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As if we needed one more reason... From Grassroots Motorsports, May 2003 Quote:
The Weighting Game by David Vizard
Weight is a Racer's Worst Enemy: Part 1 of This Series Examines How Less Weight Equals More Speed.
...Crankshaft Torsional Damper
...It is commonly accepted that having the lightest possible damper may not be good for crank life, although it will allow the engine to deliver its best power. The reality of the situation, though, is that in terms of power, the reverse is almost always true. This observation is based on many hours of dyno testing crank torsional vibrations versus power.
A modern, quality camshaft profile is based on highly complex mathematical formulae intended to produce a profile that will generate, as nearly as possible, a smooth, minimal-vibration lift curve at the valve. All these equations assume the cam is rotated at a constant speed.
Many years ago, cam expert Harvey Crane was questioned about the effect of torsional vibrations transmitted from the crank to cam on their calculations. His answer: "It will invalidate all our computations and profile fine-tuning."
The implications here are that the valvetrain would then have less control over the valve motion, absorbing more power to drive it and causing valve float and/or valve bounce earlier in the rpm range. All of these factors mean less power, not more.
This is exactly what my dyno testing showed. On an engine of nominally 400 horsepower, swapping out a 14-ounce aluminum hub/pulley for a 15-pound--but highly functional--damper increased output by more than 11 horsepower. In addition to less power, the lighter hub allowed the crank to torsionally flex as much as 250 percent more than with the damper.
...To sum up crank dampers, the rule here is simple: Forget the weight and just make sure you get one that does what it is supposed to do--damp. This will allow the car to go faster, longer....
Side note: Where should weight be shaved?
1)Pistons, rings, connecting rods, and internal hardware (not for the faint...)
2)Clutch and flywheel assembly
Function before fashion.
'96 Contour SE
"Toss the Contour into a corner, and it's as easy to catch as a softball thrown by a preschooler." -Edmunds, 1998
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Newbie
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Excellent Post! There's been a lot of discussion about this.
1998.5 Contour SVT
72K
Bone Stock
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Wow thats wondeful news man,great info.
98 3.0 svt: Sold
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CEG\'er
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Don't forget that today's engines have tighter bearing tolerances. The crank exerts pressure on main and con rod bearings but with little tolerance and too thin an oil film, bearings stress, displace oil and block oil passenges leading to failure.
Gear drives, chain driven cam shafts and uneven firing order all invite damaging engine vibration causing early valve train fatigue and loss of HP.
A lighter flywheel/damper in theory should only let an engine rev faster/freer. It should not affect HP, but will have a perceived HP increase at the track because the car will accelerate faster by reaching peak power quicker.
stock 1998 silver frost SVT E0 #1545 out of 6535
* K&N drop-in air filter
* DMD
* Koni's w/ stock springs
* Autolite double platinum
* Tranny cocktail
* Mobil 1 Snyth Oil @ 60K miles
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Originally posted by holycowSVTpaul:
A lighter flywheel/damper in theory should only let an engine rev faster/freer. It should not affect HP, but will have a perceived HP increase at the track because the car will accelerate faster by reaching peak power quicker.
Elsewhere in the article, the author addresses this very issue. Rotating mass does affect how much hp is delivered through the wheels. Not crank hp, of course. According to the author, all hp is generated at the top of the piston, and "it's all downhill from there." Reciprocating weight within the crankcase, rotating mass further on, as well as friction, all absorb energy, and thus hp. How much of your torque is used up accelerating the flywheel's mass? There is both a linear (in the direction of the car's travel) and rotational element to this.
Given a choice between shaving weight and adding crank hp, this author would choose the former.
Function before fashion.
'96 Contour SE
"Toss the Contour into a corner, and it's as easy to catch as a softball thrown by a preschooler." -Edmunds, 1998
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My opinion of the DMD is not only does it make the rev range much more refined it also seems to Accelerate better, I remember before I had it fitted it grunted and growled much more, it really does give a balanced feel, this isn't fitted to any mondeo's from stock that I am aware of, many of you guys know how good they are I don't know any other UK Mondeo who has one. I suppose its difficult to tell them how good they are.
Mondeo (UK Model) GhiaX 2.5 v6
DMD 2003 Version
GhiaX 2000 Spec
Semi Automatic Climate Control
Power Folding Mirrors, Japan Stylie
Ford OEM RSAP
Latest Sump Revision
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"Absolut Rara."
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"Absolut Rara."
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What I see in that article does make sense. . . The DMD does in fact "use up" more horsepower than the standard damper does, simply because it is a heavier mass hanging on the end of the crank. But, on the flip side, when you have a crank whipping and flexing because you aren't dampening things torsionally enough, that is affecting the power losses due to friction, often severely. As the DMD eats up more hp, it also allows the rest of the system to not bind up as much, freeing up wasted power. And according to that article, often times it is a net gain in power delivered to the flywheel. I'm not exactly certain how the #'s work out on a Duratec as far as greater power. but given what we know about Duratec crank whip, it wouldn't surprise me if similar gains were realized. All that said, I think it is advisable for most folks to go get one for the sake of longevity of the engine anyway, regardless of potential power benefits. Do I have one? No, I actually don't. Though, its been a moral battle for me to decide whether or not to get one. See, I swore to myself I wouldn't do any expensive engine work on the contour, unless the engine let go and I had to do it anyway . . . So, when its time for that new motor, lol, its definately getting a DMD.  Oh, and in response to where else you can take weight out in an engine; you take it out everywhere you can without sacrificing the strength the engine needs to run the way you plan it to. Pistons, rods, block, crank, heads, valvetrain, etc. etc. Its always a trade-off though, the more material you remove, the wekaer the part becomes. The lightest part in the world doesn't do squat if its so fragile the engine breaks as soon as you fire the thing up . . .
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Originally posted by Rara:
Do I have one? No, I actually don't. Though, its been a moral battle for me to decide whether or not to get one. See, I swore to myself I wouldn't do any expensive engine work on the contour, unless the engine let go and I had to do it anyway . . . So, when its time for that new motor, lol, its definately getting a DMD.
the DMD isnt an expensive engine mod. you can get one for under 50 bucks and if you put it on yourself. the labor is free, or if a friend does it for you, because you arent good with tools, it is a beer or maybe two. unless, you want your engine to give way so you can get something with a little more liters to it? 
Oo (xxx)oO
o xxxxxxxx o
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Wonder who's been saying all this for many months...
2000 SVT #674
13.47 @ 102 - All Motor!
It was not broke; Yet I fixed it anyway.
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I even did the dmd! you can do it!!!
~~~~~~Mike~~~~~~
Black 2006 VW Rabbit
Silver 2000 Contour SVT - SOLD
~~~~ The Car~~~~~
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