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Do I 'need' a harmonic damper?

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#1 RTz



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Posted 03 June 2009 - 05:59 PM


That looks great
But dont you need a dampner on the L series engines

With all due respect, yes, you do need a damper, unless you are planning to tear-down the bottom end of the motor after every few runs/outings (depending on how hard you are hitting it - ask Jeff Priddy) and have the budget to replace parts fairly regularly.

Even on normally-aspirated inline four-cylinder engines, we have seen crankshaft journal flexing of two degrees or more with no harmonic damper installed, in our dyno/torsiograph tests. In serious performance applications, you can expect that much flex to shear cranks at the flywheel after a few laps in a road race environment. Inline-six cranks are notoriously worse (ask the BMW racers what they have been going through.)

Anyone who wants to read-up on exactly what harmonic dampers actually do can click the link below for a technical document which our head of damper development wrote:

Click Here (230K PDF)

Chris @ BHJ

Regards, Ron

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#2 NavyCuda


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Posted 13 June 2009 - 05:30 PM

I found it quite interesting that turbocharging caused more issues than supercharging... Doesn't sway my love for turbos though!

#3 Phlebmaster


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Posted 17 June 2009 - 02:05 PM

Ron, what was the original thread you got the first quote from? I want to see what "looks good" so I know what the reference is.

Thanks, Aaron
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#4 bschiltz


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Posted 25 August 2009 - 07:43 AM

This summer I worked on a river survey project on the Platte River here in Nebraska. The survey company I was working with had an airboat they used to survey the riverbed. It had a Chevy 4.3 in it but had no harmonic dampener, just the pulley. Can an airboat or other special application get away with this due to less rotating mass in the drivetrain (simple gear box and prop vs. transmission, driveshaft, diff., wheel and tire) or is this just bad judgement from whoever built the boat?
1979 280ZX with '86 305 and 700R4

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