Crank Dampner needed or not?

[mcfly]

all type R honda engines have no harmonic dampener. a single metal pully the size of our water pump pully. It's very different.

[Terrh]

yeah, rotaries are 100% damper free too

but I bet you'd guessed that :P

[Dragon Humper]

That's what I was referring to with the J-spec ATI (RH9) Damper, I've been to Fuji Dynamics and they had an ATI Damper for about $750 (street, $1000 for the race) and I see I can get them out of the States on FleaBay now for $460.

I wish I could find the article that showed an issue with the (I'm assuming it's the street) US sourced damper.

So to clarify, McFly, your running the street ATI from down south to 9000 with no specific issues with the damper itself (split blocks aside)?




"You can only balance a for 1 RPM. For example my crank is balanced for 4000rpm."-VorteXxe

That's not entirely true. There is a big difference between balancing and harmonics. Even a perfectly balanced motor can have harmonics. Every engine design has it's own harmonic RPM (some have 2 points). V6 (90* and 60*), V8, V10 (is a bad one) and V12 engines typically have a natural harmonic at a lower RPM than in-line engines do. The in-line 6 is the best engine design for low to mid RPM because there are virtualy no harmonics (compared to a V engine), which is why they make an excellent Diesel engine.

An un-balanced engine (just slaped together with new parts with no regard) will exibit a HIGH and huge LOW frequency harmonic which will do damage but is more obvious as you can feel it in your butt as your driving your car. A $1000 damper isn't going to help much as they are not designed to do much about that. A perfectly (within a half gram) balaced engine will exibit a HIGH ferquency harmonic (many actually) that will converge at a specific RPM and really get that crank a-twistin' to the point of actual measurement in the half to 1 full degree area. This is potential damage that you won't feel.

What the stock dampers do is dampen the harmonics at a specific RPM (4000 for example) because engineers found that a particular engine design had it's many harmonic frequencies converge at 4000 RPM and could measure it tangebly (sp?). What a ATI damper does is dampen across a wide range of RPM's (apparently not at 9000 LOL) making the engine much happier all around. Even the valve train can produce harmonics (as well as react to them) so a good damper can go a long way to engine longevity.



Jon.

[mcfly]

I fractured a block with the oem damper

I have a Race ATI Damper though now(the big one)

Do you mean the HKS ati? ATI makes the pully and hks sells them.

[GTR-Dad]

Don't get confused between vibration resulting from imbalance and torsional crankshaft vibration. They may interact a bit, but the biggest source of torsional crankshaft vibration (which is what a damper deals with) is the power stroke. The crankshaft acts like a stiff torsion spring and goes through some angle of twist every time a cylinder fires. Then it springs back. You can imagine that #1 will result in the greatest angle of twist as torque is applied at one end of the crank and reacted by the flywheel at the other end.

Don't use 'harmonic' interchangably with 'vibration'. Harmonic refers to vibrations at multiples of the primary vibration frequency. The primary frequency can induce higher frequency harmonics, which is no big deal until one of the frequencies coincides with the natural frequency of the 'tuning fork', the crankshaft in this case. When the natural frequency is at a multiple
of the exication frequency in an elastic system the vibration amplitude increases a bit more with each cycle until something breaks.

Enter the damper. As I understand it, the damper soaks up the high frequency component of the power stroke and any high frequency harmonics in the crankshaft thereby reducing the peak torsional accellerations and resulting torsion loads on everything connected to the crank.

Dampers for dummies summary.
The damper makes your engine run smoother so it doesn't wear out as soon or suddenly break just when you're having fun.

Hope this helps.

Dan

[Dragon Humper]

Dan:Yea, that too, thanks for adding to my lame attempt at Dampers for Dummies .

Another way to think of it is, it's to a crank what a shock is to a spring in your suspension.

McFly: the large one eh? I just found one on FleaBay for $700 (race version) which comes with 10% underdrives for all acc. I think it was marketed by HKS(at Fuji Dynamics), I just saw the price tag and pooped myself so I can't remember.:shock:


Cheers........

Jon.

[mcfly]

the race damper comes with a water pump pully that is larger, which also happens to be the alt pully.

HKS's is made by ati usa

[GTR-Dad]

Another way to think of it is, it's to a crank what a shock is to a spring in your suspension.

Perfect analogy! Now drive over a series of humps on the road that are perfect for getting your car bouncing. Do that until suspension bottoms out and/or body work crashes on the pavement. That's how your crank feels without a damper!

Dan

[mcfly]

cant we just call it the resonating frequency

[GTR-Dad]

cant we just call it the resonating frequency

LOL! Go for it!

Did you hear the one about the young engineer fresh out of school who took his car in for a wheel balance? The tech asked him if he knew why they put weights on both the inner and outer sides of the wheel.

The guy puffs up a little and says "Yeah, because you can resolve any primary imbalance with discrete weights applied in planes that bound the plane of the imbalance." The tech looks at him and says, "Actually, if you don't it'll wobble."

Cheers,
Dan