Dyno Fail - Question
Thread Starter
Le Mans Master
Joined: May 2000
Posts: 8,729
Likes: 1,508
From: Redmond WA
Dyno Fail - Question
A while back I was watching someone dyno a small block on an engine dyno (not a roller). Nothing noteworthy except there was no flexplate or converter. It was a neutral balance motor, so shouldn't have mattered.
After about the 4th run, the harmonic balancer rubber smoked and and disintegrated, ending the session.
Now here's my pet theory and I'm curious if anyone thinks its possible: I think the damper is there to dampen the sudden acceleration and deceleration of the crank from combustion events. If you remove the mass of the flywheel or converter, now the crank "speeds up and slows down" a lot more every firing.
I'm wondering if all this extra "work" could have overworked the rubber ring in the balancer, causing it to fail.
Or was it just a coincidence?
After about the 4th run, the harmonic balancer rubber smoked and and disintegrated, ending the session.
Now here's my pet theory and I'm curious if anyone thinks its possible: I think the damper is there to dampen the sudden acceleration and deceleration of the crank from combustion events. If you remove the mass of the flywheel or converter, now the crank "speeds up and slows down" a lot more every firing.
I'm wondering if all this extra "work" could have overworked the rubber ring in the balancer, causing it to fail.
Or was it just a coincidence?
Last edited by davepl; Apr 30, 2018 at 11:34 AM.
Burning Brakes
Joined: Aug 2016
Posts: 1,021
Likes: 409
From: Bremerton Wa.
SBC with a stock dampener are notorious for slipping about the inner shell.
Especially if the dampener has some miles on it already.
A mark across both inner/outer shells with a paint pen will confirm this.
MHO, use an ATI dampener on performance builds.
Never seen one on a dyno without a flexplate/flywheel myself, even if it is a neutral balance.
Especially if the dampener has some miles on it already.
A mark across both inner/outer shells with a paint pen will confirm this.
MHO, use an ATI dampener on performance builds.
Never seen one on a dyno without a flexplate/flywheel myself, even if it is a neutral balance.
Drifting
Joined: Apr 2015
Posts: 1,276
Likes: 317
I’ve always had flex plates on mine, and no performance built motor should have a stock damper. That said, back in the early 90s I had several Stroked LT1’s dynoed with stock dampers, but they where new cars and engines, not some decades old dinosaur.
John
John
Team Owner
Joined: Jan 2007
Posts: 29,063
Likes: 1,839
From: cookeville tennessee
Also seen in the c5 with a blower r turbo on it even a new per damper go bad & do crap
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Burning Brakes
Joined: Aug 2016
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From: Bremerton Wa.
Safety Car
Joined: Oct 2007
Posts: 4,204
Likes: 1,075
From: South Florida
A while back I was watching someone dyno a small block on an engine dyno (not a roller). Nothing noteworthy except there was no flexplate or converter. It was a neutral balance motor, so shouldn't have mattered.
After about the 4th run, the harmonic balancer rubber smoked and and disintegrated, ending the session.
Now here's my pet theory and I'm curious if anyone thinks its possible: I think the dampener is there to dampen the sudden acceleration and deceleration of the crank from combustion events. If you remove the mass of the flywheel or converter, now the crank "speeds up and slows down" a lot more every firing.
I'm wondering if all this extra "work" could have overworked the rubber ring in the balancer, causing it to fail.
Or was it just a coincidence?
After about the 4th run, the harmonic balancer rubber smoked and and disintegrated, ending the session.
Now here's my pet theory and I'm curious if anyone thinks its possible: I think the dampener is there to dampen the sudden acceleration and deceleration of the crank from combustion events. If you remove the mass of the flywheel or converter, now the crank "speeds up and slows down" a lot more every firing.
I'm wondering if all this extra "work" could have overworked the rubber ring in the balancer, causing it to fail.
Or was it just a coincidence?
first gear it will be highest. the least amount of force produced on behalf of the engine would raise engine rpm the fastest in the numerically lowest gear, as 1st. If you take it out of first, its in neutral, and try wide open throttle the engine rate of change is too fast to be realistic simulator of load. In other words it wouldn't necessary be in the design paramter of a given combustion engine to be able to accelerate at WOT in neutral (or even worse, with no flywheel or converter or anything else behind it). Thus, "low load" or "neutral revving" isn't what you are looking at in a dyno run of any kind. Their armature or mechanical device connected to the engine whatever-you-call-it-thing produces a load, a counter force on the crankshaft, to simulate typical engine rate of change as found in typical operation. A 'variable load dyno' can usually also apply enough load to decelerate the engine at WOT, thus allowing us to 'see' what an engine tuned to withstand such torture would require, if we are not the original creators of that engine (we usually are not this person/people so need to experiment)
Drifting
Joined: Apr 2015
Posts: 1,276
Likes: 317
The engine dyno uses a water brake, and the load can be varied from none to enough to kill it. You could go wide open to 7k and using the water brake, back the rpm down. You can make it pretty brutal for the engine 
Last edited by JHEBERT; Apr 29, 2018 at 10:43 PM.
Thread Starter
Le Mans Master
Joined: May 2000
Posts: 8,729
Likes: 1,508
From: Redmond WA
Burning Brakes
Joined: Dec 2015
Posts: 1,096
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From: Denver Colorado
The definitions of words are defined by their use and context. That's how language evolves, that's why a definition for "literally" can be used as a "statement emphasis enhancer" and why the word "idiot" no longer means somebody who is gifted and skilled.
The fact that the word "dampener" is used quite often to refer to the device that deadens vibrations shows that a definitions for the word dampener is exactly that. This Chrysler Harmonic Dampener Puller is a perfect example.
Also, colloquialisms, they exist. Trying to correct someone's use of language when its blatantly obvious from context what they're talking about does nothing to serve the conversation. Does his use of the word "dampener" suddenly mean you don't understand what he's saying? Just because you don't use the word the way everybody else does doesn't mean his thoughts and ideas are no longer conveyed appropriately.
The fact that the word "dampener" is used quite often to refer to the device that deadens vibrations shows that a definitions for the word dampener is exactly that. This Chrysler Harmonic Dampener Puller is a perfect example.
Damper refers to something that deadens, restrains, or depresses, an adjustable plate for controlling a draft, and one that deadens vibrations. Damper‘s corresponding verb is dampen, which means to deaden, restrain, or depress. Of course, dampen also means to make slightly wet. A dampener is someone or something that dampens. So damper and dampener can both refer to one that deadens sound vibrations.