Josh, did David Vizard include information about the engine speeds at which valve train stability was effected?
The 6th order Harmonics of a six cylinder inline tend to be pretty pronounced, from the data I've found, but is the valve train stability a problem at such low engine speeds, or at much higher rpm?

CJ

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Part of Tyrde-Browne Racing

No, all he wrote in that piece was the one generality. I imagine someone knows the answer to your question, but it isn't me.

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Joshua

I would run a good damper. Seems like cheap insurance. However, inline 6s have less harmonic vibes than V8s or inline 4s, theoretically.

Lou

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Home of Slant6-powered fun machines since 1988

Yep no joke, I agree. Theoretically an inline six has severe harmonics in destructive ranges well within the engine speeds where it normally makes power.
At the dragstrip, all bets are off.
At the same time, I'm getting feedback from various sources that say the blower provides a considerable sink to the damaging harmonics care of the load at the other end of the belt. Not only the load, but the internal dimensions of the blower.
Belt driven accessories apparently help. A single serpentine belt is reportedly a better way to go where harmonics are concerned, than individual belts to accessory loads. Though it's unsubstantiated as yet it's starting to make sense. The harmonic transmits, and is eaten by the accessory that destructively interferes with the harmonic. apparently new cars come with AC pumps that run all the time, incorporating a one time clutch in case of compressor failure. This contributes to harmonic dissipation. Having multiple resonant loads allows for dampening across a wide range of engine speeds. It simplifies final harmonic computations, and reduces weight and size of the damper itself.
Similar to how multi-coatings on lenses provide destructive interference at specific wavelengths of light, but don't appreciably attenuate light transmission at other frequencies. (Power for us.)
I can't seem to land on effects at given engine speeds for other effects, like valve train instability resulting from harmonics. That's a complicated question. There's a multitude of dimensions to take into account but where the harmonic is dampened prior to transmission, an attenuated harmonic should be experienced through the timing set. Maybe.

I guess I'll be the guinea pig.
It's all waves.
Back to the dancing wu li masters.

I should have been a shoemaker.

CJ

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Part of Tyrde-Browne Racing

Doesn't Terry Littlejohn run the same blower you are going to use? You could ask him.

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Official Cookie and Mater Tormentor.

Good plan! I thought Terry ran a 4-71. I'll have to look at that again.

The 4-71 or the 6-71 should present a similar dampening effect.

CJ

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Part of Tyrde-Browne Racing