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Thread: Not atkinson cycle engine

  1. #81
    Oh I think I was just misunderstanding you then. That was actually the video I was trying to find earlier by the way!

    The reason the velocity increase creates the additional tumble or swirl, or both (it actually depends heavily on RPM I believe) is in the head/valve design. Basically, with low velocity, the particles kind of slide off the valve and the ports and just "seep" into the piston. You notice there's only a slight tumble in the cylinder without the tumble valve in this case. Its not stimulated to do so, and as such a lot of the fuel that is injected (in this case into the cylinder directly) doesn't spread out, it kind of follows gravity and stays lower next to the piston. This leads to a cooler piston of course, but you have an obvious lean -> rich trend. The rich areas will generate excess soot, the lean areas excess NOx, and the flame front wont be as uniform (which this simulation doesn't seem to show, it appears to just be a CFD of the air and fuel particles), and that means a loss in cylinder pressure and torque.

    PI does a little better in this regard, but still suffers nonetheless. And actually DI can cheat a little bit with their piston bowl design itself. A lot of DI engines have a unique bowl design in the piston, and this is to encourage this fuel mixture process you see happening. Basically the bowl redirects fuel from being shot at the piston up into the cylinder air itself I believe, and I think this is why things like the Ecoboost truck dont have IMRC, but I will admit, I'm not an expert on the whole process in a DI engine on fuel spreading and piston design, being much more familiar and having read much much more on the design for PI stuff.

    But basically, the idea here is that valve is speeding up the particles into a jet, like putting your finger over your hose to make it spray. Say you're cleaning off dirt on your garage door. If you just let it trickle out, the water runs down the garage door. If you spray it out with a higher velocity, the water will bounce off your garage more in a jet, even though its the same amount of water. Same idea here. The IMRC basically causes the air to jet up, and it bounces off the head/valve design creating the charge motion that helps the fuel particles spread around. Same idea here as say adding food coloring to water. If I just poor it in, it slowly seeps in. If I add some velocity and stir it up, I significantly accelerate this mixing process.

    So yes, they're skipping steps and may be cutting it short saying: Velocity = Power & Torque here, and you're right thats misleading, and I'm not trying to encourage that view point. Its actually the side effect of what they can do with the increased flow velocity, that is, promote better charge mixture, which promotes a better burn, which means better everything: power, emissions, etc.

    Also, the restriction doesn't mean it'll be less CFM. You can have 300 CFM of water move through a 3" pipe, or through 6" pipe, but in the 3" pipe itll be moving faster. That's what theyre doing.
    I know what you're thinking, that causes a pressure drop, and you're right, it does! But remember, the ECU targets a set Desired Airflow. Based on current VE and desired airflow, it can figure out a needed manifold pressure and throttle plate aircharge needed, and adjusts the throttle to reach this goal. So if you keep airflow desired the same, but now add that pressure drop, it opens the throttle slightly to counteract that.
    Essentially, you operate the engine in a condition knowing that pressure drop is there, because you're using that to increase the overall efficiency of the process. You're trading unused throttle for increased performance at the same airflow.

    At high velocities and flows you get at WOT, you naturally get the tumble, and no longer want the IMRC there increasing the velocity more (and causing that big pressure drop!) You want WOT, and you want the lowest pressure drop you can get, so thats why you fold them out of the way. You also are lucky in this situation to not need them anymore to create the velocity you needed to get a jet of air, as the natural amount of air you're shoving through does this for you

    I hope I'm explaining this clear enough, and I really thank you for not getting upset with me as I commonly encounter whenever something like this happens on other forums! Thats why I'm back and making another post, because you weren't being argumentative just to be mean, and I really appreciate that. Now I just have to hope I can explain it so you see how it increases power and economy. But I do agree as well, its not as simple as velocity = power here, but what they use that velocity to do, and they do kind of leave that out of their explanations, but they're not outright lying that the IMRC doesn't help them increase power and efficiency at these lower airflow values.

  2. #82
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    Quote Originally Posted by Bugasu View Post
    Oh I think I was just misunderstanding you then. That was actually the video I was trying to find earlier by the way!

    The reason the velocity increase creates the additional tumble or swirl, or both (it actually depends heavily on RPM I believe) is in the head/valve design. Basically, with low velocity, the particles kind of slide off the valve and the ports and just "seep" into the piston. You notice there's only a slight tumble in the cylinder without the tumble valve in this case. Its not stimulated to do so, and as such a lot of the fuel that is injected (in this case into the cylinder directly) doesn't spread out, it kind of follows gravity and stays lower next to the piston. This leads to a cooler piston of course, but you have an obvious lean -> rich trend. The rich areas will generate excess soot, the lean areas excess NOx, and the flame front wont be as uniform (which this simulation doesn't seem to show, it appears to just be a CFD of the air and fuel particles), and that means a loss in cylinder pressure and torque.

    PI does a little better in this regard, but still suffers nonetheless. And actually DI can cheat a little bit with their piston bowl design itself. A lot of DI engines have a unique bowl design in the piston, and this is to encourage this fuel mixture process you see happening. Basically the bowl redirects fuel from being shot at the piston up into the cylinder air itself I believe, and I think this is why things like the Ecoboost truck dont have IMRC, but I will admit, I'm not an expert on the whole process in a DI engine on fuel spreading and piston design, being much more familiar and having read much much more on the design for PI stuff.

    But basically, the idea here is that valve is speeding up the particles into a jet, like putting your finger over your hose to make it spray. Say you're cleaning off dirt on your garage door. If you just let it trickle out, the water runs down the garage door. If you spray it out with a higher velocity, the water will bounce off your garage more in a jet, even though its the same amount of water. Same idea here. The IMRC basically causes the air to jet up, and it bounces off the head/valve design creating the charge motion that helps the fuel particles spread around. Same idea here as say adding food coloring to water. If I just poor it in, it slowly seeps in. If I add some velocity and stir it up, I significantly accelerate this mixing process.

    So yes, they're skipping steps and may be cutting it short saying: Velocity = Power & Torque here, and you're right thats misleading, and I'm not trying to encourage that view point. Its actually the side effect of what they can do with the increased flow velocity, that is, promote better charge mixture, which promotes a better burn, which means better everything: power, emissions, etc.

    Also, the restriction doesn't mean it'll be less CFM. You can have 300 CFM of water move through a 3" pipe, or through 6" pipe, but in the 3" pipe itll be moving faster. That's what theyre doing.
    I know what you're thinking, that causes a pressure drop, and you're right, it does! But remember, the ECU targets a set Desired Airflow. Based on current VE and desired airflow, it can figure out a needed manifold pressure and throttle plate aircharge needed, and adjusts the throttle to reach this goal. So if you keep airflow desired the same, but now add that pressure drop, it opens the throttle slightly to counteract that.
    Essentially, you operate the engine in a condition knowing that pressure drop is there, because you're using that to increase the overall efficiency of the process. You're trading unused throttle for increased performance at the same airflow.

    At high velocities and flows you get at WOT, you naturally get the tumble, and no longer want the IMRC there increasing the velocity more (and causing that big pressure drop!) You want WOT, and you want the lowest pressure drop you can get, so thats why you fold them out of the way. You also are lucky in this situation to not need them anymore to create the velocity you needed to get a jet of air, as the natural amount of air you're shoving through does this for you

    I hope I'm explaining this clear enough, and I really thank you for not getting upset with me as I commonly encounter whenever something like this happens on other forums! Thats why I'm back and making another post, because you weren't being argumentative just to be mean, and I really appreciate that. Now I just have to hope I can explain it so you see how it increases power and economy. But I do agree as well, its not as simple as velocity = power here, but what they use that velocity to do, and they do kind of leave that out of their explanations, but they're not outright lying that the IMRC doesn't help them increase power and efficiency at these lower airflow values.
    Nope I see how it could be benificial I think we both understand that side of imrc. What I'm trying to also figure out, because there's no you tube video for it, is how the imrc can affect very livc. Which I think I pretty clearly showed that is what Ford's intention with the new valve timing and phasers is. They tell me no that's not what they are doing. Then tell me talk to a dealership. I really can't trust what Ford always tells me. So I have to resort to forums like these and hopefully people will see it like I see it and explain it to me.

    And for the record to get 300cfm through a pipe half the size requires more pressure aka FI. Our natural pressure is the atmosphere. You understand this I understand this higgs understands this. Now can we just focus on the livc and how Ford increases this to past a power beneficial point and starts to push volume back into the manifold?
    Last edited by murfie; 02-05-2016 at 01:23 AM.

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    Bugasu, nice post.

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    Quote Originally Posted by murfie View Post
    Nope I think we both understand that side of imrc. What I'm trying to also figure out, because there's no you tube video for it, is how the imrc can affect very livc. Which I think I pretty clearly showed that is what Ford's intention with the new valve timing is.
    Then why are the imrc open with 14+ mp have the same cam events as 1-10 with imrc closed? They don't need to block the effect of livc if more rpm are involved? Or is it only because the imrc have nothing to do with blocking livc?

    All the engines in the last 100 years that don't use imrc but still have livc.....

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    Quote Originally Posted by Higgs Boson View Post
    Then why are the imrc open with 14+ mp have the same cam events as 1-10 with imrc closed? They don't need to block the effect of livc if more rpm are involved? Or is it only because the imrc have nothing to do with blocking livc?

    All the engines in the last 100 years that don't use imrc but still have livc.....
    Because just as bugasu showed at higher rpms or more open TB angles the IMRC is just restriction. That's when those MPs are used. I'm specifically referring to MPs 3-6 or any of the lower MPs that are higher than 20. And if you notice the fuel economy array trys to stay either at 14 or 21. Both much less than 20. my only explaination for there being late IVO points in higher MP is for the eco boost benefits from miller timing. Do you really think with very livc there wouldn't be some kind of effect from the imrc against the fuel and air being pushed out of the cylinder? Also the imrc open and close times are very tricky to follow against the MPs. It's not as simple as low and high MPs they have their own distance path along the fuel economy array.

    FTFY
    All the engines in the last 100 years that don't use imrc but still have fuel mixture problems.....
    Last edited by murfie; 02-05-2016 at 01:26 AM.

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    Quote Originally Posted by murfie View Post
    Because just as bugasu showed at higher rpms or more open TB angles the IMRC is just restriction. That's when those MPs are used. I'm specifically referring to MPs 3-6 or any of the lower MPs that are higher than 20. And if you notice the fuel economy array trys to stay either at 14 or 21. Both much less than 20. Do you really think with very livc there wouldn't be some kind of effect from the imrc against the fuel and air being pushed out of the cylinder? Also the imrc open and close times are very tricky to follow against the MPs. It's not as simple as low and high MPs they have their own distance path along the fuel economy array.
    Have you logged what the mapped points are doing while driving? How about with imrc action? It's pretty straightforward....you can pump the pedal and open and close the imrc at will and watch the mapped points jump from 1-10 to 14-22 or whatever the upper end is with perfect correlation. The mapped points change from 1-10 to 14+ based on the imrc position not the other way around.

    As far as the effect of the imrc against livc, no I don't think it does anything at all because every compression stroke the engine and any other engine ever makes has an open but closing quickly intake valve and there is never a time where it closes btdc.

    Btw, the 11-14 has nearly identical valve events and no imrc. You agree the imrc helps at low rpm with air going in but what benefit would they create by serving as a livc blocker? They aren't blocking the livc events while open and valve events are identical with MP14+ so why not just advance the intake cam to close it sooner with the lower MPs? You get the same effect, they can be late again with RPM.... It might make more sense if we didn't have variable valve timing and just wanted to do something at low rpms with a fixed long duration cam.
    Last edited by Higgs Boson; 02-04-2016 at 11:51 PM.

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    Quote Originally Posted by Higgs Boson View Post
    Have you logged what the mapped points are doing while driving? How about with imrc action? It's pretty straightforward....you can pump the pedal and open and close the imrc at will and watch the mapped points jump from 1-10 to 14-22 or whatever the upper end is with perfect correlation. The mapped points change from 1-10 to 14+ based on the imrc position not the other way around.

    As far as the effect of the imrc against livc, no I don't think it does anything at all because every compression stroke the engine and any other engine ever makes has an open but closing quickly intake valve and there is never a time where it closes btdc.

    Btw, the 11-14 has nearly identical valve events and no imrc. You agree the imrc helps at low rpm with air going in but what benefit would they create by serving as a livc blocker? They aren't blocking the livc events while open and valve events are identical with MP14+ so why not just advance the intake cam to close it sooner with the lower MPs? You get the same effect, they can be late again with RPM.... It might make more sense if we didn't have variable valve timing and just wanted to do something at low rpms with a fixed long duration cam.
    So what is your explanation of the open close tables for imrc? Why do complicated if it's just based on the valve timing MPs. Maybe Eric can look into it and shed some light on why the scanner follows the valve timing MP and not its own open close tables when its based on voltage? Its also kinda funny when I look at that its called variable intake and displacement on demand kinda like what Im talking about with the effective compression ratio.

    The 11-14 cams do have similar valve events, but the 11-14 didn't have two way phasers. Why would Ford spend extra money on a part to accomplish the same thing? You see what I'm seeing they are opening the valve after TDC while cruising. I'm not talking .050 or .006 but true opening. What would they do that for? I'm saying to give an atkinson like effect. My other explanation for IMRC is to keep air and fuel in the same cylinder and not get pre mixed fuel and air flowing back into the manifold.

    slope.PNG

    In the speed density you have blowthrough slope(Stock Gt tables are all 0) which happens at valve overlap. You also have slope which would refer to the LIVC and very LIVC timing pushing charge back into the manifold.
    the units of these tables are inmg/LBm what that is is pressure per pound mass. In english that means the volume by weight of air being pushed out of the combustion chamber not into the exhaust but into the intake because at this point the exhaust has been long closed. As you can see the values in MP 3(not in picture) and 4 or where the car tries to cruise for best fuel economy(1250-2500rpms) the numbers are quite high. in tables 5,6,7 when the IMRC closes the amount of air being pushed out of the combustion chamber drops significantly. This is the displacement on demand not the tumble and swirl increasing the total volume of air going into the cylinder. as you go to the higher MP like 21 and 14 you see the volume of air being pushed out raise in the lower RPMs but fall off in the higher RPMs because of the LIVC increases but not anywhere near the cruising MPs. Compare this to an 11-14 tune. you will see nothing like it. you will see as MP goes up a bump goes through the RPM range but with numbers almost half the cruising points of the 2015+. For fuel economy you want the VCT to follow a path with high numbers for power you want it to be trying to follow the lowest numbers possible.
    Last edited by murfie; 02-05-2016 at 03:38 AM.

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    So, we have a decent understanding of what the IMRC does and the valve events required to operate the engine at low engine speeds with the IMRC's closed. So what is the reasoning for having them? Is it strictly fuel economy and emissions? At first glance it was to have an increase in velocity at low engine speeds to help the 2015 coyote maintain low rpm torque and maintain relatively decent fuel economy with the larger intake and exhaust cam profiles compared to previous years. Would this be correct?

    Kris

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    But have you logged the MPs is all I am asking.....

    Variable Intake and Displacement on Demand is just the title for the section which houses other PIDs for other brands, like GM.... go into your Graphs parameter list and search "displacement" and you will see DoD pids under the same heading.

    You aren't going to get premixed fuel in the intake any more than any other engine does due to LIVC. They all have it.

    The coefficients are combined to get SD values. You can't look at one table and expect to find a solution, you know that. The IMRC are not the only thing that determines airflow. The MY's have different cams, in some places, especially midrange do have different cam events, different intake manifolds (I am sure the 15 flows a lot more if it needs IMRCs to slow the air and mix it up and low speeds as well vs the 2014..... You have to solve the whole equation, not just look at one variable. You are the math wiz, please solve this (without predisposition) for us:

    Screen Shot 2016-02-05 at 7.34.04 AM.jpg

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    Quote Originally Posted by kris5597 View Post
    So, we have a decent understanding of what the IMRC does and the valve events required to operate the engine at low engine speeds with the IMRC's closed. So what is the reasoning for having them? Is it strictly fuel economy and emissions? At first glance it was to have an increase in velocity at low engine speeds to help the 2015 coyote maintain low rpm torque and maintain relatively decent fuel economy with the larger intake and exhaust cam profiles compared to previous years. Would this be correct?

    Kris
    The answer these days is always fuel economy and emissions, however, like many innovations today geared towards that, there are performance benefits also because we are working with efficiency in general. IMRC, direct injection, etc....even turbocharging, originally used for power, is now used for efficiency and power while using less displacement.

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    Quote Originally Posted by Higgs Boson View Post
    The answer these days is always fuel economy and emissions, however, like many innovations today geared towards that, there are performance benefits also because we are working with efficiency in general. IMRC, direct injection, etc....even turbocharging, originally used for power, is now used for efficiency and power while using less displacement.
    So we can all agree on the IMRC do their job, but the end result could leave us with performance on the table. I tell you what, I have a feeling tuning aftermarket camshafts in the 2015 coyote with an IMRC delete manifold, even stock, is going to be a hell of a headache. All VCT MPs need to be altered more than likely.

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    I think if they are degreed stock and installed the same way it might now be too bad.....but I do think it could be a nightmare if the are set up like an 11-14.

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    OK if you want me to break the IMRC patent down for you and not read it yourself I will.

    1. the intercept of the regression is calculated. Note that the intercept is independent of IMRC (intake manifold runner control position).

    Equation: (value in offset table) multiplied by (barometric pressure/ 29.92). Because it is independant of IMRC you dont need this table to think about what IMRC is doing.

    2. The slope is calculated as a function of imrc (IMRC position) and cam timing. the slope term with the IMRC open is calculated in first equation. the slope term with the IMRC closed is calculated second equation.

    Equation 1: slope open. The ECU just looks up the value MP 14-OP are open
    Equation 2: slope closed. again just looks it up. MP 0-13 are closed

    No math involved just need to look at those tables to figure out IMRC effect on Air flow during LIVC. Smaller numbers less air pushed out bigger numbers more air pushed out.

    3. Although the imrc is a two position device, provision is made for a continuous device. The IMRC is quick but not quick enough it still requires time to open and close they calculate this.

    equation: slope= actual IMRC position times IMRC open slope+(1 minus actual position)times IMRC closed slope. This is easier to program the equation for actual position but we can use simple algebra and get the real equation to calculate for actual IMRC position.

    real equation:
    first factor out actual IMRC position: slope = (Actual IMRC times (1 minus Actual IMRC))times(open slope+closed slope)
    second divided (open slope+closed slope) slope/(openslope+closed slope)=actual IMRC times (1 minus actual IMRC)
    third divide by (1 minus Actual IMRC) and FOIL the denominator slope/(openslope minus (Actual times open) plus closed slope plus (actual times closed))=actual IMRC
    fourth simplfy slope/(open slope plus closed slope)= actual IMRC position
    open slope and closed slope will just be two MPs one on an open IMRC table another on a closed IMRC table.

    4.you can optionally augment the slop-offset estimation of engine breathing using a quadratic term.
    The quadratic terms are just looked up by the ECU same as slope and even put into the same IMRC transition formula as slope. This Is to describe the air flow going in to the combustion chamber.

    no equation for this but since we know Quadratics describe parabolas we know The formula would describe the intake stroke length. In your PV diagram it would be the shape of the curve for raising cylinder volume. We know this because the tables are negative values. We can also know the Larger the number the sharper this curve will be and the smaller the number the flater this curve will be. You wont see much about the IMRC from these numbers in regards to what I'm talking about. Just the speed at which volume(air fuel mixture) goes into the cylinder.

    Normally negative quadratic describe a parabola that opens down ward.

    You would look at these tables to see the tumble/swirl effects.

    5. Besides the intercept, slope, and quadratic terms, there are several additional terms in the inferred map formula. Equations that factor in the IATand ECT. Not much to do with the IMRC but important.
    The other thing factored in would be EGR. The effect of EGR is to increase the manifold pressure with inert gas at a given mass air flow. EGR is looked up in a table called MAPPEREGR. We don't have access to this. The MAPPEREGR constant reflects the fact that the EGR is hotter, and if an air charge temperature sensor is used instead of a manifold charge temperature sensor the temperature effect will not be captured.

    6. If you are wondering why blow through slope was left out its because the stock tables are all 0. It is never factored into the stock intake and exhaust flows. They are nice for giving you the option for it later after you have modified the engine enough. We can thank Ford racing for that. Also the imrc would have no effect on creating blow through.

    That's the Infered MAP speed density with all the tables we have access to. Its not actually as complicated as it looks. The rest of the patent goes on to use the Infered MAP with flow models and temperature corrections. We don't have access to all these models. I think I saw a little bit about the throttle body but noting about the intake manifold. I hope this helps you see what I see in the slope tables. IMRC open/closed has a direct relationship to these tables.

    My plan when I get my cable very soon is since my car is stock I will find a relationship between maf calculated map and the offset values. I will then have a friend help me put it in a spread sheet and make correcting the speed density easier for all of us. I may even include correction of the other variables if my friend is willing to make that complicated of a spread sheet. He may just want to compile a program because that's easier for him.

    Excuse the picture I created it on my phone

    S= slope
    Q= quadratic
    Bts= blow through slope

    sketch-1454707026738.jpg

    I want to make it clear that in a PV diagram the volume refers to cylinder volume not air volume. Blow through slope and slope refer to an air volume. Quadratic term and offset refer to an Air pressure. so while thinking about this you have to think about the piston speed or the cylinder volume rate of change and the effect it has on the air flow. You would need to overlay two PV diagrams to see both cylinder volume and air volume vs pressure.
    Last edited by murfie; 02-06-2016 at 06:34 AM.

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    Blow through slope is 0 on my car and 0 on the 11-14's I have seen. Should it not have some value if it means something?

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    Well with the stock intake and exhaust being a restriction you will not get blow through. So in the pv chart this Will be a straight line drop in pressure at the tdc end not a curve that would reduce the size of the pumping loop. Zero slope/ blow through slope would be a straight up and down line. As numbers get smaller parabola curves get sharper at 0 they are just a line. The bts line would be short and may even look like a sharp point. With no blow through and increased overlap your line will get longer and no longer become just a point. So unless your engine starts flowing well enough to have blow through you want that sharp point to reduce the pumping loop.

    This is where if you are looking for more power you need to reduce slope and increase blow through slope.

    Blow through is not a good thing. It's necessary for higher HP when N/ A but having purely good air and fuel go out the exhaust is a waste. FI you want to minimize blow through and slope is decreased because of more pressure in the intake. This is why "Miller timing" is a good thing.

    So ideally you want 0 bts. 0 slope. And infinity quadratic(this would be a flat line and no tumble/swirl). In reality you cant achieve this but you can try. Quadratic causes a spike in the pumping loop which in the real world helps but if you have 0 bts and move slope toward 0. You want to lower the quadratic spike or you get pressure which causes restriction.

    This is the ideal PV.

    ideal-air-standard-otto-cycle.png

    People look at the bts and the quadratic but ignore the slope. This is why when you change your vct you must also change the new restriction caused by the IMRC. Unfortunately this makes it complicated but is the only way vct changes will give us benefits. It will also be better in the final result.
    Last edited by murfie; 02-05-2016 at 08:23 PM.

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    I have logged the MPs. Stock I did not change anything to try to get it into OP mode. When every thing I tried failed I gave up and moved on. Stock below 4k it goes to 21 and after it splits then slowly moves moved toward 14. Non of my logs have this even distribution you all talk about. I see maybe 2-5% values move across as more value is taken from 14 than 21 but I do not see any even distribution.

    All engines have livc true. They just don't have it to the same degree that the 15+ cars do. Im not trying to argue that its a bad thing. Im saying ford is utilizing it to a greater extent than necessary.
    Last edited by murfie; 02-06-2016 at 06:44 AM.

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    A better name for it is lean burn or part-time lean-burn (also known as "lean mix" or "mixed lean")

    https://en.wikipedia.org/wiki/Lean-burn#Principle

    you can read all about hondas approach to it here from this wikipedia page. Compared to our GT it sounds very familiar. Also as you can see the tumble isnt to mix fuel and air evenly through out the cylinder but concentrate it in the area of the spark plug. That's what I see in that you tube video. They were having trouble in California because these types of engines produce more NOX emissions and require a different catalytic converter system. Explains why to pass emissions you need the green cats and not just regular high flow type. It also explains why AFR's are not leaner while cruising.

    Ultra lean mixtures with very high air–fuel ratios can only be achieved by direct injection engines. With our engines using port injection that has OVI capability, shown in the you tube video, Its even more crucial to have a good tumble of air when the engine is operating in the lean burn timing. If you had a manifold that didn't help with it I would imagine random misses while cruising and knock while cruising due to unsuccessful ignition and poor flame spread for complete combustion. the relative "imprecise" nature of a carburetor limited the MPG abilities of the concept that now under Multi-Port fuel Injection allows for higher MPG too.

    So it creates a high pressure zone of air surrounding low pressure zone that contains the fuel near the spark plug. This surrounding high pressure zone extends up the runner and to the back of the IMRC flaps. That is what I mean by blocker. In a turbo or supercharger application that pressure returns to the propeller wheel. The you tube video doesn't show the flow of air back up the intake runner. As the flame wave propagates from the spark through the cylinder it is introduced to more air and the burn gets leaner as the wave travels.

    so my next question is how does the stock IMRC hole compare to the GT350 hole. If the GT350 hole is larger can we modify the stock flap some to maintain this high pressure barrier but allow for more air volume to get into the cylinder?
    Last edited by murfie; 02-07-2016 at 07:21 PM.

  18. #98
    Senior Tuner
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    Higgs when you log IMRC you need to look at the highest and lowest values of voltage after setting up a graph use the + and -. If you look at just the average you wont see exactly what the IMRC is doing, but just the position it is in most of the time. I just got to take some new logs and looked at it. just like I described MP 6/7 they start to open and 8/9( very hard to actually get good hits on) they go from an open state and start to close.

  19. #99
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    I know this is an old thread, but I just completed some testing that is somewhat befuddling. I have a 2018 GT and started with a "mainstream" aftermarket cal. For various reasons, I could not test against the stock Ford cal. I logged 4 miles of steady-state driving at 75 mph (~2000 rpm and .35 load) and tested different cam timing combinations with the goal of achieving better fuel economy.

    Test 1: IVO - 28-30, EVC - 18-20. Ignition timing averaged 32.1 deg. Fuel flow averaged 18.7 lb/hr. This was as the cal was supplied.
    Test 2: IVO - 30, EVC - 40. Ignition timing averaged 35.2 deg. Fuel flow averaged 19.4 lb/hr. I changed the Mapped Point Index array to achieve the cam timing, so the ignition timing moved due to the Mapped Point change.
    Test 3: IVO - 35-38, EVC - 45-47. Ignition timing averaged 36.2 deg. Fuel flow averaged 20.1 lb/hr.

    Factory stock cam timing is IVO 40, EVC 50 at this load and speed. I am a little thrown off because as my tests moved more towards Atkinson cam timing, the fuel economy fell measurably even though the ignition timing increased accordingly. Factory stock ignition timing in this region is around 37 deg (IMRC closed) to a little over 40 deg (IMRC open). I wonder if adding 4-6 deg spark timing to test 3 would offset the 7% loss in fuel economy and then some to achieve a net improvement. It's hard to imagine it would.

  20. #100
    Advanced Tuner
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    Quote Originally Posted by engineermike View Post
    I know this is an old thread, but I just completed some testing that is somewhat befuddling. I have a 2018 GT and started with a "mainstream" aftermarket cal. For various reasons, I could not test against the stock Ford cal. I logged 4 miles of steady-state driving at 75 mph (~2000 rpm and .35 load) and tested different cam timing combinations with the goal of achieving better fuel economy.

    Test 1: IVO - 28-30, EVC - 18-20. Ignition timing averaged 32.1 deg. Fuel flow averaged 18.7 lb/hr. This was as the cal was supplied.
    Test 2: IVO - 30, EVC - 40. Ignition timing averaged 35.2 deg. Fuel flow averaged 19.4 lb/hr. I changed the Mapped Point Index array to achieve the cam timing, so the ignition timing moved due to the Mapped Point change.
    Test 3: IVO - 35-38, EVC - 45-47. Ignition timing averaged 36.2 deg. Fuel flow averaged 20.1 lb/hr.

    Factory stock cam timing is IVO 40, EVC 50 at this load and speed. I am a little thrown off because as my tests moved more towards Atkinson cam timing, the fuel economy fell measurably even though the ignition timing increased accordingly. Factory stock ignition timing in this region is around 37 deg (IMRC closed) to a little over 40 deg (IMRC open). I wonder if adding 4-6 deg spark timing to test 3 would offset the 7% loss in fuel economy and then some to achieve a net improvement. It's hard to imagine it would.
    How about performing 3 tests like before but only with the intake changing and a static exhaust setting. Then take those same 3 intake settings you chose from first test and pick a new static exhaust setting for the next 3 tests.

    Interesting!
    Knock Retard is the reduction or prevention of knock by lowering ignition timing:

    (+) Adding Knock Retard = Reducing Timing. PCM is seeing knock.
    (--) Lowering Knock Retard = Increasing Timing. PCM isn't seeing knock.
    __________________________________________________ ________

    2014 Mustang GT Premium. VMP Gen2R Supercharged with an FTI 3000rpm Converter. JLT, BMR, Steeda, Viking, etc.
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