How to VCT tuning

[mJolnir]

I read an article from Master Engine Tuner about vct tuning, he said i should move vct table up, then down, check for knock and compare with the previews setting. If the tune is close and only needs a few tweaks that would work ok, but on aftermarket cams or even different manifolds like cobra jets it would take a lot of iterations to get it optimized.

How are you working the VCT tuning, and is there a method to do it on the track? (i get a lot of track rental invitations)

[Jn2]

You want to do it while on a dyno this way you can see how the curve changes based on what you change. Doing it on the track introduces too many uncontrollable variables that won't lead to accurate VCT adjustments.

[mJolnir]

You want to do it while on a dyno this way you can see how the curve changes based on what you change. Doing it on the track introduces too many uncontrollable variables that won't lead to accurate VCT adjustments.

Any method to not have to go through 100 dyno passes?

[MRRPMBRP]

Just go to place in the torque table & adjust. Most likely you have throttle errors too, if positive throttle error, add torque at that place, & vice versa

[Bill88stang]

are you looking for a good starting point to where to start moving the cams? if so I am too

[Thatwhite5.0]

The "proper" ways to tune VCT is change OP IVO all to 0. Change all OP EVC to 0. Then choose an RPM, say 4500 and retard the EVC by 2's, each time doing a pull. Once you found which angle 4500 makes the most power, take note, move on to 5000 RPM and do the same thing. Keep all of your best EVC angles through the RPM. Next 0 out your EVC and move on to IVO, getting the best angle per RPM. Then put your best IVO and EVC together and you have the best angles for your set up.

There are ways to do it without a dyno too, it just takes time to collect data.

[CCS86]

The "proper" ways to tune VCT is change OP IVO all to 0. Change all OP EVC to 0. Then choose an RPM, say 4500 and retard the EVC by 2's, each time doing a pull. Once you found which angle 4500 makes the most power, take note, move on to 5000 RPM and do the same thing. Keep all of your best EVC angles through the RPM. Next 0 out your EVC and move on to IVO, getting the best angle per RPM. Then put your best IVO and EVC together and you have the best angles for your set up.

There are ways to do it without a dyno too, it just takes time to collect data.

Why wouldn't you want to make the incremental EVC/IVO changes at all RPMs, then overlay curves and compare at each RPM increment. Seems like that would greatly reduce the number of pulls required.

Also, won't EVC/IVO affect one another? IE, just because a certain IVO value works best with EVC zeroed, doesn't mean it won't change when EVC is modified.

What techniques can you use without a dyno? I guess if you were using the same stretch of road and trying to keep temps equal, you could use Virtual Dyno to compare logs.

[Bill88stang]

I tried messing with the virtual dyno but they don't show a 15-17 mustang in there. picking up my hp tuners vcm unit tomorrow so I can finally start learning on my car.

[C_Murph12]

I asked my guy who is an OE calibrator and he strongly advised against doing this on the street or the track. "You need to spend some time on a load bearing dyno to do this properly otherwise you're just "tooning." Guys in the aftermarket aren't treating this like the science that is and that's why there are so many people like Lund making money hand over fist from people that could probably get pretty close if they chose to spend their money wisely"

[120Motorsports]

On the street if you measure your air flow numbers during each pull higher air flow equals more power if the numbers are low its having trouble breathing

[veeefour]

On the street if you measure your air flow numbers during each pull higher air flow equals more power if the numbers are low its having trouble breathing

Tuning cams with MAF reading is as stupid as looking for water with a stick...it works if you believable so...

[murfie]

Tuning cams with MAF reading is as stupid as looking for water with a stick...it works if you believable so...

LOL
The same thing could be said about just looking at a dyno number, or any single number. Dyno numbers are just another piece of data.
You have to look at it all through a lens of plausibility, which is usually only gained from experience(lots of pulls and logging), to make sure you have repeatability everywhere, to optimize any one thing.
Ford seems to do ok with just looking at a MAF signal for a great many things, but only because they have a high degree of accuracy in the rest of their models.

Targeting the highest load at all possible RPMs, will optimize torque and power everywhere, for the given fuel. Keeping load as high as possible after peak torque, will result in the best HP. Again, garbage data in , garbage results out.

[veeefour]

LOL
The same thing could be said about just looking at a dyno number, or any single number. Dyno numbers are just another piece of data.
You have to look at it all through a lens of plausibility, which is usually only gained from experience(lots of pulls and logging), to make sure you have repeatability everywhere, to optimize any one thing.
Ford seems to do ok with just looking at a MAF signal for a great many things, but only because they have a high degree of accuracy in the rest of their models.

Targeting the highest load at all possible RPMs, will optimize torque and power everywhere, for the given fuel. Keeping load as high as possible after peak torque, will result in the best HP. Again, garbage data in , garbage results out.

Looking for MAF signal is OK, but without psychical baro sensor it's more about correct model and guesstimattion.

I've compared few stock cars on very good dyno - torque model was off only by few Nm's so it's accurate AS LONG YOU KEEP IT STOCK.
Now no matter what you do if you go aftermarket you can forget about that model forever, even simple MAF temp correction is affected by your new CAI.
Humidity goes +20% and your MAF to actual torque ratio is already in deep shit...this is where you have only a theory and I have at least 100h of experience LMAO

Not often I do not agree with you but add +1 to the list.

Now +2018 Bosch ECU has a physical baro sensor...

[Zap]

it works we have actually watched air flow numbers on the dyno just to be able to do it without a dyno but everyone works different use whatever you are comfortable with and what works for you

[engineermike]

Air flow measurements can?t tell you how efficiently you are using the air. For instance, spark timing will not change airflow but can certainly affect power.

[murfie]

So for optimizing VCT purposes, What would your approach be with regards to timing while figuring it out?

I would say lock it low away from actual detonation borderline, find VCT angles with the highest loads giving you the best cylinder fill, then go back and optimize timing to MBT or borderline. On a dyno you could do the same thing, just find the highest torque instead of load. By lock it low I dont mean pick a value like 10 or 15, but something proportional to what the MBT value is. So like instead of just running some expensive high octane fuel and MBT timing, just have a timing curve shaped like the MBT curve but half or some other proportion of the value that keeps you away from detonation.

[engineermike]

Man, that?s a can of worms...I can certainly see why ford uses the ?mapped point? approach. Because 28 is way less than infinity. I don?t think it?s really fair to lock the timing at a low value because different cam timings will have different MBT?s. So, if you lock spark timing at one value then a cam timing that might have a higher MBT would be unfairly penalized. I can?t imagine an accurate way of doing it short of running it through an array of possible combinations of load, speed, ivo, evc, spark, cmcv, and perhaps even a/f. The number of combinations is staggering. I bet ford has an automated process for running an engine through all these combinations to find optimums.

As a side note, murfie, I?m noticing that my ?mainstream? cal seems to have changed cam timing such that Atkinson is not taken advantage of at all. At cruise my ivo is typically 30 and evc is 10-20. Stock on an ?18 is 40/45 typically. What was your conclusion around Atkinson vs cmcv? Does cmcv affect whether or not atkinson can be effective, in your determination?

[murfie]

Can of worms is right.

I think it was actually Otto Vs CMCV/Atkinson, and I was looking for tuning improvements for fuel economy in most of those old discussions.
What do you mean by effective, whats the goal? Fuel mileage Late IVC. Power earlier IVC for more effective compression. I posted a link to a spreadsheet in one of these thread that tracked all four IVO, EVC, EVO, and IVC in a Bi-doughnut graph and showed how different angles effected compression and power stroke length.

IMRC/CMCV what ever you want to call them, only effect distribution of fuel ratio in the cylinder, so while the average AFR my be your 14.08 to 1, where the spark plug is should be richer, and further from the spark plug leaner, making the flame front change its speed in a predictable way as it travels. Usually beneficial for combustion stability with very low cylinder filling conditions. Regardless once the manifold pressure or VCT allows cylinder fills with a more dense charge, stability is just a side effect and CMCV become a restriction.
Great for reducing emissions and improving fuel economy as you can run at lower air and fuel mass in the cylinder that are still stable. You don't gain part throttle torque by using Atkinson like VCT strategy.

[veeefour]

Air gets denser, your MAF sensor measures the volume your baro sensor can measure the density but you don't have any baro sensor on 1&2 gen coyote. Gen 3 has one build inside the PCM.

Watching your MAF and thinking more flow makes more power is wrong. If you see 20lb more you are making more power for sure.
But if are going to tweak the cams and look for 1-2lb flow change then you should stop tuning those cars and try other profession.

[murfie]

MAF sensors measure mass. The MAF reads a higher value on a low DA day than it does on a higher DA day.
Baro sensors, like MAP sensors, measure pressure.
Obviously in both cases you have temperature sensors.
Volume is a static given volume, like manifold, cylinder, or MAF tube(a function of the transfer).
Density is calculated by the ECU. Yes air density changes, the ECU does a damn good job keeping track of it or fueling would be all over the place, baro sensor or not.

FYI humidity has a very minimal effect on air density until like 130f*-140*f(55-60*C)(328-333*K), at which point you have other things robbing you of power to worry about. Kinda why they didn't even bother putting in a compensation table for it. So much for all your experience/wasted time.

moist air density.PNG