Turbo95Max and I installed a VI on my car today.

I searched and there are many different opinions on the optimal activation point for the VI. So, what IS the best RPM to activate the VI? 4600? 4800? 5000? 5200? Please state and argue for your choice... Let's make this the definitive thread.

 

Your best bet is to tune it on the dyno.

But, if not, most people have had the best results setting it between 5000 and 5100.

 

Also another variable. Do you have an aftermarket ECU? It seems that 5200 was the number for people without the JWT ecu. 5000 seems like the # with the ECU.

 

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From what I have noticed the activation on the dyno indicated 5400 to be optimal, but when people go to the track 5000 seems to work the best. I'll be going to the track tomorrow and will do runs at different activation points. I'll reply with my reslults.

 

5000-5100rpm is optimal with the ECU. 5300rpm seems optimal without the ECU. All data from track time.


Dave

 

The theoretical activation point will be the same regardless of gear, but in reality there is a delay between when the RPM switch activates and when the VI opens. The faster the engine is revving, the later in the RPM the VI will open. In first gear you are ripping thru the RPM so fast it probably opens 5 or 600rpm late. In 2nd gear its probably 3-400rpm late, and in 3rd gear, as demonstrated by Mr. Cranman's dyno.

I have mine set at 5200 and I can actually feel the switchover right now. That is not good. It should be seemless, theoretically. It should switch at the exact point where the curves of mevi open and mevi closed cross. I'm going back to 5000, I don't feel it opening when I have it set at 5000.

 

I've done 28 Dyno runs now - 15 NA and 13 Boosted.

I tried the following points:

4000 1x
4500 1x
4800 2x
4900 2x
5000 4x
5200 3x
5400 2x
5600 1x

5000 was the best switchover point on the Dyno - Auto, 3rd Gear....stock ECU.

Also, I gained .3 seconds at 5000 at the track, and only .1 second at 5200. Problem with the track however is that there are more variables in play (hook up time, track conditions, etc) then on a Dyno.

All my Dynos were taken with relatively the same temp and humidity.

IanS