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Re: Rotating Assembly Weight Reduction [Re: WILD BILL] #626827
02/28/10 10:37 PM
02/28/10 10:37 PM
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Posts: 2,076
Mooresburg, Tn
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'72CudaRacer Offline OP
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Quote:

Maybe that's why Scott and Dale did all my balancing on a day I wasn't there to help




I might be better off if he would just run me off...I know he would be!
Can I watch??? Can I help??? Please??? Dan? Now, where did he go, again? HaHaHa.

Re: Rotating Assembly Weight Reduction [Re: Sport440] #626828
03/01/10 11:46 AM
03/01/10 11:46 AM
Joined: Oct 2007
Posts: 4,219
New York
polyspheric Offline
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Herb Adams says a lot things.
That approximation might have some merit - if referring to a specific radius of rotation.
1 lb. off the center of the crank does nothing.
1 lb. off the pin at 3.31" stroke does something.
1 lb. off the OD of a 440 counterweight does a whole lot more.


Boffin Emeritus
Re: Rotating Assembly Weight Reduction [Re: '72CudaRacer] #626829
03/01/10 12:13 PM
03/01/10 12:13 PM
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Posts: 4,219
New York
polyspheric Offline
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Weight off pistons: 225 grams × 8 = 1800 grams reciprocating weight = 63.49 oz.
Weight removed from crank for balance @ 50% factor: 900 grams rotating weight = 31.75 oz.
Total weight off crank: 2700 grams = 95.24 oz. = 5.95 lbs. just for the pistons.

Weight off rod bearings: 4 grams × 8 = 32 grams rotating weight + 32 grams balance = -64 grams = 2.26 oz.

Rod weight loss: you added the 8 grams that you identified as a loss. In addition, we don't know how this was distributed.


Boffin Emeritus
Re: Rotating Assembly Weight Reduction [Re: polyspheric] #626830
03/01/10 03:05 PM
03/01/10 03:05 PM
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nc
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emarine01 Offline
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My chevy 400 block builder buddy runs cast steel cheepo stroker cranks with real light pistons and cuts the OD on the crank counter weights to balance, He is seeing 650hp and 7k min on his builds with no failures to date, so weight does seem make a lot of difference

Re: Rotating Assembly Weight Reduction [Re: emarine01] #626831
03/01/10 06:11 PM
03/01/10 06:11 PM
Joined: Jan 2003
Posts: 1,235
TN
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65racer Offline
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Brian,

I shot you a PM,
let me know if you
got it, been having
internet service problems

Dave

Re: Rotating Assembly Weight Reduction [Re: polyspheric] #626832
03/01/10 06:53 PM
03/01/10 06:53 PM
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Posts: 6,591
Canton, Ohio
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Sport440 Offline
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Canton, Ohio
Quote:

Herb Adams says a lot things.
That approximation might have some merit - if referring to a specific radius of rotation.
1 lb. off the center of the crank does nothing.
1 lb. off the pin at 3.31" stroke does something.
1 lb. off the OD of a 440 counterweight does a whole lot more.





totally! It was a approximation IMO, with No specifics to radius of rotation. As you state the further out, the better the effect. mike

Re: Rotating Assembly Weight Reduction [Re: polyspheric] #626833
03/01/10 07:48 PM
03/01/10 07:48 PM
Joined: Aug 2009
Posts: 2,076
Mooresburg, Tn
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'72CudaRacer Offline OP
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Quote:

Weight off pistons: 225 grams × 8 = 1800 grams reciprocating weight = 63.49 oz.
Weight removed from crank for balance @ 50% factor: 900 grams rotating weight = 31.75 oz.
Total weight off crank: 2700 grams = 95.24 oz. = 5.95 lbs. just for the pistons.

Weight off rod bearings: 4 grams × 8 = 32 grams rotating weight + 32 grams balance = -64 grams = 2.26 oz.

Rod weight loss: you added the 8 grams that you identified as a loss. In addition, we don't know how this was distributed.




So, is this a good thing? Or just useless knowledge? With this amount of weight reduction, will it make a diffence as to what the engine will "see"?
I'm thinking that it can't hurt.

Re: Rotating Assembly Weight Reduction [Re: 65racer] #626834
03/01/10 07:50 PM
03/01/10 07:50 PM
Joined: Aug 2009
Posts: 2,076
Mooresburg, Tn
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'72CudaRacer Offline OP
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Quote:

Brian,

I shot you a PM,
let me know if you
got it, been having
internet service problems

Dave




No mail from The Champ.

Re: Rotating Assembly Weight Reduction [Re: Sport440] #626835
03/01/10 08:55 PM
03/01/10 08:55 PM
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Akron, Ohio U.S.A.
roadhazard Offline
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Quote:

Hey Greg I see what happend with the 4.77# vs the 6.88#

Brian had both sets of numbers listed in grams 3126 - 2136 and typoed a 3 and 2 switch. You did the math for the 3126, Brian did the math for 2136. After rereading the post the 2136 gram number is the correct one. So 4.7# is the number.

6.8 - 4.7 its all in the right direction. mike




Yes Mike it's all in the right direction

Brian those mods should pick your car up a bunch and with a lighter bob weight it should be more durable also
You have a Sweet looking ride. What's her best time and MPH?

Re: Rotating Assembly Weight Reduction [Re: roadhazard] #626836
03/01/10 10:14 PM
03/01/10 10:14 PM
Joined: Aug 2009
Posts: 2,076
Mooresburg, Tn
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'72CudaRacer Offline OP
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Brian those mods should pick your car up a bunch and with a lighter bob weight it should be more durable also
You have a Sweet looking ride. What's her best time and MPH?




Thanks Greg,
Most of the tracks around here are 1/8 mile, except Bristol and even they run brackets on 1/8.
Mid to high 6.8x, @ 98-99 mph, 60' 1.46/1.47. Last spring we went to Z-Max for Pinks All Out, 1/4 mile at approx 600' lower altitude, I went 10.873 @ 122.29, 1.481 60', 1/8 mile on that same pass was 6.869 @ 98.77. I'll include a photo from the rear of that pass.
Car weighs 3270 lbs w/ me, SS springs, 11.5 X 29.5 MT, all steel, fiberglass hood.
I really don't have a clue as to what this new engine will do, I just hope it don't mess up my combination. This car has always been deadly consistant. The guys that I race with will tell you that my reaction times will be from .00x-.070, but count on the car running dead on.

Last edited by '72CudaRacer; 03/01/10 10:54 PM.
Re: Rotating Assembly Weight Reduction [Re: '72CudaRacer] #626837
03/02/10 01:12 PM
03/02/10 01:12 PM
Joined: Jan 2003
Posts: 9,944
Weddington, N.C.
Streetwize Offline
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Just remember that the bobweight % reduction by itself really applies to freewheeling....when applying power the net gain is lower (overall) because you have to calculate total which is the sum of all the rotating masses the motor is "seeing" from the nose of the crank to the back tires. it's still a reduction but the net reduction (in terms of the % TOTAL amount of mass being rotated) is obviously less. In the end the motor can only rotate under load as fast as the load it is driving through will allow it to.

Last edited by Streetwize; 03/02/10 01:24 PM.

WIZE

World's Quickest Diahatsu Rocky (??) 414" Stroker Small block Mopar Powered. 10.84 @ 123...and gettin' quicker!

https://www.youtube.com/watch?v=-mWzLma3YGI

In Car:

https://www.youtube.com/watch?v=PjXcf95e6v0
Re: Rotating Assembly Weight Reduction [Re: Streetwize] #626838
03/02/10 01:20 PM
03/02/10 01:20 PM
Joined: Jan 2003
Posts: 10,150
Frostbitefalls MN (Rocky&Bullw...
gregsdart Offline
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Another factor is RPM at launch/total rpm loss and recovery in each gear. The less rpm change, the less gain. A super speedway nascar racer probably won't see much, but a car with a tight converter and wide gear splits will.
Other factors would be change in size of any rotating part exposed to the crankcase, which would change the drag from windage.


8.582, 160.18 mph best, 2905 lbs 549, indy 572-13, alky
Re: Rotating Assembly Weight Reduction [Re: gregsdart] #626839
03/02/10 09:36 PM
03/02/10 09:36 PM
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Posts: 6,591
Canton, Ohio
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Sport440 Offline
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Canton, Ohio
I like the combined two aspects that both Wize and Greg point out.

1. The motor underload can only rev as fast as the load its driving through will allow it.

2. The limited RPM rev range in witch the said motor will operate in with its combined vert stall and rpm shift points.

Both combined would have a effect on any total net effective HP gain of any rotational weight losses.

IMO, no doubt theres a performance gain, but the bigger gain IMO would be the reduced G forces on parts by thousands of pounds. mike

Last edited by Sport440; 03/03/10 12:00 AM.
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