KP Racing Metering block - Dyno Results

[NiekL]

Great topic. I'm going to use the STIC on my PWK38 AS, i got this carburator mounted on my modified YZ125. Here in the Netherlands we have deep sand tracks wich put some stress on the engine, so i'm curious how the bike will do with the STIC.

 

As the season is over here, this winter i try to find as much information as needed to start 'safe' using the STIC. Keep it up guys!

[harrperf]

Im not confirming the STIC DOES atomize/vaporize better..

What I will comment on is:

Ive encountered interesting things on the dyno that sugggest it IS doing so.

The problem with just about every consumer on the market is their understanding on what produces most of the power on a two stroke.

Secondly, every two stroke owner when push comes to shove wants more low end, some willingly will sacrifice top to get it, most have an ego that wont sacrifice top.

A pipe change is the single most effective way to move power. A pipe spacer is a very simple way to accomplish relatively small but noticeable movements in power.

To illustrate this, everyone talks about porting as the answer, but how is it that a cr or ktm 125 has nearly the same ex timing as the cr or ktm 250 and yet they have far different rpm peaks?

If you do a little digging, it turns out most 85cc have similar port timings to most 250cc.

How is it possible they rev so high and The 250 so low?

The glaringly easy observation between the 85, 125, and 250 is the pipe dimensions. 85 revs most, 125 less, 250 even less, and what do you know... the 85 has shortest pipe, 125 middle although very similar to 85 and similar peak rpm, 250 longest.

There is more to this than just the pipe or just the ports...but you can not raise the exhaust port on ANY of these motors and experience a huge rpm shift. you will just loose torque, often gain no hp, and sign off nearly dead same rpm.

Pipe temperature (avg gas temp inside across the whole pipe) determines just how fast the waves move. colder is slower/low rpm best hotter is faster higher rpm)

What Ive found is the STIC is influencing the pipe largely enough that people are seeing large gains in over rev. But if you add a spacer to the ex... it shifts your gains down the power curve and you will give up those over rev gains but pick up front side and peak gains.

AKA anyone out there who expects a magic carb part to transform their power to just what they always wanted is kidding themselves. But using what it gives you to make use of its gains where you want to place them... is possible.

Its been my experience however that people asking for more low end... arent really asking for more low end. This is why many lectron and smart carb users are tickled pink. On the dyno neither product delivers more low than a stk carb.

If you like the throttle response and crisp feeling of a lectron vs OEM you would like the STIC very much. Dyno charts pigeon hole the actual riding changes too narrow. over 50 percent of even a supercross pros riding time is spent under 50 percent throttle... and this is where most people actually comment on performance...

Aka a mikuni at WOT performs better than a stock PWK. yet there is no shortage of people who spend time and money to swap and swear the pwk is better...

[FGR01]

If you like the throttle response and crisp feeling of a lectron vs OEM you would like the STIC very much. Dyno charts pigeon hole the actual riding changes too narrow. over 50 percent of even a supercross pros riding time is spent under 50 percent throttle... and this is where most people actually comment on performance...

Aka a mikuni at WOT performs better than a stock PWK. yet there is no shortage of people who spend time and money to swap and swear the pwk is better...

 

 

Especially on a 250.  Most riders spend the majority of their time rolling around 1/8 to 1/2 throttle.  Even some fast guys as they carry momentum better and don't need to ride with a heavy right hand.  This is why I always tell people not to rely on WOT plug chops so much for jetting and to concentrate more on getting their needle and pilot right since that is where they spend most of their time.  But trying to get people to accept and admit this is usually a losing proposition, as you said, due to ego.  Their response, "you might be slow but I am frickin wide open Bro!!"   OK......

[c-slak]

That they don't auto compensate, I can believe it, no worry. ?

But about the rest that you wrote, how do you explain it? What physics principle is behind it? Better vaporization, or something else?

 

James from JD Jetting did a comparison of a Keihin PWM, SmartCarb, and Lectron all tuned for max torque of his dyno.  He ran A/F ratios off them and saw that both the SmartCarb and the Lectron both ran at peak torque at a far leaner setting than the Keihin.  He has his theories and I will defer to his knowledge as I feel he is more of an expert in this regard than me. 

 

I will update this post with the link to the results he posted on KTMTalk if I find them.

[SticSuperTorque]

Subject: altitude compensation:

 

 

In Re: STIC vs prior art and the aftermarket

 

 

Dear MS/Sirs:

 

The STIC process creates its own artificial [but real] metering system; it has its own fuel vaporizing control and delivery system that operates independent of conventional engine suction and atmospheric pressure. The STIC process solved a problem that thwarted the engineering and scientific community for over 100; year; this mystery remained until the invention of the STIC methodology; see the following excerpts from the STIC SAE engineering paper to be published in 2017.

 

The STIC designed [invented] processing has several unique new inventive features; here is one of them that address changes in altitude. Of course atmospheric pressure is the basis of conventional differential pressure of which the normal carburetor and engine are dependent on. The STIC system is uniquely unlike other prior art carburetor systems that depend on atmospheric pressure to determine its final calibration. The “APT” and “Lectron” have different techniques to pressurize the bowl. You will notice that the Lectron carburetor has bowl vents that communicate with atmospheric pressure. The APT carburetor initially has frontal vents that communicate with atmospheric pressure; however the APT appears to be capturing forced air to pressurize the float bowl. Both systems rely on exiting the fuel through a restricted outlet wherein a specially calibrated needle with a flat back side is used for final calibration of the fuel into the carburetor bore.   

 

The STIC system; never been invented before now; you are witnessing a history making new invention that will change the way we think about combustion efficiency.  Here are some of the STIC features that no other system has:

 

    High pressure acceleration circuit.

 

    Self-regulating fuel curve and volume increase in flow rate based on air speed and dynamic intake pressure interpretation; that changes the rate of vaporization as well as regulating the fuel volume flow rate.

 

    Designed escalation [multiplication] of the fuel flow rate of delivery.

 

    Methods to cause supreme mixture of the fuel to oxidizer surface area.

 

    Method to increase the density of super cooled fuel vapor.

 

    Method to deliver a robust super-dense air/fuel/vapor mixture to the engine in micro seconds; you will find it difficult to gag the engine as the STIC system changes to instant delivery based on seeing a substantial positive pressure wave emanating from the intake system

 

The STIC process creates an artificial [but real] system that has its own fuel vaporizing control and delivery system that operates independent of conventional engine suction and atmospheric pressure. In this case of STIC; atmospheric pressure; while it is part of the equation; it plays a less significant role in the STIC’s total calibration process. The STIC is unique in the fact that it is designed to create its own fuel delivery based on air speed and ever fluctuating pressures within the intake system. The STIC system has a unique communication link that is capable of making calibration changes in fractions of one second.

 

The Internal Combustion Engine [iCE] induction problem has plagued the scientific and engineering community for over +100-years without resolve; that is until now, welcome to the STIC methodology!

 

STIC SAE paper:

 

Author Heinz Heisler of Vehicle and Engine Technology; discusses the limitations of single jet carburetion based on his previous understanding.  He states the following: “If a jet is chosen to give the correct mixture at one predetermined speed, then at speeds below this, insufficient petrol will be forced into the air stream, producing a weak mixture and loss of power.  With higher speeds, the quantity of petrol induced into the air stream will increase at a greater rate than the increase of air consumption, so that an over-rich mixture will be produced. It can be concluded that a petrol-jet orifice can be selected over only a narrow speed range,” [5]. For the usual type of spark-ignition engine operating under given atmospheric conditions, the load is determined by particular values of any two of the following variables: 1) torque output, 2) speed, 3) throttle position, 4) of air flow, and 5) pressure in the inlet manifold.” “It is evident that the fuel-air ratio required is a unique function of air flow only at a given speed. The steady-state signal analysis varies drastically from the dynamic signal analysis, especially for non-linear systems, [10]. Thus, except in constant-speed applications, an additional control, sensitive to at least one of the variables listed, must be provided if air flow is to be used as one controlling element.” [7][8]. “It is a common challenge when linear system theory is used to describe non-linear effects. Since the system is input signal dependent on non-linear systems, the linear system theory is only able to handle peace-wise descriptions, at the most, [2].Limitations to the traditional designs.

 

Richard Stone, the author of Introduction to Internal Combustion Engines (Second edition), states: “With fixed jet carburetion there is no automatic mixture enrichment as the throttle is opened. The pressure drop in a carburetor impairs the volumetric efficiency of an engine and reduces its power output,” [6].

It is obvious that Author Heisler’s and Stone’s explanations are correct for their time; however, the new evolving STIC high vaporizing single jet concept now changes the previously written word. The new STIC concept has a progressive never ending fuel curve, and it accelerates to unheard of levels of performance with a single jet without the aid of auxiliary acceleration systems; thus you are witnessing a change in a paradigm; just as Professor Blair predicted.

 

Background to the STIC Technology

Author Charles Fayette Taylor, 1985; author of The Internal Combustion Engine in Theory and Practice Volume 1, and 2; addressing ideal air/fuel charge in the two-stroke engines. Taylor claims: “….note, in the idealized scavenging process, described not only is the cylinder filled with the fresh mixture, but also no fresh mixture escapes from the exhaust ports, and thus all of the mixture supplied remains to take part in the subsequent combustion and expansion.” Within his title; Taylor is careful to add the word Theory as a disclaimer, of which means that calculated values based on uncertain measurements and fluctuating values are just that; a theory. In his appendix, Taylor addresses: Ideal Flow in passages of Varying Area wherein he states the following; “Many engineering problems involve the flow of fluids through passages of varying areas. To deal with such cases; a useful approximation is the assumption that the stream of fluid has uniform velocity, temperature, and pressure across any section at right angles to the flow.” Taylor; in the section titled: Carburetor Design and Emission control for Spark-Ignition Engines; recognizes and describes a missing carburetor control link in single jet carburetors; however, He was not aware of the STIC system that fully addresses the missing carburetor link that allows a continuous escalating fuel curve, as it did not exist at the time of the writing. Author Charles Fayette Taylor, Volume 1 and 2; [9] states: “The fuel-air ratio should vary as a function of the load under normal steady running conditions.

 

STIC comment: As science and discovery continue to evolve, changes are inevitable. Be prepared to explore changes in the way one thinks about combustion efficiency and the processes required to achieve it. A paradigm is defined in science and epistemology (the theory of knowledge); as a distinct set of concepts and thought patterns including theories that one believes. Paradigm shifts are on the horizon. Scientists, engineers, inventors and others throughout the history of Internal Combustion Engine (ICE) and its related systems have presented some calculated, and theoretical processes; addressing induction, combustion, and exhaust systems that involve complicated formulas based on known and unknown values. Professor Blair reveals the uncertainty in the prediction of the dynamics associated with the mysteries still within the Internal Combustion Engine and states the following; “Without a basic understanding of unsteady gas dynamics, the mysteries of intake and exhaust tuning will remain just that.” In essence, Professor Blair states that calculated results based on black art theory are still a mystery. A multitude of inconsistent changing values, estimations and guessing as to their meaning and influence produce unpredictable results; or theories at their best [1]. I now welcome you to the STIC methodology that provides the missing communication links that control vaporization and fuel curve flow and management independent of conventional differential pressure. Hang on, it is wicked hot! Inventor X

Edited December 7, 2016 by SticSuperTorque

[c-slak]

Yes, you have made a very good point here. If the float bowl is sealed from atmospheric pressure (which is not on the PWK, TMX and Lectron) then it could indeed auto-compensate, if there's something else that does it.

But on any carb where the float bowl is at atmospheric pressure, to me it seems impossible that it would auto compensate.

However, I have read in several places that they do, so I'd like to be proven wrong, if I am, but as I must trust my physics studies, I wish I got a physics explanation, not a matter of faith.

 

I don't doubt that, I have read this whole thread and others with great interest, and I've seen that some of you have witnessed that the SLIC does work as advertised. And for me it is enough to believe it.

But I'm a extreme-enduro rider, and gains in mid and high RPM don't interest me. But if it has other qualities that may interest me, I may purchase an otherwise off-price PWK block/turret for me and the use I make of my motorbike.

Moreover, anything that is carb related interests me, hence my recent questions.

Thank you and to all that replied my questions and are bringing interesting and objective facts to this discussion. Please consider that not everyone is interested in mid and high RPM power gains, but may be anyhow very interested in other kind of improvements at lower RPM's. Not just torque, but throttle response, vaporization (and thus getting less fourstroking and misfires), etc.. I am not really interested in an answer like "yes, it improves those too!" (although I would have no problems to believe it), but only physics explanations may convince me enough to spend this (for me relevant) sum of money for an apparently motocross-only device. I tried to understand why it is said that the SLIC someway adapts itself to air density changes, and since my physics studies tell me that it cannot auto-compensate for air density, I am looking for a different explanation, if my request sounds as constructive as it indeed is.

Cheers,

Maverock

I can only speak real world experiences thus far.  I also ride singletrack quite a bit and so low/off throttle and throttle response is very important to me.  Once my bike is up to temperature with the STIC metering block, there has been no...  I repeat 0... 4 stroking when at low/part throttle.  I wish I could give you a reason behind it but I can simply tell you my experiences.  And as I mentioned previously, I believe I am 1 pilot size too big.  I am probably leaving that for now as the weather is starting to cool out here.

[harrperf]

I am also trying to pin point the physics via data measurement.

I have a cool idea on how to do this - and have started acquiring some items to do it.  

 

Some comments I haven't previously posted.

I had a 3 day yz250 dyno session - where I tested a host of ideas.  

Some tests worth commenting on

With the STIC system - I was able to drop 2 full points of compression and make the exact same power as I did 2 points higher, I did so in 1 point steps - only bowl changes.
With the STIC system I was able to retard ignition up to 4 degrees with the exact same power as 4 advanced - same curve too - this is odd to those who know ignition effects.

With the STIC system I am able to do a carb modification that previously had trade offs.  My mod pwk is worth 1-1.5 hp almost across the entire curve by itself - coupled with the STIC the gains are larger PLUS no previous headaches in throttle response I used to get.

With STIC I can run a large range of main jets - and still run good power - as well as no misfires typical to being 5 steps too rich.

 

On a std carb - dropping 4 degrees timing was a massive power loss

On std carb dropping 2 points compression was again a large power loss.

And on std carb my mod carb is worth power but NOT something I sell to trail or weekend warrior mx riders....it's for those who actually NEED more power...as it used to trade some low throttle opening response.

 

The bottom line for me - I expected this product to be a flop 8 months ago and it sat on my shelf for almost 2 months before I decided to test -the smart carb DOES NOT perform better on the dyno for me, neither does the lectron.

This STIC initial test was measurably better by a good bit which sparked my curiosity. 

Then trackside testing after first dyno session and the rider swore it was 20 percent better in all categories in back to back to back swapping on same track same day REALLY sparked my interest...

I've been "wasting" time ever since on how to solve the why - as well ways to utilize it to our best potential.  I got hammered by people online when I said the smart carb sucked.  It was even put out there by smart carb that I was working for lectron...which is hilarious - I've never sold a lectron in my life nor do I choose to use them but I do feel the lectron a superior product to the SC and an all around solid option for many riders who want to swap for whatever reason.

 

My goal is to offer my customers the fastest bikes on the planet - with the power delivery they desire (not so easy to hit both) - and it seems for now - this product is offering me a chance to improve our packages in a simple way...literally a bolt on.  

[harrperf]

JD jettings test results on a new ktm250sx with the whole range of carbs.

I'd personally be interested in a few things - he showed HUGE afr variance in carbs down low - but all nearly identical performance.
 

this can actually NOT be a true AFR reading - but it would be interesting to have tried to optimize timing for each carb too...as I've seen huge needs to change timing when changing fuel delivery on some carb systems.

[c-slak]

JD jettings test results on a new ktm250sx with the whole range of carbs.

I'd personally be interested in a few things - he showed HUGE afr variance in carbs down low - but all nearly identical performance.

 

this can actually NOT be a true AFR reading - but it would be interesting to have tried to optimize timing for each carb too...as I've seen huge needs to change timing when changing fuel delivery on some carb systems.

This is the 1 I was referring to.

[SticSuperTorque]

December 7, 2016

 

Subject: Atmospheric pressure

 

Clarification; addressing differential pressure; in normally aspirated [meaning non-turbo/super charged] engines and carburetors that are dependent on atmospheric pressure [14.7 psi at sea level] to travel to a lower pressure within the Internal Combustion Engine [aka ICE].  Lower pressure drop in the engine is caused by several events, one of those is piston displacement [suction] created by the piston down-stroke [four-stroke] and by the piston up-stroke [two-stroke]. When the two-stroke hits the scavenging pulse; called hitting the pipe; this will cause an additional suction [scavenging] transmitted to the fuel intake system. The STIC metering system solved and invented methods to cause fuel delivery and superior vaporization; to occur instantly independent of atmospheric pressure. The STIC methodology pulls any connective residual pressures into the mixing process, and this includes ever-changing atmospheric pressures; thus atmospheric pressure has little contribution to the STIC metering process. Inventor X   

[SticSuperTorque]

December 7, 2016

 

Further discussions addressing the two stroke revival:  Over the top; please forgive me.

 

The mystery of two-stroke intake and exhaust tuning  

 

For those that want to get into the problems and mysteries that have confronted the scientific and engineering community addressing the two-stroke Internal Combustion Engine; I suggest you read Professor Gordon Blair’s series of books. Wherein he is addressing the two and four stroke engines; in particular, his book addressing the “Advances in Two-Stroke Cycle Engine Technology;” written by Professor Gordon P. Blair, Published 1999 by SAE, ISBN 0-89883-102-2. During his lifetime, Blair; considered to be one of the great gurus [expert authority] in engine development and technology.

 

Is change for the two-stroke on the horizon?

 

Blair: “Is tomorrow, or the 21st Century, going to produce yet another volte-face?” Volte-face is defined as; change of direction, about face, a reversal in a paradigm, [3].  Perhaps very few understood the possibility of the new changes that are before us except Professor Gordon P. Blair. In his last days he knew that science and discovery would continue to evolve; addressing the issues of unsteady gas dynamics; addressing the remaining mysteries of the unpredictability of the intake, combustion, and exhaust systems. In his forward he emotionally states the following: Remarkably, Blair knew that he was still dealing with black art as he states the following at the closing of his Forward:

 

 

Blair: “I had had the inestimable privilege of being around at precisely that point in history when it became possible to unravel the technology of engine design from the unscientific black art which has surrounded it since the time of Otto, Diesel, and Clerk. That unraveling occurred because the digital computer permitted the programming of the fundamental unsteady gas dynamic theory, which has been in existence since the time of Rayleigh, Kelvin, Stokes, and Taylor. For me, that interest was stimulated by a fascination with high-performance engines in general, motorcycles in particular, and two-strokes even more particularly. It is a fascination that has never faded.” Regressing back to the beginning of his forward, he is careful to state: “Without a basic understanding of unsteady gas dynamics, the mystery of intake and exhaust tuning will remain just that.”

 

Is there a system that can address ICE engine dynamics forces, temperatures, specific gravity, density; sound and pressures that are traveling at the speed of sound; these dynamic conditions are just a few of fluctuating changing conditions that one must deal with in calculating the proper induction system. In fact, the scientific and engineering community consensus; based on our present knowledge; it is impossible to scientifically determine the precise intake length and to have a fuel system that could calculate the precise fuel delivery in every revolution per minute [rpm] throughout the entire operating range in microseconds.

 

An additional control; must be provided!

 

Author Heinz Heisler of Vehicle and Engine Technology; discusses the limitations of single jet carburetion based on his previous understanding.  Heinz: “Except in constant-speed applications, an additional control, sensitive to at least one of the variables listed, must be provided if air flow is to be used as one controlling element.” He states the following: “If a jet is chosen to give the correct mixture at one predetermined speed, then at speeds below this, insufficient petrol will be forced into the air stream, producing a weak mixture and loss of power.  With higher speeds, the quantity of petrol induced into the air stream will increase at a greater rate than the increase of air consumption, so that an over-rich mixture will be produced. It can be concluded that a petrol-jet orifice can be selected over only a narrow speed range,” [5]. For the usual type of spark-ignition engine operating under given atmospheric conditions, the load is determined by particular values of any two of the following variables: 1) torque output, 2) speed, 3) throttle position, 4) of air flow and 5) pressure in the inlet manifold.” “It is evident that the fuel-air ratio required is a unique function of air flow only at a given speed. The steady-state signal analysis varies drastically from the dynamic signal analysis, especially for non-linear systems, [10]. Thus, except in constant-speed applications, an additional control, sensitive to at least one of the variables listed, must be provided if air flow is to be used as one controlling element.” [7][8]. “It is a common challenge when linear system theory is used to describe non-linear effects. Since the system is input signal dependent on non-linear systems, the linear system theory is only able to handle peace-wise descriptions, at the most, [2].Limitations to the traditional designs.

 

The additional control has been found!

 

I now introduce you to the STIC methodology; the additional control that Heinz speaks of and the question that Blair suggested; “Is tomorrow, or the 21st Century, going to produce yet another volte-face?” Volte-face is defined as; change of direction, about face, a reversal in a paradigm, [3].

 

STIC, how does it work?

 

Here are the facts and one of the explanations as to why and how the STIC metering systems reveal the hidden potential within each engine regardless of whether is it stock or modified. The STIC process has several inventive features that do not exist in other carburetors or fuel injection.  The more sophisticated carburetors such as Webers and Dellortos can be and have been improved with the STIC process; yes, even the most fundamental simple carburetors, even for lawnmowers are subject to improvement with the addition of the STIC process. The STIC process calculates input signals from the engines fluctuating pressures and is able to adjust the vapor production and flow rates in fractions of one second.  All calculations are made independent of atmospheric pressures and the engine suction; calculated to be in less than  sixty-thousandths of one second.  Respectfully Inventor X  

[Maverock]

Im not confirming the STIC DOES atomize/vaporize better..

What I will comment on is:

Ive encountered interesting things on the dyno that sugggest it IS doing so.

The problem with just about every consumer on the market is their understanding on what produces most of the power on a two stroke.

Secondly, every two stroke owner when push comes to shove wants more low end, some willingly will sacrifice top to get it, most have an ego that wont sacrifice top.

A pipe change is the single most effective way to move power. A pipe spacer is a very simple way to accomplish relatively small but noticeable movements in power.

To illustrate this, everyone talks about porting as the answer, but how is it that a cr or ktm 125 has nearly the same ex timing as the cr or ktm 250 and yet they have far different rpm peaks?

If you do a little digging, it turns out most 85cc have similar port timings to most 250cc.

How is it possible they rev so high and The 250 so low?

The glaringly easy observation between the 85, 125, and 250 is the pipe dimensions. 85 revs most, 125 less, 250 even less, and what do you know... the 85 has shortest pipe, 125 middle although very similar to 85 and similar peak rpm, 250 longest.

There is more to this than just the pipe or just the ports...but you can not raise the exhaust port on ANY of these motors and experience a huge rpm shift. you will just loose torque, often gain no hp, and sign off nearly dead same rpm.

Pipe temperature (avg gas temp inside across the whole pipe) determines just how fast the waves move. colder is slower/low rpm best hotter is faster higher rpm)

What Ive found is the STIC is influencing the pipe largely enough that people are seeing large gains in over rev. But if you add a spacer to the ex... it shifts your gains down the power curve and you will give up those over rev gains but pick up front side and peak gains.

AKA anyone out there who expects a magic carb part to transform their power to just what they always wanted is kidding themselves. But using what it gives you to make use of its gains where you want to place them... is possible.

Its been my experience however that people asking for more low end... arent really asking for more low end. This is why many lectron and smart carb users are tickled pink. On the dyno neither product delivers more low than a stk carb.

If you like the throttle response and crisp feeling of a lectron vs OEM you would like the STIC very much. Dyno charts pigeon hole the actual riding changes too narrow. over 50 percent of even a supercross pros riding time is spent under 50 percent throttle... and this is where most people actually comment on performance...

Aka a mikuni at WOT performs better than a stock PWK. yet there is no shortage of people who spend time and money to swap and swear the pwk is better...

Well said, harrperf ? I and my experience agree with every single word you wrote.

[Maverock]

I can only speak real world experiences thus far.  I also ride singletrack quite a bit and so low/off throttle and throttle response is very important to me.  Once my bike is up to temperature with the STIC metering block, there has been no...  I repeat 0... 4 stroking when at low/part throttle.  I wish I could give you a reason behind it but I can simply tell you my experiences.  And as I mentioned previously, I believe I am 1 pilot size too big.  I am probably leaving that for now as the weather is starting to cool out here.

 

This is very interesting, thank you. ?

My interest in evaluating improvements in fourstroking is not accidental, because fourstroking is a clear indicator of bad vaporization and slow combustion in general, which in the low-throttle range are particularly critical due to the insufficient scavenging caused primarily by low crankcase pressure (that is a problem, although it's the pipe that "pulls" gases more than the crankcase is "pushing" them, the crankcase pressure retains its importance, especially at part-throttle) and consequent pollution with remaining/entrapped previous-cycle exhaust gases (which, not being completely oxidised, deplete oxigen from the fresh mixture, effectively enriching it, other than heating it and thus increasing chances of subsequent detonation). Combustion speed is of outmost importance in any engine, particularly in a 2 stroke engine, and that is certainly helped by fine vaporization, as the STIC promotes. When combustion is not quick enough, the engine won't tolerate as easily any excess of fuel in the mixture.

Sorry if I don't express myself too clearly, English is not my native language. However, I hope you got the point I was trying to make.

Edited December 8, 2016 by Maverock

[Maverock]

With the STIC system I was able to retard ignition up to 4 degrees with the exact same power as 4 advanced - same curve too - this is odd to those who know ignition effects.

I timidly offer you an explanation:

As we know very well, compression helps burn mixture faster, other than having the best possible expansion ratio. Because of the former, if mixture burns very quickly now (thanks to the STIC block), clearly you don't need anymore a high compression, as you now complete combustion in sufficient time already.

Higher compression would still retain an advantage because of the higher expansion ratio (which is thermodinamically always convenient), but this is probably compensated-offseted by the fact that you didn't re-map the CDI to re-tune the ignition advance to its optimal value (you should have reduced ignition advance to compensate for the quicker burning and reduced combustion incubation period), maybe you moved the stator-pickup plate but it's not the same thing as making a new optimal curve map, and also (although I think this played a secondary role) the higher compression causes more losses, as we know, which negatively compensates too.

Of course, it's better (and safer) to use the lower compression ratio of the two. But if you could remap the ignition advance map (not just add a fixed amount of retard everywhere), you probabily would still have gotten better performance from the higher compression head. IMHO.

 

 

With the STIC system I was able to retard ignition up to 4 degrees with the exact same power as 4 advanced - same curve too - this is odd to those who know ignition effects.

I use a fully programmable CDI that lets me experiment with the greatest freedom possibile with advance, 3D maps (4D with gear sensor), etc.. and I gained a lot of experience in combustion thanks to it.

The relative insensitivity of the engine to ignition advance changes is a sign that it is safely away from detonation, but yet to the peak of the (parabola-like) function that relates ignition advance on the x-axis and effective produced torque on the y-axis. Sensitivity to ignition advance increases the more we move on the left (excess advance, and higher risk of detonation) or on the right (retard) of this parabola, and as for some engines the onset of detonation is already on the right of the peak of this graph, they show more sensitivity to ignition advance, as the advance lies on a steepier part of the graph.

This doesn't cover it all, though. The speed of combustion (which depends not only by the squish, but also by swirl-like turbulence which depend by the angle of transfer ports, etc..) makes also the parabola narrower or wider, what matters is that we get good (peak) combustion pressure about 10-15 degrees after TDC as you already certainly know, but if the combustion is quick, a (reasonable) shift in ignition advance won't affect mechanical output much, while if combustion is slow, it will probabily do it more. But I have to think more about this issue, thank you for stimulating it.

 

With the STIC system - I was able to drop 2 full points of compression and make the exact same power as I did 2 points higher, I did so in 1 point steps - only bowl changes.

Just curious, what squish clearance are you using? And, is it the same radially accross the whole squish area? (in my KTM engine, I have 1.00mm squish at the edges, and 1.20mm at the centermost part of the squish. The piston is flat).

[frdbtr]

December 7, 2016

 

Subject: Atmospheric pressure

 

Clarification; addressing differential pressure; in normally aspirated [meaning non-turbo/super charged] engines and carburetors that are dependent on atmospheric pressure [14.7 psi at sea level] to travel to a lower pressure within the Internal Combustion Engine [aka ICE].  Lower pressure drop in the engine is caused by several events, one of those is piston displacement [suction] created by the piston down-stroke [four-stroke] and by the piston up-stroke [two-stroke]. When the two-stroke hits the scavenging pulse; called hitting the pipe; this will cause an additional suction [scavenging] transmitted to the fuel intake system. The STIC metering system solved and invented methods to cause fuel delivery and superior vaporization; to occur instantly independent of atmospheric pressure. The STIC methodology pulls any connective residual pressures into the mixing process, and this includes ever-changing atmospheric pressures; thus atmospheric pressure has little contribution to the STIC metering process. Inventor X   

 

Are you saying that with your metering block system that you will not lose horsepower at altitude?

[Maverock]

@SticSuperTorque: many thanks for the interesting insights you have written above. I appreciate your incredibly indeep knowledge of carburetors, and I would like to ask you a question, this time about a stock, completely original, PWK:

 

Is it, the original PWK (thus without the STIC jet block) someway auto-compensating? Or completely not doing it? Its bowl is always at atmospheric pressure, so I think it is not auto-compensating, but you have made very good points about the STIC, and maybe they (even partly) apply to the original PWK jet block too?

 

Suppose I have to re-jet the original PWK depending solely on an air density change, which I am able to calculate correctly from pressure, temperature and relative humidity data. Now comes the doubt, and hence the question: if, to make an example, the air density increased by 10%, should I change the section of the jets to allow 10% more of flow (i.e. increase the diameter by the square root of 1.10, so go from e.g. a main jet with 1.50mm of diameter to one of 1.57.. of course the flow doesn't exactly follow the area, but to a good approximation it does, and I don't want to complicate things too much here. Also, I know for the needle it would be more complicate, but let's talk jets only, for simplicity) or the carburetor partly self-compensates for the air density changes, and the correction ratio should thus be lower, and not directly proportional to the ratio of the 2 air densities? It all comes down to the Venturi effect, but I'm asking your help as you certainly have a more clear and complete view than mine on the subject. As often happens, a (Google) research on the web only augmented confusion: some say that normal (TMX, PWK with original jet block) carburetors self-compensate altitude (pressure) changes to some extent, but not temperature ones (and how on Earth could they do it? This is a very important point.. could a carburetor not auto-compensate pressure change, but do it for temperature changes? If so, how?), others say they (at least original PWK's) don't.. I learnt not to trust "spin doctors" (the web is full of them) and ask real experts, and here I am at the right place, to get a definitive answer I can trust on this issue that has gained me some sleepless night (literally ? ). Thank you very much for your help.

The only thing that prevents me now from purchasing (and reviewing, and even endorsing and wanting to import it in Italy then) a STIC block is its price, certainly worth it for the market it was intended to (motocross), but - given that an excellent product is considered excellent by those that used it, but those that don't know it yet are often wary - and by the fact that I belong to the enduro (more extreme/trial than anything) where mid and high rev power is not so important, although I reckon that it gives benefits at low RPM's too and at part-throttle as well, as witnessed before by c-slak, which I certainly believe, so I am really interested in your product but I have, right now at least, to be realist with my wallet. My situation is worsened by the weak EUR (plus international shipping costs, but more importantly import costs (custom duties and VAT)) that would inevitably skyrocket the (already high, for me and most enduro riders, which are notoriously broke, as enduro is a "meager" sport than motocross, at least here) price.. However, I wish I could test one, in my real-riding conditions, so please don't get me wrong, if I was wealthy I would not think twice to purchase one, as this is the exact type of mods that make me enthusiast, and I am starting to save for it. ? It's a real big sum though after international shipping and duties+VAT, the EUR is weak too, this is really a pity because if the STIC works, and I am sure it does, you could sell plenty of them here, but I believe in all honesty that the price would be a giant obstancle. Only you can know what are the real production costs, and how much you can lower the final price and thus make the # of sales explode. It's a delicate equilibre, I know, a tradeoff between price and production costs, which is complicated also by how many units you are industrialized to produce. I can only offer you my view of it, I am certain that if the price was low enough, and the gains are those witnessed (and, again, I certainly believe it), you would sell plenty also in Europe. But with a high price (made more difficult by the extra costs we would have to import it), I believe the sales would drop to near zero. Please take my words as constructively as possible. I really want to congratulate myself with you for what you achieved.

Edited December 8, 2016 by Maverock

[numroe]

STIC, how does it work?

 

Here are the facts and one of the explanations ...

I can see a lot of information about the gains at high RPMs, and especially in the 2-strokes over-rev range.

 

As Maverock asked ... Are they any gains from this device in a 2-stroke motor that is rarely fully revved out? Or rarely used above 1/2 throttle?

 

Say for example in a CR500 or a 300cc 2 stroke used on technical trails, would the rider experience any benefits such as more consistent throttle response, less sensitivity to altitude and air temp, or better fuel economy?

[KPRacing]

I can see a lot of information about the gains at high RPMs, and especially in the 2-strokes over-rev range.

As Maverock asked ... Are they any gains from this device in a 2-stroke motor that is rarely fully revved out? Or rarely used above 1/2 throttle?

Say for example in a CR500 or a 300cc 2 stroke used on technical trails, would the rider experience any benefits such as more consistent throttle response, less sensitivity to altitude and air temp, or better fuel economy?

Yes, there are gains from just off idle to the overev. The engine picks up stronger, quicker, & cleaner. Some customers have claimed the fuel consumption was less but Ipersonally gave not tested this.

[numroe]

Yes, there are gains from just off idle to the overev. The engine picks up stronger, quicker, & cleaner. Some customers have claimed the fuel consumption was less but I personally gave not tested this.

I guess you are describing benefits over the full RPM range, at 1/3 to WOT.  Which is excellent, no doubt.

 

Thinking about throttle position...

 

I guess no advantage for fuel supplied via the pilot circuit.  The gains come from the improved vaporisation through the needle jet (metering block) which is certainly in use from 1/3 to WOT. Correct?

 

If I'm guessing right, and I'm using under 1/3 throttle a lot, then does that mean that more benefits are possible if I make adjustments to use less of the pilot circuit and more of the needle jet? I've never tried do that. I thinking perhaps a smaller pilot and a needle that is richer on the straight section.

[KPRacing]

The pilot & main metering circuit are connected & are communicating as well as the varying intake pressure waves, differential pressures, ect. So the entire range is improved over a standard fueling system.

Experimenting with different combinations could most definately reveal something that better suits your specific needs. But I personally would tune it to be clean everywhere & then use the airscrew for adjustment of the entire fuel curve for bigger temp swings, bigger humidity changes, bigger elevation changes, ect. The system seems to run good evening when running a bit rich. I've had the airscrew in as far as 1/4 turn from full closed & it finally started to act as little rich but only if you let it idle for about 3-5 seconds. As soon as I hit the throttle, the bike immediately responded as if it was jetted perfect. So with the airscrew barely open, the bike drove & ran great (for moto conditions). I had the screw as far out as 2&1/2 turns & again, it ran good. The main has been run 4-5 sizes over what was best & it still ran clean & strong. It's simply a very forgiving system.

Edited December 8, 2016 by KPRacing@SticSuperTorque