Alpha N map shape examples?

Hello all,

I’m currently working on tuning a car using Alpha-N strategy for the first time. My biggest issue is, the base map, using a normal speed-density “shape” to my VE map seems to have the lambda readings going all over the place from cell to cell. I use the same trick Andre teaches in the course for getting a rough shape into the base map. This is usually close enough to where I can get the car running smooth enough to do a little road tuning. However, this particular car (which is my personal car) is running a rather large cam with quite a bit of overlap, and trying to tune it using my usual speed density strategy just isn’t going to work well. It’s a 427” LS7, and the cam is about 26.5-27° of overlap. So, at idle it is only about 25-30kpa of vacuum, far less than what we see in my friend’s TT car that has a similar engine setup, with a far less aggressive cam.

Does anyone have any examples of an NA Alpha-N map that I can reference for general VE map shape? Or does anyone have any tricks to getting a map shaped out better? For clarity, I’m not asking for a working map. I know that’s not possible. Just some examples for some general VE map shape. I’d like to get at least the street driving area of this VE map more or less sorted before I hit the dyno to sort timing and WOT ramp runs. I need at least somewhat smooth to get enough momentum to get up the hill at the end of my street (10% grade) so I can get it out onto the road.

Any help you guys can give is greatly appreciated.

Is the fuel calculation still taking MAP into account or is it using BAP or some other assumed pressure? Is differential fuel pressure compensated in the fuel calculation? Is there an idle valve or brake booster etc that allows air to bypass the throttle?

One thing to keep in mind is the common LS DBW throttle has a funny scallop shape in it which makes the TP Vs airflow relationship unusually linear at small openings. You dont see a huge airflow difference between say 0% TP to 25%TP like you do with most throttles.

The map below is not a great example but probably the closest I have - LS3 race engine, stock intake manifold and DBW throttle. The VE calculation uses MAP in this case but this one was setup incorrectly with the differential fuel pressure assumed to be a fixed value (which it very much wasnt in the returnless setup). So the values around idle are smaller than they should be giving a more exaggerated range of VE. If fuel pressure comp was setup correctly the range of VE values would be more like 60-103% rather than the 38-103 range shown here. So you will have to imagine a less exaggerated version of this shape.