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Thoughts on dual pattern custom cam grind
https://slantsix.org/forum/viewtopic.php?t=21698		 Page 3 of 4
Author:  DusterIdiot [ Sun Feb 04, 2007 3:04 pm ]
Post subject:  I would like to see...
Quote:
Now: Can we please see some comparative data with standard vs. these special valves on an engine of broadly similar technology to the ones we run (any American OHV Six or V8 should be fine)?
I would like to see a setup (with recipe sheet:cam, build, compression, valve sizes, carb setup, part numbers, etc...) and some pics of the setup before and after....only because the same claim/arguement for these guys, occurred over 20 years ago when Rhoads came out with their "super Bleed" lifters that was to be the "end all" to having too big a cam for street use...I have yet to hear a chevy die hard in this town swear by them (most just swear about them...)

Don't mean to be skeptical, just need a bit of "proof" in the pudding... :wink:


-D.Idiot
Author:  argentina-slantsixer [ Sun Feb 04, 2007 8:28 pm ]
Post subject: 
I'm not skeptical about the powre valve. In fact, I was just thinking of variable valve timing and retrofiting in older engines with less complicated ways such as this

MIke: does the "sleeve" that rides inside the intake port and below the valve head has to touch the port walls? (i'm gessing: not!) this is the reason why I asked about big ported runners. Is this kind of magnetic or is just relying on pressure differentials ? (fine with me, I hathe EFI and I love carbs due to the fact that carbs works on pressure differentials, and no matter how much tech you can talk into me, I'm always gonna believe (because I have compared) that the same engine, with a good carburetion and a good EFI makes more power and torque with a good carburetion rather than a good efi setup. No discussion about the mileage... EFI is great at that.
Author:  mpgmike [ Mon Feb 05, 2007 7:26 am ]
Post subject: 
When the flapper is against the valve, it looks just like any other valve for the most part. The flapper is a ring that is about 9 mm wide. There are interlocking grooves in the head of the valve that help the flapper to seal. There are no springs or magnetisms involved. The flapper is free to go to the open or closed position. Nothing abnormal protrudes into the port.

Mike
Author:  SlantSixDan [ Mon Feb 05, 2007 7:45 am ]
Post subject: 
Quote:
The flapper is free to go to the open or closed position.
Next question: What kind of design and testing has gone into making sure that remains the case once the engine has some miles on it and normal valve crud builds up?
Author:  mpgmike [ Mon Feb 05, 2007 8:00 am ]
Post subject: 
I don't think there has been any long term testing on worn out engines dumping oil through the guides. There has been long term testing on normal engines in a good state of repair.

To share some of the developmental history with you, the first gen of these valves were installed in an engine about 7 years ago. After about 30k miles there was an evident problem. The heads were pulled and sure enough, the valves were failing. The inventor slightly re-engineered them and used a higher quality material in them. The current long-term test engine was pulled apart with 50k miles on the valves and everything was inspected. The Powre Valvz looked like they did when they were installed, even under a "microscope" so to speak.

As for how they work with crud built up, I would suspect not very well. If somebody were to go through the trouble of pulling the head, and go through the expense of purchasing/installing the Valvz, and do it in an engine with bad rings and guides, they might have problems. As I said, I don't think there has been any testing on bad engines long term.

The "normal" valve crud doesn't build up. Dust doesn't settle on a moving train. The constant opening and closing of the flapper keeps the internals of the valve clean. Like I said, after 50k miles they were still clean (where it counts) and working perfectly with no signs of wear and tear.

Mike
Author:  AnotherSix [ Mon Feb 05, 2007 10:47 am ]
Post subject: 
It does seem very likely that the flapper would end up sticking or wearing long before the normal service life of a normal valve and guide would be over. What lubricates them? After working with quite a few high output two strokes in the past I thought about using reed valves in the intake track along with the normal valves in the head on a four stroke. They would have to be close to the intake port and there are plenty of reed cages made that would flow more than enough. One of my big issues with that idea was how would putting all this in the intake tract would affect max flow. On a two stroke the cages dump right into the crankcase and are not shrouded, there are no other valves and the exhaust chamber is tuned to draw the mixture thru all the way into the chamber itself and them have a reversion wave to jam it back into the crankcase. You can easily compensate for the restriction. They would of course need to have the reeds replaced on some interval as well, which is a second issue. It would be pointless to enhance low the low end torque of a high rpm cam at the expense of mid to high rpm power, just put in a smaller cam and be done with it. If the variable valves limit flow like it appears to me that they probably do, you likely end up with less overall for a bunch of trouble. The 327 chevy torque figures are way too low in the mid range for even a low compression two barrel with a stock cam on a conservative dyno. Has anyone flow tested these in any kind of head? If they limit flow they could only help below peak torque and would cut output from there on up.
Author:  mpgmike [ Mon Feb 05, 2007 4:23 pm ]
Post subject: 
Quote:
It does seem very likely that the flapper would end up sticking or wearing long before the normal service life of a normal valve and guide would be over. What lubricates them?
I would assume you would be correct, but the most miles that have been put on this new technology is 50k, and they came out basically looking like they did when they went in. Speaking of lubrication, the gasoline lubricates electric fuel pumps and injectors. It might be interesting to see if there was any wear on a 50k mile E-85 engine, where there is very little gasoline. Would there be lack of lubrication wear issues with the alcohol? I don't know the answer.
Quote:
It would be pointless to enhance low the low end torque of a high rpm cam at the expense of mid to high rpm power, just put in a smaller cam and be done with it. If the variable valves limit flow like it appears to me that they probably do, you likely end up with less overall for a bunch of trouble.
When the flapper is closed, the valve flows exactly the same as the 1-piece it replaces. The only time the flapper would be open (closing off the flow through the intake seat) is when there is more pressure in the cylinder than the intake port. In those instances, you really don't want flow anyways; which is why the Powre Valvz are beneficial. I don't have the charts, but from conversations with the inventor, peak torque and HP are usually within 2 HP of what it was with the 1-piece valves.
Quote:
The 327 chevy torque figures are way too low in the mid range for even a low compression two barrel with a stock cam on a conservative dyno. Has anyone flow tested these in any kind of head? If they limit flow they could only help below peak torque and would cut output from there on up.
I agree with the 327 numbers. I wonder if the seats weren't cleaned up and maybe the exhaust valves and seats refaced while it was apart. It just so happens that this chart is the only one I have at my disposal for the time being. Flow numbers on a flow bench would be 100% unchanged with the Valvz. On a flow bench, the flapper would always be tight against the valve and the flow wouldn't be altered.

The peak of the power band doesn't change with the Powre Valvz. It is the area below peak that improves, but not at the expense of the peak. Again, peak torque remains unchanged. Peak flow remains unchanged. The changes are when the valve overlap is too much for the rpm/load of the engine, and then the only change is that you aren't pumping exhaust gasses back into the intake charge. Being so incredibly different, I can understand how it might be difficult to visualize exactly how they work. If I haven't done an adequate job of explaining it, please offer me another chance.

Mike
Author:  BigBlockBanjo [ Mon Feb 05, 2007 5:13 pm ]
Post subject: 
Whenever you could get some shots up, "A picture is worth a thousand words"! :) I'm trying to visualize this....it looks like the split second that the inner valve snaps open would cause alot of wear. Maybe not in low CR motors, but how would it react in a 11:1 motor? Also, does the "secondary" valve seal? on the seat? If so, it would change the installed height of the spring.
I guess the best thing would be to sit back and let you get some more legwork done! :D
Lots of homework, lots of potential.....
BBBanjo
Author:  mpgmike [ Mon Feb 05, 2007 6:22 pm ]
Post subject: 
Again, the only pic I have is at www.PowreHaus.com and /6.org won't allow me to upload pics. The valve is engineered so that the installed height is the same as stock. The only engineering that is left to be done is the individual applications. The functionality and durability is all engineered and proven, at least in the internal testing.

As anything new comes along, healthy skepticism opens the doors to thought. Thought opens the doors to new applications, and often times improvements. Also, as new products find their way into engines, the story begins to tell itself. No longer are claims limited to those involved with the product. Users share their experiences and even more knowledge is gained. I haven't been this excited about something since I got involved with the engine that would run on used engine oil, pickle juice, Mountain Dew, and liquified fermented pig waste. [The inventor of that engine turned out to be a crook, even though the technology works.]

Mike

ps, I still have one of these engines in my garage, and it will still run on practically anything you throw in the tank.
Author:  sandy in BC [ Mon Feb 05, 2007 7:32 pm ]
Post subject: 
Image
Author:  AnotherSix [ Mon Feb 05, 2007 8:05 pm ]
Post subject: 
It's not hard to visualize how it is supposed to work. The questions are really about whether or not it has it been tested and proven to work. Even a small backcut on a normal valve affects flow for the better. So seeing a 9mm thick disk under the head of a valve begs a trip to the flow bench. Will be, would be or should be could then be replaced with a solid answer. Were you saying you believe the 327 numbers are relevant? Not if it was running on all eight! Not even close! It would be great if this really works, but the proof should be easy to come up with if it does. Questions are reasonable, the burden of proof falls to the person making the claims. Here is one more thing to think about, in leu of real testing. Valves open and close very fast at high rpm. If the flapper, being free to flap and kind of heavy, is only moved by airflow it may not even get open before the valve slaps it shut again. A real test would prove or disprove this potential flaw in the design (theory?). The reed valves I referred to in two strokes are either fiberglass or graphite and weigh almost nothing, they have to or they would not work. How about a couple of real tests with some real data? The pig $!# story does not help the cause.
Author:  SlantSixDan [ Mon Feb 05, 2007 8:22 pm ]
Post subject: 
We are all just guessing and supposing without the one set of data that will satisfy all these questions: Pure comparison tests. Same engine with all the same components, tested on the same dyno, with and without the special valves. No different cam, no different compression, no different anything except the special valves. A second paired test could ideally be added, with a camshaft normally considered too large for street use. The idea here would be four conditions:

1) Stock-type cam, standard valves (known to run well, control condition)

2) Stock-type cam, special valves (test condition)

3) big cam, standard valves (known to run poorly at low speed, control condition)

4) big cam, special valves (test condition)

Without these data (and only these data) we are all just tossing around interesting ideas about a theory the validity of which can be argued both for and against. If things come together logistically, I may be willing to put up a test pony for such back-to-back-to-back-to-back testing, subject to conditions.

Since we are tossing theory around, let me add this to the pot: Intake charge dilution does bad things to volumetric efficiency, but it has since the early 1970s been used as a control strategy for NOx emissions. Charge dilution lowers peak combustion chamber temperature, which in turn reduces NOx formation. What is going to happen to NOx levels if we substantially eliminate charge dilution...?
Author:  panic [ Tue Feb 06, 2007 8:17 am ]
Post subject: 
The reed has continued to arouse curiosity for 4-stroke use for decades.
I'm a bit concerned about how much cranking pressure a reed can capture, since you will see 150 or more psi trying to escape, but hot 2-strokes (with similar pressures) only have primary compression coming back, perhaps 25 psi. The reed may simply give up.
Yes, there is some flow restriction but I don't think any serious work has been done to install a big reed cage right down above the bowl to get the highest vacuum without disturbing the seat area.
Whatever flow reduction vs. valve curtain area could be minimized with more reed area and carbon fiber (low inertia) petals, but since reed also allows very late IVC much longer intake duration with all the extra added to the closing side may more than make up for it.
I've also seen some comments for NOT have much intake area available right after TDC, since this preserves vacuum for later in the stroke, rather than use it to pull exhaust gas back in until the EV closes.
I think overlap will be a problem since the pressure differential here is fairly low except when the exhaust is tuned in to a specific RPM, which means the reed won't open until well after TDC so no scavenging or cross-flow except at tuned speeds.
Because of this, the best target may be an engine that has a "mild" (low to mid power) range with closed exhaust where high overlap is a problem anyway, since it would allow much higher vol. efficiency (filling) from the late IVC without the usual reversion and loss of compression.
Author:  AnotherSix [ Tue Feb 06, 2007 10:11 am ]
Post subject: 
Yes I dropped the reed idea over ten years ago for many reasons. The normal intake valve would still need to be the primary valve. Re-designing a head was (is) out of the question. A new intake was possible. Good reeds are not cheap and they would need to be replaced often, so this would not be for a street driver. And it would just be done to bump up the low end. The pressure limitation of the reeds would limit the cam timing, so there is a catch 22. About testing the valves in question. That is what needs to be done. Dan's outline is the only way to do this. Get a baseline, make one change, test again. I would add to the schedule a pre-qualification of the valve in a cylinder head on a flow bench, a stock and cleaned up port if possible. It may end there without the time and cost of a buildup. It should be easy to ship a valve to a willing party who can do this. If the numbers fall off above the midrange with the stock engine test I would drop it at that point as well. Of course durability is another matter and would be the final area to test and develop. For everyone who had input about dual profiles, thanks. It still appears to need more research and experimenting.
Author:  mpgmike [ Tue Feb 06, 2007 2:47 pm ]
Post subject: 
I was on the phone with the inventor yesterday for over 2 hours hashing different things out. I asked him if he had other dyno charts besides the 327 and he replied yes. He said he didn't like to flaunt them because the dyno he has access to starts at 2000 RPM and the Valvz work better the lower the engine speed. Thus, the differences on a stock engine at 2k and above weren't as good as they would be at lower speeds (as the claims suggest). I asked him for copies of them and will share them as soon as they are available.

As for NOx emissions, NOx is formed at temps above 2200 F for extended periods of time. It isn't just a temperature issue, it is a time issue. If removing the exhaust gasses from intake charge speeds up the burn, then in actuality the charge is fully consumed and out before NOx has much of a chance to form. Many newer engines with good fast burn cylinder heads etc don't even use an EGR valve; it isn't needed. Fast burns reduce EGTs as well.

I'll liken it unto a bow and arrow. Take a 100# arched bow and a 100# compound bow. From the edge of a field, shoot 3 arrows with each bow going strictly for distance. Three times out of 3 the compound bow will overshoot the arched bow and by a large margin. Why? Because the arched bow delivers its 100# of thrust over about a foot and a half of string travel, while the compound bow delivers that same thrust over a mere 4" or so of string travel. The energy is released quickly and has a much more effective push against the arrow.

For the engine, a fast burn releases the chemical energy in the fuel quickly and sling-shots the piston down the bore; whereas a slow burn is still releasing chemical energy as the exhaust valve opens. Reducing (or eliminating) exhaust gasses from the intake charge allows the flame to propogate faster, delivering a more powerful push against the piston with less timing advance.

Did I answer the NOx question? Did I get side tracked? Sorry.

Mike
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