I'd never heard that before.

I had heard this, but doubted that the decrease in viscosity would have much effect on "centering."

 Other factors have to be cast or steel (forged) cranks. Piston weights, heavier being able to absorb more of the shock load and transmitting less to the crank. The cast cranks typically absorb more shock with their lower stiffness numbers (yield strength), but fracture more quickly. I'd bet the numbers for the damper are established by empirical tests, based on experience with a known engine combination. Rather than some formula. Although with Cad/Cam it would be possible to calculate. Harmonics of the materials would also play a part, meaning our stiffer rods and cranks probably make the situations Worse! 

Frank/Rebop

Bristol, In ( by Elkhart) 

I believe this is going to be lengthy so try to bear with me.

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The problem with the Fluidamper design is that it simply doesn’t do as well a job at dampening crankshaft harmonics as some of the other designs that are out there for the performance engines. Some of the other damper designs that are available include the elastometer (most oem, Romac, Prof Prdts, Pioneer, Summit, etc.), dual elastomer (ATI), friction (Fisher), and mechanical (TCI). For the factory engines, the oem engineers have done a superb job in designing a damper that does the intended job while being cost effective. The basic premise of a harmonic damper is to control crankshaft shock loads that are imposed when the ignition fires before top dead center. This is technically only a first order of harmonics level of control whereas the dual elastometer design is able to put an additional measure of control to the second order of harmonics that are also present. When a damper does not do an adequate job of controlling these forces, then these forces are simply redirected back into the confines of the engine instead of being absorbed by the damper. This takes away horsepower that would have normally been directed to the flywheel and forces the crankshaft to reabsorb these forces while at the same time creates the potential for engine damage usually in the form of crankshaft breakage.

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As far as the fluid filled dampers not being as effective as other styles, there are a variety of factors including the free weight or inertia ring in the fluid as well as the viscosity of the fluid itself. But fluid dampers were originally developed for the diesel engine industry where shock loads were heavy in the lower rpm ranges. Lincoln used fluid filled dampers on the 337 CID Flatheads in the early Fifties but I’m not aware of them being used on any other oem car applications other than this. I’ve balanced a multitude of fluid filled balancers and they all exhibit a given amount of imbalance regardless of brand. Part of this imbalance is a result of an inertia ring that free floats and because of this, it’s not in a centered position within the damper housing at balancing speeds. Upon talking with a Fluidamper engineer about the imbalance issues, the problem was in the fluid not being at operating temperature thus preventing the inertia ring to center itself at rpm. I lived with that answer for about two years until doing a series of tests that confirmed that the overall balance of the assembled components was the problem, not the temperature of the fluid being used. Although I will balance a customers engine with a supplied fluid damper, I’ll not assemble any.

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The issue confronted by the hobbyist (you and me) is that any modifications performed to an engine in regards to cubic inch, compression ratio, ignition timing, etc. then changes the attributes required for a damper to control the harmonics at the crankshaft level. The common solution is to use some form of a factory oem damper but there are those who will opt for some form of an aftermarket damper because it is required by rules or other factors. In the case of the Y, the oem dampers are marginal at best in a performance situation. Unfortunately the price is a large factor in any kind of damper purchase and pricing for the various aftermarket dampers that are available goes from mild to wild. Because the different racing sanctioning bodies require an SFI approved damper in some of their classes, the market is wide open to a variety of harmonic damper designs that will fit these classes. As a general rule, as the compression ratio is increased, then so is the need for a heavier damper to absorb the additional shock loads transmitted through the crankshaft. Some of the tricks of the trade in minimizing damper weight while providing adequate dampening attributes includes aluminum hubs, varying damper thicknesses and diameters, different sized elastometer rubbers, more or less friction on the movable parts, etc.

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Also, is there some method to calculate the mass required for a given amount of Cylinder pressure, or is this also a function of the crank stiffness, rotatng mass? Flywheel weight?

Although I can perform the math for centrifugal mass, the math for what’s happening with stiffness of components and combustion pressures thrown into the fray is way out of my league. Undoubtedly the oem engineers have some guidelines as far as damper sizing goes as the oem dampers do get heavier as the compression ratio or performance levels go up. Dyno testing on my end has reitterated this point when testing a variety of weighted dampers on high compression engines as heavier dampers are more beneficial than the lighter ones as the compression ratio goes up. On low compression engines, there is no apparent benefit to using a heavier than stock damper but no detriments to their use also. Damper weight is like the octane level on fuel. If an engine requires high octane fuel, then it’s detrimental to use a low octane fuel but for an engine that uses low octane fuel, the use of a high octane fuel will not be a show stopper. The same analogy applies to damper weight.

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As far as the myriad of damper designs available, dampers are like oil in that good marketing can sell the worst of products while poor marketing can be the failure of a good product.

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Disclaimer: Just my opinion.

Lorena, Texas (South of Waco)

Well, we want to get the Bonneville record back for the Y, and he needs to beat that Dodge by a nice margin.

 He still has the record at Maxton and El Mirage!

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

Let's see, you have the record, or did for a while, and I broke. WHO needs help?

Frank/Rebop

Bristol, In ( by Elkhart) 

John, Charlie, PC, Frank, and especially Ted, thanks for the input.  Wow, that is what this forum is all about.

I did email Fluidampr, but they haven't returned it yet.  I was hoping to see if they had helped any Y-Blockers in the past.

I called Jerry Christenson and we had a great conversation.  We have talked on the phone for a couple of years now and I should have thought to call him earlier.  Sometimes you just do not want to go to the well too often.  Jerry doesn't do the internet, so he has no idea of the sharing that goes on here unless someone calls him and fills him in.  He is a most generous person with his time and expertise.  There is no need to print everything he said because it would just be rewriting what Ted stated.  However, he likes ATI, don't like fluid filled dampers, ATI is expensive, likes the idea of a scrub unit with a machined spacer for the front seal, and by all means I should get rid of the stock damper.

Please feel free to continue this thread as I need all the help I can get............Thanks

Charlie Burns Laton, Ca (South of Fresno)



BurnsRacing981@gmail.com

Ted,

        What's the problem with the FluidDamper? I don't question the results, but I don't understand the reason. Very interesting that a solid Factory cast damper produced good numbers, That goes against everything I ever read! Which probably means it's 100% correct.

        Also, is there some method to calculate the mass required for a given amount of Cylinder pressure, or is this also a function of the crank stiffness, rotatng mass? Flywheel weight?

Frank/Rebop

Bristol, In ( by Elkhart) 

After doing two different dyno sessions concentrating on harmonic damper testing with a pair of FE engines, fluid filled dampers were far from being adequate performers when compared to other brands and designs as well as when compared to the stock oem dampers. For a performance Y, the ATI brand of dual elastometer dampers is my damper of choice and especially where the rules require an SFI approved damper. ATI does make a hub for the Y which allows their dampers to be used with the stock Y timing pointer but the pricing for them has skyrocketted during this last year so be prepared for sticker shock. The ATI (or other brands) damper for an LS1 engine is also an option as they have a longer snout and merely need about 0.004” honed from their bore to allow them to fit the Y’s crankshaft snout. I can’t tell you off hand if this damper’s snout is long enough to clear the stock Y timing cover but I have to cut the snout down to fit the marine covers.

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A standard scrub damper with a machined spacer behind it for the timing cover seal is also another option as these have come through the shop and will work with the standard Y timing cover with the sleeve in place. The same 0.004” must be machined from these dampers also. With these retrofitted dampers, the 0 mark on the outer ring isn’t in the right place and you have to reference another number for the TDC but these dampers are at least marked the whole 360°. This is just a nuance to saving a bit of expense if using one of the scrub dampers in lieu of the one that’s specific for the Y and it’s one of these retrofits from ATI that’s on my roadster engine now.

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If ordering an ATI damper that’s made for the Y, then specify drawing #SK069 for the correct hub.

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Older links regarding the aforementioned dyno testing.

Club Cobra 64406

FE Forum 1057338408

FE Forum 1117417685

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And more links on the subject on this site:

http://forums.y-blocksforever.com/Topic2966.aspx
http://forums.y-blocksforever.com/Topic7834.aspx
http://forums.y-blocksforever.com/Topic9059.aspx
http://forums.y-blocksforever.com/Topic11223.aspx

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A little lengthy but as you can tell, I’m not a fluid filled damper fan. Disclaimer: Just my opinion.

Lorena, Texas (South of Waco)

I wonder if you sent a stock damper to FluidDamper if they would be able to whip something up. They could remove the ring and the rubber and install one of their own dampers.



Edit; I just sent Fluidampr an email. You might want to connect to their website and do the same.



http://www.fluidampr.com/index.html



Click on the 'contacts' link to leave them a message.

Best regards,



Paul Menten

Meridian, Idaho

Doesn't one of those damper companies make a "bolt on" damper for a bird? Then you'll just have to line up your alternator.



Maybe if 10 or 20 of us get together we can persuade one of those companies to produce one. I'm up for it.



There was a good discussion about these a while back.


Lawrenceville, GA

John,

Thanks for the reply.  I will call Jerry asap.  If anyone else has ideas, please do not hesitate to jump in.  Together we will have an even better running Y.  (Next years goal for Bonneville.....130mph).

Charlie Burns Laton, Ca (South of Fresno)



BurnsRacing981@gmail.com