dad has worries about UD pullies

trinity_gt said:

From research and basic knowledge of engine function.

Are you one of those that erroneously calls the harmonic damper on the 4.6 a "balancer"? Do you understand the concept of torsional vibration in a crankshaft and the need to dampen it? Do you understand the concept of harmonics and resonance? Do you know where the oil pump drive gear is, in the engine, relation to the harmonic damper?

And even though I disagree with him calling it a "balancer", this is what Sean Hyland says in his book "How to Build Max Performance 4.6-litre Ford Engines":

"The harmonic balancer is essential in providing a trouble-free service life for the crankshaft. The oil pump failures on engines using stock oil pumps can be attributed to a harmonic problem that manifests itself by breaking the oil pump gears.

The first instances of oil pump failure we encountered were the result of trying a small crankshaft flange instead of a balancer. There also seems to be increased instances of oil pump failure when some brands of underdrive pulley kits are used. I believe this is due to inadequate damping with the reduced diameter harmonic damper provided. SHM recently developed an underdrive harmonic balancer that retains 92% of the original mass." - pg 19

I now await proof from you that torsional vibration in the crank cannot cause oil pump failure on these motors.

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Yes, I’m aware that the modular engines are internally balanced and to a certain extent I agree with you. But in the same instance the cases being referred to are stock engines being spun past their normal parameters with either the addition of excessive horsepower or RPM. I guess if you bought a lowball cheap set of piggy back U/D pulleys, then engine harmonics might be increased to a certain extent that over a looooong period of time could contribute to some form of driveline failure, but for your average Joe just looking to kick up another 100hp out of his 4.6L, it never seems to be a problem.

That being said, it’s interesting that Sean Hyland Mororsports claims to have revolutionized the theory of driveline harmonics by developing a balancer that magically cures this issue. A more accurate description of the company that is SHM brings the words “Hack Artists” to mind. I live not more than about 3 1/2hrs from them and they’ve screwed up more mod motors than every other specialty company combined. He’s probably one of the last people I’d be taking advice from in regards to the understanding of Fords line of Modular engines. It’s a good theory, and in extreme cases a correct one, but for every one person who says adding a set of U/D pulleys screwed their motor, I’ll show you 50 that have gone 100,000+ without so much as a hiccup!

reenmachine said:

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Hardly Newbie....and I recal you being one of the first ones to pipe up about it yourself. Back up that statement!