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|16th August 2005, 13:40||#31|
Senior - BHPian
Join Date: Jul 2004
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There are various ways of calculating the efficiency levels of an engine but at times the calcs go a bit too far... assuming that a basic engine of 1.5 litres capacity has been tuned without anything done in to increase its volumetric efficiency and running 8 PSI of boost the following would be true.
Boost Pressure (psi): 8
Turbo to Mani Pres. Drop: 1.5 psi
Compressor Efficiency: 85%
Intake Temp (*F): 68
Intercooler Efficiency: 70%
Drivetrain Loss, %: 20%
Engine Speed (RPM): 6500
Volumetric Efficiency : 80%
MAP (psi): 22.7
Approx. Horsepower (crank): 145.3178159
Approx. Horsepower (wheel): 116.2542527
Now lets say you increase the efficiency of the intercooler to about 85% and the VE of the engine to around 85% then:
Approx. Horsepower (crank): 160.663327
Approx. Horsepower (wheel): 128.5306616
at this given rate a turbo city 1.5 exi would have to run about 22PSI of boost to achieve 200 bhp on the wheels. (this would however mean about 252 bhp on the flywheel).
As for the FE more the boost more the fuel required however you can tend to run it lean and get awsome milage but destroy the engine.
Hence I guess it would be better to put a disclaimer saying that the bhp figures are for the flywheel rather than the wheels itself.
|18th August 2005, 16:07||#35|
Psycho: the figures of 200 is bhp . bhp is always measured at the crank. its not the turbo alone there is also stage 1 and stage 2 of nos. that is why the car has je pistons to drop compression. and to burn all this mixture under so much pressure we use the MSD.
|19th August 2005, 03:14||#36|
Join Date: Mar 2005
Thanked: 0 Times
just to correct what z klasse mentioned previously. the decals and the graphics on the car is done by my friend chirayu of xtreme graphix from bandra. only the paint job is done by the owner. this car is fast ,really fast. it has the works,just to name a few - fidanza flywheel
centerforce clutch,aqua mist msd boost timing retard and many more. tuned by ks motorsport
Last edited by superpower : 19th August 2005 at 03:16. Reason: add on
|19th August 2005, 20:20||#38|
|19th August 2005, 23:23||#39|
It is the ‘theoretical’ Power that an engine can develop by the expansion of gases inside its cylinders, such as by means of ‘indicator cards’.
It is the Power that an Engine can deliver for ‘useful’ work, i.e. at its Flywheel and is measured on ‘Test-Beds’ using ‘Pony Brakes’ or ‘Dynamometers’.
If we want to measure the BHP of a car it is measured at the wheels.
If we want to measure the BHP of the engine it is measured at the flywheel .
Is this correct ?????
|19th August 2005, 23:27||#40|
you have answered your own question.. bhp of a car at the wheels.. also known as horse power.. power that the engine can produce known as brake horse power at the crank or flywheel..
|20th August 2005, 17:33||#41|
Senior - BHPian
Join Date: Jul 2005
Thanked: 46 Times
bhp can be measured anywhere. It can be at the flywheel, it can be at the gearbox, it can be at the propshaft, or it can be at the wheels. It doesnt matter. Whats important is, the figure will keep on reducing as you move away from the flywheel and towards the wheels due to losses.
ihp is the indicated horsepower. It is the power that the engine produces without taking into account mechanical losses. these mechanical losses are known as fhp or frictional horspower.
So, ihp = bhp+fhp.
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