Alpha-N barometric correction

[Touge Master]

Hi there,

I'm trying to figure out how to deal with barometric pressure changes in Alpha-N calibrations.
I know there is a MAP rescale based on atmospheric pressure but i wonder how it works when the car has been tuned on medium to high altitude.

Lets say a ITB tuned car on 1000 meters above sea level, that's around 90kpa atmospheric pressure.
So 100% TPS equals 90 kpa aprox and minimun percent TPS can be real high on wild cams ITB engines so lets say 50 kpa.

How the rescale option will affect fuelling and ignition when the same car runs at sea level?
Does the Hondata calculate above 100% TPS using the boost tables?

Thanks in advance.
Best regards.

[Spunkster]

ITBs are difficult to tune to begin with. What may work at high altitude may require a bit of retuning at a lower altitude or at sea level. This is the reason that most manufacturers do not offer ITBs from the factory.

http://www.hondata.com/help/kmanager/ma ... tsub=alpha

As the help file states: Scale calculated MAP by atmospheric pressure - scales the resultant table index by the current atmospheric pressure (based on standard pressure being 1013.25 mbar), in order to partially compensate for changes in air pressure and elevation.

[Touge Master]

Thanks for the reply Spunkster.

I've tuned many systems using Alpha-N and never need a retune. Just a proper baro and IAT correction. That leads to aprox. same altitud fuel differences as MAP based systems only being superseded by MAF based systems in elevation change stability. I know is difficult but just seems to me that in Hondata is more difficult than in other systems, let me explain why.

I think that Hondata don't uses a true Alpha-N (TPS vs RPM) just translate a TPS voltage value to a MAP value. The fuel and ignition maps remain MAP based but not based in MAP raw voltage, instead they use TPS voltage. Is just a way of give voltage stability to a kind of unstable input as is MAP voltage on wild cams, ITB setups.

Can you please tell me if, in an Alpha-N calibration, the "Engine Load" condition of Nitrous control is raw MAP or TPS to MAP converted/calculated values?

Thanks in advance.

[Touge Master]

Can you please tell me if, in an Alpha-N calibration, the "Engine Load" condition of Nitrous control is raw MAP or TPS to MAP converted/calculated values?

Thanks in advance.

Can i get a reply for this please?

Maybe i haven't explained the question propertly.

Best regards.

[Hondata]

The TPS is used for table indexes rather than the MAP sensor. I'm not sure why you think that this is not alpha-n.

[Touge Master]

The TPS is used for table indexes rather than the MAP sensor. I'm not sure why you think that this is not alpha-n.

I haven't said is not Alpha-N, i've said is not a true Alpha-N.
A true Alpha-N is just TPS vs RPM, being strongly recommended the use of IAT and barometric correction. An air pressure sensor is not needed unless used for reading open air for barometric correction, never reading vacuum as a MAP sensor.

The Kpro needs the MAP sensor to be connected and reading vacuum to index the TPS vs RPM tables so for me is not a true Alpha-N system.
Yes it's works, and can be tuned pretty decently, but IMHO a true Alpha-N with a separate barometric correction table is far easier to setup.

Can you please answer me the question about "Engine Load" in Nitrous control?

Thanks in advance.
Best regards.

[Hondata]

You're mistaken: KPro uses only TPS to index the fuel & ignition tables - MAP is not used, even if it needs to be present.

Nitrous controls under alpha-n use the converted TPS value rather than MAP.

If you have a question that specifically related to the tuning of a vehicle, I'd be happy to answer that, but arguing about whether TPS is used an an index with alpha-N is a waste of our time.

[Touge Master]

Nitrous controls under alpha-n use the converted TPS value rather than MAP.

Thanks.

Best regards.