Another Alpha N question

[slabbielad]

Hi,

I'm currently working on a microsquirted GSXR1100 Turbo. I'm grappling with the fuelling algorithm choice. I'm sure that the SD based setup won't work on my application as I have ITBs & the turbo meaning MAP will saturate pretty quickly at low speeds hence I think I need to be loking towards Alpha N. From the previous experience I have with other ECU systems they have always been Alpha N with MAP correction. From looking through the MS1 Extra documentation it appears that this feature was there (from the MS1 Extra manual) :

Hybrid Alpha N system adds KPa to an Alpha_N setup. See the Aplha-N settings section for more details on Alpha-N. This means that the KPa value becomes part of the fueling calculations, the same as in Speed density, so when you go into boost the fueling will increase even when you have the same VE value. The addition of fuel for boost comes through the MAP term in the fuel equation:
PW = REQ_FUEL * VE * MAP * E + accel + Injector_open_time

Am I missing something or is this feature missing from the implimentation on the MS2 (Microsquirt) implimentation?? Can this be done with the Alpha N option on Microsquirt?? I know the algorithm can be changes based on RPM but that isn't what I want.

Any thoughts chaps & lasses??

Stew

[grippo]

There is hybrid alpha N on both base and extra code, and both can be used to bring in MAP over a high rpm range. But there may be some specialized features in extra.

[Bernard Fife]

slabbielad,

It's referred to as "Alpha-N Blending" in the documentation: http://www.megamanual.com/mt28.htm#sa

Lance.

[24c]

Lance
There doesn't seem to be much in that link Is this the same as what you are describing ?
http://www.77e21.info/mstuning.htm

[slabbielad]

Just looking through the updates in the V2.889 Code (Microsquirt remeber) & the fuelling is derived :

When this is done, then the fuel pulse width is:


PW = Req_Fuel * .............. * MAP(kPa x10)/ Baro(kPa x10)...

So does this mean that if I select Alpha N & don't do a speed density changeover (or set it so its above the peed the engine will ever see) I will get correction from MAP once it goes above 100kpa?? Am I reading this correctly??

I guess I can't use the original V2 code as I won't have the dual spark option which I'm using (2 double ended coils with wasted spark).

Seems to be the more I read on this the more confused I become. Would be easy if I had anything other than a Microsquirt ECU!!

Stew

[grippo]

The options for alphaN are simple: you can use alphaN below rpm1, a mix between rpm1 and rpm2, and map/ speed density above rpm2. OR, you can reverse it and use map/SD below rpm1, mix in between and alphaN above rpm2.

When you use alphaN it calculates an equivalent map from the throttle position and your table of equivalent map vs tps position. This equivalent map (which can just be throttle position if you want) and the rpm are then used to go into the VE table and get a VE. In the blend region it calculates BOTH an alphaN and a SD VE value and then interpolates between them depending on where in the rpm region you are.

If you have a turbo, then you can use map at high tps/high rpm since boost continues to climb after you have maxed out the throttle. But you also get extra enrichment from the VE table, because the full term in the eq is map x VE(rpm,map), where 'map' can be either sensor map or a 'map equivalent' gotten from a table of equiv map vs tps.