Secondary Butterflies

[just gone]

I just know I'm going to regret this. 

So we have basically (I'm probably over simplifying) 3 camps here? I won't attempt to place all the various personalities in the camps. I think, if I'm close to being correct, that they will self populate.

Camp one: The engine is a simple air pump, ANYTHING restrictive in anyway in the intake tract has a negative impact on airflow at all rpms and thus hurts performance at all rpms. Even if camp one were to agree with the some of the theories of camp two in regards to reversion entrapment, it feels that the positives (trapping reversion if any) does not out weigh the negative of having restrictions in the intake in the first place. Camp one thinks that mostly the poor souls in camp two are being bamboozled by tall tale theories propagated by those with financial interests in leaving intake tract restrictions in place.

Camp two: At certain lower rpm ranges and air velocities, a restriction can help trap any reversion in the airflow that might be caused by (I'm way out of my depth here) VVT allowing the intake valve being partially open during the piston up stroke and/or some wave theory type stuff that a reverse wave occurs in the intake tract when the moving air (because of it's inertia) hits the closed intake valve. Thus, because of the restriction (secondary flies) the reversion is at least partially trapped and slightly pressurizes the intact tract so that when the intake valve next opens more air fuel mix will enter the combustion chamber than would have done had the restriction not been in place. This camp two position is only valid at the lower rpms and agrees with what camp one is saying only at higher rpms.

Camp three: HUH?          (to start off the self population of camps, I'm in this one, in case it wasn't already obvious.)

Sometimes, those in camp one and camp two feel so strongly about their positions that they appear to not like one another and they say things that might get the thread locked for a bit. When in fact they actually do like one another much much more  than they like all those popcorn chompin', fence sittin', dummies in camp three. 

[B.D.F.]

Well perhaps I can deflect a few arrows headed your way Marty.... :-)

Probably not a bad summation you have there. Of course life is never that simple but for the big picture, all induction and exhaust systems could be tuned for a particular velocity. In reality it is not practical for street vehicles and besides, even if a system were static tuned (meaning a fixed reaction at a given RPM and throttle opening), it could not apply to different bikes at different temperatures, altitudes, humidity levels, etc., etc.

In our very specific example, it is my opinion that the secondary 'flies do not and will not 'tune' the system anyway; while they certainly do restrict the intake area they also add things like von Karman vortices which are impossible to 'tune' as they are a system disturbance and do nothing to enhance flow in any way but in fact greatly disturb flow. The simple version of what those are are the vortices that make a flag flap or a piece of paper flap in a wind. The method of tuning would be to change the length of the intake tract (best way) or possibly a slide- type venturi area changing mechanism (dubious at best) but certainly not a plate in the fluid flow turning to act as a valve- that just makes a mess of the fluid flow as well as presenting a restriction.

Another thing to remember is that in the days of carburation, there had to be a pressure drop in the carburator to draw fuel into the air stream. So getting a lot of flow and still having a pressure drop at the venturi (the narrow throat of the carburator) was important. Fuel Injection eliminates this need as the injectors will place the correct amount of fuel into the cylinder without any need for a venturi.

I would encourage anyone interested in the matter to do a bit of research rather than believing anyone on any forum- take a few minutes and look at fluid flow and I think the answer will make itself clear.

Brian

I just know I'm going to regret this. 

So we have basically (I'm probably over simplifying) 3 camps here? I won't attempt to place all the various personalities in the camps. I think, if I'm close to being correct, that they will self populate.

Camp one: The engine is a simple air pump, ANYTHING restrictive in anyway in the intake tract has a negative impact on airflow at all rpms and thus hurts performance at all rpms. Even if camp one were to agree with the some of the theories of camp two in regards to reversion entrapment, it feels that the positives (trapping reversion if any) does not out weigh the negative of having restrictions in the intake in the first place. Camp one thinks that mostly the poor souls in camp two are being bamboozled by tall tale theories propagated by those with financial interests in leaving intake tract restrictions in place.

Camp two: At certain lower rpm ranges and air velocities, a restriction can help trap any reversion in the airflow that might be caused by (I'm way out of my depth here) VVT allowing the intake valve being partially open during the piston up stroke and/or some wave theory type stuff that a reverse wave occurs in the intake tract when the moving air (because of it's inertia) hits the closed intake valve. Thus, because of the restriction (secondary flies) the reversion is at least partially trapped and slightly pressurizes the intact tract so that when the intake valve next opens more air fuel mix will enter the combustion chamber than would have done had the restriction not been in place. This camp two position is only valid at the lower rpms and agrees with what camp one is saying only at higher rpms.

Camp three: HUH?          (to start off the self population of camps, I'm in this one, in case it wasn't already obvious.)

Sometimes, those in camp one and camp two feel so strongly about their positions that they appear to not like one another and they say things that might get the thread locked for a bit. When in fact they actually do like one another much much more  than they like all those popcorn chompin', fence sittin', dummies in camp three. 

[MAN OF BLUES]

i'm in camp 7


 

[just gone]

...it is my opinion that the secondary 'flies do not and will not 'tune' the system anyway; while they certainly do restrict the intake area...

OK then, camp one.

i'm in camp 7
 

Of course you are.

[Steve in Sunny Fla]

well.obviously I'm in camp two, but lets keep in mind the cam LC' play into my point.

  I'll also point this out - if you have or had a c-10, and have used my 2 minute mod jet kit, you have experienced what controlling reversion through intake restriction can do for the low end power and peak power (more everywhere, dyno proven).  I've also experimented with different head flow capacities on my c-10, going from stock, to a high velocity ported head (filled with epoxy for smaller ports) and now I have a more conventionally ported head head on shoodaben.  I have run several different cams in shoodaben.  To my knowledge I'm the only person who has dialed in and changed the cam timing in a c-14. I do the work - not just the talk, and sometimes things turn out different than what we would expect, but you won't know that until you actually try it and stick it on the dyno.

  Let me add something to simplify this... as I've previously stated, my point is that a properly done fly map would be like having fly by wire. the computer would limit opening when the engine doesn't have the capability to injest a WOT gulp even though that's what the operator called for.  Steve

[gPink]

Steve, I have also heard of exhaust reversion and having anti reversion cones in exhaust manifolds/headers. How is it determined that a reversion condition exists since it is internal and cannot be seen?

[Steve in Sunny Fla]

well, in extreme conditions, it can be seen. Think of a old style dragster with velocity stacks. You could see the fuel puffing back out of the stacks on reversion pulse. virtually all engines do this to some degree. The shorter the overlap, the less reversion there will be, which is why the vvt retards the intake cam, to lessen the intake to exposure to pressure. By trying different tuning, an experienced tuner can descipher what power losses are being caused by reversion, the effects of multiple carburetion ( the phenomenon of the same column of air going back and forth in the intake track) etc.  Long tube headers are also a way of suppressing reversion at low rpm, as it takes so long for the pulse to go back up the header pipe it's missed it's chance to create a great deal of passive egr action.

  With VVT, the late opening of the intake at low revs suppresses reversion at overlap, but can also expose the late closing point in which cylinder pressure is rising with the piston and gets pushes back out the intake track.  This is a delicate tuning balance to achieve, properly timed intake opening and closing points.  the same cam can be biased to top end or bottom end power, depending on the lobe center. This is where vvt comes in and speads the power across a much wider rpm range than a fixed position cam does. If fo no other reason the VVT and the base cam duration is the the single most reason comparing what works on a zx14 and what works on a c-14 is an apples to oranges argument.  Steve

[Deziner]

I think what many fail to take in to account when thinking about how an internal combustion engine functions is, the valves don't operate like an electric switch. They are not instantaneously open or closed. Some of the variables include timing, duration, overlap (when both valves are open), and lift. All of these variables have affects on the other parts of the package.

The engine needs to be viewed as a "package" or "system". Changing one aspect can, and often does, have a dramatic affect on other aspects. Especially the cam system. Virtually everything is affected by the cams. They are a very deep well to delve into.  It's like the difference between going to the gym (fuel mapping) and actually changing the DNA (cam changes).

I wrote this to try to clarify this stuff for those who are unfamiliar with this stuff, not to correct anyone. Until I have a firm grasp on something, I need big picture view. That's just me. Throw in to the mix the fact that nature doesn't always work the way we think it should, real world experience speaks the truth.

[Gigantor]

Fred Harmon Youtube video about Guhl reflash effect of secondary flies

https://www.youtube.com/watch?v=z5GBtbFJOJY

[maxtog]

Fred Harmon Youtube video about Guhl reflash effect of secondary flies

https://www.youtube.com/watch?v=z5GBtbFJOJY

I'm not sure I understand what the video is supposed to be relaying

[B.D.F.]

https://www.youtube.com/watch?v=abLB7aTmnE4

And remember, they are far better than these more expensive knives:http://www.williams-sonoma.com/shop/cutlery/zwilling-henckels-knives/

'The new 'Ginsu 'flie tune' cures anti reversion fields at all sub- light speeds.' There is the sound bite for the sales pitch.

 

Brian

I'm not sure I understand what the video is supposed to be relaying

[Rembrant]

I'm not sure I understand what the video is supposed to be relaying

That little screen Fred has set up is the Dynojet/PC LCD-200. It has some generic analog gauges that you can add your own inputs to. In this case, Fred tapped into the output wires from the secondary fly position sensor. (It is just another sensor the same as the TPS, but on the end of the secondary fly pivot shaft). So, he scaled the voltage of the analog gauge so that it would show the movement of the secondary flies.

He did some runs in ECO mode to show the stock secondary fly action, and then he did runs (like this one I believe) to show the secondary fly action in the Guhl Reflash.

I have no idea how accurate it is...I don't always agree with Fred's tests...but you get the gist of it. I'm not sure if the gauge was scaled for 90 degrees of travel or not...but it probably should be to match the fly movement properly. He also did tests of the traction control system with and without the secondary flies, but they were pretty crude tests imho....not that it matters much, once the rumor was started...

I think if you peruse his Youtube vids, you'll see that they all kind of follow one another, etc. They'll make more sense that way.

I have to give the guy credit for all the stuff he does and the time he puts into it, even if I often don't agree with him.

Rem

[Gigantor]

Anybody ever heard of Woolrich tuners? They have maps for the Connie

http://www.woolichracing.com/products/kawasaki/1400-gtr-zg-1400-concours-14/kawasaki-1400-gtr-zg-1400-concours-14-ecu-flashing.aspx

[Rembrant]

Anybody ever heard of Woolrich tuners? They have maps for the Connie

Yup, sure have. I had the Woolich bench flashing ECU kit and later the Log Box Pro kit for the C14.
They don't have any maps...their kits are the tools/equipment/software to create the maps.