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-   -   Max kmpl , and how to achieve it (https://www.team-bhp.com/forum/technical-stuff/28072-max-kmpl-how-achieve-3.html)

I can see that a lot of suggestions and tricks for better mileage here... But, surprisingly people seem to have forgotten a very simple, yet effective trick - Carpooling !! It instantly doubles your mileage... reduces your driving stress.. and is an ultimate, cool way to commute to your office in major cities, as it helps reduce the traffic as well.

IMHO, we should all give it a try, at least once, and see what wonders it does to your daily drudgery of commuting to work. So.. rather than worrying about 5-10 % gains in the mileage, just start carpooling with someone and get a 100% gain.

Carpooling may not work for everyone, does not work in my case, I work odd-ball hours and there is no fixed time to go and come back. 2 weeks back I was everyday coming home between 2-4 a.m in the morning and that's when I really apprciated the investment I made in my carb zen.

car pooling will definately save other car's fuel ..but it wont ctretch the litre ..for that thing to happen we need to use invent or manipulate certain things so when we want power we will gwr power when we want milage we will gwt milage and both the times we will get it more efficiently than the manufacturer!

as everyone knows , the engines are designed to run at specific temp to run most efficiently. the temp varies from @73 deg to 97 deg depending upon the manufacturer's preferences and applications.
untill that temperature is attended, most of the engines use richer mixture and lean it as the temp approches the oprating temp.<engines should behave like that too!>
plus there are lot of parasitic losses like thicker engine oil to move around<more power required>extra cool combustion chamber<too much heat being wasted in getting the temp high, till then very low thermal efficiency is available>
tolerances of the engine are measured at the oprating temp.and various metals have various coefficient of expansions .so they expand or contract at different rate at different temp.

so lower or higher temp rob lot of frictional horsepower.
when we switch off the engine in the evening generally its preety hot .
when we start it in the morning its cold down to atmosphere temp @15 -20 deg and the desired temp is @50 to 60 deg higher and till then we will be loosing engine life+fuel+loss of power.
***if we add a heat accumulator to the cooling path.store the hot coolent in a theramaly insulated accumulator in the eve . when we start the engine it will get much warmer coolent to oprate.
we can also use thermostatically oprated heater running on hot exhaust gases to worm up the coolent even faster.
this will save at least 5 to 15 percent fuel+all the benifits of warmer engines!

Hi Turbosam,

Just needed some clarificaiton in the comments posted by you in the Woomer Coolent section.

Is the above commets applicable only to MPFI cars or are they applicale even to Carb cars, as carb cars to the best of my knowledge are not intelligent as there are no sencors like MPFI.

Hi,

AFAIK, carb engines do not, by themselves, increase the rpm or fuel mixture when the car is cold. But, all the disadvantages of a cold engine apply equally to MPFI and carb engines. What is effectively means is that a carb engine would take longer to achieve the optimal temperature than an MPFI engine. But, the drive-ability of a carb engine is not affected as much during the cold start. My Zen MPFI feels somewhat sluggish during a cold start than the carb M800.

That said... Turbosam, I like your idea of keeping the engine warm by using a heat accumulator. But the mechanism shouldn't affect the cooling action which is required during summer afternoons.

Would it help if we cover the car when we get back to home in the evening? I think, the 10-12 hours would be sufficient to loose all the heat by morning. After all.. it's metal.

I have a different idea... what if we add a small, electric heater and place it near the engine? It will draw the power from the battery and pump hot air on top the engine to bring it to nice 40-45 degs. The only drawback is having to wait for 2-3 minutes before you switch the car ON, but the heater can operate even when the car is running. After the driver 'thinks' that the engine has achieved an optimal temperature, the heater can be turned OFF.

Folks, what is RPM zone (or speed?) at which we get best mileage?

Sorry if posted already.

sathya_nars, I would suggest you dont bother looking at the rpm meter. Instead, listen to the engine, as if it were a living being. It will tell you when you should upshift/downshift etc. If it sounds strained, you are not doing it right. I am sure, you will get the hang of it after some time.

Ofcourse, if you are one of those that love to hear the engine growl, this is not going to help you with FE. :)

the amount of heated air required will sap the battery . as u will be needing close to 10 20 cubic feet of heated air per minute. you will be needing equivalent od 7 to 8 hair dryers<normally rated @1000-1500 watts, 746 watts/hr is one hp>
and it will only <if it does> heat the air .
engine will still be at much lower temp than required
as u are not heating the coolent and or oil, u are not heating the metal part of the engine and its around 40 to 100 kgs of metal which will be sapping the heat .
heat accumulator should be added to the coolent path.it will increase the coolent capacity by close to 5 -6 litres.
generally thats the amount of coolent <actually antifreeze+so called distilled water>so 50%of coolent at 15 deg<overnight cooling> and 50 % coolent at 60 deg <90+ deg when stored with assumed heat loss>in cold engine will warm up the engine much faster.
it will also affect the engine performance positively even in hot summer as more the coolent to absorb the heat from the engine lesser the fluctuations in coolent temp.accumulator will not add the heat to the cooling medium. infact if the radiator or its fan is malfunctioning then because od 100%more liquid to assimilate the heat, it will help u drive safely much longer as it will give some breather time to the radiator. it will be of great help when car is pushed to the max. the sudden rise in the heat transfered to the coolent will be well managed by the cooling system.because of double the volume. .
pay off -- plumbing , positioning. 5 -6 kgs of extra dead weight in the tight engine compartment>and extra cost for extra coolent.
in exchange it will extend the engine oil life,coolent life cooling system life .in fact it will add years to the engine life too .
plus little bit of fuel saved .
plus a lot of emissions reduced!

Varies from engine to engine. Basic factor being the torque curve and where the peak torque is produced.

Trying to understand this.
On the one hand EGR seems to induce a drop on power. But is that only when it is active ?

Is it switched off, say, when one floors the throttle ? If so, would the engine power still be lower ?

if the e.g.r is external then cutting off the e.g.r /disabling its function can potentially increase the powerback to normal.
if the combustion enhancer is built in or added-like cooler ,denser air ,lesser humidity,higher actual compression ratio hotter than required plug better functioning exhaust system, and lesser octane fuel the things may be different .
it may increase the combustion temp and may induce knocking.
if the car is equiped with good knock sensor+ecu is programmed with very wide range if ignition retard then the ecu will retard the timing till the knock fades away .the power will drop slightly at wide open throttle under load at max torque rpm-when volumetric effency is at the peak- but it wont harm the engine .
if e.g.r. system is buit in -that is good amount of inlet and exhaust valve timing overlap -the fresh air fuel will be mixture will be contaminated with the flue gases , the exhaust gases occupy the space in the combustion chambers so lesser fresher air can be admitted <loss of volumatric efficiency>plus the flue gases slow down the combustion process <less thermal efficiency>plus less happy marriages of oxygen and fuel molecules as the non combustible gases dilute the oxygen content . though lot of CO get one more O atom to get converted in to less harmful CO2.
it reduces polution at the cost of efficiency on all the fronts.
in this case all u can do is reduce the cam timing, overlap. change cam events <nearly re engineer the engine >and hope that u know cam designing better than some <though not all> engine designers!!!lol:

as getting good torque spread and good power band with no or minimum cam overlap@ top dead centre really needs lot of knoledge+willingness of the manufacturer and then the cost goes high . the developement also take a lot of expensive qualified man hrs if one wants to design the engine based on better overall efficiency in mind.
lot of overlap figures will definately give lot of power but at the cost of thermal, mechanical ,volumatric efficiencies.

technically engine has to work as an efficient pump. and engine has to work as a heat exchanger.
the rpm at which the engine works most efficiently as a pump AS WELL AS heat exchanger is the point where it is most efficient.
then how to find it ?
its the rpm at which max torque is produced .
engine will be converting max possible< to the specific engine> air fuel in to heat and max heat in to mechanical energy.
so technically engine is most efficient at that rpm .
fuel efficiency in terms of kmpl depends upon the weight of the car.air drag,overall gear ratio, tyres. no of wheels,ancelliries,coolent temp,driving style, conditions power to torque ratio,and lot more.lol:

The Bourke Engine
check this out ..:Shockked:

this was the engine fitted in shells milage marathon car <gave in excess of 300mpg.in 72 or 77