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Joined: Feb 2003
Posts: 117
CEG\'er
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CEG\'er
Joined: Feb 2003
Posts: 117 |
Originally posted by DemonSVT:
Originally posted by 99fordsvt:
2-3HP for bolting on some ring of rubber and steel on the end of the crank???? Come on! It was done for NVH, not durability or power.
Don't bother with him.
Check out his other "posts" Particularly in the GB thread on UD pulleys. 
Fast forward to 2004 and Demon SVT's webpage..........
"DMD & Oiling Issue Information
The DMD was done for NVH reasons. It will not help crank whip nor is crank whip the main killer of engines."
Demon webpage 2004
Sometimes closure is a good thing. Demon - keep up the good fight, but just take it a bit easier on CEG newbies (which I was at the time)
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Joined: Sep 2000
Posts: 9,602
Hard-core CEG'er
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Hard-core CEG'er
Joined: Sep 2000
Posts: 9,602 |
Originally posted by 99fordsvt:
Fast forward to 2004 and Demon SVT's webpage..........
Actually that's been on my website for almost a year now and in my notes a lot longer. (matter of fact not much after this post IIRC)
This post you dug up was all based on "repeated" information told to us by someone that doesn't visit these boards anymore of his own choosing. There was some technical leg work done on the side but the majority of the information was looked at as fact and not conjected theory.
So yes I definitely agree that sometimes it's good not to take things as they come and do the research yourself since the DMD was designed for NVH purposes and doesn't factor really into anything else.
Yes "technically" being as it is a heavier & dual mode damper it will reduce a small amount more of both torsional bending & vibration respectively. However reducing crank whip was not it's intended purpose nor is the reduction of any significant amount comparatively.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Joined: Jun 2000
Posts: 1,469
Hard-core CEG\'er
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Hard-core CEG\'er
Joined: Jun 2000
Posts: 1,469 |
Demon,
How do you know the degree to which crank whip is affected?
From a NVH standpoint, there is a substantial improvement (especially in higher rev ranges)...I would "assume" that the vibration reduction is a related to crank whip reduction. I talked with Judge years ago, IIRC he thought bench testing showed a substantial reduction. The 2-3 HP DMD gain on the dyno "may" support less frictional loss..though this is admittedly withing the error range of the dyno.
Duratec is a VERY smooth motor with the DMD..I guess it is hard for me to understand how you would get this improvement without reducing whip to a significant degree..
1999 Amazon Green SVT Contour (#554/2760)
"People demand freedom of speech as a compensation for the freedom of thought which they seldom use."
-Soren Kierkegaard (as posted by Jato)
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Joined: Sep 2000
Posts: 9,602
Hard-core CEG'er
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Hard-core CEG'er
Joined: Sep 2000
Posts: 9,602 |
Torsional vibration (harmonics) dampening and reducing the whip (actual bending and reflexing) of the crank are two different things.
The extra weight is the only thing that would affect the whip problem by acting as a stronger counter balance. However in that case then the opposite can be said that a lighter flywheel would actually make the problem worse.
This is why I state the 3L crank and it's already heavier integral counterweights would be a better deterent.
I never weighed the 3L crank but was told the difference is fairly significant. Weight that is integral to the crankshaft itself plays an exponentially greater factor on whip, vibration, and harmonics.
From a layman's terms my 3L with the stock damper is smoother then my 2.5L with the DMD was. Even with just a 9lb flywheel out back.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Joined: Aug 2004
Posts: 618
Veteran CEG\'er
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Veteran CEG\'er
Joined: Aug 2004
Posts: 618 |
Originally posted by DemonSVT:
From a layman's terms my 3L with the stock damper is smoother then my 2.5L with the DMD was. Even with just a 9lb flywheel out back.
Question, did you have the 9 lb flywheel on both motors. It would make sense the heavier 3L crank was smoother without the DMD vs 2.5 with DMD and same flywheel on bot setup's.
Just curious.
E0 SVT
Kids, yeah, I have kids. How many do you want?
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Joined: Jun 2000
Posts: 1,469
Hard-core CEG\'er
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Hard-core CEG\'er
Joined: Jun 2000
Posts: 1,469 |
That helps..But it seems you are saying the DMD is not really a DMD? I thought the point of a more complex (expensive) part with an attached but distinct damper ring (as opposed to just making the part just bigger/heavier), with a different distance from crank midpoint was to specifically target bending vibration. This is what I understood from Judge as well as Terry..perhaps I misunderstood??
Have you somehow gotten your hands on harmonic/bending specs for these motors? You have a way of finding this stuff..
Thanks..
1999 Amazon Green SVT Contour (#554/2760)
"People demand freedom of speech as a compensation for the freedom of thought which they seldom use."
-Soren Kierkegaard (as posted by Jato)
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Joined: Sep 2000
Posts: 9,602
Hard-core CEG'er
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Hard-core CEG'er
Joined: Sep 2000
Posts: 9,602 |
Originally posted by Bike2112:
Question, did you have the 9 lb flywheel on both motors. It would make sense the heavier 3L crank was smoother without the DMD vs 2.5 with DMD and same flywheel on bot setup's.
The 2.5L had the stock flywheel (~21 lbs)
So one end of the crank dropped 12lbs & the other 2lbs.
That is a very significant drop in rotational mass. Especially the large diameter flywheel weight.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Joined: Sep 2000
Posts: 9,602
Hard-core CEG'er
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Hard-core CEG'er
Joined: Sep 2000
Posts: 9,602 |
Originally posted by Dan Nixon:
I thought the point of a more complex (expensive) part with an attached but distinct damper ring (as opposed to just making the part just bigger/heavier), with a different distance from crank midpoint was to specifically target bending vibration.
You are correct. That is exactly what it does.
It dampens vibrations in a second frequency mode. Mainly the second mass dampens rumbling noise level which at such low Hz (200-400) is more felt then truly heard. (think bass speakers) Hence why it's more NVH related.
No I have not been able to hunt done any specific specs other then information from two different people that state the mode was chosen for NVH reasons.
One of them works for Ford and the other I don't know. However he knows enough detailed technical information that if he doesn't he is a contractor for them in the engine field.
I agree that less torsional vibration is good for longevity. However that's not to say the stock damper is bad. That is something that is impossible to really quantify.
Does the stock damper allow for 200k miles and the DMD 220k miles???  
For that matter then does no damper mean only 100k miles???
We are talking real world driving with a full powertrain attached verses an engine on a test stand... Quantifying longevity would be very hard indeed.
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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Joined: Mar 2002
Posts: 1,325
Hard-core CEG\'er
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Hard-core CEG\'er
Joined: Mar 2002
Posts: 1,325 |
 That is all
97 Contour SE MTX
K&N 3530, UR UDP, 19# Injectors, mystery mod, FMS wires, Fordchip.com chip, SVT: TB, Flywheel, clutch, exhaust
04 Grand Caravan SXT
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