All Kinds Of Conversions
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Joined: Mar 2006
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From: tacos
Vehicle: 2000 Elantra
as stolen from edelbrock
EDIT: LINK ADDED CUZ IT CHANGED...
http://www.edelbrock.com/automotive/sport_...act/tech_3.html
<div class='quotetop'>QUOTE </div><div class='quotemain'>About Mile per Hour and Revolutions per Minute
First find the vehicle speed, MPH and the consequent engine RPM operating range:
Formula for MPH
MPH = TIRE RADIUS � 168 x ENGINE RPM � GEAR RATIO
Example: What MPH at 6500 RPM with a 4.9 rear axle and 14 inch radius
tire in 4th (1:1) gear?
MPH = 14 � 168 x 6500 � 4.90 � 1 = 111 MPH
Example: in 3rd gear (1.34)?
MPH = 14 � 168 x 6500 � 4.90 � 1.34 = 83 MPH
Note: Tire Radius is distance, in inches, from center of wheel to the top of the tire.
Note: Gear Ratio is Rear Axle ratio divided by Transmission Gear ratio.
Formula for RPM
RPM = 168 x GEAR RATIO x MPH � TIRE RADIUS
Example: Using the first example, what will be the RPM after shift from 3rd to 4th gear at 83 MPH?
RPM = 168 x 4.90 x 83 � 14 = 4880 RPM
Formula for Gear Ratio
GEAR RATIO = TIRE RADIUS x RPM � 168 � MPH
Example: Using the first example, what Gear Ratio is required for 120 MPH at 6500 RPM?
GR = 14 x 6500 � 168 � 120 = 4.51
Formula for Tire Radius
TIRE RADIUS = 168 x MPH x GEAR RATIO � RPM
Example: Using the first example, what tire radius for 110 MPH but at 6000 RPM with a 4.11 gear?
168 x 110 x 4.11 � 6000 = 12.7 inches
Note: Approximately a 25" diameter tire. Remember that the tire radius will be less during hard acceleration than when the vehicle is standing still. Also, radius will be greater at high speed due to tire expansion from centrifugal force.
Computing HP & Torque
Formula for HPQ
HPq = (0.00426 x MPH)3 x WEIGHT
HPq = Engine horsepower required to reach MPH in quarter mile
Note: understates HP required at speeds exceeding 100 MPH.
Note: assumes engine HP must be 2 x the HP required at drive wheels.
Example: What engine HP is required to achieve 110 MPH in a 3200 pound
vehicle in 1/4 mile?
HPq = (0.00426 x 110) x (0.00426 x 110) x (0.00426 x 110) x3200 = 329 engine HP
Formula for HP and Torque
HP = Torque x rpm � 5252 � Torque = HP x 5252 � RPM
Example: What torque is required to generate 329 HP at 6000 RPM?
T = 329 x 5252 � 6000 = 288 foot pounds @ 6000 RPM
Example: What torque is required for 296 HP at 4880 RPM?
T = 296 x 5252 � 4880 = 319 foot pounds @ 4880
About Cubic Inches, Volumetric Efficiency,
Flow Bench Conversion and CFM
Formula for VE
VE = (CFM x 3456) � (CID x RPM)
If VE (volumetric efficiency) is less than 1 (or 100%) the amount and quality of charge in the cylinder is reduced so less torque is produced. VE above 100% is a supercharging effect and more torque is produced.
Power Level Stock Performer Torker II Perf. RPM Victor Jr. Victor
Peak VE% 60-80 75-90 90-100 95-105 105-115 110-122
Flow Bench Conversion Factor
VE = (CFM x 3456) � (CID x RPM)
Typically flow bench values are given for a pressure drop of 28 in H2O. To convert flow figures from a different pressure drop to 28 in H2O use the formula above.
Example: You have flow figures of 152 cfm at 10 in H2O. What if the same head was flowed at 28 in H2O?
CFM H2O = 152 x �Ëâ€*Å¡(28�10) = 254 cfm
Formula for CID (cubic inch displacement)
CID = NUMBER OF CYLINDERS x SWEPT VOLUME
Note: CID = N x 0.7854 x bore x bore x stroke (all in inches)
Example: What is CID of a V8 with a �30 over�, 4 inch bore and 3.48 inch stroke?
CID = 8 x 0.7854 x 4.030 x 4.030 x 3.48 = 355 cu. inches
Formula for CFM
CFM = CUBIC FEET PER MINUTE
A measure of air flow into and out of an engine (CFM = CID x RPM x VE � 3456). Example: What CFM is consumed by a 355 CID engine at 4500 RPM if VE = 105% (1.05)?
CFM = 355 x 4500 x 1.05 � 3456 = 485 CFM
Example: What CFM by the same engine at 6400 RPM if VE has fallen to 95% (0.9)?
CFM = 355 x 6400 x 0.95 � 3456 = 625 CFM
About Compression Ratio
Formula for CR
CR = COMPRESSION RATIO = CYL. VOLUME @ BDC � CYLINDER VOLUME @ TDC
= 1 + (SWEPT VOLUME � VOL @ TDC)
= 1+ (0.7854 x BORE x BORE x STROKE) � (CCV + HGV + PDV)
CCV = Combustion Chamber Volume, in cubic inches
Note: if volume is given in cc�s then � 16.4 to get cubic inches.
HGV = Head Gasket Volume, in cubic inches,
= Head gasket compressed thickness x 0.7854 x bore x bore
PDV = (Piston Deck Volume) + (Piston Dome Effective Volume)
= (0.7854 x bore x bore x deck to piston distance) + (volume of piston depressions - volume of piston bumps)
Example: What is CR of the engine in #9 if heads have 72 cc chamber, head gasket is compressed to 0.040 inch and flat top pistons give 0.025 deck clearance at TDC?
CCV = 72 � 16.4 = 4.39 cubic inches
HGV = 0.040 x 0.7854 x 4.030 x 4.030 = 0.51 c.i.
PDV = 0.025 x 0.7854 x 4.030 x 4.030+ 0- 0 = 0.32 c.i.
CR = 1+ (0.7854 x 4.030 x 4.030 x 3.48 � (4.39 + 0.51+ 0.32))
= 1+ (44.39 � 5.22) = 9.5 CR
About Fuel System Flow
Formula for Injector Size per Hp
LBS/HR = HP � 16
In general if you use BSFC = .50 and an acceptable duration of 100% then use above formula for an eight cylinder engine.
Note: lbs/hr. = ((BSFC � 8) x HP) � Peak Inj. Duration
Example: You plan to make 448 hp. What size injector should you use?
lbs/hr = 448 � 16 = 32
Injector Conversion - lbs/hr to cc/min
CC/MIN = LBS/HR X 9.71 OR LBS/HR = CC/MIN X .103
Example: How many cc/min. does a 32 lb/hr. injector flow?
cc/min = 32 x 9.71 = 311 cc/min
Pump Flow Conversion Factors
GPM = lbs/hr � 369.8
Used to convert lbs/hr to gallons per minute (of gasoline).
Note: typically GPM = HP � 740
Example: Your engine uses 221 lbs. per hour of fuel. What are the fuel system requirements?
GPM = 221 � 369.8 = 0.60 gal/min</div>
EDIT: LINK ADDED CUZ IT CHANGED...
http://www.edelbrock.com/automotive/sport_...act/tech_3.html
<div class='quotetop'>QUOTE </div><div class='quotemain'>About Mile per Hour and Revolutions per Minute
First find the vehicle speed, MPH and the consequent engine RPM operating range:
Formula for MPH
MPH = TIRE RADIUS � 168 x ENGINE RPM � GEAR RATIO
Example: What MPH at 6500 RPM with a 4.9 rear axle and 14 inch radius
tire in 4th (1:1) gear?
MPH = 14 � 168 x 6500 � 4.90 � 1 = 111 MPH
Example: in 3rd gear (1.34)?
MPH = 14 � 168 x 6500 � 4.90 � 1.34 = 83 MPH
Note: Tire Radius is distance, in inches, from center of wheel to the top of the tire.
Note: Gear Ratio is Rear Axle ratio divided by Transmission Gear ratio.
Formula for RPM
RPM = 168 x GEAR RATIO x MPH � TIRE RADIUS
Example: Using the first example, what will be the RPM after shift from 3rd to 4th gear at 83 MPH?
RPM = 168 x 4.90 x 83 � 14 = 4880 RPM
Formula for Gear Ratio
GEAR RATIO = TIRE RADIUS x RPM � 168 � MPH
Example: Using the first example, what Gear Ratio is required for 120 MPH at 6500 RPM?
GR = 14 x 6500 � 168 � 120 = 4.51
Formula for Tire Radius
TIRE RADIUS = 168 x MPH x GEAR RATIO � RPM
Example: Using the first example, what tire radius for 110 MPH but at 6000 RPM with a 4.11 gear?
168 x 110 x 4.11 � 6000 = 12.7 inches
Note: Approximately a 25" diameter tire. Remember that the tire radius will be less during hard acceleration than when the vehicle is standing still. Also, radius will be greater at high speed due to tire expansion from centrifugal force.
Computing HP & Torque
Formula for HPQ
HPq = (0.00426 x MPH)3 x WEIGHT
HPq = Engine horsepower required to reach MPH in quarter mile
Note: understates HP required at speeds exceeding 100 MPH.
Note: assumes engine HP must be 2 x the HP required at drive wheels.
Example: What engine HP is required to achieve 110 MPH in a 3200 pound
vehicle in 1/4 mile?
HPq = (0.00426 x 110) x (0.00426 x 110) x (0.00426 x 110) x3200 = 329 engine HP
Formula for HP and Torque
HP = Torque x rpm � 5252 � Torque = HP x 5252 � RPM
Example: What torque is required to generate 329 HP at 6000 RPM?
T = 329 x 5252 � 6000 = 288 foot pounds @ 6000 RPM
Example: What torque is required for 296 HP at 4880 RPM?
T = 296 x 5252 � 4880 = 319 foot pounds @ 4880
About Cubic Inches, Volumetric Efficiency,
Flow Bench Conversion and CFM
Formula for VE
VE = (CFM x 3456) � (CID x RPM)
If VE (volumetric efficiency) is less than 1 (or 100%) the amount and quality of charge in the cylinder is reduced so less torque is produced. VE above 100% is a supercharging effect and more torque is produced.
Power Level Stock Performer Torker II Perf. RPM Victor Jr. Victor
Peak VE% 60-80 75-90 90-100 95-105 105-115 110-122
Flow Bench Conversion Factor
VE = (CFM x 3456) � (CID x RPM)
Typically flow bench values are given for a pressure drop of 28 in H2O. To convert flow figures from a different pressure drop to 28 in H2O use the formula above.
Example: You have flow figures of 152 cfm at 10 in H2O. What if the same head was flowed at 28 in H2O?
CFM H2O = 152 x �Ëâ€*Å¡(28�10) = 254 cfm
Formula for CID (cubic inch displacement)
CID = NUMBER OF CYLINDERS x SWEPT VOLUME
Note: CID = N x 0.7854 x bore x bore x stroke (all in inches)
Example: What is CID of a V8 with a �30 over�, 4 inch bore and 3.48 inch stroke?
CID = 8 x 0.7854 x 4.030 x 4.030 x 3.48 = 355 cu. inches
Formula for CFM
CFM = CUBIC FEET PER MINUTE
A measure of air flow into and out of an engine (CFM = CID x RPM x VE � 3456). Example: What CFM is consumed by a 355 CID engine at 4500 RPM if VE = 105% (1.05)?
CFM = 355 x 4500 x 1.05 � 3456 = 485 CFM
Example: What CFM by the same engine at 6400 RPM if VE has fallen to 95% (0.9)?
CFM = 355 x 6400 x 0.95 � 3456 = 625 CFM
About Compression Ratio
Formula for CR
CR = COMPRESSION RATIO = CYL. VOLUME @ BDC � CYLINDER VOLUME @ TDC
= 1 + (SWEPT VOLUME � VOL @ TDC)
= 1+ (0.7854 x BORE x BORE x STROKE) � (CCV + HGV + PDV)
CCV = Combustion Chamber Volume, in cubic inches
Note: if volume is given in cc�s then � 16.4 to get cubic inches.
HGV = Head Gasket Volume, in cubic inches,
= Head gasket compressed thickness x 0.7854 x bore x bore
PDV = (Piston Deck Volume) + (Piston Dome Effective Volume)
= (0.7854 x bore x bore x deck to piston distance) + (volume of piston depressions - volume of piston bumps)
Example: What is CR of the engine in #9 if heads have 72 cc chamber, head gasket is compressed to 0.040 inch and flat top pistons give 0.025 deck clearance at TDC?
CCV = 72 � 16.4 = 4.39 cubic inches
HGV = 0.040 x 0.7854 x 4.030 x 4.030 = 0.51 c.i.
PDV = 0.025 x 0.7854 x 4.030 x 4.030+ 0- 0 = 0.32 c.i.
CR = 1+ (0.7854 x 4.030 x 4.030 x 3.48 � (4.39 + 0.51+ 0.32))
= 1+ (44.39 � 5.22) = 9.5 CR
About Fuel System Flow
Formula for Injector Size per Hp
LBS/HR = HP � 16
In general if you use BSFC = .50 and an acceptable duration of 100% then use above formula for an eight cylinder engine.
Note: lbs/hr. = ((BSFC � 8) x HP) � Peak Inj. Duration
Example: You plan to make 448 hp. What size injector should you use?
lbs/hr = 448 � 16 = 32
Injector Conversion - lbs/hr to cc/min
CC/MIN = LBS/HR X 9.71 OR LBS/HR = CC/MIN X .103
Example: How many cc/min. does a 32 lb/hr. injector flow?
cc/min = 32 x 9.71 = 311 cc/min
Pump Flow Conversion Factors
GPM = lbs/hr � 369.8
Used to convert lbs/hr to gallons per minute (of gasoline).
Note: typically GPM = HP � 740
Example: Your engine uses 221 lbs. per hour of fuel. What are the fuel system requirements?
GPM = 221 � 369.8 = 0.60 gal/min</div>