What Is The Significance Of ‘bhp’ Value Of An Engine?

[Yasith]

Can somebody explain the significance of ‘bhp’(Brake horsepower) value of a engine and its’ impact on performance of the Car? It is bit confusing. For example Micro Trend has 1075cc engine it only gives 45 bhp, while Maruti 800cc engine gives 35 bhp. On the other hand Chery QQ 812cc engine gives 51 bhp.

[Arc Angel]

Can somebody explain the significance of ‘bhp’(Brake horsepower) value of a engine and its’ impact on performance of the Car? It is bit confusing. For example Micro Trend has 1075cc engine it only gives 45 bhp, while Maruti 800cc engine gives 35 bhp. On the other hand Chery QQ 812cc engine gives 51 bhp.

http://auto.howstuffworks.com/horsepower.htm

[SlViper]

Can somebody explain the significance of ‘bhp’(Brake horsepower) value of a engine and its’ impact on performance of the Car? It is bit confusing. For example Micro Trend has 1075cc engine it only gives 45 bhp, while Maruti 800cc engine gives 35 bhp. On the other hand Chery QQ 812cc engine gives 51 bhp.

Have a horse attached to your car and let the horse to pull your car forward while you accelerate your car to pull backwards.

The no of horses needed to pull your car forward while you accelerate backwards is horse power. It's simple as that.

And also like that you can calculate donkey power, dog power, cat power etc. Try it; still no one has tried it before. Good luck.

[Pericles]

The number of horses to hold the car still, I think.

[xviruz]

According to my knowledge hourse power is not depend on only the capacity of the engin.there are differnt types of thing which changes the bhp(horse power)..mainly that is the technology has been used..thats why above you've mentioned types you can not think of a relationship between bhp and cc...

Edited November 26, 2007 by xviruz

[ruwan67]

Dear Yasith,

Actually SIVIper saying not a joke because Sr. Jams Watt who introduced the HP concept of measuring power, really was measured from Pony. 1hp is equal who can pull 33,000pounds rate of one feet per minute.

The bhp break house power really introduced to world due the instrument which measures power. It consists of pulley, belt and spring weigh. One end of belt fixed and other end hang to weigh while putting around the pulley. Then the pulley is fixed to engine. When Engine start the pulley is rotating and belt get tension due friction and tension force can read from weigh. The same pulley-belt mechanism is used as a Break. If you open lath a machine you can see it use for sudden stopping of lath chuck rotation.

So that is how the BREAK came to bhp.

Similarly engine bhp is measured from power at crank shaft without gear box etc.

Only the Engine capacity the cc cannot provide answer along with out knowing engine rpm at its max power.

More cc and more rpm has more power. More cc and less rpm less power.

It can simply explain as bhp= (pounds=engine CC)x(feet/min= rpm)

Regards,

Ruwan

[Sha7]

Have a horse attached to your car and let the horse to pull your car forward while you accelerate your car to pull backwards.

The no of horses needed to pull your car forward while you accelerate backwards is horse power. It's simple as that.

And also like that you can calculate donkey power, dog power, cat power etc. Try it; still no one has tried it before. Good luck.

Horsepower can be explained more precisely than above,

The term "horsepower" was coined by the engineer James Watt (1736 to 1819) in 1782 while working on improving the performance of steam engines. This occurred while using a mine pony to lift coal out of a coal mine. He conceived the idea of defining the power exerted by these animals to accomplish this work. He found that, on the average, a mine horse could pull (lift by means of a pulley) 22,000 foot-pounds per minute. Rather than call this "pony" power, he increased these test results by 50 percent, and called it horsepower i.e. 33,000 foot-pounds of work per minute.

Under this system, then, one horsepower is:

1 hp ≡ 33,000 ft·lbf/min

= 550 ft·lbf/s

= 550 × 0.3048 × 0.45359237 m·kgf/s

= 76.0402249068 kgf·m/s

= 76.0402249068 × 9.80665 kg·m²/s³

= 745.69987158227022 W

[Yasith]

Only the Engine capacity the cc cannot provide answer along with out knowing engine rpm at its max power.

More cc and more rpm has more power. More cc and less rpm less power.

It can simply explain as bhp= (pounds=engine CC)x(feet/min= rpm)

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Hi Ruwan, this is what I was exactly looking for, thanks a lot.

Is this implies that when you are looking for more efficient engine, you should go for bhp value than the cc value?

[Yasith]

And also like that you can calculate donkey power, dog power, cat power etc. Try it; still no one has tried it before. Good luck.

We have "Man Power" !!!! Which is used to measure something else (LOL)

[Sha7]

Hi Ruwan, this is what I was exactly looking for, thanks a lot.

Is this implies that when you are looking for more efficient engine, you should go for bhp value than the cc value?

Not exactly….

The true power that your car gets for the drive = Engine hp – bhp

Let’s think the an engine generates 1000 hp. But the whole power won’t go to the drive. Some of the power will go to alternator, gearbox, air-conditioned, etc and to overcome the friction of all moving parts of the car.

The power that goes to other operations than the drive is the bhp.

For an example if you turn the air conditioner off you can get more power to the drive. That’s because by turning off the AC you reduce the bhp. So that more power goes to drive.

[miniace]

This explains the half horse power best

Guys just follow this link and you can get a good idea about BHP.

http://en.wikipedia.org/wiki/Horsepower#Br...power_.28bhp.29

MINIACE

[ruwan67]

Hi Ruwan, this is what I was exactly looking for, thanks a lot.

Is this implies that when you are looking for more efficient engine, you should go for bhp value than the cc value?

Gear box friction loss, Air-condition all are unavoidable loss however has been developed, and are developing every day.

Meanwhile, engine bhp not only depends on cc and rpm. If it is turbocharged, it can get more bhp for less cc. Recently, I sow CAT engine with 6 turbo it likes truck engine but can pull a ship.

If you want to compare engine efficiency for close range of cc , check if it is fuel injection, variable valve timing then definitely it is more efficient.

If the power steering is drive by electrically it has less power loss.

If the gear box is CVT it provide unnecessary acceleration loss.

If all engins has carb, then select less cc for high bhp.

Regards,

Ruwan

[Pericles]

Hi Ruwan, this is what I was exactly looking for, thanks a lot.

Is this implies that when you are looking for more efficient engine, you should go for bhp value than the cc value?

Don't mix up efficiency with this. That implies getting the max usage out of the fuel used. Least waste, in terms of unburnt fuel that leaves the combustion chambers. Mind thats efficient engine, not efficient car, which implies cars milage. The only bearing the power will have on the efficiency will be how much power it takes to move the car. Heavier car will take more power to move. A smaller engine, tho efficient in terms of fuel usage, might not produce the power to move the car unless running fairly hard. In this case, a more powerful engine, even tho using more fuel when ideling, will use less fuel to move the vehicle as it produces the power needed without working as hard.

And now, if I have totally confused you, take two asprin, and try reading Wiki and Howstuffworks in the morning.

[ruwan67]

I have converted the formula for easy. For aspirated (not turbo) internal combustion engine hp at crank shaft ( for any engine –VVTI , EFI etc)

hp=engine cc x rpm/86098

From the engine data which is normally given by manufacture cc, bhp, rpm

Effy=bhp/hp

lager Effy is the good one

Regards,

Ruwan

[Yasith]

Thanks you guys....thanks alot.....

[Yasith]

I have converted the formula for easy. For aspirated (not turbo) internal combustion engine hp at crank shaft ( for any engine –VVTI , EFI etc)

hp=engine cc x rpm/86098

From the engine data which is normally given by manufacture cc, bhp, rpm

Effy=bhp/hp

lager Effy is the good one

Regards,

Ruwan

As an exercise I compared three cars Maruti 800, Maruti Alto Lxi, and Chery QQ

Maruti 800: 795cc; 37bhp@5000; 59Nm@2500; 650kg

Maruti Alto Lxi: 795cc; 47bhp@6200; 62Nm@3000; 740kg

Chery QQ: 812cc; 52bhp@6000; 70Nm@3500-4000; 880kg

Therefore,

Effy Values are…

Maruti 800: 0.8004

Maruti Alto Lxi: 0.8199

Chery QQ: 0.9189

What about the Torque value, how does it affect the efficiency? Does it mean lower the Torque lower the fuel consumption, And does it have to do anything with cars ability to run in difficult terrains, going up-hills...etc?

[ruwan67]

Are you going to kill me anyway I did few calculations

Keep it mind I haven’t got any energy loss from gearbox to tiers

If you can see the above your cal QQ has more efficient

On the other hand if you divide bhp/cc the power generate by a 1cc can found

MAruti 37/795= 0.047

Alto 47/795= 0.059

QQ 52/812=0.064

As all aspirated O2 atoms are same for 1cc. Hence the power bhp per 1cc, QQ has the max efficiency

But??????? It has more cc therefore it consumes more petrel. Meanwhile Alto has almost same bhp per 1cc the compare to QQ Alto is the best in fuel economy.

If torque is known then bhp can be found from following formula

bhp=T xrpm/5252 T(ft lbf)

1Nm=0.738 ft lbf

So for max torque

Maruti bhp = 0.738 x 59 x 2500/5252= 20.7hp

Alto bhp = 0.738 x 62 x 3000/5252= 26.1hp

QQ bhp = 0.738 x 62 x 3750/5252= 36.9hp

Still QQ has more bhp for max Torque

For max bhp the torque by inverting formula

Maruti T = 37 x5252 /(0.738 x 5000)= 52.7 Nm

Alto T = 47 x5252 /(0.738 x 6200)= 54 Nm

QQ T = 52 x5252 /(0.738 x 60200)= 61.7 Nm

Still QQ has more Torque for max bhp

If you divide bhp/ mass

Maruti 37/650=0.057

Alto 47/740= 0.064

QQ 57/880= 0.059

Alto and QQ are same. Therefore performance of both in flat land and uphill area same

Conclusion: I think for good pickup QQ best for racing enthusiast because it has more Torque

But considering fuel economy and efficiency and common performance(Uphill, flat land) Alto is good.

[Pericles]

Conclusion: I think for good pickup QQ best for racing enthusiast because it has more Torque

This, people, is that you call "getting carried away on a wave of BS". You don't even use the words "racing enthusiast" and "QQ" in the same sentence man! Try running a race with a QQ and see how many pieces you leave on the track. "racing enthusiast" my darkly pigmented bottom.