dynamic ballancing |
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dynamic ballancing |
Harpo |
Oct 8 2012, 05:45 PM
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#1
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Senior Member Group: Members Posts: 1,304 Joined: 21-August 11 From: Motor City aka Detroit Member No.: 13,469 Region Association: None |
I just received my new KB 96mm 2.0 pistons and 2.0 "H" beam rods. I was going to send all of my rotating components out to be dynamically ballanced because I thought it was the right thing to do.
I weighed all of my rods on a scale acurrate to .0001 Kg and they are all the exact same weight. Same with my pistons. So here is the dumb question if they are all the same they why ballance them? I think that I will just ballance the crank, flywheel, clutch and fan. Am I missing something here? Thanks David |
wndsrfr |
Oct 8 2012, 05:52 PM
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#2
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Senior Member Group: Members Posts: 1,428 Joined: 30-April 09 From: Rescue, Virginia Member No.: 10,318 Region Association: MidAtlantic Region |
So here is the dumb question if they are all the same they why ballance them? I think that I will just ballance the crank, flywheel, clutch and fan.
Am I missing something here? Thanks David [/quote] Nope, you're not missing anything. On our horizontally opposed engines, the rods and pistons perfectly counterbalance each other, so they're not included when balancing the rotating assembly. On a 'V' engine the shop does make up "bob weights" to simulate the pistons & rods since the crank is not 180 degrees opposed.... |
VaccaRabite |
Oct 8 2012, 05:54 PM
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#3
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En Garde! Group: Admin Posts: 13,441 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
Wow. Where did you get them from? Was balancing part of the price?
Dynamic balance is more then just pistons and rods. Its everything that spins. Crank, flywheel, clutch, ect. Still a good idea, since you ARE building a performance engine. Zach |
VaccaRabite |
Oct 8 2012, 06:09 PM
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#4
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En Garde! Group: Admin Posts: 13,441 Joined: 15-December 03 From: Dallastown, PA Member No.: 1,435 Region Association: MidAtlantic Region |
Nope, you're not missing anything. On our horizontally opposed engines, the rods and pistons perfectly counterbalance each other, so they're not included when balancing the rotating assembly. On a 'V' engine the shop does make up "bob weights" to simulate the pistons & rods since the crank is not 180 degrees opposed.... Bad info... Pistons and rods DO need to be balanced. Does not matter if its a T1 or a T4, they absolutely need to be balanced. On a stock T4, the max difference between lightest and heaviest rod is 6 grams, and max weight difference between lightest and heaviest piston is 10 grams. (page 11 of your haynes manual). This is the MAX allowable difference. In practice you want to have the rod/piston combo to be balanced to within 5 grams from the lightest to the heaviest (the weight of a penny). If you plan on spinning the engine up, you want the total difference to be as small as possible. The built combo includes the pin and bearings. Zach |
wndsrfr |
Oct 8 2012, 06:12 PM
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#5
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Senior Member Group: Members Posts: 1,428 Joined: 30-April 09 From: Rescue, Virginia Member No.: 10,318 Region Association: MidAtlantic Region |
Nope, you're not missing anything. On our horizontally opposed engines, the rods and pistons perfectly counterbalance each other, so they're not included when balancing the rotating assembly. On a 'V' engine the shop does make up "bob weights" to simulate the pistons & rods since the crank is not 180 degrees opposed.... Bad info... Pistons and rods DO need to be balanced. Does not matter if its a T1 or a T4, they absolutely need to be balanced. On a stock T4, the max difference between lightest and heaviest rod is 6 grams, and max weight difference between lightest and heaviest piston is 10 grams. (page 11 of your haynes manual). This is the MAX allowable difference. In practice you want to have the rod/piston combo to be balanced to within 5 grams from the lightest to the heaviest (the weight of a penny). If you plan on spinning the engine up, you want the total difference to be as small as possible. The built combo includes the pin and bearings. Zach He said that they're already perfectly balanced.....I meant that they aren't included in the dynamic balancing step if they're already perfectly balanced..... |
Harpo |
Oct 8 2012, 06:38 PM
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#6
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Senior Member Group: Members Posts: 1,304 Joined: 21-August 11 From: Motor City aka Detroit Member No.: 13,469 Region Association: None |
I have access to a nice scale that is acurate to .0001 KG
All four KB pistons & pins measured .500 KG All four 2.0L "H" beam rods measured .525 KG I'm asking the questions because I don't know Thanks DAvid |
Cap'n Krusty |
Oct 8 2012, 06:41 PM
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#7
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
The rods need to be balanced end for end, not just total weight.
The Cap'n |
wndsrfr |
Oct 8 2012, 07:29 PM
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#8
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Senior Member Group: Members Posts: 1,428 Joined: 30-April 09 From: Rescue, Virginia Member No.: 10,318 Region Association: MidAtlantic Region |
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914werke |
Oct 9 2012, 12:36 AM
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#9
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"I got blisters on me fingers" Group: Members Posts: 10,049 Joined: 22-March 03 From: USofA Member No.: 453 Region Association: Pacific Northwest |
curious how you balance (end to end) an forged H beam rod?
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messix |
Oct 9 2012, 12:44 AM
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#10
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AKA "CLUTCH KILLER"! Group: Members Posts: 6,995 Joined: 14-April 05 From: between shit kickers and pinky lifters/ puget sound wa.north of Seattle south of Canada Member No.: 3,931 Region Association: Pacific Northwest |
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6freak |
Oct 9 2012, 11:15 AM
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#11
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MR.C Group: Members Posts: 4,740 Joined: 19-March 08 From: Tacoma WA Member No.: 8,829 Region Association: Pacific Northwest |
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6freak |
Oct 9 2012, 11:16 AM
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#12
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MR.C Group: Members Posts: 4,740 Joined: 19-March 08 From: Tacoma WA Member No.: 8,829 Region Association: Pacific Northwest |
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