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Rotating Assembly Weight Reduction

Posted By: '72CudaRacer

Rotating Assembly Weight Reduction - 02/28/10 04:53 PM

I balanced my rotating assembly yesterday, and if my math is correct, I lost almost 4 3/4 lbs. New pistons, pins, rings, retainers = 888 grams, old = 1113 grams (old DC/TRW pistons) New H-beam rods were only 8 grams lighter than stock LY rods, but are bushed and have ARP 2000 7/16" cap screws and should be MUCH stronger. Plus King Pro rod bearings are 4g less than Clevitte 77.
That comes to 237g/ hole X 8 = 1896g, plus the 240g removed from crank shaft = 2136g total weight removed from rotating assembly. (1g = 28.349 oz.) 3126g = 75.34 oz = 4.7 lbs
Anyone know what the engine will "see" because of this?
And then we add approx. 3.5 more points of compression (from 10.0:1 to 13.5:1) and a set of alum Stealth heads, we can do more of this

Brian

Attached picture 5835636-drags5-30025w.jpg
Posted By: AndyF

Re: Rotating Assembly Weight Reduction - 02/28/10 04:58 PM

Sounds about right. Less weight on the nose of the car, less weight to rotate and less weight that has to be stopped and started every spin of the crankshaft.
Posted By: tboomer

Re: Rotating Assembly Weight Reduction - 02/28/10 05:00 PM

Interesting,Brian...What did the ly rod weigh...
Posted By: Ron Silva

Re: Rotating Assembly Weight Reduction - 02/28/10 05:03 PM

You did good! I have always been a big believer in weight reduction.

Here is 10 pounds of dead weight, GONE!

Attached picture 5835659-MVC-028F.JPG
Posted By: WILD BILL

Re: Rotating Assembly Weight Reduction - 02/28/10 05:07 PM

Sounds like we're in the same boat. I dropped 7.7+ lbs off my rotating assy, upped the CR from 8.6-1 to 12-1, and opened the heads up a lot and now have no clue what's in store
Posted By: roadhazard

Re: Rotating Assembly Weight Reduction - 02/28/10 05:11 PM

Quote:

You did good! I have always been a big believer in weight reduction.

Here is 10 pounds of dead weight, GONE!






I lost 415 grams off my valve train last year!

EDIT:My calc says 3126g = 110.2664oz = 6.8915#
All I can say is Hold On and Sinch Your Belts Tighter
Posted By: Sport440

Re: Rotating Assembly Weight Reduction - 02/28/10 05:20 PM

Herb Adams had a comparison chart on rotatating vs static weight. On a rotating assembly each 1# loss was worth 2 HP.

So if you were to accept that as Fact, then a 4.7# loss = 9.4 HP

Whether its true or not. No doubt a 4.7# loss off the rotating assembly is a win, win deal. mike
Posted By: '72CudaRacer

Re: Rotating Assembly Weight Reduction - 02/28/10 05:39 PM

Quote:

Interesting,Brian...What did the ly rod weigh...



Stock LY rod, with a 1/8" hole in the top of the pin end, pin end floated (not bushed), ARP bolts (stock style), nuts, & no bearings = 860g
The big ends were not resized if I remember correctly. I measured them and found them to be acceptable.
Posted By: '72CudaRacer

Re: Rotating Assembly Weight Reduction - 02/28/10 05:42 PM

Quote:

You did good! I have always been a big believer in weight reduction.

Here is 10 pounds of dead weight, GONE!



Did you rifle drill the crank???
That shouldn't affect the balance, because it's on the center line of the rotating mass, just lower total weight, correct?
Posted By: tboomer

Re: Rotating Assembly Weight Reduction - 02/28/10 05:45 PM

Thanks,Brian!
Posted By: '72CudaRacer

Re: Rotating Assembly Weight Reduction - 02/28/10 05:46 PM

EDIT:My calc says 3126g = 110.2664oz = 6.8915#
All I can say is Hold On and Sinch Your Belts Tighter



I have 1g = .0352 oz, 1 oz = 28.349g. Or is that not correct?
Posted By: Sport440

Re: Rotating Assembly Weight Reduction - 02/28/10 06:15 PM

Quote:

EDIT:My calc says 3126g = 110.2664oz = 6.8915#
All I can say is Hold On and Sinch Your Belts Tighter



I have 1g = .0352 oz, 1 oz = 28.349g. Or is that not correct?




Maybe its not exact but roughly 454 grams = 1#

454/16 oz. = 28.375 grams a oz. So you are correct.

That 110.266 grams per oz. is a mistake. His total grams converted to pounds is correct. mike

3126/454= 6.8854 pounds.
Posted By: sturmenater

Re: Rotating Assembly Weight Reduction - 02/28/10 07:30 PM

It will most defently help your engine live longer not spining all that extra weight
Posted By: 65racer

Re: Rotating Assembly Weight Reduction - 02/28/10 07:54 PM

Brian, how's it going?
Seems like your gonna step it
up quite a bit.
Get it ready, racing season is
just around the corner.

Maybe I should have made mine
quicker, but didn't want to
mess with my combo.

Good luck
Dave

ps,,,,, If anyone around your neck of the
woods is looking for a new enclosed
trailer, send them my way, I have that
28' I need to get rid of.
Posted By: '72CudaRacer

Re: Rotating Assembly Weight Reduction - 02/28/10 08:43 PM

Davey, I sent you a PM.
Brian
Posted By: roadhazard

Re: Rotating Assembly Weight Reduction - 02/28/10 10:19 PM

Quote:

Quote:

EDIT:My calc says 3126g = 110.2664oz = 6.8915#
All I can say is Hold On and Sinch Your Belts Tighter



I have 1g = .0352 oz, 1 oz = 28.349g. Or is that not correct?




Maybe its not exact but roughly 454 grams = 1#

454/16 oz. = 28.375 grams a oz. So you are correct.

That 110.266 grams per oz. is a mistake. His total grams converted to pounds is correct. mike

3126/454= 6.8854 pounds.



So he took off 6.88# not 4.7# correct?
I was using a converter that I found online and yes I made a mistake 1g = .03527396oz
Hope I didn't cause any problems
Posted By: '72CudaRacer

Re: Rotating Assembly Weight Reduction - 02/28/10 11:03 PM

Hey Greg,
4.75 or 6.8, it's still a LOT. Biggest thing by far was the pistons. These are domes, flat tops would be even more. I have a JE flat top here that weighed 58g per hole less than my Ross'.
Brian
Posted By: Sport440

Re: Rotating Assembly Weight Reduction - 02/28/10 11:51 PM

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
Posted By: '72CudaRacer

Re: Rotating Assembly Weight Reduction - 03/01/10 03:25 AM

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



I think I need to take a break. Yesterday at the machine shop, Dan is letting me do as much as I can. (I'm a mechanic, not a machinist) Anyway, I'm weighing everything and balancing rods & pistons and filling out balancing work sheet. I get done and he comes over to set up balancer, and finds that I've recorded small end at 255g and big end at 297g (597g was correct) for a rod total of 552g, 300g light. Good thing he don't trust me yet!
Sorry about that.
Brian
Posted By: WILD BILL

Re: Rotating Assembly Weight Reduction - 03/01/10 03:30 AM

Maybe that's why Scott and Dale did all my balancing on a day I wasn't there to help
Posted By: '72CudaRacer

Re: Rotating Assembly Weight Reduction - 03/01/10 03:37 AM

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.
Posted By: polyspheric

Re: Rotating Assembly Weight Reduction - 03/01/10 04:46 PM

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.
Posted By: polyspheric

Re: Rotating Assembly Weight Reduction - 03/01/10 05:13 PM

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.
Posted By: emarine01

Re: Rotating Assembly Weight Reduction - 03/01/10 08:05 PM

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
Posted By: 65racer

Re: Rotating Assembly Weight Reduction - 03/01/10 11:11 PM

Brian,

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

Dave
Posted By: Sport440

Re: Rotating Assembly Weight Reduction - 03/01/10 11:53 PM

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
Posted By: '72CudaRacer

Re: Rotating Assembly Weight Reduction - 03/02/10 12:48 AM

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.
Posted By: '72CudaRacer

Re: Rotating Assembly Weight Reduction - 03/02/10 12:50 AM

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.
Posted By: roadhazard

Re: Rotating Assembly Weight Reduction - 03/02/10 01:55 AM

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?
Posted By: '72CudaRacer

Re: Rotating Assembly Weight Reduction - 03/02/10 03:14 AM

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.

Attached picture 5839768-PinksAllOutCharlotte42009037.JPG
Posted By: Streetwize

Re: Rotating Assembly Weight Reduction - 03/02/10 06:12 PM



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.
Posted By: gregsdart

Re: Rotating Assembly Weight Reduction - 03/02/10 06:20 PM

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.
Posted By: Sport440

Re: Rotating Assembly Weight Reduction - 03/03/10 02:36 AM

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
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