Higgs, did you use any of the data from the stock GT350 tune to tune your car?
Higgs, did you use any of the data from the stock GT350 tune to tune your car?
@murfie, You asked if I read that patent, the answer is yes. You need to read further than the first paragraph, and that patent gives a huge view into Ford's VE. If you had read further, and gotten to the part about the slopes, you can see Ford defines the pushback ratio which was what I was referencing.
"Variable r_pb is an effective pushback ratio characterizing a portion of a cylinder mixture that may be pushed into the engine intake manifold from the cylinder as the piston moves in a direction toward the cylinder head while the intake valve is open."
Also, you can read through Ford's very old patent on the original IMRC here:
https://patents.google.com/patent/US6155229A/
The purpose has not changed, and believe it or not, the intake valves were held open into the compression stroke back in 1999 as well.
Yes but I slightly altered a little bit of it.Originally Posted by rhinogt
More like 1899.
The patent for blow through is only talking about when valve over lap is occurring. Nothing about LIVC. Variable r_pb is not talking about pushing anything back into the intake manifold during the compression stroke but the push back caused by the cylinder filling up and pressurizing and the rest of the air just going out the exhaust valve or even reversing the flow back into the intake manifold. This particularly happens under boost conditions. To solve it you move the IVO more toward TDC. In N/A application you need to have a very very good flowing intake system to achieve this and have IVO opening quite a bit before TDC to get the cylinder filling and pressurizing fast enough to get a noticeable amount of blow through and reversion. Reversion is not the same as livc atkinson effect. Two different periods of the stroke.
The patent I posted actually describes the IMRC not the older CMCV systems. I referred you to it so that you can follow the numbers in the speed density tables of the newer systems.
Cool, that's kinda what I figured would be the easiest way to start.
IVO always occurs BTDC @ .006 even though many times you might see it ATDC @ .050
The numbers in the tune seem to be at .050
This is why you see some conversations about negative overlap or underlap and sometimes about overlap. I have never seen a stock cam with overlap at .050 but always at .006. A bigger aftermarket cam will have overlap at .050 and it is a noticeable rough idle.
The stock Mustang cams overlap -51 at idle/park @ .050 but are right at 0 overlap at .006. A big cam might have 15 degrees of overlap @.050 and 65 @ .006.
So take a duration of 200 on the intake like the stock Mustang cam. IVO at TDC means IVC at 20 ABDC. Get a bigger cam like a 244 duration and now you can IVO at 5 BTDC and still close at 59 ABDC.
The reason the stock cams seem like Atkinson Cycle is because they are so small.
Again, if you read it, you can see the pushback ratio is used, calculated, etc at ALL times. Not just blowthrough. They specifically are referring to it in reference to the slope of the line that represents the maximum amount of air a cylinder can hold at a given manifold pressure. I referenced that patent because it describes this effect, as well as going on to amend basically the patent you were showing for blowthrough effects. The 5.0 blowthrough tables are not populated because it obviously doesn't take place on the car as it rolls off the showroom floor, at least not in a significant enough amount to warrant being a part of the system. This however does not invalidate the pushback ratio as described in the patent.
LIVC air being pushed back into the intake is precisely what the pushback ratio is describing. It happens at all times, not just during blowthrough.
Perhaps a DMR of the value for your strategy would convince you, but that'd need some work from Eric
The patent you refer to I am also quite familiar with. Its to account for the effect of IMRC on VE. All of Ford's VE patents usually mention the effect of IMRC on VE, because it has an effect. In the oldest ones it was the "swirl control" valve. The adjustment of the IMRC has an effect on VE, and as such must be characterized by the VE system. It however, states nothing about what IMRC is for. Just that they compensate VE for it.
There's even a VE compensation for OVI in some vehicles for the slope and intercept I believe in some vehicles. The model is very thorough in characterizing the engine, but VE is about Airflow and things that have an effect on it. So lots of things play a part in it, including what are essentially miniature throttles in each intake port which would have a drastic effect on the MAP vs Aircharge curves.
I don't know why you're thinking they do something they don't. IMRC has existed for quite a long time across many different manufacturers, all for the same reasons. The only thing fancy about the new IMRC is that it is much less of a restriction than it was before because it now moves almost entirely out of the way.
Its for emissions and low-air velocity performance. I don't get where you're coming with the other ideas.
Yes over lap always occurs to some degree. It's a good thing. But like they say to much of a good thing.
But the point is I'm not talking about over lap when I say atkinson effect. I'm talking about the amount of LIVC. When the exhaust is closed and instead of starting compression the intake valve stays open and it starts pushing what it already pulled in to the combustion chamber back up into the intake manifold because it has no where else it can go.
The overlap stuff is me on a tangent, just read the parts about the intake valve. ;-)
They haven't opened and closed the intake valve at TDC and BDC since I think the 1800s. There is a history on it somewhere, I couldn't find it quickly. 100 years ago they found out that the air flow is more dynamic than that.
When the intake opens BTDC it is going to get a little exhaust in the manifold and when the exhaust closes ATDC it is going to get some exhaust in the cylinder. When the intake closes ABDC it is going to push mixture back into the manifold a little bit also. So it is not uncommon at all for the intake manifold to house things other than pure intake air.
Exactly they don't tell you what imrc is for. You have to look at the numbers and the times that imrc is open and closed and think about air volume and flow. What I'm seeing is They do not try to improve tumble and swirl but they act like a quick way to increase effective compression ratio by making it harder for what the piston pulled into the cylinder harder to be pushed back into the manifold. This is during low throttle and rpm when livc is at its most extreme. Once the cams rotate to a more optimal position the imrc would just restrict airflow into the cylinder.Again, if you read it, you can see the pushback ratio is used, calculated, etc at ALL times. Not just blowthrough. They specifically are referring to it in reference to the slope of the line that represents the maximum amount of air a cylinder can hold at a given manifold pressure. I referenced that patent because it describes this effect, as well as going on to amend basically the patent you were showing for blowthrough effects. The 5.0 blowthrough tables are not populated because it obviously doesn't take place on the car as it rolls off the showroom floor, at least not in a significant enough amount to warrant being a part of the system. This however does not invalidate the pushback ratio as described in the patent.
LIVC air being pushed back into the intake is precisely what the pushback ratio is describing. It happens at all times, not just during blowthrough.
Perhaps a DMR of the value for your strategy would convince you, but that'd need some work from Eric
The patent you refer to I am also quite familiar with. Its to account for the effect of IMRC on VE. All of Ford's VE patents usually mention the effect of IMRC on VE, because it has an effect. In the oldest ones it was the "swirl control" valve. The adjustment of the IMRC has an effect on VE, and as such must be characterized by the VE system. It however, states nothing about what IMRC is for. Just that they compensate VE for it.
There's even a VE compensation for OVI in some vehicles for the slope and intercept I believe in some vehicles. The model is very thorough in characterizing the engine, but VE is about Airflow and things that have an effect on it. So lots of things play a part in it, including what are essentially miniature throttles in each intake port which would have a drastic effect on the MAP vs Aircharge curves.
I don't know why you're thinking they do something they don't. IMRC has existed for quite a long time across many different manufacturers, all for the same reasons. The only thing fancy about the new IMRC is that it is much less of a restriction than it was before because it now moves almost entirely out of the way.
Its for emissions and low-air velocity performance. I don't get where you're coming with the other ideas.
Start from 1200rpm in a high gear and tell me the imrc is closed at full throttle. This would give you a point where air is moving at is slowest through the engine. Show me a log of this. My logs don't show the imrc closed during this time but open allowing for as much air to flow into the cylinder as possible. You only need the imrc for quick on demand torque while the engine is trying to be fuel efficient.
Just look at how much smaller of a hole that flap makes the intake manifold runner. My best guess is 2/3 of the port blocked off. Funny 2/3 if the stroke is not used and the port size is reducedces the same amount until the cams are in a better position.
driving-2015-mustang-things-want-know-640x480.jpg
Last edited by murfie; 02-04-2016 at 06:09 PM.
IMRC wouldn't be closed at full throttle, and has never been in any Ford calibration I've ever seen. At full throttle you typically have enough airmass per cylinder, even at the lower RPMs, to not need them, and as you allude, its a restriction in the intake and they don't want a pressure loss in an Optimum Power scenario. Youre in a high load scenario.
Look at how they command it. High Load Desired is always open. The targets in Best FE and Best Drivability are Load thresholds, and they open at higher loads. Lower load, low RPM is low airflow velocity. Which is why Load and RPM are the conditions keyed off of for determination of it being open or closed. Under Optimum Power mode, they open up because the air has enough velocity to naturally swirl or tumble through the head and valves per normal.
And they have told us what IMRC is for since they first put it in a vehicle: economy and emissions in scenarios with low air velocities.
You are wrong low load/ low rpm is a high vacuum condition. Vacuum is directly proportional to the speed the air is moving. You open the throttle and air doesn't move faster more gets in and it moves slower. You say it's critical to increase turbulence in a condition where air is moving slower. With the throttle wide open at low rpm its velocity will be at its slowest. You don't make more power by getting air to move faster. You make more power by moving more volume or as I'm saying keeping as much volume in the cylinder.
Cfm is what you want. Cfm is a volume not a velocity.
Think of how a vacuum cleaner works.
Last edited by murfie; 02-04-2016 at 06:27 PM.
I can see this is going nowhere. I don't know how to convince you otherwise. If you think air is moving its fastest at the lowest air masses in the cylinder, (I.e. when mass flow rate is at its lowest), which is the complete opposite, I don't know what to say.
MAP is at a local maximum when the valve first opens, as the cylinder is most filled. It drops as air moves into the cylinder. If your MAP signal wasn't filtered you'd actually see this (and with two MAP sensors you can actually use these drops to determine when valves are opening and which valves are opening, some higher performance small engines do this for example). That pressure difference between the cylinder and the manifold is what makes it move. The larger the pressure difference, the faster the flow, and the more air that can fill the given volume. This is why more MAP = More airflow, thats why you see MAP being proportional to aircharge, and that's why VE equations are MAP and RPM for a base.
I don't know what I can tell you to convince you otherwise, and I'm obviously a pretty poor teacher because I don't know if I'm communicating any of this right.
Is this the first time you've had a car with IMRC/TGV/Swirl Control Valves/etc? They've existed for a long time, and their purpose is well documented throughout literature. I posted that earlier patent about its purpose:
"The CMCV provides a tumble flow of intake air at high engine speeds and a swirl-type air flow at low engine speeds."
"A deflector can also be positioned adjacent the edge of the intake port into the combustion chamber. The deflector helps direct the air flow into a swirl pattern in the combustion chamber."
Some other reading on this:
For example Ford actually for a time didn't use IMRC to achieve this, instead utilized a slight offset in multi-valve opening chambers to create this turbulence:
https://patents.google.com/patent/US6705261B2/en
"Charge motion in the combustion chamber is an important factor for generating turbulence which in turn enhances the burn rate in the engines. However, the tumble and/or swirl generation often comes at the expense of discharge coefficient, thus reducing the maximum power output of the engine."
The discharge coefficient is what you're talking about, it is a restriction, which is why they have it on an actuator to disable in the first place
I don't know what else I could say to convince you of the purpose of IMRC. It improves on ever increasing demands for emissions, fuel efficiency, etc by allowing the engine to be more efficient at low air velocities where charge motion isnt strong enough to distribute the air and fuel evenly.
That patent doesn't even mention the use of cam shafts but rather very expensive electro-mechanical actuators to operate the valves 100% of the time. By doing this they can control when the two valves openings independent of each other. Another patent I've seen mentions a multi lobe co axis independent phasing cam shaft. They don't exist yet other wise GM would have them in the lsx/ltx motors.
If you are referring to the separation wall between the two values and using a butterfly valve to block off the amount if of air going to one valve to create swirl then I understand what you are referring to.
This doesn't explain how you make more power by defying physics of getting more volume into the cylinder with a smaller hole. The volume of air going into the cylinder is going to be determined by the bottle neck of the intake system. If you have x amount of air going through the TB you can not get any more than x going into the cylinder by reducing the intake port size. Or vise versa. Sure you can get more tumble and swirl but how does that make more power? The injector does a perfectly fine job of distributing fuel as the air goes into the cylinder.
Thats just it. You're assuming the injector does fine on its own to suddenly create a perfectly mixed air fuel setup. It doesn't. The injector does a good job of atomizing the fuel, which is not the same thing as distributing it. Charge air motion (tumble/swirl) is vital to get a good combustion event. Without it, you get worse emissions as you have rich spots and lean spots, and an uneven flame front (flame speed is drastically different in rich vs lean conditions) which means you don't combust as efficiently, you don't get the same BMEP out of the motor, and you thereby lose torque.
We aren't getting more volume of air into the cylinder. You're stuck on more power = more air, which while not inherently false, is inherently simplified. Almost every factor of the engine plays a role in power production for a given amount of fuel and air, ultimately limited by perfect efficiency of the combustion process. Compression ratio for example has a big effect. By definition better fuel efficiency means more power for the SAME amount of fuel. You can do more work (travel a longer distance) with the same amount of fuel.
The IMRC does create a restriction, but in this case it actually is a net benefit in the situations its used. It actually improves the overall efficiency of the motor in these situations, and it does this by adding much needed charge motion.
Nothing about it is defying physics, I think you're not understanding what it actually does and are trying to come up with some reason it supports your case instead of sitting down and just looking at what it does. If you believe an injector instantly distributes air-fuel perfectly, and that a vacuum has higher air velocities than WOT, both of which are things that actually defy physics, then I don't know what I can tell you that will convince you otherwise.
I bow out. You can continue down your course, I tried to offer helpful input, but I just don't have the motivation to try to explain why you're wrong anymore. You're welcome to continue down your path, and don't be shocked if more inquiries to Ford end with them not confirming your thoughts.
I totally understand what you are saying. Every thing you are trying to show me. Here is a video of it you might really enjoy.
https://youtu.be/OcXEwsrPQIQ
What I'm saying is Ford is claiming a power increase by a velocity increase. The velocity increase makes no sense. They should just say by directing The flow of air better. Saying increased velocity leads people to think more air volume.
"These plates play a huge role in the 2+ mpg and 20 lb/ft increase over the 2011+ Mustangs by keeping the port velocity high under low RPM driving."
The tumble and swirl makes sense. I'm just trying to add that while the engine is using timing giving more livc these plates can also restrict the volume being pushed back into the manifold.
I'm just pointing out that the information and explanations you are providing to me are misleading. Just like Ford's explanations. Then I'm trying to add information that maybe no one had thought about.
Last edited by murfie; 02-04-2016 at 09:05 PM.
They do not restrict the force pushed back into the intake, we already had this discussion. There is more than one cylinder acting on the intake manifold. Things are happening so fast at 3000 much less 7000 RPM that the air is moving out the exhaust. It's 100 steps out the exhaust for every step back into the intake manifold. This flow of air you are imagining would only be a factor at 1 RPM, not 650 - 8000.....
BTW, the cam events are exactly the same whether the IMRC are open or closed as I am sure you know. If air is moving slower at high RPM (which it is not due to the increased speed of the pistons) then why would the IMRCs be open and still have the same valve events? You wouldn't.
lb/min and CFM are rates of flow.....cubic feet PER MINUTE and lbs PER MINUTE.....that is a rate, not a volume. That is a volume in motion, not static.
CFM, what is it
Cfm times the amount of time gives you total volume. Time is a constant factor when talking about air flows.
So when you hear cfm you shouldn't think rate you should think volume. Bad explanation on my part sorry.
So when the intake valve is left open for more than 2/3 of the compression stroke where does that air go? It has to go back into the intake. And you can say the cam is not aggressive enough all you want. The duration is the duration and the valve being open is the valve being open. The ecu gives exact ivo and ivc weather is at .050 or .006(it is .006). We know the lift and duration of the cams are more than the 11-14. That's why I'm saying with the imrc closed its acting against this force. I get the feeling you think I'm talking about over lap. I'm not, I'm talking about the late intake valve closing. Or the modern day atkinson effect what ever you want to call it. You can't say the engine isn't atkinson because look at the .050 value. Then look at the opposite phase angle and say well look at the .006 value.
I didn't say air was moving slower at high rpm.
I said low rpm and throttle blade wide open.
The air velocity will be greatest at the bottle neck, but you will have the smallest amount of total volume or cfm at that point as well. The imrc direct air flow more than try to speed it up.
Last edited by murfie; 02-06-2016 at 03:51 AM.
The intake being left open is not left open at maximum lift it is almost closed and closing at that time. It is pressure relief and/or pumping loss relief, not cylinder expansion. Also as I said, there are other cylinders acting on the intake manifold so they can certainly pull while another pushes and the overall effect is nothing after they all had their turn.
Not talking about overlap, I know this.....but you are looking at this action in a vacuum, pun intended.
If you are going to call this engine Atkinson, you are calling every engine made in the last 100 years Atkinson because they all close the intake after bottom dead center. Is that your intention? If that is not your intention then you need to rethink what Atkinson really means and what the real purpose of IMRC are and what the real purpose of closing intake ABDC is....
Can you imagine how little spark lead we could get if IVC was BDC? How low max RPMs would be? Power production would be the worst. In fact, it was the worst when they did it.....IVC after BDC just allows the motor to spin rather than chug.
Last edited by Higgs Boson; 02-04-2016 at 10:56 PM.
I have already explained that I understand why leaving the valve open abdc is beneficial. I'm looking at both the Ivo and ivc as .006 events. The 259* duration is kinda a give away when they claim 263* duration. Now that means if Ford moves the ivo more than 2* past tdc the only reason for this is to move ivc further into the compression stroke. That to me is trying to achieve an atkinson like effect. They move the intake up to 20* atdc. If you add that to the already livc(which has its benefits) you get very livc.
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