connecting rod & rod length too stroke info

[87vette81big]

Re: connecting rod info

:mrgreen:

 

[grumpyvette]

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/

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.
related info
http://garage.grumpysperformance.com/index.php?threads/another-496bbc.5123/

http://garage.grumpysperformance.com/index.php?threads/496ci-revamped.14642/

http://garage.grumpysperformance.co...n-wrist-pins-one-really-over-looked-part.978/

http://garage.grumpysperformance.co...g-and-installing-connecting-rods-pistons.247/

http://garage.grumpysperformance.co...-about-your-potential-dream-bbc-combos.14607/

http://garage.grumpysperformance.co...-articles-you-might-want-too-look-over.14682/

http://garage.grumpysperformance.co...ng-and-basic-piston-ring-info-youll-need.509/

http://garage.grumpysperformance.com/index.php?threads/rotating-assembly-bearings.9527/

http://garage.grumpysperformance.com/index.php?threads/maximizing-piston-to-bore-ring-seal.3897/

http://garage.grumpysperformance.com/index.php?threads/big-block-chevy-info.710/#post-72463

http://garage.grumpysperformance.co...in-height-compression-height.5064/#post-66240

http://garage.grumpysperformance.com/index.php?threads/scat-cranks-related-info.10930/

http://garage.grumpysperformance.com/index.php?threads/tall-deck-options.14678/

 

[grumpyvette]

Since people can understand pictures so much better here is a graph of piston position vs crank angle for a full revolution of the crankshaft to compare the 5.7" rod and 6" rod.


link too bore vs stroke info on hundreds of engines
http://users.erols.com/srweiss/tablersn.htm

Big difference, right? :rotfl: Just for your reference the biggest difference is 0.0179".


Here's the rod angle.

At least this has a difference. A whole 1.026 degrees. An argument could be made that this would cause less wear on the bore. However, it occurs at the mid-way point of the stroke and I find that argument rather baseless unless someone can post up proof of an 5.7" rod 383 engine with the worst bore worn in the middle. The most wear occurs at the top of the bore where the rod angle is very little.

I really don't see where these ~huge~ changes between the 2 rods are going to make a hill of beans difference for a street going engine.

Now, if you wanted to wring every single possible HP out of the engine then maybe.

The ones making comments about how this makes such a huge difference in a street going application really need to post proof of the difference. Links to nice engine build aren't proving anything.

 

[87vette81big]

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 $$$$.

 

[grumpyvette]

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

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.

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

 

[87vette81big]

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.

 

[grumpyvette]

“An engine produces peak torque at the rpm where it is most efficient.”

Recently I’ve had several conversations with racers who wanted to build engines with long crankshaft strokes and small cylinder bores. When I questioned them about their preference for long-stroke/small-bore engines, the common answer was that this combination makes more torque. Unfortunately that assertion doesn’t match up with my experience in building drag racing engines.

My subject is racing engines, not street motors, so I’m not concerned with torque at 2,000 rpm. In my view, if you are building an engine for maximum output at a specific displacement, such as a Comp eliminator motor, then the bores should be as big as possible and the stroke as short as possible. If you’re building an engine that’s not restricted in size, such as a heads-up Super eliminator or Quick 16 motor, then big bores are an absolute performance bargain.

I know that there are drag racers who are successful with small-bore/long-stroke engines. And I know that countless magazine articles have been written about “torque monster” motors. But before readers fire off angry e-mails to National DRAGSTER about Reher’s rantings on the back page, allow me to explain my observations on the bore vs. stroke debate.

In mechanical terms, the definition of torque is the force acting on an object that causes that object to rotate. In an internal combustion engine, the pressure produced by expanding gases acts through the pistons and connecting rods to push against the crankshaft, producing torque. The mechanical leverage is greatest at the point when the connecting rod is perpendicular to its respective crank throw; depending on the geometry of the crank, piston and rod, this typically occurs when the piston is about 80 degrees after top dead center (ATDC).

So if torque is what accelerates a race car, why don’t we use engines with 2-inch diameter cylinder bores and 6-inch long crankshaft strokes? Obviously there are other factors involved.

The first consideration is that the cylinder pressure produced by the expanding gases reaches its peak shortly after combustion begins, when the volume above the piston is still relatively small and the lever arm created by the piston, rod and crank pin is an acute angle of less than 90 degrees. Peak cylinder pressure occurs at approximately 30 degrees ATDC, and drops dramatically by the time that the rod has its maximum leverage against the crank arm. Consequently the mechanical torque advantage of a long stroke is significantly diminished by the reduced force that’s pushing against the piston when the leverage of a long crankshaft stroke is greatest.

An engine produces peak torque at the rpm where it is most efficient. Efficiency is the result of many factors, including airflow, combustion, and parasitic losses such as friction and windage. Comparing two engines with the same displacement, a long-stroke/small-bore combination is simply less efficient than a short-stroke/big-bore combination on several counts.

Big bores promote better breathing. If you compare cylinder head airflow on a small-bore test fixture and on a large-bore fixture, the bigger bore will almost invariably improve airflow due to less valve shrouding. If the goal is maximum performance, the larger bore diameter allows the installation of larger valves, which further improve power.

A short crankshaft stroke reduces parasitic losses. Ring drag is the major source of internal friction. With a shorter stroke, the pistons don’t travel as far with every revolution. The crankshaft assembly also rotates in a smaller arc so the windage is reduced. In a wet-sump engine, a shorter stroke also cuts down on oil pressure problems caused by windage and oil aeration.

The big-block Chevrolet V-8 is an example of an engine that responds positively to increases in bore diameter. The GM engineers who designed the big-block knew that its splayed valves needed room to breath; that’s why the factory machined notches in the tops of the cylinder bores on high-performance blocks. When Chevy went Can-Am racing back in the ’60s, special blocks were produced with 4.440-inch bores instead of the standard 4.250-inch diameter cylinders. There’s been a steady progression in bore diameters ever since. We’re now using 4.700-inch bores in NHRA Pro Stock, and even bigger bores in unrestricted engines.

Racers are no longer limited to production castings and the relatively small cylinder bore diameters that they dictated. Today’s aftermarket blocks are manufactured with better materials and thicker cylinder walls that make big-bore engines affordable and reliable. A sportsman drag racer can enjoy the benefits of big cylinder bores at no extra cost: a set of pistons for 4.500-inch, 4.600-inch or 4.625-inch cylinders cost virtually the same. For my money, the bigger bore is a bargain. The customer not only gets more cubic inches for the same price, but also gets better performance because the larger bores improve airflow. A big-bore engine delivers more bang for the buck.

Big bores aren’t just for big-blocks. Many aftermarket Chevy small-block V-8s now have siamesed cylinder walls that will easily accommodate 4.185-inch cylinder bores. There’s simply no reason to build a 383-cubic-inch small-block with a 4-inch bore block when you can have a 406 or 412-cubic-inch small-block for about the same money.

There are much more cost-effective ways to tailor an engine’s torque curve than to use a long stroke crank and small bore block. The intake manifold, cylinder head runner volume, and camshaft timing all have a much more significant impact on the torque curve than the stroke – and are much easier and less expensive to change.

 

[87vette81big]

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.

 

[philly]

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.

 

[87vette81big]

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.

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

 

[87vette81big]

So what's the Real Game Plan ?

What's Yours ?

I know Mine.

 

[philly]

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.

 

[philly]

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.

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

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

 

[87vette81big]

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.

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.

 

[philly]

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.

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.

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

 

[87vette81big]

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.

 

[philly]

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.

 

[87vette81big]

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.

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.

 

[Grumpy]

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.

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.

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.

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.”

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.

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.

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.”

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

 

[Maniacmechanic1]

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.