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#1
Jamz14

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I have 4 different VVT mechanisms that fit to the intake cam. All four are different in a number of ways. Some of the differences are factory differences. Some differences appear to be modifications or deletes to the mechanisms. I was hoping that someone with experience with these mechanisms might be able to help guide me. I spoke with Mazda and they confirm a number of different revisions but were unable to provide any detail as to what the revisions were. Drawings have been impossible for me to find.

 

1. The first thing I noticed is some seem to have a plunger and spring and some do not. Some of the plungers are different sizes. All of the mechanisms I think have the form and structure to support the plunger and spring even though it isn't there.

 

   a) Did some come stock without this plunger and spring?

   B) If not and putting aside legality for the moment, it appears that the mechanism will work without this plunger. True?

   c) It looks like the purpose of the plunger is to lock the mechanism prior to the right RPM is reached and the mechanism is engaged. Correct?

  d) Possible advantages of not using the plunger and spring?

 

2. One of the mechanisms had no leaf springs or U shaped sealing bars.

 

   a) Again it appears that they mechanism is able to function without these as it came off of a functioning car. True?

   B) Possible advantages of these not being used?

   c) Were there versions that didn't come with these?

 

Thanks in advance for your comments and thoughts.


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#2
Jamz14

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Sorry for the stupid emoticons above. Evidently a parenthesis and the letter b means something other than intended.


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#3
Steve Scheifler

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I’ve gone through two distinct versions but both had all the key pieces. The obvious difference between the two was that one had the little hydraulic piston in the center “rotor” of the mechanism and a small removable orifice in the face of the cam gear hub. The other was just the opposite with the piston/plunger in the cam gear and the orifice in the rotor. The pistons were different, one a larger diameter and I think longer, maybe even with seals around it, or maybe just grooves. Been a few years. Ultimately I went with the one with the larger better looking piston, reasoning that it might have been a revision less likely to wear with age and drag or stick. I did not find that there was a difference in range of motion but again I worked on only two. Other than that I don’t have much to offer.
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#4
FTodaro

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Can you post a picture of what you are taking about for us less informed?


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#5
chris haldeman

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My understanding.........
2 variants from Mazda. Tested both back to back on dyno. No advantage

The pins are different between them but serve the same purpose. They lock the devise for install and fire up when oil pressure isn’t present.

I have seen plenty where there is damage around the pin locking area that came off good running cars.

Missing the pin in my opinion only would not affect performance. Also note you can tell a car with a bad lock pin because it will clatter at fire up.

Now for the missing springs below the “apex” seal type piece.... somebody took it apart and lost them with out even knowing. While the car will run it will be bleeding oil badly and I would expect a loss in performance.

Psa for anybody messing with more than 1 at a time DO NOT MIX PARTS. You will have massive issues
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#6
Jim Drago

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My understanding.........
2 variants from Mazda. Tested both back to back on dyno. No advantage

The pins are different between them but serve the same purpose. They lock the devise for install and fire up when oil pressure isn’t present.

I have seen plenty where there is damage around the pin locking area that came off good running cars.

Missing the pin in my opinion only would not affect performance. Also note you can tell a car with a bad lock pin because it will clatter at fire up.

Now for the missing springs below the “apex” seal type piece.... somebody took it apart and lost them with out even knowing. While the car will run it will be bleeding oil badly and I would expect a loss in performance.

Psa for anybody messing with more than 1 at a time DO NOT MIX PARTS. You will have massive issues

+1

Same exact experience. When I found the second version several years ago.. I thought I found something.. excited to test only to find nothing :( 


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#7
Jamz14

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Thank you for the feedback. It is appreciated.

 

A couple of of thoughts:

 

There are at least 3 variants. I know this because I am looking at them (at least before I sent one back to the owners car), and there are at least 3 version numbers at Mazda.

 

There are types of advantages that don't appear on a dyno. For instance, reliability modifications. If there is nothing different between these variants, why do they exist? Why would Mazda retool multiple times if there wasn't a difference?

 

One of the variants I saw also had the cam shaft nose pin hole modified and opened up. I believe this allowed more timing or the timing to be had before the expected RPM point for the timing adjustment. "Coincidentally" this is the one with no plunger and spring as well as no leaf seal springs and bars. Is it possible that someone that was savvy enough to modify the nose pin hole accidentally forgot the leafspring and bar seals? Is it possible that someone that didn't know what they are doing opened it up afterwards and forgot the springs and seals? Sure it is possible. But unlikely.

 

I don't know why not having those seals would "bleed oil". These seals are internal to the overall sealing of of the mechanism and they would not see pressure that I know of until the oil solenoid that feeds the VVT system is opened at RPM. Once it is seeing pressure, why would it matter that oil is "bleeding" from one cavity to the other? Once it fills all cavities where is is the oil going to bleed to? I can envision a possible delay in building pressure until all cavities are filled, but maybe that is why they were removed, if they were. To fill ALL cavities faster. But once they are filled, there should be no bleeding of pressure or oil that I can see.

 

I think that there might be a benefit of no plunger and spring in a couple of ways.

 

1. The plunger might stick every now and then causing you to not receive the benefit at times. It is easy to see how that might happen and might be a reason for Mazda changing the shape of the plunger to a stepped design.

 

2. Removing the plunger might cause a faster initiation of it kicking in.

 

Both of the above would not show on a dyno unless on item 1 it happened to stick during one of the pulls (possible but unlikely).

 

All of the above except what I have observed with my own eyes might be off. I am not an expert and why I am asking others. Not  trying to say I know things about these that others don't. I am trying to understand them.


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#8
Steve Scheifler

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Without going through all of that and trying to compare it with what I think I know, how do you envision modifications to that pin & hole allows more timing? The range is defined by the concentric “rotor” and housing and I don’t believe the pin restricted motion within that range.

As for the oil bleeding off, yes of course it’s all internal to the engine, nobody meant to imply otherwise, but if it’s going where it shouldn’t then it by definition is at least slower getting where it should, and I see no potential performance benefit to that. I’d wager that someone just inadvertently made a mess of it or very much mistakenly believed they had come up with a clever idea. That’s not to say there isn’t a way to modify them for some actual benefit, I posted about that a couple years back, but what you found doesn’t seem logical to me.
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#9
Jim Drago

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Without going through all of that and trying to compare it with what I think I know, how do you envision modifications to that pin & hole allows more timing? The range is defined by the concentric “rotor” and housing and I don’t believe the pin restricted motion within that range.

As for the oil bleeding off, yes of course it’s all internal to the engine, nobody meant to imply otherwise, but if it’s going where it shouldn’t then it by definition is at least slower getting where it should, and I see no potential performance benefit to that. I’d wager that someone just inadvertently made a mess of it or very much mistakenly believed they had come up with a clever idea. That’s not to say there isn’t a way to modify them for some actual benefit, I posted about that a couple years back, but what you found doesn’t seem logical to me.

 

Circa 2012-13, I built an adjustable VVT pulley to test, trying to figure if/why and how I was getting beat so badly in my VVT builds.  I found you could decrease peak Tq, decrease peak power.. But the best performance I found was when it worked as designed by Mazda. 


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#10
Steve Scheifler

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Circa 2012-13, I built an adjustable VVT pulley to test, trying to figure if/why and how I was getting beat so badly in my VVT builds. I found you could decrease peak Tq, decrease peak power.. But the best performance I found was when it worked as designed by Mazda.


And while troubleshooting mine I plugged in a stand-alone ECU so I could mess with VVT actuation on the dyno, and within the physical limits of the unmodified mechanism I found pretty much the same as you. That wasn’t a surprise given that VVT was added primarily to make the car feel torquier in grocery-getter mode without sacrificing its sporty nature at higher revs.
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#11
Jamz14

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Steve, Jim,

 

I'll start by saying that you are probably right. I don't think I have found something here. I don't know, that is why I discuss with others. My first reaction when I see things like this is to think that I am stupider than the person who did it and what am I missing. Not to think I am smarter and they screwed up. My way keeps me open to new ideas. The other way I will never see what they do.

 

Steve, the pin hole enlargement is no different then guys enlarging the cam gear nose pin slot opening, or mashing the cam nose pin in order to rotate it away from stock one way or another on the non VVT cars. Any movement of the cam gear in relation to the cam changes the mechanical timing. I know you know this. Whether it is retarding or advancing, it is indeed changing. Whether thats beneficial or not, doesn't change the fact that it is different.

 

As for the seals. I do not know whether it is beneficial or not. But again, better to think it is and ask why than to dismiss it and be blind. That said, I potentially disagree (again I don't know). There is no longer or shorter path. Oil has to get to all the areas around those seals. We are not talking about oil having to go where it shouldn't. Oil MAY be getting to where it needs to go faster without the seals. Would you see that on the dyno? Doubtful but certainly not if you weren't looking for it. Even then doubtful. To minuscule a difference to know that you were seeing a difference or not. Same is true with the potential faster engagement without the plunger and spring. You wouldn't see higher torque and power. But maybe the mechanism engages just fractionally faster without the resistance and time that it takes the plunger to retract against the spring and allow the mechanism to rotate. You would never see that on the dyno unless you were really looking for it in advance. The difference would be too small. None of this adds power or torque. But what it potentially does is speed up the time it takes to deliver the stock power and torque it was designed to provide. That is a minuscule advantage. But still an advantage.

 

All of that said, I can see the other side in that removing the seals can degrade performance. It needing the sealed up area in order for the oil pressure to push against. Like two stroke crank seals. Maybe. Just assuming that the person who did this knew what they were doing.

 

So Jim, how were you being beat by others VVT package? :)


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#12
Steve Scheifler

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I’m not following you on the pin. I haven’t had one apart, contemplating how it works for some years but I don’t believe that pin is comparable to the indexing dowel on a standard cam gear, so I don’t see how a sloppy fit accomplishes anything other than risking it jamming or not functioning at all. Perhaps I’m not clear on what you described or in my memory of the mechanism. In any case, I don’t assume I know anything let alone everything, but I still would bet against any benefit at all from the things you describe. If you come up with more than random speculation to prove otherwise I will certainly concede that I’m wrong.
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#13
Jamz14

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Steve, the goal isn't to get you to concede being wrong. The goal is to learn what is right. All of this is more than random speculation. At worst it is specific speculation. Tear one apart at least and look. At least I did that before coming up with this specific speculation stuff.

 

I have moved the removal of the plunger and spring past specific speculation into a theory. A theory being an idea that is supported by evidence. Last night I observed the wear marks on the mechanism caused by the plunger dragging across it as it engaged and disengages. This at the very least suggest that engagement of the mechanism will be faster without it. As well as suggesting the possibility of it sticking not fully engaged or disengaged. The wear marks had a stepped pattern. This also suggested the possibility of it not fully rotating and engaging all of the time. None of this will normally be seen on the dyno. Only if it stuck on one of the pulls would it be seen.

 

Jim, no comment on how they were beating you?


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#14
Steve Scheifler

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Steve, the goal isn't to get you to concede being wrong. The goal is to learn what is right. All of this is more than random speculation. At worst it is specific speculation. Tear one apart at least and look. At least I did that before coming up with this specific speculation stuff.
...


Point is, I DID take them apart and study them, and put them back together, and tested them. Or did you miss that part? You haven’t proven that the modified (or f’d up) mechanism actuates faster, and even if you manage that you haven’t offered anything to support your assertion that fractionally faster is in any way better. Faster is really just sooner to the opposite extreme, right? This isn’t nitrous injection, it’s cam timing and we HAVE tested different crossover points, and there is no reason to believe that simply making it adjust more quickly is beneficial. If anything, a more abrupt change in cam timing is likely to cause momentary issues with fuel and ignition timing because the slow-ass stock ECU isn’t equipped for such a sudden change. How’s THAT for a “theory”? :)

But all in fun and for the pure entertainment value of arguing with you. You have your theories and that’s fine, just don’t expect that even IF there’s something to it anyone will chime in to confirm.
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#15
chris haldeman

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The vvt pulley is a common tech item at scca super tour events. If anything was found James throw it away and replace with new part.
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#16
Jamz14

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Steve, you are proposing a hypothesis, not a theory. You are right, I haven't proven. That would be a law and not a theory. I did miss the part where you said it was years since you had. But it has been so long that you cant recall the nose pin hole so maybe there is something else being missed. I am going to assume by arguing you mean that in the most collegect way and we are discussing. I am not arguing with you. If the plunger is scraping along the mechanism enough to wear it in a stepped pattern, is it not possible that the plunger is sticking? If so, wouldn't you agree that one stuck open or closed is not good regardless of how fast? You do think that it working is a good thing for the vvt car yes?

So I will give you that the slow ass ecu doesnt respond fast. But that is true whether the mechanism opens quick or slow. So if the mechanism opens quick it takes the ecu X amount of time to react. If it opens slow it takes the same X amount of time to react. Fast plus x is still faster than slow plus X. Does that make sense? That is a legit question and not trying to split hairs with you.

But now we are getting to it. I dont expect much real input and discussion. That must be because people are very concerned that other people might do something illegal with the information and doesnt anyway suggest that they are doing something illegal right? Trust me, I know that anyone thinking that they are getting speed secrets here is a fool.

All of this is illegal. But just like Jim exploring illegal adjustable cams, I am exploring this to understand. I dont even know what I am looking for. Just exploring. Knowing this stuff isn't always about cheating. Many times it's about understanding. With that understanding I might be able to diagnose a car that isn't behaving properly in a legal configuration.

Chris, I get that. But it isn't good enough for me to say to myself, oh this is modified so throw away and get a new one. I want to know what is going on. Wouldn't you do the same thing? So far 3 smart people have commented and you all tested. Why? Why not just accept the unit as mazda gave you seeing how it cant be modified? You did because you wanted to know. For a variety of reasons. Anything wrong with me being as curious as you 3?
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#17
Jamz14

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Let's dump the subject. As you pointed out, I've got about all the useful information I'm going to get here.
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#18
Steve Scheifler

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Let's dump the subject. As you pointed out, I've got about all the useful information I'm going to get here.


Not so fast. To answer one of your questions, no, faster is not better. You over-simply things. You need to consider how an ECU works, primarily from lookup tables based on various conditions/signals. If those conditions, or something like the VVT, change at the expected rate then the ECU can accommodate those changes and supply the correct response with respect to fuel and ignition timing etc., keeping things “optimal” for those conditions throughout. But if conditions change too quickly and the ECU can’t keep up then there is a period of time when the combination is SUB-OPTIMAL which may be a minor and harmless stumble costing you time when you assume it should help, or at the other extreme may trigger the first bit of detonation in an already marginal “lean & mean” engine. And the thing about detonation is that once it starts it feeds off itself even if conditions return to what is otherwise safe. I’m not predicting that would be the result, but my point is that your assumptions about this hypothetical faster actuation, which I’ve already shown to be no benefit, are almost certainly erroneous because there is actual potential for a negative impact.
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#19
Jamz14

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You haven't "shown" that faster isn't better. You have speculated that it isn't and that the ecu cant keep up. What is the response time of the ecu and what is the difference in time with or without the plunger? Am I talking about lightening faster without it? No. You arent suggesting that the computer cant manage the speed of normal engagement, why is it unable to with slightly faster engagement? Do you know for a fact that the computer is on the ragged edge of handling the vvt and any faster and the engine will detonate?

And none of what you are saying addressed the potential to stick. I think sticking may be one of the reasons for a mazda redesign of the plunger shape. They changed the mechanism multiple times. They didnt do that for no reason. And I doubt the computer got faster to handle the redesigns. So there seems to be an implied truth with there being redesigns, that improvements can be done to it that wouldn't require a different computer. Why redesign something that is perfect as is, or redesign to a form that the computer cant handle? I'd believe you alot more if you could explain to me what was changed by mazda and why was it changed.

Now I do have a question of, if removing the plunger does help prevent sticking, or is potentially a bit faster in actuation, why didnt mazda remove it with one of the iterations? This question causes me to worry that removing might be bad. I dont believe I'm smarter than factory engineers. The only thing that causes me to move away from factory engineers is knowing they are designing for a different application than we are building the cars for. It is good for their application that the knock sensor can pull timing. It is bad for our application that the knock and temp sensor pull timing.
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#20
Steve Scheifler

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No time just now for a complete response but your first statement is incorrect. I believe that I HAVE sown that faster has no potential to be overall better. I don’t need to see that on the dyno directly. My contention is that dyno testing CAN and does show that moving the engagement point a few RPM earlier yields no such benefit. Your imagined “faster” would at best be equivalent to just that, slightly earlier engagement. Meanwhile as I’ve pointed out, at worst “faster” could be problematic. So I see no potential upside and at least a possibility of a downside.
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