The new method is quite simple to set up:

Check VemsTune dialogs and help !

GenBoard/UnderDevelopment/AlphaN and Below is old, OBSOLETE information, the hybrid_rpm_... method is difficult to set up, not supported now (0,0 RPM or 25500,25500 RPM applies according to "load multiplication" setting). The new method is superior and simpler to set up.

TPS-MAP blending for hybrid_rpm_a < RPM < hybrid_rpm_m ; Load-multiplier - overview through examples

Traditionally, 3 modes are most practical:


[[Manual: Detailed.Control.Alpha.Config]]

Tuning is definitely more difficult than pure MAP based speed density.

Note that it is highly recommended to place an RPM bin (r table) on both hybrid_rpm_a and hybrid_rpm_m (3200 and 4800 RPM in the example) because the tables will look strange (and possibly steep) between these columns. The reason is the smooth, continuous change. The function that selects relevant table-lines blends smoothly from TPS to MAP as the RPM goes up from hybrid_rpm_a to hybrid_rpm_m.

Otherwise the TPS is highly nonlinear at low RPM, as an example, TPS=6% can result in 70% of the available power at 1000 RPM. Also note that any changes in the TPS sensor position (or calibration) will affect the VE table heavily in the alpha-n region.


Who uses it?

I only know a racing team with ITB-s that uses VEMS with alpha-n on a 4-cyl. Unfortunately they don't publish their stuff (to protect their" work" ). I know they blend from alphan to MAP from 2000 to 3000 RPM.

Single throttle-bodys should not be a big problem either.

GRM team MembersPage/GrmRacer has ITBs and will be trying it. as always we'll post our configs and tables. 4 clyn, 16v, 2.0L huge cams.. nitrous. Got the AlphaN working, There is a table that is MAP/RPM Ignition retard this needs to ZERO or else you will have ignition retard where you do NOT want it. Selecting AlphaN does not disable it. Runs like a scalded dog now! It is faster than my JCW mini! on less that 2000 USD

I'm (PeepPaadam?) going to use ITB's (from GSXR750)on my Porsche 931 Turbo though I was wondering if I could get away with the speed density tuning only and not blending?

I (MembersPage/JanneMantyla) use it on my Honda 16V SOHC engines with CBR954RR 42mm ITBs. Daily driver, works very smoothly, easy to tune too and pretty good fuel economy.

[[Manual: Detailed.Control.Alpha.Operate]]

See also