Tuning ITBs on a Racecar and what I learned.

Tuning concepts, methods, tips etc.

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muythaibxr
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Re: Tuning ITBs on a Racecar and what I learned.

Post by muythaibxr »

dontz125 wrote:Given the dependance on % baro, are ITB tunes more sensitive to elevation changes than pure SD?
No, they should be less dependent...
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muythaibxr
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Re: Tuning ITBs on a Racecar and what I learned.

Post by muythaibxr »

whittlebeast wrote:Is there a way to derive an ITB map with the data I have in MLV? This car is not the slightest bit streetable and I would not be able to get on the dyno till after race season. I only have about 4 events left this season that I will be able to get to.
There may be, It could certainly be done if you can figure out what load would be with itb mode in each situation.
What is the formula for ITBLoad?
Basically it scales 0-90 kpa down to 0 to load at switchpoint when in SD, and it scales switchpoint tps to 100% tps down to load at switchpoint to 100 when above the switchpoint. This way you get a smooth transition from overrun loads all the way up to 100%, switching to alpha-n where it makes sense.

Ken
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KenK
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Re: Tuning ITBs on a Racecar and what I learned.

Post by KenK »

7/7/16

From the discussions so far, I can see that elevation issues are significantly more problematic with a normally aspirated motor. In a turbo charged or blown motor, elevation issues would be a non-issue as the ABS pressure at any given load would be constant up to the elevation where the turbo or blower could not keep up with the demand. In most cases, I would think that this would be at an elevation somewhere above 1800 meters.

In my case, I am running a naturally aspirated motor and lower loads and RPM regions are very important to me. WOT loads are important in that I don't want the motor to go lean and I can see that happening at higher elevations.

Since my car is not street legal, so I have limited tuning opportunities as well. Additionally, where I run the motor is quite often at different elevations.

Something that I would like to find is some kind of data logger that can be tide to the MS2 that is not a laptop. What are you guys using??

Ken
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Re: Tuning ITBs on a Racecar and what I learned.

Post by whittlebeast »

I use the onboard SD card in the MS3x setup. Shadow dash my be an option for you. All you need is a spare Android hard wired to the ECU. Data rates are fairly fast.

See http://tunerstudio.com/index.php/cablesandbluetooth

Andy
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Re: Tuning ITBs on a Racecar and what I learned.

Post by muythaibxr »

KenK wrote:7/7/16

From the discussions so far, I can see that elevation issues are significantly more problematic with a normally aspirated motor. In a turbo charged or blown motor, elevation issues would be a non-issue as the ABS pressure at any given load would be constant up to the elevation where the turbo or blower could not keep up with the demand. In most cases, I would think that this would be at an elevation somewhere above 1800 meters.

In my case, I am running a naturally aspirated motor and lower loads and RPM regions are very important to me. WOT loads are important in that I don't want the motor to go lean and I can see that happening at higher elevations.

Since my car is not street legal, so I have limited tuning opportunities as well. Additionally, where I run the motor is quite often at different elevations.

Something that I would like to find is some kind of data logger that can be tide to the MS2 that is not a laptop. What are you guys using??

Ken
The feature is designed to factor in barometric pressure. It should be fine as long as the baro correction curve and air temp correction curve are correct.
Megasquirt is not for use on pollution controlled vehicles. Any advice I give is for off road use only.
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Re: Tuning ITBs on a Racecar and what I learned.

Post by Moody »

muythaibxr wrote:
dontz125 wrote:
muythaibxr wrote:1 table in ITB mode.
Well - one table and two curves. Curious - what's the workload / effort like, tuning the switchpoint curves?
Easy. Drive it a bit while datalogging, use MLV scatter plot to map the throttle position at 90 %baro, set the switchpoint curve to what you find, and leave the load at switchpoint curve alone with its defaults unless you have a really good reason not to.

I have followed this advise but a have a small question, I am expecting to see the "curve" for the swithpoint to be set in a straight line all the way across the rpm range? for an example on my log the 90% of Baro is 12% throttle position, so I will just leave the line straight across 12% from idle to the redline on the tps switchpoint graph (left).... Am I thinking correctly?
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Re: Tuning ITBs on a Racecar and what I learned.

Post by Stedi »

Hey I did these visualisations of how the ITB load is calculated when I tried to get my head around it.

Sorry I don't have a tune & log for you (yet) of my car. Currently just driving with alpha-n to get some data.
Just upgraded to MLVHD and histogram seems to be a nice way to get the 90kpa - tps curve, what kinda filtering one should apply to the data to get the correct curve?

The 90kpa - tps value seems to vary wildly depending on the tpsdot.
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Re: Tuning ITBs on a Racecar and what I learned.

Post by Peter Florance »

I've got limited experience with ITB mode, but it seems to work very well.
Both cars I tried to tune had setup problems, so have not yet finished.

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Re: Tuning ITBs on a Racecar and what I learned.

Post by muythaibxr »

Moody wrote:
muythaibxr wrote:
dontz125 wrote:Well - one table and two curves. Curious - what's the workload / effort like, tuning the switchpoint curves?
Easy. Drive it a bit while datalogging, use MLV scatter plot to map the throttle position at 90 %baro, set the switchpoint curve to what you find, and leave the load at switchpoint curve alone with its defaults unless you have a really good reason not to.

I have followed this advise but a have a small question, I am expecting to see the "curve" for the swithpoint to be set in a straight line all the way across the rpm range? for an example on my log the 90% of Baro is 12% throttle position, so I will just leave the line straight across 12% from idle to the redline on the tps switchpoint graph (left).... Am I thinking correctly?
No it probably won't look like that.

Mine goes in a mostly straight line connecting 5% at idle to ~20% at redline.
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Re: Tuning ITBs on a Racecar and what I learned.

Post by muythaibxr »

Stedi wrote:Hey I did these visualisations of how the ITB load is calculated when I tried to get my head around it.

Sorry I don't have a tune & log for you (yet) of my car. Currently just driving with alpha-n to get some data.
Just upgraded to MLVHD and histogram seems to be a nice way to get the 90kpa - tps curve, what kinda filtering one should apply to the data to get the correct curve?

The 90kpa - tps value seems to vary wildly depending on the tpsdot.

You should use the scatter plot like I said. It makes it easy to see and discard outliers. There will be some at fast TPSdots because MAP always lags behind throttle position.
Megasquirt is not for use on pollution controlled vehicles. Any advice I give is for off road use only.
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Re: Tuning ITBs on a Racecar and what I learned.

Post by whittlebeast »

Here is where I wound up. Fortunately the motor came apart in a big way and it looks like I will be starting over with a B18A. The next motor will be ITB unless I can find a version with a variable length intake.

The final tune and data logs can be found here.

http://www.nbs-stl.com/CRX/CRX%20ITB%20Last%20Day.zip

The car was running fantastic until a rod cap exited the block and shot thru the radiator.

Andy
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Re: Tuning ITBs on a Racecar and what I learned.

Post by whittlebeast »

I posted this on a different thread but I wanted to include it here now that the motor is starting to get close. Notice that the fueling makes a transition to ITB tuning at about 85 KPA or about 30% TPS. I am going to try AN primary tuning with SD secondary table next, just for fun.

<<<<<<<<<<<<<<<<<< snip >>>>>>>>>>>>>>>>>>

Here is a series of screen shots off my ITB Honda race motor. The data has been filtered to only show data where the motor is making some power. I did that by filtering out data below a MAPxRPM of 2800. The plot on the right only shows 3500 to 8500 RPM in 500 RPM increments. Keep in mind that I was tuning this motor SD primary and AN as a secondary load multiplied.

http://www.nbs-stl.com/tuning/ITB%20Pow ... %20RPM.png

http://www.nbs-stl.com/tuning/ITB%20Pow ... %20TPS.png

http://www.nbs-stl.com/tuning/ITB%20Pow ... %20MAP.png

http://www.nbs-stl.com/tuning/ITB%20Pow ... ttling.png

http://www.nbs-stl.com/tuning/ITB%20Pow ... rtions.png

http://www.nbs-stl.com/tuning/ITB%20Pow ... Totals.png

http://www.nbs-stl.com/tuning/ITB%20Pow ... %20AFR.png

All shots are the same data but the color has been changed to demonstrate different things.

Added: Keep in mind that this MAPxRPM vs DC pattern only happens on ITB motors. Almost all other motors wind up as a nearly straight line.

Andy
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Re: Tuning ITBs on a Racecar and what I learned.

Post by Laminar »

Did you remove all of the images/files from your site?
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Re: Tuning ITBs on a Racecar and what I learned.

Post by whittlebeast »

Yes. It was not my choice.
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Re: Tuning ITBs on a Racecar and what I learned.

Post by dll67 »

I hope you find somewhere to host them ... There was a plethora of excellent info there
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Re: Tuning ITBs on a Racecar and what I learned.

Post by SteinOnkel »

I, too, would be very thankful if you could re-upload the images.

Perhaps to an image hosting site like imgur?
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Re: Tuning ITBs on a Racecar and what I learned.

Post by eekoog »

I just found this thread. Great infos there.

PLEASE can you re host your pics ? I never saw them and i am sure it would be immensely helpful.

Thank you Andy.
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