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what does ivo/ivc setting actually affect ?

Started by jjdalynh, August 25, 2018, 04:25:46 PM

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jjdalynh

title says it.  just looking for education. 

Ohio HD

So that the MAP data instructs the ECM when exactly to fire the injectors is what I always understood. 

98fxstc

Quote from: Ohio HD on August 25, 2018, 04:47:28 PM
So that the MAP data instructs the ECM when exactly to fire the injectors is what I always understood.
:up:
I know TTS has it, not sure about the others
will have a nice idle if you get it right
the theory is that there is no point having the air/fuel mixture hitting the back of a closed intake valve
more effect at lower rpm
doesn't matter too much after about 3000 ? rpm because your valves are opening and closing pretty quick

rigidthumper

Manifold pressure varies greatly during the various phases of the engines events, & cam timing affects the manifold pressure. They needed a way to measure MAP (manifold absolute pressure) consistently, (they do this by counting the number of teeth on the flywheels, and poll the sensor at the same time) so they could determine load. They use this to help build the spark & fuel tables.
They use IVO/IVC to help keep the measurements in a normal range.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

jjdalynh



what would be the detriment (what's the symptom) of having ivo off by a tooth (or 2?). 

Coyote

For one thing, your MAP at idle could be too high or too low. Possible less stable as well I would guess.

rigidthumper

Use a data logger and see where idle MAP (Kpa) stays. If your idle @ normal operating temp is some where between 35-45 Kpa, you're prolly close.
Ignorance is bliss, and accuracy expensive. How much of either can you afford?

jjdalynh

 :oil:
Quote from: rigidthumper on August 25, 2018, 07:23:07 PM
Use a data logger and see where idle MAP (Kpa) stays. If your idle @ normal operating temp is some where between 35-45 Kpa, you're prolly close.

it's in the lower range.  a 30 sec idle average at 33.62.  high 37.61, low 31.33.
Woods 8 cam, (stock CDE table). idle avg 1035 (set to 1030) high 1109, low 912. 

Frédéric CM

IVO affect the MAP reading at low rpm only (<2000), IVC affect the map reading on all the rpm range.

jjdalynh

Quote from: Frédéric CM on August 26, 2018, 10:56:44 AM
IVO affect the MAP reading at low rpm only (<2000), IVC affect the map reading on all the rpm range.

can you elaborate?

Gordon61

September 09, 2018, 02:45:00 AM #10 Last Edit: September 09, 2018, 02:54:47 AM by Gordon61
Me and Frederic were chatting about this a while back.

The moving piston sucks the air/fuel in, the injector spits the fuel, the ECU is the bit that tells the injector when to start spitting and when to stop, but, the injector is only designed to spray so much fuel per second.

IVC must have something to do with when to stop the injector spitting fuel.  By the time the piston gets to BDC there is no more suck happening so it would only be the inertia of airflow that would bring in any more fuel.  I expect the injector stops a bit before IVC but that number is probably in the calculation somewhere.

If you do some sums, you realise that the period of time the intake valve is open is not always long enough for the injector to get the fuel past the open valve.

e.g.
1 rev (360º) @3500 = 17.1ms
the Andrews 57H that we were discussing is open (@ .053”) for 236º = 11.2ms

so 10ms of fuel for example doesn’t (or doesn’t need to anyway) spit on the back of the valve, 16ms does.  Or, anything above an injector duty cycle of 32.8% the fuel is spitting on the back of a closed valve ...so IVO is kind of irrelevant.

So that's IVC ...at the very least there is no point spitting fuel after the valve is shut and that affects all across the rev range.

At lower revs, there is plenty of time between the valve opening and closing to get all of the necessary fuel spat in. BUT... the complicated bit is that the amount of suck (MAP) changes over the travel of the piston so when to spray the fuel affects how well the air/fuel is mixed.  Incidentally, one of the other guys told me that spitting some fuel on the back of the valve may actually give better atomisation than waiting until the valve is actually open.  This is where IVO comes into the calculation and has an effect.

I came to the conclusion that IVO was crucial to getting a well mannered machine at lower revs. Well, IVO and CDE :)

jjdalynh

so, are we trying to sample/start sampling when the valve is just opening/closing or when it's still/just closed?   i understand that MAP and temp is a measure of how much air is in the intake getting sucked into the cylinder, but is it a single point/small window sampling of MAP to calculate volume of charge or is it a continuous sampling of the entire intake cycle?

i also understand CDE, and that it's hard to correctly calculate.  with a woods 8 cam and the fast ramps that it has i'd think that the CDE would necessarily be fairly high at low rpms (36 deg overlap) and drop precipitously at higher rpms due to the velocity of the intake charge at that point. 

i also can see how CDE would be able to be somewhat ignored by using VE settings to account for the dilution (making it seem like their is worse breathing at low rpms than it actually is).

KE5RBD

Quote from: jjdalynh on August 25, 2018, 05:20:16 PM


what would be the detriment (what's the symptom) of having ivo off by a tooth (or 2?).
If you have one cam off to the other, then the compression will vary about 20#s between cylinders.  Say the rear cam is advanced 1 tooth then the compression on the rear cylinder is going to be about 20#'s higher than the front.  If it is 1 tooth retarded then about the same only front will be higher.  If both are off then you can expect higher compression if advanced or lower if retarded.  If either is the case bike may be hard to start and will not run real well and is impossible to tune right.  If bike was running right and now it isn't and the cam chest hasn't been into not likely the cause of issue. 
As to your original question IVO and IVC.  The close greatly effects the cranking compression.  With stock compression on later model Twin Cams around 41 degrees on the Intake closed is the norm.  Not saying won't work well with few more degrees.  With increased compression ratio you can run higher closed numbers.  For instance a stock twin cam with 30 degrees exhaust close you are around 191 cranking compression.  With a 41 degree close you are at 182 cranking compression which is little low and torque down low will suffer greatly.  With 10.5 compression on same 41 degree cam you get around 203 which is more ideal.  With the stock 30 cam you will be up around 214 cranking.  An engine builder/cam manufactor told me to pick cam by compression ratio is good rule of thumb.
2019 FLHTK Hammock Seat S&S MK 45 Slip ons Street Tuner.

1FSTRK

Quote from: KE5RBD on September 10, 2018, 02:05:17 PM
Quote from: jjdalynh on August 25, 2018, 05:20:16 PM


what would be the detriment (what's the symptom) of having ivo off by a tooth (or 2?).
If you have one cam off to the other, then the compression will vary about 20#s between cylinders.  Say the rear cam is advanced 1 tooth then the compression on the rear cylinder is going to be about 20#'s higher than the front.  If it is 1 tooth retarded then about the same only front will be higher.  If both are off then you can expect higher compression if advanced or lower if retarded.  If either is the case bike may be hard to start and will not run real well and is impossible to tune right.  If bike was running right and now it isn't and the cam chest hasn't been into not likely the cause of issue. 
As to your original question IVO and IVC.  The close greatly effects the cranking compression.  With stock compression on later model Twin Cams around 41 degrees on the Intake closed is the norm.  Not saying won't work well with few more degrees.  With increased compression ratio you can run higher closed numbers.  For instance a stock twin cam with 30 degrees exhaust close you are around 191 cranking compression.  With a 41 degree close you are at 182 cranking compression which is little low and torque down low will suffer greatly.  With 10.5 compression on same 41 degree cam you get around 203 which is more ideal.  With the stock 30 cam you will be up around 214 cranking.  An engine builder/cam manufactor told me to pick cam by compression ratio is good rule of thumb.

You may want to read the thread from the beginning, then reread his question.
"Never hang on to a mistake just because you spent time or money making it."

KE5RBD

Quote from: 1FSTRK on September 10, 2018, 03:14:08 PM
Quote from: KE5RBD on September 10, 2018, 02:05:17 PM
Quote from: jjdalynh on August 25, 2018, 05:20:16 PM


what would be the detriment (what's the symptom) of having ivo off by a tooth (or 2?).
If you have one cam off to the other, then the compression will vary about 20#s between cylinders.  Say the rear cam is advanced 1 tooth then the compression on the rear cylinder is going to be about 20#'s higher than the front.  If it is 1 tooth retarded then about the same only front will be higher.  If both are off then you can expect higher compression if advanced or lower if retarded.  If either is the case bike may be hard to start and will not run real well and is impossible to tune right.  If bike was running right and now it isn't and the cam chest hasn't been into not likely the cause of issue. 
As to your original question IVO and IVC.  The close greatly effects the cranking compression.  With stock compression on later model Twin Cams around 41 degrees on the Intake closed is the norm.  Not saying won't work well with few more degrees.  With increased compression ratio you can run higher closed numbers.  For instance a stock twin cam with 30 degrees exhaust close you are around 191 cranking compression.  With a 41 degree close you are at 182 cranking compression which is little low and torque down low will suffer greatly.  With 10.5 compression on same 41 degree cam you get around 203 which is more ideal.  With the stock 30 cam you will be up around 214 cranking.  An engine builder/cam manufactor told me to pick cam by compression ratio is good rule of thumb.

You may want to read the thread from the beginning, then reread his question.

I actually did read the entire post and jjdalynh asked three questions.  I answered two of them and made note of which one I was attempting to answer.  Why did you put this statement about "You may want to read the thread from the beginning, then reread his question." I did answer the first one last, so obviously you didn't read my post. 
2019 FLHTK Hammock Seat S&S MK 45 Slip ons Street Tuner.

1FSTRK

Quote from: KE5RBD on September 10, 2018, 05:30:00 PM
Quote from: 1FSTRK on September 10, 2018, 03:14:08 PM
Quote from: KE5RBD on September 10, 2018, 02:05:17 PM
Quote from: jjdalynh on August 25, 2018, 05:20:16 PM


what would be the detriment (what's the symptom) of having ivo off by a tooth (or 2?).
If you have one cam off to the other, then the compression will vary about 20#s between cylinders.  Say the rear cam is advanced 1 tooth then the compression on the rear cylinder is going to be about 20#'s higher than the front.  If it is 1 tooth retarded then about the same only front will be higher.  If both are off then you can expect higher compression if advanced or lower if retarded.  If either is the case bike may be hard to start and will not run real well and is impossible to tune right.  If bike was running right and now it isn't and the cam chest hasn't been into not likely the cause of issue. 
As to your original question IVO and IVC.  The close greatly effects the cranking compression.  With stock compression on later model Twin Cams around 41 degrees on the Intake closed is the norm.  Not saying won't work well with few more degrees.  With increased compression ratio you can run higher closed numbers.  For instance a stock twin cam with 30 degrees exhaust close you are around 191 cranking compression.  With a 41 degree close you are at 182 cranking compression which is little low and torque down low will suffer greatly.  With 10.5 compression on same 41 degree cam you get around 203 which is more ideal.  With the stock 30 cam you will be up around 214 cranking.  An engine builder/cam manufactor told me to pick cam by compression ratio is good rule of thumb.

You may want to read the thread from the beginning, then reread his question.

I actually did read the entire post and jjdalynh asked three questions.  I answered two of them and made note of which one I was attempting to answer.  Why did you put this statement about "You may want to read the thread from the beginning, then reread his question." I did answer the first one last, so obviously you didn't read my post.

Forgive me if I am mistaken but I believe the OP posted here in the tuning section because he was asking about "what does ivo/ivc setting actually affect?" in regards to the IVO/IVC settings in the tuning programs. Most of the replies by others are about the same thing, software settings, that tell the ECM when to poll the map sensor so it gets a pressure reading the software can work with accurately. It is called IVO/IVC but does not have to or very often match exact cam events.
"Never hang on to a mistake just because you spent time or money making it."

jjdalynh

This was about what does the IVO/IVC setting in the software do and what does the Delphi ECM do with the value.  does it take the IVO crank tooth number setting and take a single MAP sample there, or does it start at that value and read MAP for more than 1 crank teeth and do a calculation based on that (when below 2000 RPM)?  TTS has a method for figuring out best IVO at idle, so it would seem this is below 2K and high vacuum whereas IVC is determined during runs on dyno at 3500RPM and above.  So, in a speed density system knowing that MAP and displacement and intake temp and VE can be used to calculate the volume of air going in (displacement and temp being easy to understand), how exactly is the correct MAP reading determined (understanding that MAP is going to be variable throughout the engines cycle)?

Frédéric CM

You can do the TTS method for determining the IVO using the MAP reading at idle for each IVO value.
Enter them on the XLS file attached and choose the setting with the more inflection.

jjdalynh

Quote from: Frédéric CM on September 11, 2018, 06:25:35 AM
You can do the TTS method for determining the IVO using the MAP reading at idle for each IVO value.
Enter them on the XLS file attached and choose the setting with the more inflection.
Nice, thanks.  So in your example 7 would obviously be the recommended setting.  This presumes that you are able to change this param yourself.  I don't have the tuners version of winpv so It's not available to me to experiment with directly.  I haven't tried too hard reversing the .pvt file format.  Seems that there's a checksum in there at a couple spots, so locating and editing the hex file obviously isn't enough. 


jjdalynh

do you use the PV to set the idle speed to those RPM breaks when you are logging, or is that just a chosen set of breaks for the idle run recorded?

Frédéric CM



Gordon61

Quote from: jjdalynh on September 11, 2018, 06:09:11 AM
does it take the IVO crank tooth number setting and take a single MAP sample there, or does it start at that value and read MAP for more than 1 crank teeth and do a calculation based on that (when below 2000 RPM)?

Good question, and and one for whoever knows the intimate capabilities of and developed the ECU I suspect.

A typical intake cycle is shown here... https://www.hotrod.com/articles/ctrp-1008-intake-reversion/

While integrating MAP variation over the time the valve is open would be more accurate, picking a single point and guesstimating the MAP variation profile may get it close enough and is possibly what is done.

If I remember correctly someone once told me that IVC was when a reading was taken for CDE purposes, while the IVC was the main reading used for fuel purposes.

IVO together with CDE tuning I found helps smooth out horrible transitions you can get between VE table cells in the low load area ...smoother, not as deep a hole in the VE table down there seemed to give me a much smoother ride at lower revs.