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MAP Tooth IVC & IVO

Started by Ohio HD, December 21, 2021, 05:50:26 PM

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Ohio HD

In the Power Vision map under airflow there are two settings associated to intake valve open and close.

MAP Tooth IVC and MAP Tooth IVO.

The value shown for these I assume are the tooth count on the left flywheel. There are 32 teeth on the flywheel. How is the value for this determined? This MAP shows the IVC as a value of 30. How do you arrive at that? Cam timing is measured in crankshaft degrees. How do you determine where tooth 1 through 32 are in relation to the cam timing without actually measuring degrees of the crank against the cam timing? Or am I way off course?


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rigidthumper

Winpep 8 has a built in program called cam cruncher, which is supposed to have data for setting that.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

Jamie Long

The IVO/IVC settings in the PV calibration represent the crank tooth that corresponds with the intake valve open & close event related to MAP read. These settings directly affect the broadcasted MAP and are related to CDE effect which is used up to 60KPA. It's important to understand while these setting change reported MAP they don't change the actual running engine manifold pressure, IVO/IVC values are used as part of the calculation when the ECM polls the MAP sensor (plugging in a vacuum gauge to the split manifold will provide some insight to what goes on, especially at idle)

On Twin Cam engines the range of values we typically work with are IVO 6/7/8 and IVC 29/30. In the great majority of calibrations the IVC ends up 30, and IVO will depend on the camshaft; lowering the IVO value will lower MAP. When we develop a base calibration we look for the settings that give the best normality in the light/mid VE tables and a MAP curve that's proportional to actual engine load (rather than focus on idle MAP). In most Twin Cam moderate engine combinations the base settings we start with are 30/7 and if we need to lower the map a bit we drop IVO to 6 

hrdtail78

How ECM detects position of crank.  The ECM can detect the missing tooth.  Then it see the leading edge of no 1 tooth.  It also knows that 56.25 degrees after it see the leading edge of no 1 tooth.  That number 1 cylinder (rear) will be TDC.  All this tells the ECM crank position in a 360.  With a 4 stroke engine we need to give the ECM some kind of sync info to tell the ECM what phase the engine or stroke of engine.  Most engines out there use a something directly off cam.  The harley ECM uses the MAP sensor to detect intake stroke.  Once it knows crank position and phase.  It can know when to fire ignition and injectors.  It can also know when to poll the map reading.

So, as was mentioned.  You change tooth count and tell the ECM when valve events open with in a range of 11.25 degrees.  The degrees of rotation from leading edge to leading edge of teeth.  Programs with more resolutions can change this from leading edge to trailing edge and bring down the resolution to 64 tooth events instead of 32.

If you have no program to help with this.  A left case have, fly wheel, degree wheel and known valve timing events will also get you there.

In my opinion.  It would all be much easier to just use the cam as sync.  They actually had it all set up in the TCAA engines.  Pick up in cam cover and tooth on cam sprocket.  BUT that is neither here nor there.
Semper Fi

Ohio HD

Quote from: Jamie Long on December 22, 2021, 08:10:08 AMThe IVO/IVC settings in the PV calibration represent the crank tooth that corresponds with the intake valve open & close event related to MAP read. These settings directly affect the broadcasted MAP and are related to CDE effect which is used up to 60KPA. It's important to understand while these setting change reported MAP they don't change the actual running engine manifold pressure, IVO/IVC values are used as part of the calculation when the ECM polls the MAP sensor (plugging in a vacuum gauge to the split manifold will provide some insight to what goes on, especially at idle)

On Twin Cam engines the range of values we typically work with are IVO 6/7/8 and IVC 29/30. In the great majority of calibrations the IVC ends up 30, and IVO will depend on the camshaft; lowering the IVO value will lower MAP. When we develop a base calibration we look for the settings that give the best normality in the light/mid VE tables and a MAP curve that's proportional to actual engine load (rather than focus on idle MAP). In most Twin Cam moderate engine combinations the base settings we start with are 30/7 and if we need to lower the map a bit we drop IVO to 6

Ok, I see. The value is not a direct correlation to "exact" cam timing values. I did notice in a couple of MAPS I have the IVO is 6 and another is 8. The number 8 MAP being a larger motor and more radical cam.

The bike will be professionally tuned so that would take care of adjustment. I was just trying to better understand the MAP tables and some of the settings like this one that I'm not familiar with.

Ohio HD

Quote from: hrdtail78 on December 22, 2021, 09:40:22 AMHow ECM detects position of crank.  The ECM can detect the missing tooth.  Then it see the leading edge of no 1 tooth.  It also knows that 56.25 degrees after it see the leading edge of no 1 tooth.  That number 1 cylinder (rear) will be TDC.  All this tells the ECM crank position in a 360.  With a 4 stroke engine we need to give the ECM some kind of sync info to tell the ECM what phase the engine or stroke of engine.  Most engines out there use a something directly off cam.  The harley ECM uses the MAP sensor to detect intake stroke.  Once it knows crank position and phase.  It can know when to fire ignition and injectors.  It can also know when to poll the map reading.

So, as was mentioned.  You change tooth count and tell the ECM when valve events open with in a range of 11.25 degrees.  The degrees of rotation from leading edge to leading edge of teeth.  Programs with more resolutions can change this from leading edge to trailing edge and bring down the resolution to 64 tooth events instead of 32.

If you have no program to help with this.  A left case have, fly wheel, degree wheel and known valve timing events will also get you there.

In my opinion.  It would all be much easier to just use the cam as sync.  They actually had it all set up in the TCAA engines.  Pick up in cam cover and tooth on cam sprocket.  BUT that is neither here nor there.

Thanks Jason, a good explanation.
As I mentioned above, the bike will be tuned professionally, so it won't be me. I just wish to better understand what's going on in the MAP and effect on the motor.

 

hrdtail78

The function point of it:  You are basically centering your MAP based tables to get the most resolution for the different loads that need to be tuned for.  This is easier to see with map based VE tables.  For the most part.  Closed throttle should be some of the lowest KPA areas, and anything under load should show an increase of KPA.  If you are idling at 70 kpa.  You have less resolution for load areas and more resolution for no load or decel.  If you are idling at 20 kpa.  You have plenty of load area resolution but very little no load/decel area and it can be so low that light throttle cruising is too low for closed loop.  If you are 30-40 kpa.  You still have good resolution for load, light cruise and decel.  BUT same concept for target and spark.

Like mentioned.  It doesn't change how engine is running but a tool that will allows for a better final tuned bike.

Semper Fi

Jamie Long

December 22, 2021, 02:19:34 PM #7 Last Edit: December 22, 2021, 02:23:56 PM by Jamie Long
Good points above, its also important to note changing the IVO/IVC has the potential to affect any table that is driven by MAP load; commanded AF, timing, VE, and also quite a few other functions such as decel fuel cutoff, thresholds for closed loop operation, decel spark, spark temp correction just to name a few.

For example; if you had a calibration with IVO 8 and change the IVO to 6 and it lowered light load MAP by 15 Kpa, this would be enough to lower MAP enough where it could potentially affect overall operation, response, & tunability if the appropriate tables are not attended to.

 

hrdtail78

Basic cam cruncher for closing and opening.  Some knowns.  There are 32 teeth.  360/32= 11.25 degrees.  If we know the 5th tooth (56.25 degree) is at the CPS at rear tdc.  45 more degrees we are at tdc for front,  45/11.25= 4.  TDC front is tooth 9.  This would equate to BDC for front is another 180, 180/11.25=16.  16+9=25.  BDC of front is tooth 25.  25 becomes the constant.  Intake closing of the 640 is 60.  60/11.25= 5.3.  5.3+25 is 30.3.  Intake closing of the 570 is 40.  40/11.25=3.5.  25+3.5=28.5

Since we already now TDC of front is 9.  9 is our constant.  Intake opening of the 650 is 25.  25/11.25= 2.2.  9-2.2=6.8.  The 570 opens at 20.  20/11.25=1.7.  9-1.7=7.3

Now the rub.  First we are getting event numbers off cam card.  Not the actual opening and closing of valve.  The second is it isn't dealing in whole numbers with opening or closing.  This is why in TTS the estimated numbers don't always line up with using the actual opening and closing tools in Data Master, and why using the cam cruncher gets you real close but some trial and error is still needed.

Remember that these number only work with TC's.  The 56.11 constant does not work with the relocated CPS in the m8's. 
Semper Fi

Colvinb

I noticed after an update of winpep on my laptop that the cam cruncher tab is no longer there and I can't seem to find it anywhere. Anybody else have this issue?

hrdtail78

Quote from: Colvinb on December 28, 2021, 08:02:25 PMI noticed after an update of winpep on my laptop that the cam cruncher tab is no longer there and I can't seem to find it anywhere. Anybody else have this issue?

You need to reinstall and check the proper boxes to have it come up.  Scott from DJ can give the finer details or send a good email that can walk you through it. You got to make sure something is in the directory and PV must be in link mode yada yada.  Embarrassed to say that it isn't my strongest suit with computers.
Semper Fi

hdmanillac

Quote from: Jamie Long on December 22, 2021, 02:19:34 PMGood points above, its also important to note changing the IVO/IVC has the potential to affect any table that is driven by MAP load;...

Yes but sometimes it is useful to change these values for example when doing a stage 2 with an exotic camshaft.
2017 FLHR + 2019 FXLR + 2007 XL1200R

hrdtail78

Quote from: hdmanillac on December 30, 2021, 12:01:20 PM
Quote from: Jamie Long on December 22, 2021, 02:19:34 PMGood points above, its also important to note changing the IVO/IVC has the potential to affect any table that is driven by MAP load;...

Yes but sometimes it is useful to change these values for example when doing a stage 2 with an exotic camshaft.

I don't think anyone is saying changing IVO/IVC means MAP based tables don't need to be changed during tuning.  If anything.  I think this is more of reason to say to tune these tables after receiving the cal.  Somebody at a desk somewhere sets up these tables or sets them to what they have seen for a close combo.  Then when actually tuning you find a different setting that works better for the actual combo at hand.  Overlap and exhaust have influence over MAP readings. 

I brought up VE's and used it as an example because more people are familiar with this table.  But since it does affect all tables with KPA as an axis.  I recommend visiting all of them. 

Insert rant about starting cals are for a starting point only (here)   
Semper Fi