Billet Oil pump gears Vs Ati Damper
 

There was a question in a p.m. as to why I thought the ATI super damper wasn't necessary if you got the billet oil pump gears, so I put together what I thought about this.

Think of the crank shaft like soft rubber. When the crankshaft has a lot of load put on it it’s like pushing down on any of the rod bearings. Anytime this happens the crankshaft "smiles" It’s not a lot, maybe .0001 to .0003 inches. After the load goes away the crank snaps back to go to neutral and over shoots its mark this makes it smile in the other direction, and it keeps going until it is mostly calmed down. The big problem with this is that we have a bunch of these guys hitting the crank, and this creates a bunch of these movements up and down. Some of them cancel and some of them combine. The combining part is what we definitely don't want.

The whole reason this effects the oil pump gears is because of the tolerance they are cut to. I have a set of gears here with over 200k miles on them and they still get "stuck" if you don't rotate them exactly like the engine does. So when your crankshaft smiles it takes a little knock as it’s trying to rotate, and it’s designed to take them. The problem is when you add boost or more R.P.M. instead of your engine getting 100 light knocks maybe it gets 1000 heavy knocks.

Now in any part there are 2 types of defects present. These are static defects and dynamic defects. A dynamic defect means the defect in the part is growing. Static means they are sitting idle.The way you define which are which comes from the load. If you have a very heavy load this turns all the little cracks in the part to dynamic cracks. That’s our problem. So what we've done by increasing these knocks and the number is we've made some more cracks dynamic and then we give them more chances to grow. So the part will take this abuse until one of the cracks will make it deep enough that the part can no longer take the load and it disintegrates the whole oil pump gear.

So what does the ATI-super damper due to fix this problem? You could think of the super damper as muffler to all these vibrations. Everything is calmed down, and it does that by turning these vibrations we were talking about up there into heat. If you ever feel one you'll notice it runs warm.

Now the reason I was saying that that wasn't the real solution is because the damper can only effect what it feels and after the fact. So while the damper will make your oil pump gear last longer because after it feels the first smile of the crankshaft it begins to kill off the other resonances, your oil pump gear has already taken that first shot.

The thing is we already have a damper on our cars that takes care of the resonance getting too much out of hand. Where the real issue comes from are the engineers at Mazda being very good at what they do. They designed this part so that it was absolutely no more expensive than it had to be, and they done just that. The oil pump pretty much never fails if it is run in a stock engine.

The solution is to just improve the part and make it to where these new harder knocks no longer grow cracks so it doesn't matter how many knocks the gears take it is not going to make a difference.

Thanks for the explanation. Wasn't exactly what I was expecting to read, but it gives a good comparison of both items. I feel better about not wanting to run an Ati Damper now.

and theres no more of these gears avalaible right.......?

Yea, if you want I can put you on a list to do the next batch. I think I have 3 right now.

I somewhat disagree with the damper acting "after the fact".

the physics are more that it changes the resonant frequency and amplitude of the entire system. it's just like the dynamat bell at the car audio shop. the one without dynamat goes "ding" and rings for a while. the one with dynamat makes a dull "dink" and does not ring.

the damper actually reduces the instantaneous amplitude of the crank vibrations and prevents further excitation from resonance.

Instantaneous eh? Speed of a wave in a solid isn't as good as light, and it will traverse the length of the crank before even getting to the damper. I wouldn't say it necessarily changes the physics of the whole system. From a descritized model of the crank that compression of the crankshaft will be felt going through each cross section until it hits the damper. The damper itself absorbs some energy and reflects the rest of the energy back down the crank.

The length of the crankshaft and the wavelength and frequency of the wave or just wave velocity and starting location would determine where destructive crankshaft resonances are. It reminds me of tuning an intake trumpet for some weird reason... if the wave gets to the end and bounces back in time for a set of waves to construct then the crankshaft literally becomes a standing wave just like plucking a guitar string. From the wave equation…

http://upload.wikimedia.org/math/9/5...1ac2db18cf.png


And the solution for 2 waves (you can add more)... Well I couldn't find... it should be something like

2yo*sin(dk/2*t*x+dw/2*t)*sin(kbar*x+wbar*t) ... Looks about right...


Vg=dw/dk? Vp=wbar/kbar? When the group velocity would be zero or around it that’s when bad stuff happens. The absorber on the end should do absolutely nothing to change when Vg=0 occurs which would change the resonances and truly change the system. Instead what it will change is the average amplitude of the standing wave, which is a good thing.

My gripe about ATI damper is, how much better is it really? Did the engineers miss any frequencies when designing the stock damper that are now at a dangerous level under increased waves due to a high performance motor? It is unlikely, a damper like that responds very flatly, and even if they did miss one, the new billet oil pump gears are probably a magnitude of 10 less in flaws due to process. Are the waves in the engine really going to up by a factor of 10? Nah.

where is the first batch?

https://www.miataturbo.net/forum/showthread.php?t=24594

Should be getting to me soon to ship out.

First of all aftermarket dampers do not work any better than stock dampers, they are simply tuned for a different rpm range. Aftermarket dampers are usually tuned for higher rpms but have less coverage for lower rpms, its a trade off. Unless your motor is a "RACE" only, then a stock damper is more than enough.

Another factor is the crank material cast iron vs. forged steel plays even a bigger role, but thats a different subject.


Ben

thanks for taking the time to put that out there, great read.

So at what rpm point would you consider it necessary? It seems like it just comes down to being another piece of the puzzle. Not really necessary if you have the billet gears, but it will offer some added insurance regardless.

a higher output motor is going to have different forces on the crank than a stock output motor. that's why the oil pump gears fail, remember?

I got one cheap and plan to use it. the best defense is a good offense :)

The problem is no one really knows the answer to that question, besides the engineer who designed the new damper. Only he knows how it performs exactly, and unless they publish numbers of efficiency then you have no idea. You also have no idea how the stock damper performs. I would think its not much of a difference, because if they were much much more efficient it could be mass produced and it would be on the car as O.E.M. Something like this would improve fuel efficiency and decrease N.V.H. increase horsepower and yet my 03 Focus still has a piece of dynamat wrapped around the crank pulley as a damper.

I have a feeling like alot of aftermarket parts there is alot more fiction then truth as to the great efficiency increase in one of those dampers over stock, and how much it's really going to contribute to the life of your oil pump gears.

too bad the ati damper isn't purple, or i'd buy it. FM > *

You can usually get spec sheets on balancers. However no balancer in the world will cover all of the rpm range. If you have a motor thats going to be used on the street that means 80% of your operating rpm is between idle and 4000. While a race car once it hits the track may never see under 3000rpm. A race can can justify an aftermarket balancer, although I dont know why you would want one. All my life I have never seen a motor failure due to harmonics and assuming you had harmonic damage it would take thousands of miles to develope. I have never seen a race car motor with 100,000 miles on it.

So whats the answer. The answer is if your running a cast iron crank, run the stock balancer. Place a cast iron crank next to a forged steel. Stand them both up on end and tap the snout of each crank. The forged steel crank is going to sit there and ring for while. The same thing can be said when you work in a machine shop and your turning a brake rotor. If you dont place the rubber damper around a steel rotor it will start ringing as its turned. Different rpms will cause a different amounts of frequency. I have ran with and with out balancers. alot of blower motors for the V8 cars such as ford dont even use a harmonic balancer. Its interesting to note that the pulley belts used will also provide dampning.

Final answer = Its mostly over rated and I doubt you will notice any difference. The savings if any are going to be over time and in a street car the original balancer offers the most protection.

It's more that just crank and oil pump woes. I can't find the article right now but there was a test of a ~500hp V8(SBC I think) with and w/o the ~20lb HD.

The motor made something like 30bhp less w/o the HD. The problem was that due to the harmonics, the lifters weren't able to accurately follow the cam. They were bouncing, meaning that a valve could be slightly unseated when it was supposed to be closed.

Not sure if this would ever apply to us, probably something else would break before that point. I just found it interesting.

[QUOTE=dvcn;317218]It's more that just crank and oil pump woes. I can't find the article right now but there was a test of a ~500hp V8(SBC I think) with and w/o the ~20lb HD.QUOTE]


Im not trying to say the balancer didnt help, Im simply stating that you can fix the effects of something without addressing the cause. 30hp gain tells me the guy has something else wrong with the motor. A motor balanced wrong could cause this then adding into the equation a forged steel crank and a gear drive instead of a timing chain would just add more fuel to fire. As far as balancing there are no standards, some guys balance with in .01 gram, some 1/2 gram, some say with in 4 grams is ok. Many motors get balanced wrong too. Incorrect bob weight calculations, many factors are involved. Either way the virbrations are still being produced, its just the balancer is aborbing them, which is still a loss in energy. With all things being equal who is to say if they fixed the root problem they could not have a 60h.p. increase.

4K rpm what kinda miata do u drive take it to 7k and then do it agian. Street miatas go to 7k all the time and race miatas top 8 god my grandma drives harder than that.

Unless your grandma idles her miata at 4000rpms at every stop light her AVERAGE rpms is still much lower. No one said she couldnt hit 7,8K...

Maybe you forgot how your grandma is going to reach 7K rpms. You have to pass other rpms to make it to 7K. although grandma may touch 7,000K everytime, she is still passing 4k,5k,6k, twice. Once up and once down, making your average rpm lower. You NEVER NEVER choose a balancer based on the max RPM you turn, you base it on the average rpm your car sees. What sence would it make to buy a balancer that offers the best protection at 7K, when you only hit it once and for only .2 seconds.

[QUOTE=Brainsboy;317246]

Aren't the dangerous harmonics that the damper is trying to get rid of from the actual firing of the cylinders, and not the inherent imbalances of a piston engine? A crank is just a big torsional spring, and when a cylinder fires and shoves down on the crank, the crank flexes. This is just like plucking a guitar string, that vibration travels down the crank, bounces off the damper, and goes back down the crank. If the timing of that vibration coming back down the crank happens to be in phase with another cylinder firing, it will add to the size of that wave, and you get constructive interference that can add up and up and destroy things.

What the damper does is change the timing of that wave reflecting back down the crank, and absorbs some of the wave energy so the wave reflected back down the crank has less power than the one that arrived.

Even a perfectly balanced motor will still have these crank flex harmonics, and will still need/benefit from a harmonic damper.