Real motors like V8's

[Oldfart1stATV]

For starters here's the simple basics for getting the FIRST round of numbers for a motor.

Bore= the simple diameter of the hole.
Stroke= the distance the piston travels to it's highest point from it's lowest

First note, again this is first round stupid simple stuff. Note that the only parts mentioned so far are the hole and a distance the piston travels. No cranks, no cams, no valve trains, no gaskets nothing fun yet. But they are true and factual definitions.

Next let's tackle displacement.

Displacement= the volume of air displaced by a piston on a single cycle.

Volume for a cycl= the formula: V = h(pi symbol)r2

H=height of the cyl
r= the radius of the cyl.

Where the hell is the damn pi symbol on a key board?

Anway, the way to figure gross displacement is:

Displacement=Stroke *(missing pi symbol)*(bore/2) squared* the number of cyl.


OK, hang on, I gotta do some cut and paste. I don't have a pi symbol and the friggin' multiplication symbol is a f*ckin astric.

I can't work like this.

But, so far we have covered the definition and formulae for bore, stroke and displacement. Lemme figure out how I can post real stuff. This sucks.

To get to Regal, hang on I'll get more. This is where the real fun starts. This starting point is only the gross number. Deck height, gasket thickness, piston shape, ring placement, and a sh*t load of other crap is coming up. I'll either find a way to type it or write and scan it. Or if I can find it in a nutshell I'll link to it.

A

 

[regal81455]

1. See the attached definition of a stroker kit from Wikipedia, Stroker Kit - Wikipedia, the free encyclopedia, here too rod length does not come into the definition of a "stroker", now the term "long rod stroker" that means something entirely different and both change the characteristics of the motor and how it behaves, with the later there's no way to accomodate this with out changing the internal cylinder volume or really having extremely tight tolerances. The first isnt accomplishing much other than the effect the longer rod has on combustion timing, the second does raise CR but I hope you know exactly what you're doing or boom!!

2. While what you say is true about stroke and how it's measured, I too am right...see the attached article, paragraph 2, halfway down...Im reading and i quote "The total distance traveled by the piston as it moves from bottom dead center to top dead center. It is determined by the diameter of the circle traveled by the connecting-rod journals of the crankshaft as the crank is rotated. Total stroke can be calculated as twice the distance from the centerline of the crankshaft to the centerline of one rod journal"...boy its seems I said this to someone somewhere else??? ( Stroke Any Engine - How To - Hot Rod Magazine ) This is an extremely rich and useful article, you should check it out.

 

[regal81455]

As for the formula to figure displacement, i wasnt being entirely fair you are correct when you were saying its cylinder volume ( stroke x 3.14(PI) x radius of bore squared ) X the number of cylinders.

 

[Oldfart1stATV]

Jeezuz..

FormulasPredicting Power BHP = PLAN/33,000
P is brake mean effective pressure, in PSI
L is piston stroke, in feet
A is the area of one piston, in square inches
N is the number of power strokes per minute
Piston Speed Cm = .166 x L x N
Cm is mean piston speed, in feet per minute
L is stroke, in inches
N is crankshaft speed
RPM Brake Mean Effective Pressure (BMEP) 2-Stroke BMEP = (HP x 6500)/(L x RPM) 4-Stroke BMEP = (HP x 13000)/(L x RPM)
L = Displacement in Liters i.e., 80 cc = .08 Liters 1 ci. = 16.39 cc Piston Acceleration Gmax = ((N^2 x L)/2189) x (1 + 1/(2A))
Gmax is maximum piston acceleration, in feet per second squared
N is crankshaft speed
RPM L is stroke, in inches
A is the ratio of connecting rod length, between centers, to stroke
Piston Stroke Motion S = R cos X + L cos Z
S = the distance piston wrist pin is from center of crankshaft
R = the radius of the crankshaft wrist pin
L = the length of the connecting rod
X = the angle of the wrist pin
Z = the angle of the connecting rod or sin
X = R/L sin Z
Piston Travel vs. Crank Rotation d = ((S/2) + L) - (S/2 cos X) - L sin[cos-1 (S/2L sin X)]
S = Stroke (mm)
L = Connecting Rod Length (mm)
X = Crank Angle Before or After TDC (deg) Note: (L) Rod Length is usually 2 times the (S) Stroke OR For Spreadsheets and some Calculators HT = (r + c) - (r cos (a)) - SQRT(c^2 - (r sin (a))^2)
r = s/2
dtor = PI/180
a = d x dtor
HT = The height of piston
r = The stroke divided by 2
c = The rod length
a = The crank angle in radians
d = The crank angle in degrees
dtor = Degrees to Radians Exhaust Systems Tuned Length
Lt = (Eo x Vs) / N Lt is the tuned length, in inches Eo is the exhaust-open period, in degrees Vs is wave speed in feet per second (1700 ft/sec at sea level)
N is crankshaft speed
in RPM Length of Curved Pipe
L = R x .01745 x Z
L is length
R is radius of the pipe bend
Z is the angle of the bend
Diffuser Proportions D2 = SQRT( D1^2 x 6.25 )
D2 is the diffuser outlet diameter
D1 is the diffuser inlet diameter 6.25 is the outlet/inlet ratio constant
Baffle Cones Lr = Le/2
Lr is mean point of the reflection inside the baffle cone
Le is the length of the baffle cone
Port Open TimeT = ( 60/N ) x ( Z/360 ) or T = Z/( N x 6)
T is time, in seconds
N is crankshaft speed, in RPM
Z is port open duration, in degrees
Compression Ratio CR = ( V1 + V2 ) / V2
CR is compression ratio
V1 is cylinder volume at exhaust closing
V2 is combustion chamber volume
Carburetor Throttle Bore Diameter D = K x SQRT( C x N )
D is throttle bore diameter, in millimeters
K is a constant ( approx. 0.65 to 0.9, derive from existing carburetor bore)
C is cylinder displacement, in liters
N is RPM at peak power
Crankcase Volume Primary compression ratio = Case Volume @ TDC / Case Volume at BDC or CRp = V1 + V2 / V1
CRp is the primary compression ratio
V1 is crankcase volume @ BDC
V2 is piston displacement
Resonance Effects F = Vs / 2¼ * the square root of A / Vc (L + 1/2 the square root of ¼ A Vs is the sonic speed Uusually about 1100 ft/sec)
A is the cross-sectional area of the inlet
L is the inlet pipe length
Vc is the flask (crankcase) volume
Average Exhaust Temperature Determine the exhaust gas temperature in Kelvin (k = C + 273.15). This is usually a function of the engine's BMEP. Torque 1.00 lb-ft = 0.138 kg-m = 1.35 N-m 1.00 kg-m = 7.23 lb-ft. = 9.81 N-m 1.00 N-m = 0.102 kg-m = 0.737 lb-ft Mass 1.00 lb = 0.454 kg = 4.45 N 1.00 kg = 2.20 lbs = 9.81 N 1.00 N = 0.102 kg = 0.220 lb Distance 1 in = 2.54 cm = 0.0000158 mi = 0.0000254 km 1 cm = 0.394 in = 0.00000621 mi = 0.00001 km 1 ft = 30.5 cm = 0.000189 mi = .000305 km 1 mi = 63,360 in = 160,934.4 cm = 1.609 km 1 km = 0.621 mi = 100,000 cm = 3281 ft Pressure 1.00 bar = 14.5 psi = 1.02 kg/sq-cm = 100 kPa 1.00 psi = 0.069 bar = 0.070 kg/sq-cm = 6.89 kPa 1.00 kg/sq-cm = 0.980 bar = 14.2 psi = 98.1 kPa 1.00 kPa = 0.010 bar = 0.145 psi = 0.010 kg/sq-cm Temperature F = 9 / 5 x C + 32 C = 5/9 (F - 32) K = C + 273.4 Area / Volume 1.00 sq-in = 6.452 sq-cm 1.00 sq-cm= 0.155 sq-in 1.00 cu-in = 16.387 cc 1.00 cc = 0.0610 cu-in Power 1.00 HP = 746 W torque (lb-ft) = 5252 x hp / rpm hp = rpm x torque (lb-ft) / 5252 The Weight of Air14.7 lbs. per sq. inch at sea level.
Air Density CalculationStdAirDensity = 1.22556 and is defined at 59.0F degrees, 0.0% humidity, and 29.92 inches on the barometer. Temp_c = (Temp-32.0) * 5.0 / 9.0; Temp_k = Temp_c + 273.0; Baro_mb = Barometer / (29.92 / 1013.0); Baro_pa = Baro_mb * 100.0; SaturationPressure_mb = 6.11 * pow(10,(7.5*Temp_c)/(237.7+Temp_c)); VaporPressure_mb = Humidity * SaturationPressure_mb / 100.0; TempVirtual_k = Temp_k / (1.0 - (VaporPressure_mb/Baro_mb)*(1.-0.622)); // D = P/(T*R) AirDensity = Baro_pa / (TempVirtual_k*GasConstant); % Std Density = AirDensity/StdAirDensity*100 Additional Conversion Factors 1 Centimeter - 0.0328084 foot; 0.393701 inch 1 Circular Mil - 7.853982 x 10 to the negative seventh square inches; 5.067075 x 10 to the negative sixth square centimeters 1 Cubic Centimeter - 0.061024 cubic inch; 0.270512 dram (U.S. fluid); 16.230664 minims (U.S.); 0.999972 milliliter 1 Cubic Foot - 0.803564 bushel (U.S.); 7.480520 gallons (U.S. liquid); 0.028317 cubic meter; 28.31605 liters 1 Cubic Inch - 16.387064 cubic centimeters 1 Cubic Meter - 35.314667 cubic feet; 264.17205 gallons (U.S. liquid) 1 Foot - 0.3048 meter 1 Gallon (U.S. liquid) - 0.1336816 cubic foot; 0.832675 gallon (British); 231 cubic inches; 0.0037854 cubic meter; 3.785306 liters 1 Grain - 0.06479891 gram 1 Gram - 0.00220462 pound (avoirdupois); 0.035274 ounce (avoirdupois); 15.432358 grains 1 Hectare- 2.471054 acres; 1.07639 x 10 to the fifth square feet 1 Inch - 2.54 centimeters 1 Kilogram - 2.204623 pounds (avoirdupois) 1 Kilometer - 0.621371 mile (statute) 1 Liter - 0.264179 gallon (U.S. liquid);0.0353157 cubic foot; 1.056718 quarts (U.S. liquid) 1 Meter - 1.093613 yards; 3.280840 feet; 39.37008 inches 1 Mile (statute) - 1.609344 kilometers 1 Ounce (U.S. fluid) - 1.804688 cubic inches; 29.573730 cubic centimeters 1 Ounce (avoirdupois) - 28.349523 grams 1 Ounce (apothecary or troy) - 31.103486 grams 1 Pint (U.S. liquid) - 0.473163 liter; 473.17647 cubic centimeters 1 Pound (avoirdupois) - 0.453592 kilogram; 453.59237 grams 1 Pound (apothecary or troy) - 0.3732417 kilogram, 373.24172 grams 1 Quart (U.S. dry) - 1.10119 liters 1 Quart (liquid) - 0.946326 liter 1 Radian - 57.295779 degrees 1 Rod - 5.0292 meters 1 Square Centimeter - 0.155000 square inch 1 Square Foot - 0.09290304 square meter 1 Square Inch - 645.16 square millimeters 1 Square Meter - 10.763910 square feet 1 Square Yard - 0.836127 square meter 1 Ton (short) - 907.18474 kilograms 1 Yard - 0.9144 meter POWER - AC CIRCUITSEfficiency = 746 x Output HP / Input Watts 3ø KW = Volts x Amps x PF x 1.732 / 1000 3ø Amps = 746 x HP / 1.732 x Eff. x PF 3ø Eff. = 746 x HP / 1.732 x Volts x Amps x PF 3ø PF = Input Watts / Volts x Amps x 1.732 1ø KW = Volts x Amps x PF / 1000 1ø Amps = 746 x HP / Volts x Eff. x PF 1ø Eff. = 746 x HP / Volts x Amps x PF 1ø PF = Input Watts / Volts x Amps HP (3ø) = Volts x Amps x 1.732 x Eff. x PF / 746 HP (1ø) = Volts x Amps x Eff. x PF / 746 1 KW = 1000 Watts Eff. = Efficiency, PF = Power Factor, KW = Kilowatts, HP = Horsepower POWER - DC CIRCUITS Torque = HP x 5280 / RPMHP = Torque X RPM / 52801 HP = 36 lb.in. @ 1750 RPM1 HP = 3 lb. ft. @ 1750 RPM Eff. = Efficiency, HP = HorsepowerOHMS LAW Volts (E) = Amps (I) x Ohms (R)Amps (I) = Volts (E) / Ohms (R)Ohms (R) = Volts (E) / Amps (I) R=Ohms, E=Volts, I=Amperes

To figure miles per hour, multiply the engine RPM by the Wheel Diameter in inches and divide this by the Gear Ratio times 336 or MPH = RPM * wheel diameter (in inches) / gear ratio * 336 To figure engine speed (RPM), multiply by the Speed in MPH, by the rear axle gear ratio times 336. Divide this by the tire diameter in inches.

or

RPM = MPH * gear ratio * 336 / tire diameter


OK kids, I ripped that off to get us started. The formulas a rather sound.

Here we see the rod that we all have been talking about isn't even mentioned until we get to the relation of crank travel vs piston travel and piston motion in general.

Why?

Because until the motor starts to work a "connecting rod" doesn't do anything. What it does do when we are working is set piston travel, acceleration and speed. basic like it has a vast amount of input to the stroke. Remember the stroke is the distance the piston travels from lowest to highest.

So in absolute truth the rod can be viewed as a stroke device and is.

With out a doubt however the most common way to "stroke" a V8 is with the crank itself.

Never said otherwise.

Note the value of the rod in each formula and if you change it's value how you affect the outcome.

That said, anyone that builds motors knows, the power is in the exhaust. Getting go juice in is easy it's what happens to it that makes or breaks a motor.

I didn't include any runner length or intake manifold volume calcs. any gasket effects on displacement and a bunch of other stuff. Just too damn much to cover, but here is some good info and a couple formulas that show the relationship of the rod to various things.

Back to Regal, the measurements you gave in the "rod thread" are not for stroke per se. They are for a motion/relation involving the stroke.

So pure and simple the rod absoluly affects and effects the stroke. If you change the stroke, that is a stroker. So yes I stand by my statements.

Once you get into the heavy math past air weight and resonance of the exhaust will find that a very little change can have a large impact.

That was what I was pointing out in the "Rod Thread". It has an effect, it changes the stroke height and compression. It's not some absolute answer to anything, it's just a matter of fact on what it does.

A

 

[Oldfart1stATV]

Regal

Read the last two paragraphs of the Hot Rod article. Oh and the "finding the longest rods" section exactly what I have been preaching.

We are in basic violent agreement.

A

 

[newnick]

Thats some interesting stuff, I wish I understood some of it.
Back to two strokes. There are some that build mini atv race motors that cut the bottom of the cylinder, some the top. There are also cylinder spacers.
While it doesn't effect stroke, it is similar to using a longer rod if cutting the bottom of the cylinder.

 

[regal81455]

Im not entirely disagreeing with you, but still stand strong about stroker motors and they have nothing to do with the rod length, its a function of the crank not the rod, the rod can only impact two things ( compression ratio and displacement, but displacement is impacted becuz of the added volume ( ie, deck height, added spacer plate, whateva ) not the rod itself...im done talking about this becuz we are getting no where and apparently we respectfully disagree with terms and while you may have been on a nascar crew doesn't make you the an authority on the subject, you can work for NASA and not know how to launch a rocket...

 

[Oldfart1stATV]

OK

Well we both agree the way you stated your formulas was wrong. While you have an opinion on a stroker, it's also wrong. The very article you posted up there from Hot Rod goes into fair detail about rods and thier importance in a stroker. They are as much a key part as the crank.

It's a system, remember?

As for the parting cheap shot, whatever. The truth is all written down here. You may read and learn or take your ball and go home. Please don't clutter anymore threads with your diatribes, though. I tried to talk this out and teach you something. You posted articles you apparently didn't read, not my fault they said exactly what I was. Nothing more I care to do for you.

A

 

[regal81455]

Again as said before I disrespectfully disagreed with you and your "terms", there was no parting cheap shot just a statement saying that you can take part in something and not necessarily be an integral part to an operation. I never meant it to be an insult, if you think your right then thats all that truly matters, i mean hell what does a 28yr old whos been working with cars and bikes for 15+ years know right?

No one ever disputed your theory about how important rod length is for a stroker motor but the term "stroker" comes from the throw of the crank, not the rod itself and if your too stuck in your ways to back down so be it. If you had read the article too then you would see they never say a stroker begins with a longer / shorter rod it always refers to the stroke of a crank. If you could put a crank w/ a shorter/longer throw in the same block and still have the deck height to allow it you would still have a stroked/destroked motor.

As for my diatribes, I do believe this is free country and this is a public forum where Im allowed to speak my mind, if you don't like too bad, deal with it...Im allowed my opinion, just like you. Im not the only one here that thinks it a bit odd that an old man has nothing better to do than to sit here and talk to kidz half his age, and make perverted and absurd comments. Perhaps you should hang with people your own age. ( Now that's a parting shot. )