some interesting conversion formula's - Aussie V8 | Holden - Ford

v8tfcorty · 16-05-2006, 06:44 PM

Many of the formulas use the value of pi which is 3.1415927
Some formulas contain notation such as ^2 which means "squared" or ^3 which means "cubed"

Convert between 1/4 mile and 1/8 mile ET's
1/4 mile ET = 1/8 mile ET x 1.5832
1/8 mile ET = 1/4 mile ET / 1.5832

Calculate 1/4 mile ET and MPH from HP and Weight
ET = ((Weight / HP)^.333) * 5.825
MPH = ((HP / Weight)^.333) * 234

Calculate HP From ET and Weight
HP = (Weight / ((ET/5.825)^3))

Calculate HP From MPH and Weight
HP = (((MPH / 234)^3) * Weight)

Formulas for displacement, bore and stroke

pi/4 = 0.7853982
cylinder volume = pi/4 x bore^2 x stroke
stroke = displacement / (pi/4 x bore^2 x number of cylinders)

Formulas for compression ratio
(CylVolume + ChamberVolume) / ChamberVolume
cylinder volume = pi/4 x bore^2 x stroke
chamber volume = cylinder volume / compression ratio - 1.0
displacement ratio = cylinder volume / chamber volume

amount to mill = (new disp. ratio - old disp. ratio / new disp. ratio x old disp. ratio) x stroke

Formulas for piston speed
piston speed in fpm = stroke in inches x rpm / 6

rpm = piston speed in fpm x 6 / stroke in inches

Formulas for brake horsepower
horsepower = rpm x torque / 5252
torque = 5252 x horsepower / rpm
brake specific fuel consumption = fuel pounds per hour / brake horsepower

bhp loss = elevation in feet / 1000 x 0.03 x bhp at sea level

Formulas for indicated horsepower & torque
horsepower = mep x displcement x rpm / 792,00
torque = mep x displacement / 150.8
mep = hp x 792,000 / displacement x rpm
mep = hp x 792,000 / displacement x rpm
mechanical efficiency = brake output / indocated output x 100
friction output = indicated output - brake output

taxable horsepower = bore2 x cylinders / 2.5

Formulas for air capacity & volumetric efficiency
theoretical cfm = rpm x displacement / 3456
volumetric efficiency = acutal cfm / theoretical cfm x 100
street carb cfm = rpm x displacement / 3456 x 0.85

racin carb cfm = rpm x displacement / 3456 x 1.1

Formulas for tire size & their effect
effective ratio = (old tire diameter / new tire diameter) x original ratio

actual mph = (new tire diameter / old tire diameter) x actual mph

Formulas for g force & weight transfer
drive wheel torque = flywheel torque x first gear x final drive x 0.85
wheel thrust = drive wheel torque / rolling radius
g = wheel thrust / weight
weight transfer = weight x cg height / wheelbase x g
lateral acceleration = 1.227 x raduis / time^2
lateral weight transfer = weight x cg height / wheel track x g

centrufugal force = weight x g

Formulas for shift points
rpm after shift = ratio shift into / ratio shift from x rpm before shift

drivehsaft torque = flywheel torque x transmission ratio

Formula for instrument error
actual mph = 3600 / seconds per mile
speedo error percent = difference between actual and indicated speed / actual speed x 100
indicated distance = odometer reading at finish - odometer reading at start

odo error percent = difference between actual and indicated distances / actual distance x 100

Formulas for MPH RPM gears & tires
mph = (rpm x tire diameter) / (gear ratio x 336)
rpm = (mph x gear ratio x 336) / tire daimeter
gear ratio = (rpm x tire diameter) / (mph x 336)

tire diameter = (mph x gear ratio x 336) / rpm

Formulas for weight distribution
percent of weight on wheels = weight on wheels / overweight x 100

increased weight on wheels = [ distance of cg from wheels / wheelbase x weight ] + weight

Formulas for center of gravity
cj location behind front wheels = rear wheel weights / overall weight x wheelbase
cg location off-center to heavy side = track / 2 - [ weight on light side / overall weight ] x track
cg height = [ level wheelbase x raised wheelbase x added weight on scale / distance raised ] x overall weight

just some trivial conversion formula's i found hope they help some one out sometime lol
regards
jerome

wabbit · 16-05-2006, 07:37 PM

nice stuff, jerome

this needs to be in the tech tips

Damian · 16-05-2006, 09:16 PM

wow thats some kool stuff there. good 1

16-05-2006, 06:44 PM	#1 (permalink)
v8tfcorty mongering in L.O.S Trade Rating: (0) Join Date: Sep 2005 Location: thailand Ride: cortina Posts: 479	some interesting conversion formula's Many of the formulas use the value of pi which is 3.1415927 Some formulas contain notation such as ^2 which means "squared" or ^3 which means "cubed" Convert between 1/4 mile and 1/8 mile ET's 1/4 mile ET = 1/8 mile ET x 1.5832 1/8 mile ET = 1/4 mile ET / 1.5832 Calculate 1/4 mile ET and MPH from HP and Weight ET = ((Weight / HP)^.333) * 5.825 MPH = ((HP / Weight)^.333) * 234 Calculate HP From ET and Weight HP = (Weight / ((ET/5.825)^3)) Calculate HP From MPH and Weight HP = (((MPH / 234)^3) * Weight) Formulas for displacement, bore and stroke pi/4 = 0.7853982 cylinder volume = pi/4 x bore^2 x stroke stroke = displacement / (pi/4 x bore^2 x number of cylinders) Formulas for compression ratio (CylVolume + ChamberVolume) / ChamberVolume cylinder volume = pi/4 x bore^2 x stroke chamber volume = cylinder volume / compression ratio - 1.0 displacement ratio = cylinder volume / chamber volume amount to mill = (new disp. ratio - old disp. ratio / new disp. ratio x old disp. ratio) x stroke Formulas for piston speed piston speed in fpm = stroke in inches x rpm / 6 rpm = piston speed in fpm x 6 / stroke in inches Formulas for brake horsepower horsepower = rpm x torque / 5252 torque = 5252 x horsepower / rpm brake specific fuel consumption = fuel pounds per hour / brake horsepower bhp loss = elevation in feet / 1000 x 0.03 x bhp at sea level Formulas for indicated horsepower & torque horsepower = mep x displcement x rpm / 792,00 torque = mep x displacement / 150.8 mep = hp x 792,000 / displacement x rpm mep = hp x 792,000 / displacement x rpm mechanical efficiency = brake output / indocated output x 100 friction output = indicated output - brake output taxable horsepower = bore2 x cylinders / 2.5 Formulas for air capacity & volumetric efficiency theoretical cfm = rpm x displacement / 3456 volumetric efficiency = acutal cfm / theoretical cfm x 100 street carb cfm = rpm x displacement / 3456 x 0.85 racin carb cfm = rpm x displacement / 3456 x 1.1 Formulas for tire size & their effect effective ratio = (old tire diameter / new tire diameter) x original ratio actual mph = (new tire diameter / old tire diameter) x actual mph Formulas for g force & weight transfer drive wheel torque = flywheel torque x first gear x final drive x 0.85 wheel thrust = drive wheel torque / rolling radius g = wheel thrust / weight weight transfer = weight x cg height / wheelbase x g lateral acceleration = 1.227 x raduis / time^2 lateral weight transfer = weight x cg height / wheel track x g centrufugal force = weight x g Formulas for shift points rpm after shift = ratio shift into / ratio shift from x rpm before shift drivehsaft torque = flywheel torque x transmission ratio Formula for instrument error actual mph = 3600 / seconds per mile speedo error percent = difference between actual and indicated speed / actual speed x 100 indicated distance = odometer reading at finish - odometer reading at start odo error percent = difference between actual and indicated distances / actual distance x 100 Formulas for MPH RPM gears & tires mph = (rpm x tire diameter) / (gear ratio x 336) rpm = (mph x gear ratio x 336) / tire daimeter gear ratio = (rpm x tire diameter) / (mph x 336) tire diameter = (mph x gear ratio x 336) / rpm Formulas for weight distribution percent of weight on wheels = weight on wheels / overweight x 100 increased weight on wheels = [ distance of cg from wheels / wheelbase x weight ] + weight Formulas for center of gravity cj location behind front wheels = rear wheel weights / overall weight x wheelbase cg location off-center to heavy side = track / 2 - [ weight on light side / overall weight ] x track cg height = [ level wheelbase x raised wheelbase x added weight on scale / distance raised ] x overall weight just some trivial conversion formula's i found hope they help some one out sometime lol regards jerome Last edited by v8tfcorty; 16-05-2006 at 06:47 PM.

16-05-2006, 07:37 PM	#2 (permalink)
wabbit smell something burning? Trade Rating: (0) Join Date: Oct 2004 Location: Rockhampton Ride: VK Commy slugmobile, Kia Rio, LH Torry Posts: 6,091	nice stuff, jerome this needs to be in the tech tips __________________ Nothing to see, here Move along, please .

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16-05-2006, 09:16 PM	#3 (permalink)
Damian Senior Member Trade Rating: (0) Join Date: Mar 2006 Location: Victoria, Hampton Park Ride: nuffin yet!! Posts: 571	wow thats some kool stuff there. good 1

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