DMD adds HP? GRM says Yes. Discuss.

Excellent Post! There's been a lot of discussion about this.

Wow thats wondeful news man,great info.

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.

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.

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.

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 . . .

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?

Wonder who's been saying all this for many months...

I even did the dmd! you can do it!!!

There actually was an SVT pre/post dyno with DMD and no other changes awhile back. Showed a gain of 2-3 HP with DMD..

With the price down to $50 (nuts..I paid $90), it may actually be a decent bang for buck (yes sadly $25/HP is not bad for an SVT) mode though it would be nice to see another confirmatory dyno. But for engine saftey its still a must do even if $25/HP is too rich for your blood..

Originally posted by mikey boy:

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?

You misunderstand, I have no problems installing one, or anyhting else for that matter. And the cost is very difficult to pass up (I may buy one now anyway) But, I did promise myself I wouldn't do any serious work to the driveline unless something broke first. I just don't want to have to wait longer than necessary to have an excuse to drop something else in there.

Besides, the XR4Ti is taking most of my "mod time" lately anyway. I've been gathering parts and whatnot for it for the past several months, and I'm only still missing a couple key items before I start tearing into it.

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.

Hey, its not what I said, its what the DYNO said..
2-3 HP is within range of dyno variability, thats why I said I would like to see conformation.

But is feasable...did you read the GRMS post above? I mean, how much power IS lost to a crank writhing in its bearings..

Whatever reason it was done for...NVH, durability, power....all 3 could potentially benefit.

You guys need to read the whole post before replying.

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.

Originally posted by DemonSVT:
Wonder who's been saying all this for many months...

Just adding further substantiation.

Once you DMD, you never go back....

where in the world do you get a DMD for 50 bucks!?

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.

DemonSVT: If my biggest fault is trying to inject some reality into these overhyped performance "mods", is that such a bad thing?

To save everyone time searching for my other "posts" on Underdrive pulleys, all I was pointing out there was that underdriving an alternator will not increase horspower. The demand is independent of alternator RPM. In other words, I'd rather have a fully charged battery and a fast spinning alternator than a slow spinng alternator and a dead battery any day. The voltage regulator only "asks" the alternator to put out what it needs. It doesn't care how fast it is spinning.

Demon SVT: Go ahead, bolt on your DMD and your Underdrive alternator pulley and head to the dyno. Do 3-4 repeats in A-B-B-A format and then report out the results. Before you tell me to, let's see your credentials. If they don't top a Master Degree in Engineering working in the Automotive R&D world including several ASME papers on high speed engine friction, then don't bother. And I'm not trying to brag - just defending myself by undeserved criticism from you.

Did I say a DMD was bad? NO. In fact I may get one for my 99 'Tour for NVH reasons. But let's be real, it is for smoother crank harmonics, not for power.

Back to the fun - sorry if I hurt the tone.

So that means another 11 hp to wheels! Excellent!!!

I don't have the article - were they only seeing increased hp numbers from extending the revable limits before valve float? If so, this is completely different from gaining hp from reduced friction and doesn't mean anything to Joe contour who isn't revving to valvetrain limits anyway.

Also, did the article talk about ignition timing scatter at all? I would think that at high rpm's you could possibly get better power from reduced scatter of the crank signal - but I have no clue how much that would buy you - if anything at all.

On the UDP thing - I would guess that an underdrive alternator pulley would have very marginal benefits as the load of the alternator is pretty much dependant on electrical draw - it may be spinning full speed but there will be very little resistance (ie free wheeling) when there is no electrical load. Now if you underdrive the fluid pumps (PS or even w/p) I would guess there'd be measurable gains from lower pumping speeds.

The DMD (nor UP Alt pulley for that matter) was never done as a performance mod. Both are reliability mods.

Also the fact you stated "the car runs off the battery & the alternator will NOT draw a load if the battery is fully charged" leads little credence to your technical ability.

The car's electrical system runs off the alternator and the alternator supplies current load as the car's electrical components demand it.

"The battery has 2 functions: It's main function is to start the engine & it's secondary function is as backup reserve for when demand levels exceed alternator output."

Quote:

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.

Where's your proof that the 2-3HP did NOT happen? (even though it did per the dyno & yes that's within it's margin of error, but that was already mentioned!)
Where's your undisputable proof that a DMD will not increase engine reliability?

Just going off the proven physic's facts alone showing it reducing destructive second mode vibrations should be proof enough that it's helping in the longevity department. Especially on an engine with a known problem in this area!

Again nobody said to install a DMD to make massive power gains. It is just an added benefit that the significant decrease in torsional bending and crank whip can equate to less parasitic drag placed on the rotating assembly and therefore make more power in the process.

Either way, I ordered one from Bill Jenkins earlier today, total, it's bout $58 or so, includes shipping, etc.

Is it recommended that I buy any other new parts along with the DMD, or can it go in by itself and be fine?

It would probably be a good time to change your serpentine belt. I got a Gatorback for $17 at Murray's.

Don't forget a new bolt.

Might as well change the seal as well, while you got the pulley off.

DemonSVT: You are missing the point. Whether the electrical load is coming straight from the alternator, or more indirectly from the battery/alternator system is irrelevant. You are splitting hairs. The load is the load.

The electrical load demanded at the alternator is what I mentioned. Going to a smaller pulley will not reduce the demanded load.

No - I can't prove that some test somewhere did not show a 2-3HP improvement. But I also can't prove that it lowered the price of tea in China at the same time. I know many of the Duratec development engineers and I know why the DMD was used - for NVH only. NOTHING repeat NOTHING to do with durability or power gains.

The physics are bolting a mass of rubber and steel on a crank and expecting even a tiny power gain do not add up.

Crank twist due to harmonics are measured in the few micron range. This will not effect the lubrication regime of the plain babbit shells, that have operating clearances in the 20-45 micron range.

You will get a lot of resistance to this from most people here. I used to argue that I beleived the same thing, but since I really don't have any data to support my beliefs I gave up talking about.

I know "procyon" is pretty knowledgable and he's stated he thinks DMD is probably only NVH as well - but like I said be prepared for a lot of resistance to the idea.

Here is what I found on Mazda USA's site

Quote:

...and crank pulley with dual-mode damper reduces crankshaft vibration.
Dual Mode Damper, which effectively eliminates crank shaft resonance (new)

Can I ask WTF is NVH?

Noise Vibration and Harshness

Originally posted by 96BlackSE:
Noise Vibration and Harshness

Thanks.

Well, its DMD time for me, given 1 DMDs now cost as much as a premium oil change, 2 my s-belt is throwing chunks, and 3 there is a debate on +/- HP (at least it wont hurt much). I now have an order fron Bill for a DMD and a Ford S-Belt, however after researching this gatorback, I think I will be keeping the ford as a spare.

Any opinions on replacing the seal, washer, etc while I am doing this?

Thanks

Originally posted by 99fordsvt:
DemonSVT: You are missing the point. Whether the electrical load is coming straight from the alternator, or more indirectly from the battery/alternator system is irrelevant. You are splitting hairs. The load is the load.

The electrical load demanded at the alternator is what I mentioned. Going to a smaller pulley will not reduce the demanded load.

Um, a smaller pulley would spin the alternator MORE!

This is a larger pulley.

A larger pulley also has the benefit of exerting more torque for the same effort, so that would provide some benefit. Not much, but some.

I'm not sure what the alternator has in the way of bearings on the shaft, but spinning less would seem to save those as well.

All in all, it's not a big gain by any stretch of the imagination. I would mainly consider it a longevity mod.

Personally, I only went for the P/S UDP.

-Lance

Yes, larger pulley = smaller ratio - sorry about that.

Originally posted by Lance Kinley:
I'm not sure what the alternator has in the way of bearings on the shaft, but spinning less would seem to save those as well.

All in all, it's not a big gain by any stretch of the imagination. I would mainly consider it a longevity mod.

That was my whole point that he has repeated missed.

You effectively slow the alternator down which adds to longevity. Especially considering the engine's main powerband is 5000-7000rpm.

The exact same thing goes for a DMD. It reduces destructive harmonics, torsional bending, and crank whip which all get worse with rpm. Also which are an area this engine is known to have a problem in. (I.E. so many damaged rod bearings with perfect mains)
Then take into account the 5000-7000rpm main powerband and the time one would spend in it to drive this car like it meant to be driven and again it's a good idea for longevity.
It was only a "theory" you might gain power due to less bending & whip. Then a couple dynos said it may be true and this article did as well. This was never a mod that was done for the power increase.

99FordSVT, here is the dyno thread (it is the second set of dynos..kinda need the look at the last 2/3 of the thread). gain was 3 HP, only change was DMD as verified at the end by another CEGer.

http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=dynodrag&Number=37746&page=&view=&sb=5&o=&fpart=all&vc=1

So what do we have:
1) does DMD reduce NVH..yes. More BMW like.
2) does DMD reduce crank bending/whip. Well, per Terry Haines (Duratec developer) and Judge (OEM damper designer), yes.
3) is crank whip a problem.?? Controversial, the above 2 experts say yes. Horse, Procyon, you, say no.
4) Has a car with DMD had bearing failure yet at CEG or NECO..Not yet to my knowlege (and I am watching). Anybody know of one?? But with more time..we will see
5) Does DMD add power...only data is dyno above. Insufficent evidence to conclude. The articles from GRMS, and Dinan (BMW fame) web page do discuss power/risk issues of removing stock damper for UDP. It DOES seem likely that it does NOT decrease power...

Each can use this info as they will..

Amen Dan.

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)

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.

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..

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.

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.

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..

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.

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.

That is all