connecting rod & rod length too stroke info

Discussion in 'Rotating Assemblies' started by grumpyvette, Oct 14, 2008.

  1. 87vette81big

    87vette81big Guest

    Re: connecting rod info

    :mrgreen:
     
  2. grumpyvette

    grumpyvette Administrator Staff Member

    Chevy V8 bore & stroke chart
    I saw this online and figured I would post it..I am going to add the popular lsx strokers soon
    CID BORE STROKE
    262 = 3.671" x 3.10" (Gen. I, 5.7" rod)
    265 = 3.750" x 3.00" ('55-'57 Gen.I, 5.7" rod)
    265 = 3.750" x 3.00" ('94-'96 Gen.II, 4.3 liter V-8 "L99", 5.94" rod)
    267 = 3.500" x 3.48" (Gen.I, 5.7" rod)
    283 = 3.875" x 3.00" (Gen.I, 5.7" rod)
    293 = 3.779" x 3.27" ('99-later, Gen.III, "LR4" 4.8 Liter Vortec, 6.278" rod)
    302 = 4.000" x 3.00" (Gen.I, 5.7" rod)
    305 = 3.736" x 3.48" (Gen.I, 5.7" rod)
    307 = 3.875" x 3.25" (Gen.I, 5.7" rod)
    325 = 3.779" x 3.622" ('99-later, Gen.III, "LM7", "LS4 front wheel drive V-8" 5.3 Liter Vortec, 6.098" rod)
    327 = 4.000" x 3.25" (Gen.I, 5.7" rod)
    345 = 3.893" x 3.622" ('97-later, Gen.III, "LS1", 6.098" rod)
    350 = 4.000" x 3.48" (Gen.I, 5.7" rod)
    350 = 4.000" x 3.48" ('96-'01, Gen. I, Vortec, 5.7" rod)
    350 = 3.900" x 3.66" ('89-'95, "LT5", in "ZR1" Corvette 32-valve DOHC, 5.74" rod)
    364 = 4.000" x 3.622" ('99-later, Gen.III, "LS2", "LQ4" 6.0 Liter Vortec, 6.098" rod)
    376 = 4.065" x 3.622" (2007-later, Gen. IV, "L92", Cadillac Escalade, GMC Yukon)
    383 = 4.000" x 3.80" ('00, "HT 383", Gen.I truck crate motor, 5.7" rod)
    400 = 4.125" x 3.75" (Gen.I, 5.565" rod)
    427 = 4.125" x 4.00" (2006 Gen.IV, LS7 SBC, titanium rods)

    Two common, non-factory smallblock combinations:

    377 = 4.155" x 3.48" (5.7" or 6.00" rod)
    400 block and a 350 crank with "spacer" main bearings
    383 = 4.030" x 3.75" (5.565" or 5.7" or 6.0" rod)
    350 block and a 400 crank, main bearing crank journals
    cut to 350 size

    ALL production big blocks used a 6.135" length rod.
    CHEVY BIG BLOCK V-8 BORE AND STROKE


    366T = 3.935" x 3.76"
    396 = 4.096" x 3.76"
    402 = 4.125" x 3.76"
    427 = 4.250" x 3.76"
    427T = 4.250" x 3.76"
    454 = 4.250" x 4.00"
    477= 4.5" bore x 3.76" stroke
    496 = 4.250" x 4.37" (2001 Vortec 8100, 8.1 liter)
    502 = 4.466" x 4.00"
    557T= 4.5 bore 4.375" stroke
    572T = 4.560" x 4.375" (2003 "ZZ572" crate motors)

    T = Tall Deck

    ALL production big blocks used a 6.135" length rod.
    common BB CHEVY piston compression heights are
    1.270"
    1.395"
    1.520"
    1.645"
    1.765"
    remember the blocks deck height, minus the piston pin height minus 1/2 the crank stroke will equal the required connecting rod length
    OR
    the blocks deck height, minus the connecting rod length, minus 1/2 the crank stroke. will equal the required piston pin height
    http://www.enginebuildermag.com/201...ton-compression-height-and-crankshaft-stroke/
    [​IMG]
    [​IMG]


    Re: connecting rod info


    http://www.strokerengine.com/RodStroke.html

    http://www.strokerengine.com/BBCengines.html

    http://www.e30m3project.com/e30m3perfor ... /index.htm

    http://www.strokerengine.com/RodStroke2.html

    http://www.stahlheaders.com/Lit_Rod Length.htm

    http://www.wallaceracing.com/dynamic-cr.php

    http://www.users.interport.net/s/r/srweiss/tablersn.htm

    http://victorylibrary.com/mopar/rod-tech-c.htm
    CLICK LINKS
    http://www.wiseco.com/Calculators.aspx
    http://www.grumpysperformance.com/strk1.png
    http://www.grumpysperformance.com/strk2.png
    http://www.grumpysperformance.com/strk3.png
    http://www.grumpysperformance.com/strk4.png

    Ford 302 Block Height 8.20
    306 Stroke 3.00 Rod 5.090 Ratio 1.69:1 CH 1.608
    306 Stroke 3.00 Rod 5.562 Ratio 1.85:1 CH 1.130
    331 Stroke 3.25 Rod 5.400 Ratio 1.66:1 CH 1.170
    347 Stroke 3.40 Rod 5.400 Ratio 1.59:1 CH 1.090
    347 Stroke 3.40 Rod 5.315 Ratio 1.56:1 CH 1.175
    Many people feel the 347 piston is too short for the street,
    so Probe offers a 5.315 so you can use the 331 piston,
    I recommend their use.

    Dart Iron Eagle 4.155 Block Height 8.70
    369 3.40 5.700 1.68:1 1.300
    380 3.50 5.700 1.62:1 1.250
    380 3.50 5.850 1.67:1 1.100

    Windsor Block Height 9.50
    351 3.50 5.956 1.70:1 1.774
    393 3.85 5.956 1.55:1 1.608
    393 3.85 6.250 1.62:1 1.325
    408 4.00 6.000 1.50:1 1.490
    408 4.00 6.125 1.53:1 1.350
    408 4.00 6.250 1.56:1 1.250
    418 4.10 6.000 1.46:1 1.450
    418 4.10 6.125 1.49:1 1.325
    418 4.10 6.200 1.51:1 1.250
    418 4.10 6.250 1.52:1 1.200
    427 4.17 6.200 1.48:1 1.215
    434 4.25 6.200 1.45:1 1.175
    The 408 and 418 are best for strip & street
    The 427 makes torque, great for trucks.

    Cleveland Block Height 9.20
    356 3.50 5.778 1.65:1 1.672
    356 3.50 6.000 1.71:1 1.450
    393 3.85 5.956 1.55:1 1.319
    393 3.85 6.000 1.56:1 1.275
    408 4.00 5.956 1.49:1 1.244
    408 4.00 6.000 1.50:1 1.200

    400M Block Height 10.30
    408 4.00 6.580 1.71:1 1.647 (0.070 below deck) Factory number
    408 4.00 6.635 1.66:1 1.670 .005 above deck BBC H-Beam Rod Cleveland KB piston 76 FT 10.6:1
    418 4.10 6.700 1.63:1 1.550
    427 4.17 6.700 1.60:1 1.515
    956 1.55:1 1.300
    Ford Big 460 Block Height 10.30
    466 3.85 6.605 1.72:1 1.770
    520 4.30 6.605 1.54:1 1.545
    520 4.30 6.800 1.58:1 1.350
    545 4.50 6.700 1.49:1 1.350
    545 4.50 6.800 1.51:1 1.250

    IDT Block 4.700 Bore
    624 4.50 6.800 1.51:1 1.250

    IDT 11.3 Block (coming soon)
    729 5.25 7.550 1.44:1 1.125

    IDT 12.0 Block (coming soon)
    763 5.500 8.000 1.45:1 1.250

    SBCScat9000.jpgBBC_crank_1_sm.jpgSCAT-SBF351-4340_Crank.jpg

    Chevy Small Block Height 9.00
    355 3.48 5.700 1.64:1 1.550
    355 3.48 6.000 1.72:1 1.250
    383 3.75 5.565 1.48:1 1.561
    383 3.75 5.700 1.52:1 1.433
    383 3.75 6.000 1.60:1 1.125
    395 3.87 5.700 1.47:1 1.363
    395 3.87 5.850 1.50:1 1.213
    395 3.87 6.000 1.55:1 1.063
    408 4.00 5.700 1.42:1 1.300
    408 4.00 5.850 1.46:1 1.150
    408 4.00 6.000 1.50:1 1.000

    400 GM Block 4-1/8 Bore
    352 3.25 6.000 1.85:1 1.375
    377 3.48 6.000 1.72:1 1.250
    406 3.75 5.700 1.52:1 1.433
    406 3.75 6.000 1.60:1 1.125
    420 3.87 5.700 1.47:1 1.363
    420 3.87 5.850 1.50:1 1.213
    420 3.87 6.000 1.55:1 1.063
    434 4.00 5.700 1.42:1 1.300
    434 4.00 5.850 1.46:1 1.150
    434 4.00 6.000 1.50:1 1.000
    You can see that put a 4.00 crank in the 350 & 400 block
    is the limit of what is possible, not what is ideal.

    Dart 4.20 Iron Eagle 9.320 Height
    457 4.125 6.125 1.48:1 1.133
    457 4.125 6.000 1.45:1 1.258
    471 4.250 6.100 1.43:1 1.095
    471 4.250 6.000 1.41:1 1.195
    471 4.250 5.850 1.37:1 1.345

    Big Block Chevy Deck Height 9.78
    460 4.00 6.135 1.53:1 1.645
    460 4.00 6.385 1.59:1 1.396
    489 4.25 6.135 1.44:1 1.520
    489 4.25 6.385 1.50:1 1.270
    503 4.37 6.385 1.46:1 1.208

    Truck Block Deck Height 10.20
    489 4.25 6.535 1.54:1 1.540
    489 4.25 6.800 1.60:1 1.275
    503 4.37 6.535 1.50:1 1.478
    503 4.37 6.700 1.53:1 1.313
    503 4.37 6.800 1.55:1 1.212
    518 4.50 6.585 1.45:1 1.415
    518 4.50 6.700 1.49:1 1.250
    518 4.50 6.800 1.51:1 1.150

    4.5 & 4.60 Big Bore BBC 10.20
    540 4.25 6.535 1.54:1 1.540
    540 4.25 6.800 1.60:1 1.275
    557 4.37 6.535 1.50:1 1.478
    557 4.37 6.800 1.55:1 1.212
    572 4.50 6.585 1.45:1 1.415
    572 4.50 6.800 1.51:1 1.150
    598 4.50 6.535 1.45:1 1.395
    632 4.75 6.700 1.41:1 1.125
    The 632 doesn't need to rev high, but many are in race cars.

    World Merlin III 4.5- 4.680 Bore 11.625 (Oliver Rods)
    632 4.75 7.100 1.49:1 2.150
    632 4.75 7.750 1.63:1 1.500
    632 4.75 8.000 1.68:1 1.250
    705 5.30 7.750 1.46:1 1.225
    750 5.60 7.650 1.37:1 1.175
    805 5.85 7.500 1.28:1 1.200
    These monster engine push the limits.
    The only way to get a good rod length compromise is with limited lifetime
    custom made aluminum connecting rods and pistons.
     
    Last edited by a moderator: Aug 6, 2018
  3. grumpyvette

    grumpyvette Administrator Staff Member

     
    Last edited by a moderator: Mar 13, 2018
  4. 87vette81big

    87vette81big Guest

    Smokey Yunick has done more back to back Dyno testing with SBC Engines than anyone.
    Chevrolet footed all the bills.
    You have to go back to his Vintage 1970's & 80's articles.
    He liked long rods.
    Eddy current brake dyno used.
    Real accurate. Few have today.

    One thing I have noticed .
    Pontiac V8 Engines built with Chevy BBC Rods don't always run as hard as expected.
    Times slower at times 1 second or more than called on.
    Professional engine builds. Not mine.
    Real Pontiac Spec Forged Rods for race non existent today.
    Sell BBC Instead.
    Crower made what I wanted.
    Costed $$$$.
     
  5. grumpyvette

    grumpyvette Administrator Staff Member

    one factor I seldom see pointed out is the fact that increases in the piston or bore diameter , has the effect of rapidly increasing the piston surface area the cylinder pressure has to push against. if we compare a 327 with a 4" diameter bore and a 400 with a 4.125" bore the increase of an 1/8" in bore diameter may seem to provide a minimal benefit, after all its an increase of from (32) times 1/8th" in diameter to, one more or (33) times 1/8th" in diameter or about a 3% increase in bore diameter, yet the surface are increase from 12.5 sq inches to the 400sbcs of 13.39square inches is a 7% increase in surface area
    http://vimeo.com/66357583
    [​IMG]
    now 7% may not seem important but with near 600 psi peak pressure in a cylinder on an average engine thats easily an extra 800 pounds of effective cylinder pressure over the piston at near tdc.and keep in mind PEAK pressure is rapidly lost as the piston on the power stroke moves away from TDC, in fact almost all the effective power or torque is generated or imparted to the piston and rod assembly and thus to the crank shaft as it descends into the bore in the first 45 degrees of crank rotation past TDC, and by the time the cranks rotated to 45 degrees past TDC the pistons moved down the bore less than 1" from its previous location at TDC.
    now you generally can assume youll get 1-to-1.2 hp and ft lbs of torque per cubic inch of displacement , adding about 7% to the piston surface area makes the engine noticeably more efficient if the cam timing and exhaust scavenging allow you to extract that power advantage.
    [​IMG]
    [​IMG]
    the short version here is that a engine thats properly configured with a larger bore has, or at least in theory has an advantage, over its whole rpm range.

    http://www.iskycams.com/ART/techinfo/ncrank1.pdf

    viewtopic.php?f=69&t=5123&p=14765#p14765
     
  6. 87vette81big

    87vette81big Guest

    Sorta explains why all the above readings that Some Pro built Pontiac V8 modern stroker engines don't perform worth a Crap on the street with E Edel heads I have seen Grumpy.
    R/S ratio in 1.4 range & E heads that flow 300-425 cfm range intake side.
    One I recall guarenteed 900 HP, costed $40 K.
    All iron 421 Poncho bored .090" over to 440 ci Ran Mid 9's N/A.
    New expensive Race Pontiac Pro Big inch 500 + ci engine in same car would never hardly get out of 11's.
    High 10's twice N/A.
    Avoided E Heads since.
     
  7. grumpyvette

    grumpyvette Administrator Staff Member

     
  8. 87vette81big

    87vette81big Guest

    There is obviously more going on than most realize Grumpy.
    Not Arguing with above observations .
    I will say what works on Chevy won't work on a Pontiac V8.
    And Visa Versa.
    A few Pontiac 455's have ran 8's & I recall one that ran 7's Normaly aspirated 20 years ago.
    All production iron Blocks, Crankshaft & Heads.
    Spun to 6,500-7k.

    Most Hog the Ports out too Big.
    No Velocity left.
     
  9. philly

    philly solid fixture here in the forum

    the science behind the big bore is universal, regardless of manufacturer... but i think your right the people with millions of hours and dollars invested dont want to give away ALL the findings for free.
     
  10. 87vette81big

    87vette81big Guest

    I don't think it matters as much on the street .
    Big Bore.
    Under square Long Stroke. Pontiac 455 Setup debunks that theory.

    Pro stock N/A Yes. Have to turn 9,000-11,000 RPM To win.

    The Big Critera is you can't beat that Hellcat N/A on an affordable plan in a 2-dr coupe car easy.
    Only practical way is Supercharge or Turbo.

    Do You Really Think Hellcat owners will leave it stock at 707 HP ?
    I Know I would not.
    Crankup boost to 1,000 HP.

    So
     
  11. 87vette81big

    87vette81big Guest

    So what's the Real Game Plan ?

    What's Yours ?

    I know Mine.
     
  12. philly

    philly solid fixture here in the forum

    why would i try to beat a supercharged v8 with an NA combo? i go turbo and whiz right by.

    and you wait and see how hat car starts wetting the bed with any real power applied to it. no way that rear is gonna hold, or that stupid 8 speed tranny either. only time will tell.
     
  13. philly

    philly solid fixture here in the forum

    with the same head, the bigger bore will breathe better, every single time, on every single motor, chevy, ford, honda, BOPC, lamborghini. thats what i meant the valve unshrouding just allows more flow
     
  14. 87vette81big

    87vette81big Guest

    I roll the Dice & Gamble at times Phil.
    Hellcat will do serious damage to Vette scene & want to be racers hotrodders.
    Shut Them all down...

    And it will finally put You & me back to work.
    No more Shit Fuck sidejobs.
    No more managers taking the glory because they have more scratch than us.
    Real Race knowledge & skills required to build .
    Done with highly skilled 2 hands we have .

    All pride shot rhey had prior.
    You & me will be hired to build Better & Faster than the Hellcat.
     
  15. philly

    philly solid fixture here in the forum

    i welcome the opportunity, and im sure you do too. nothing feels better than beating a fast car... with a faster car. :twisted:
     
  16. 87vette81big

    87vette81big Guest

    I think the only practical way to compete is Single & Twin Turbo builds.
    Vette guys don't want to deal with supercharger belts & maintenance that goes with.
    They won't give up that IRS Rear either.
    Only a select few will go solid axle.
    Like 3-5 out of 10,000-50,000 owners.
    Problem also is many cars are modded built up.
    For N/A Pump gas.
    Static & Dynamic compression too high for good turbo boost in 11-32 psi range.
    Don't know how many will start with new build with dished pistons & matching turbo camshaft grind.
     
  17. philly

    philly solid fixture here in the forum

    theres a dozen IRS vettes, zcars, and rx7's running 9.50 or faster in florida that i am aware of. so its possible... i just want to see how GM responds in the form of a ZR1 for the c7


    at any rate... all this IRS talk is giving me a headache, you know theres a million fox bodies thatll give it to a hellcat on the street no problems, f bodies too. actually theres a guy down here in a naturally aspirated 4banger civic that runs better times than the hellcat and his car works on the street. so when the hellcat comes around we'll be ready. the technology is there, nothing is unbeatable.
     
  18. 87vette81big

    87vette81big Guest

    You know I Especially like the 5.0 Fox Stang guys Phil.
    Groundbreakers & Very Fast.
    A Legecy that Chevy failed to beat.

    8.0S in 5.0 on streets in Joliet Chi town still.
    Not afraid to street race.
     
  19. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    http://www.enginebuildermag.com/201...aign=PushCrew_notification_WisecoSpoCo&_p_c=1

    An intense look at mean piston speed, inertia, and controlling the massive, destructive forces at work inside your engine.

    Engine builders have long calculated the mean piston speed of their engines to help identify a possible power loss and risky RPM limits. This math exercise has been especially important when increasing total displacement with a stroker crankshaft, because the mean piston speed will increase when compared to the standard stroke running at the same RPM.

    But what if there was another engine dynamic that could give builders a better insight into the durability of the reciprocating assembly?

    “Rather than focus on mean piston speed, look at the effect of inertia force on the piston,” suggests Dave Fussner, head of research and development at Wiseco Pistons.

    Let’s first review the definition of mean piston speed, also called the average piston speed. It’s the effective distance a piston travels in a given unit of time, and it’s usually expressed in feet per minute (fpm) for comparison purposes. The standard mathematical equation is rather basic:

    Mean Piston Speed (fpm)=(Stroke x 2 x RPM)/12

    There’s a simpler formula, but more on the math later. A piston’s velocity constantly changes as it moves from top dead center (TDC) to bottom dead center (BDC) and back to TDC during one revolution of the crankshaft. At TDC and BDC, the speed is 0 fpm, and at some point during both the downstroke and upstroke it will accelerate to a maximum velocity before decelerating and returning to 0 fpm.

    [​IMG]
    As the piston races from bottom dead center to top dead center, for a brief moment, it comes to a complete stop. This places tremendous stress on the wrist pins. Shown, these Trend pins are offered in various wall thicknesses depending on the application.
    [​IMG]The mean piston speed takes the total distance the piston travels during one complete crankshaft revolution and multiplies that by the engine RPM. Piston speed obviously increases as the RPM increase, and piston speed also increases as the stroke increases. Let’s look at a quick example.

    A big-block Chevy with a 4.000-inch-stroke crankshaft running at 6,500 rpm has mean piston speed of 4,333 fpm. Let’s review the formula again used to calculate this result. Multiply the stroke times 2 and then multiply that figure by the RPM. That will give you the total number inches the piston traveled in one minute. In this case, the formula is 4 (stroke) x 2 x 6,500 (RPM), which equals 52,000 inches. To read this in feet per minute, divide by 12. Here’s the complete formula:

    (4 x 2 x 6,500)/12=4,333 fpm

    You can simplify the formula with a little math trick. Divide the numerator and denominator in this equation by 2, and you’ll get the same answer. In other words, multiply the stroke by the RPM, then divide by 6.

    (4 x 6,500)/6=4,333 fpm

    With this simpler formula, we’ll calculate the mean piston speed with the stroke increased to 4.500 inch.

    (4.5 x 6,500)/6=4,875 fpm

    As you can see, the mean piston speed increased nearly 13 percent even though the RPM didn’t change.

    [​IMG]
    Reducing piston weight plays a huge role in creating a rotating assembly that can sustain high rpm. The seemingly insignificant gram weight of a piston is magnified exponentially with rpm.
    Again, this is the average speed of the piston over the entire stroke. To calculate the maximum speed a piston reaches during the stroke requires a bit more calculus as well as the connecting rod length and the rod angularity respective to crankshaft position. There are online calculators that will compute the exact piston speed at any given crankshaft rotation, but here’s a basic formula that engine builders have often used that doesn’t require rod length:

    Maximum Piston Speed (fpm)=((Stroke x ?)/12)x RPM

    Let’s calculate the maximum piston speed for our stroker BBC:

    ((4.5 x 3.1416)/12)x 6,500=7,658 fpm

    By converting feet per minute to miles per hour (1 fpm = 0.011364 mph), this piston goes from 0 to 87 mph in about two inches, then and back to zero within the remaining space of a 4.5-inch deep cylinder. Now consider that a BBC piston weighs about 1.3 pounds, and you can get an idea of the tremendous forces placed on the crankshaft, connecting rod and wrist pin—which is why Fussner suggests looking at the inertia force.

    “Inertia is the property of matter that causes it to resist any change in its motion,” explains Fussner. “This principle of physics is especially important in the design of pistons for high-performance applications.”

    [​IMG]
    When the connecting rod is lengthened, it provides a softer transition as the piston changes direction. The longer connecting rod also reduces the compression height of the piston and can help pull weight out of the rotating assembly.
    The force of inertia is a function of mass times acceleration, and the magnitude of these forces increases as the square of the engine speed. In other words, if you double the engine speed from 3,000 to 6,000 rpm, the forces acting on the piston don’t double—they quadruple.

    “Once started on its way up the cylinder, the piston with its related components attempt to keep going,” reminds Fussner. “Its motion is arrested and immediately reversed only by the action of the connecting rod and the momentum of the crankshaft.”

    Due to rod angularity—which is affected by connecting rod length and engine stroke—the piston doesn’t reach its maximum upward or downward velocity until
    about 76 degrees before and after TDC with the exact positions depending on the rod-length-to-stroke ratio,” says Fussner.

    [​IMG]
    Stroker cranks such as this forged LS7 piece from K1 Technologies, are a great way to add displacement. However, when the stroke is lengthened the piston must accelerate faster each revolution to cover the larger swept area of the cylinder wall.
    “This means the piston has about 152 degrees of crank rotation to get from maximum speed down to zero and back to maximum speed during the upper half of the stroke. And then about 208 degrees to go through the same sequence during the lower half of the stroke. The upward inertia force is therefore greater than the downward inertia force.”

    If you don’t consider the connecting rod, there’s a formula for calculating the primary inertia force:

    0.0000142 x Piston Weight (lb) x RPM2 x Stroke (in) = Inertia Force

    The piston weight includes the rings, pin and retainers. Let’s look at a simple example of a single-cylinder engine with a 3.000-inch stroke (same as a 283ci and 302ci Chevy small-block) and a 1.000-pound (453.5 grams) piston assembly running at 6,000 rpm:

    0.0000142 x 1 x 6,000 x 6,000 x 3 = 1,534 lbs

    With some additional math using the rod length and stroke, a correction factor can be obtained to improve the accuracy of the inertia force results.

    Crank Radius÷Rod Lenth

    “Because of the effect of the connecting rod, the force required to stop and restart the piston is at maximum at TDC,” says Fussner. “The effect of the connecting rod is to increase the primary force at TDC and decrease the primary force at BDC by this R/L factor.”

    For this example, the radius is half the crankshaft stroke (1.5 inch) divided by a rod length of 6.000 inches for a factor of .25 or 383 pounds (1,534 x 0.25 = 383). This factor is added to the original inertia force for the upward stroke and subtracted on the downward movement.



    [​IMG]
    Both the crank on the left and right are at the same point in their respective rotations. However, the piston on the left will have to travel much faster to reach top dead center at the same time as the piston on the right.
    “So, the actual upward force at TDC becomes 1,917 pounds and the actual downward force at BDC becomes 1,151 pounds,” says Fussner. “These forces vary in direct proportion to the weight of the piston assembly and the stroke to rod length and they also vary in proportion to the square of the engine speed. Therefore, these figures can be taken as basic ones for easily estimating the forces generated in any other size engine.”

    [​IMG]
    As the piston reaches top dead center on the exhaust stroke, there is no cushion of compression to help slow it down. Instead, the connecting rod takes the full brunt of the force which pulls on its beam and tries to separate its cap. Quality connecting rods are paramount to a high-horsepower, high-rpm engine.
    “We know a common measure used for many years to suggest the structural integrity danger zone of a piston in a running engine is mean piston speed,” sums up Fussner. “As the skydive instructor told his student, it’s not the speed of the fall that hurts, it’s the sudden stop. And so it is with pistons. So rather than focus only on the mean piston speed, let’s decide to also consider the effect of inertia force on the piston, and what we can do to reduce that force. And if that is not possible, make sure the components are strong enough to endure the task we have set forth.”

    This article was sponsored by Wiseco. For more information, please visit our website at wiseco.com
     
  20. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    Important info for a long life street engine.
    Every single drag racer ignores though Grumpy.
    Even the Pros rev super high with huge displacement 800-900 ci BBC's I have seen on Facebook Race Groups.

    Only way to keep piston speeds down to your liking and have tremendous torque and hp pushing past 1,000 number mark and not spending $50k is to Use a Power Adder.
    Home Built Turbo Boost the modern answer.
     

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