Biking: Fuel consumption on slope at low gear?

I was bored today with nothing to do so i went to mussoorie in the morning on my bike (Pulser 150dtsi). Came back abt 6pm. it was nice a nice ride as always recharged my spirits

But i got thinking abt something. consider going down a gentle slope with no breaks and low gear like 2nd or 3rd. The engine takes on speed(rpm) and over all acceleration/speed decreases so we don't need to apply breaks. this would be hard to get for people who have never driven down a long slope.

Anyways the question is- during that no accelerator-no break-low gear-high rpm situation does the engine use up the same amount of fuel as it would use when accelerating with accelerator at that rpm on normal road or use fuel equivalent to idling?

like say on a slope the rpm is 4000 and speed is 35km/s constant(no accelerator or break). will it use more fuel then idling?

I hope it is not confusing

nice question.
but tell me why not kill the engine insted of running at 2nd or 3rd gear?
which is not good for the bike.
Now for the fuel consumption the faster you go the more fuel the bike needs, but you can go fast only on the top gear.

But on lower gear say 2nd or 3rd and 35Kmph it will certainlly consume more fuel than with the top gear and say 50-60Kmph. (i am thinking).

Yes, it would definitely consume more fuel than at idling! Why don't you cut off the engine itself? You cant do that on a car, as the brakes stop functioning if you switch off the engine, but you can always do that for a bike!

chicha is right i think swithcing to nuetral is a good thing as engine is not shut down and very very very low amount of petrol is consumed coz to run ur engine
i think u can do this CARZzz to
BTW u have pulsar DTSI new or d old
new one got awesome design man

^^ Yes, as long as the engine is ON, the brakes work in cars too..

kalpik said:
Yes, it would definitely consume more fuel than at idling! Why don't you cut off the engine itself? You cant do that on a car, as the brakes stop functioning if you switch off the engine, but you can always do that for a bike!

i am daily going down a hill way @gear neutral, engine switched off on my maruti 800 and brakes are working JFYI

kalpik said:
^^ Yes, as long as the engine is ON, the brakes work in cars too..

you will some one by saying that brakes *only* work when engine is on

@Rollercoaster
just switch off your engine, save some fuel & help the country

M

gary4gar said:
@Rollercoaster
just switch off your engine, save some fuel & help the country

Then why not rather just ride on horseback?

lol

mehulved said:
Then why not rather just ride on horseback?

thats the best thing to do in hilly areas but it possible only when you buy me a horse

, becuase i am still unemployed and you got a hefty paying job

just donate & help me :lol:

bwt, i fond of horses

[edit] corrected

M

gary4gar said:
i am still unemployed and got a hefty paying job

WOW!!!

gary4gar said:
thats the best thing to do in hilly areas but it possible only when you buy me a horse, becuase i am still unemployed and got a hefty paying job

just donate & help me

bwt, i fond of horses

i guess some where 'NOT' is missing or u got an extra 'UN' in ur sentence

some one save the country with "solar-powererd" bikes?

seriously,where is the hydrogen(fuelcell) cars hitting the road by 2008(i read somewhere)? no alternate fuels except neutral gear driving downhill

kalpik said:
Yes, it would definitely consume more fuel than at idling! Why don't you cut off the engine itself? You cant do that on a car, as the brakes stop functioning if you switch off the engine, but you can always do that for a bike!

Who says you cant break when switching off the engine on a car?

guys, when goin down hill use ENGINE BAKING & save the damn brakes, coz the more you use the brakes, the more they get heated up = less performance they'll give.

engine braking = something which roller... :))

dude is doing. which is obviousy right thing to do.

ENGINE BRAKING does consume fuel, but its negligible (a little bit more than idling).

car or bike, when you go down-hill, use ENGINE BRAKING. :wink:

engines are designed for these kinda stuffs, so dont even worry about Engine life...

YOU SHOULD USE ENGINE BRAKING when you take a CAR down a hill.

READ the GOD DAMN USER MANUAL BOOK of your respective vehicle.

Rollercoaster said:
like say on a slope the rpm is 4000 and speed is 35km/s constant(no accelerator or break). will it use more fuel then idling?

I hope it is not confusing

obviously it'll use more fuel, coz the idling speed is 1000-1500rpm, but you're doin 4000rpm, fuel is pumped in, so...more fuel than idling speed.

just a info - my prof. told me, any vehicle, it emits max emission only when its idling.

@s180000rpm Even I wanted to say the exact same point. Using engine breaking saves the breaks. I have one friend who has mastered engine breaking. When I went for a drive with him for the frst time I was like .. .. :shock:

Dude wait .. ill put the seat belts on :shock:

^for midland(a semi-hilly route) drives,using brakes does saves fuel.and ur brakes wont worn out that fast.

its not that Brakes wear out.

i believe you know with the heat , performance of brakes degrade.

stopping distance increases.

^then this is a common practice of Jeep drivers to switch off & go in neuterr..

to save diesel!I am taliking about a distance of 1-2kms in neutral gear with brakes when needed in estates.not like from udhagamandalam coonor to Mettupalyam engine been switched off(though i does have friends who did this in bikes!).
go to any high-range areas(esp in kerala,idukki,malabar,kottayam etc) u'll see such habits.btwn dont forget jeeps always needs service as the same as old-generation amby cars or premier etc.so brakes getting hot are not a problem.moreover brake itself is not much used by drivers in kerala

i dunno, those guys whom you're talkin of dont even have proper training or knowledge in driving, so comparing them & taking them as example is ... not good.

in bikes/cars, when the drums heat , brake pad will ultimately lose the grip, so consider that.
the brakes will then Lock the wheels, not slow them, will jus lock it.

moreover brake itself is not much used by drivers in kerala

then wat do they use to slow/stop their vehicle???

^to stop- hit somewhere hard

(i am referring to pathetic driving practices in kerala)

praka123 said:
^to stop- hit somewhere hard (i am referring to pathetic driving practices in kerala)

kerala bus drivers r the fastest drivers in south, i was prayin when will i get down from bus.

^ahh!u know

what i meant.

GeekyBoy said:
Who says you cant break when switching off the engine on a car?

I said! LOL! Any new car's brake WONT work if the engine is off.. Try that with any new generation car.. The brake pedal would become hard, and you wont be able to press it. Oh.. and just try it on normal roads.. Dont try it on a slope

And s18000rpm is absolutely right about engine braking.

kalpik said:
I said! LOL! Any new car's brake WONT work if the engine is off.. Try that with any new generation car..

I think you are talking about 'ANTI LOCK BREAKING SYSTEM' i,e ABS.I read somewhere that it is not work properly after shutdown the Engine.

s18000rpm said:
ENGINE BRAKING does consume fuel, but its negligible (a little bit more than idling).

obviously it'll use more fuel, coz the idling speed is 1000-1500rpm, but you're doin 4000rpm, fuel is pumped in, so...more fuel than idling speed.

just a info - my prof. told me, any vehicle, it emits max emission only when its idling.

geez thanks u r the 1st one to actually get to the question. But i have a doubt in what u r saying. how is more fuel gonna get pumped in when i am not applying the accelerator. The only fuel permitted in the basic fuel injection systems(like in bikes.. not in computer controlled engines there the comp controls many fuel inputs) is thru the idling and accelerator. even idling fuel limit is actually done thru the accelerator as a screw holds is open just a little bit.

so when the accelerator is not open there should be no other way for the fuel to get to the engine. AFIK.

if u think abt it then what is fuel injected in for when no accelerator is applied. i.e to keep the engine running with minimum power. but when we r going down the slop then the engine is kept running with the speed the slope gives us(thru the gearbox cause in neutral the engine and bike movement are separated) but the idling fuel amount is pumped in anyways and always.

all the above are just IMHO intelligent guesses. may be i will have to ask some automobile engineers.
---
btw abt the engine waring out. LOL dudes if u go on a slope with neutral and brakes then god help ur maintenances budget. Break pads wear/rub out very fast on slopes due to constant breaking, for that sole reason 'engine breaking', as s18000rpm terms it, is used. This way the engine resistance engine provides acts as a speed limiter.

also it is a very very veru BAD idea to go down long mountain slopes with a switched off engine! do not do that! I have seen enough accident due to this.
That should only be done on roads u know like the back of ur hand and never for more then a few kms. You never know when u might suddenly need ur engines power.

mehulved said:
Then why not rather just ride on horseback?

Do u really think a horse's maintenances(his food, health, cleaning etc) is cheaper then a bikes idling fuel cost. try and ask someone who actually has a horse. u r sure to get a gr8 lecture.

rather funny how these kinda sayings come to be.

dissel said:
I think you are talking about 'ANTI LOCK BREAKING SYSTEM' i,e ABS.I read somewhere that it is not work properly after shutdown the Engine.

Nope! Im talking about NORMAL brakes, they are known as power brakes! They DO NOT work without the engine on! Actually power brakes have a component called Vacuum Booster, which enhances the brakes. If you switch off the engine, the Vacuum Booster stops working, which slowly and steadily leads to ineffective brakes, after just braking 3-4 times.

@Rollercoaster: You have got a point there!

A

while going downhill, engine braking gives u more control....and is safe too.

@Roller, when engine runs @4000rpm, what happens- Air is sucked in, & now if the air-fuel ratio mismatches, engine wont run smooth, you might feel the difference.
when next time you go down hill, notice the slight "free-play" in the throttle.

kalpik said:
Nope! Im talking about NORMAL brakes, they are known as power brakes! They DO NOT work without the engine on! Actually power brakes have a component called Vacuum Booster, which enhances the brakes. If you switch off the engine, the Vacuum Booster stops working, which slowly and steadily leads to ineffective brakes, after just braking 3-4 times.

@Rollercoaster: You have got a point there!

Well my 800 stops without any probs !!! It maybe bcoz it's an old gen car and has got no power brake.

Yeah.. 800 does not have power brakes

even the power breaks dont stop working when engine switched off. they just need more power to apply them on the break pedal. kinda like reverting to the normal breaks.

Oil fluid saturates the lines and it becomes a fixed volume, insted of when the power is on the pressure on the break is converted to oil pressure. so on power off when u press the breaks it acts like normal breaks(less then) where the pressure is passed on to the break pads via a steel cable.

^^ Try pumping the pedal 4-5 times, then you will know!

kalpik said:
^^ Try pumping the pedal 4-5 times, then you will know!

yes thats what i meant. a fixed oil amount floods the pipes. so the power is transferred from the pedal to the pads directly. I am not saying that this means the breaks fully function... just that they do work.

EDIT:

s18000rpm said:
@Roller, when engine runs @4000rpm, what happens- Air is sucked in, & now if the air-fuel ratio mismatches, engine wont run smooth, you might feel the difference.
when next time you go down hill, notice the slight "free-play" in the throttle.

i still am having difficulty buying ur theory. cause when the engine is running on higher rpm it will pull in the air from the carburetor.. but the carb wont get fuel as the fuel input is closed due to no accelerator. so only air will freely flow acc to the pressure difference in the engine.

do u guys know if pulser bikes use 'fuel injection'? cause then the fuel has other inputs directly to the engine.

EDIT:
--INFO:Wiki--
Found this - The carburetor works on Bernoulli's principle: the faster air moves, the lower its pressure. The throttle (accelerator) linkage does not directly control the flow of liquid fuel. Instead, it actuates carburettor mechanisms which meter the flow of air being sucked into the engine. The speed of this flow, and therefore its pressure, determines the amount of fuel drawn into the air stream.

As the throttle is closed, the airflow through the carb drops until the lowered pressure is insufficient to maintain this fuel flow, and the idle circuit takes over again.
--INFO--

this means that the fuel being pulled in(as well as the amount of air) is actually determined by the carb based on the throttle. so it has to mean that the fuel used on a particular engine rpm will be higher when the throttle is open. And also that it will be higher then idle fuel usage.

Now it remains to see how much difference of fuel consumption will there be?

DO NOT IDLE A BIKE DOWN A SLOPE! Its the most dangerous thing you could do. Brake drums heat up and could just about lock up result in either you skidding or you going straight down the slope at full speed. Don't even throw it in Neutral and roll it down with the engine on.

As for cars, the engine assisted brakes (power brakes) are specially designed so that people don't do this among other reasons of course. But they are made to NOT WORK because people roll down their cars. So just because your Maruti800 old model doesn't have engine assisted brakes, doesn't mean you can roll it down.

The bike running down the slope on low gear-no accel-high rpm on the other hand will NOT use as much fuel as going up the slope. RPMs don't directly relate to amount of fuel being consumed. It has much to do with the amount of BHPs being put out and all that whatnot.

You could save a little fuel, but what's the point if you end your life in the bargain?

The only bike on indian roads with fuel injection technology is the Hero Honda Glamour. The new karizma that's going to be introduced is going to have this technology. Pulsar

^^ That's what i've been trying to say! Any modern car's brake will not work (not even a little after you press the pedal 4-5 times, it will absolutely NOT WORK). But no one believes me

^I believe u,dont worry

@s18000rpm:
But i cant stop my driving habit of not using engine brake(gear) during driving through midlands and hillways.perhaps i shud start now-for the safety of others too. :-|

romba nandri macchi!

ok finally experimented with it. (i love going to mussoorie on my bike)

I went when my fuel tank was low and took 1 Liter petrol with me. Though we can get fuel easily in mussoorie but better safe then sorry and dragging bike uphill.

I managed to dry out whatever few drops were left by burning rubber
all around mussoorie

Then i put in the one liter petrol and started back for dehradun.
I clocked a total of 68kms in that liter. The distance from mussoorie to dehradun is abt 30kms with abt 40% engine breaking slope and the rest very mind acceleration(normal driving overall). My bike gives an average of abt 40-45, bit hard to get a accurate reading in a somewhat hilly place like dehradun.

So I'd finally bet then engine breaking does not use any more fuel then ideling.

Hence proved..
Lol I dont know if it applies but last time i 'Hence proved' was in 10th grade physics. After that i was abducted by computers...

You mean to say you didn't study Calculus in Mathematics?

i mean to say never was serious again to 'hence prove' something like theorems and stuff. But be assured i have been thru the same hell as everybody

besides u dotn have to write hence proved with maths. In my school it usually used with those crazy physics theorems. In colg no one actually cares.
never ment it literally.. just a random neuron across my funny mind..

What's this Calculus that everyone talks about? Always hear them talking about it in Movies...

As for hence prove, never heard of that either. And they say I'm a graduate