attach a calibrated dial, which is directly connected to the A+F mix Screw, on the Carb.. High A+F mix for High Altitudes / Ghats / Climbs, while Low A+F Mix for Flats / Speed runs / Cruise Speeds.
The Dial+Screw contraption can be carried out by means of a Cable similar to that of a Speedo Cable. it doesnt unravel at speeds / pressure. and a small Gearing Contraption can make it easier for Screw to rotate more finely at a little twist of the Dial.

[dcs]

Thanks to all for their valuable inputs. Appreciate that.

Ok, now getting back to the concern, last year in September, me and my wife planned to go to leh on the bike. (Mine is a  2007 karizma with around 50,000 kms on the odo)

Because it was just two of us travelling, and this part of the year sees almost no bikers going to Leh, we had to pack almost everything under the sun, for the unfortunate time. This meant that my bike, which generally ferries me (am around 60 kgs) had this time almost 80 kgs more (wife and luggage weight included )

This year had been really bad for the roads, and Rain God had played a havoc. Trust me, I have never seen Rohtang Pass in such bad shape ever. The extent was- I was struggling to take the bike post Marhi. The slush was at its maximum and my wife had to walk in that slush.

All said an done, we barely could manage it post Rani Nallah and after that, I ended up with the burnt clutch plates.

How we came back, and all is another part of the story, but my concern remains the same. How do we manage to get better efficiency at hills with lower atmospheric pressure.

Weight reduction, if possible, is being considered, but am still keen to get something like a Fi, wherein the amount of fuel is regulated in regards to the air available for combustion.

As of now, I have shedded aroung 5 kgs off the bike, going for another weight loss program, but lets hear it to increase the power.


all cheers
dcs

[satyenpoojary]

One easy option.
Sell the ZMA, buy the CBR.

The amount of circus you would do to plonk in a working FI may not be worth the effort and risk!

[arn]

^^^ like he said.

OTOH, if you must use the ZMA, use far superior Unicorn clutch plates and better springs.

However, even the CBR will be spinning wheels in the bog leading to Rohtang. Nothing but a very aggresive tyre pattern can help in those conditions. The Moto D and Dunlop meteors on my ZMA were filled with the mud to the extent they looked like slicks.