Hello. After reading about porting the intake elbow and buying better intake pipe. I couldn't believe what I was reading. Then I rembered that I have a megasquirt engine controller in the desktop drawer. Why not measure it my self then. Next I did a small modifications to it to have instead of one but two map sensors. Then made a very quick piggybank wiring harness to connect it to paraller to car ECM. Next day I routed quickly and ugly two hoses from the engine to the megasquirt. I took vacuum from the elbow and both vavcuum/boost from the SC plenum. Also for the readout clearance I wired accel pedal(not the plate) and engine rpm to it. Now in the log I can see how much engine has boost against engine rpm and accel pedal and elbow. It was interesting to see how the boost and elbow vacuum behaves when driving and especially in the highway where engine has more constant load and the load can be varied steadilly.

It was clearly seen that plenum vacuum turned to boost in fift gear as soon as gas pedal was over 24% open. Elbow still had like 80kpa vacuum which is ok as throttle is far from wot. But what's interesting is the vacuum at wot. Vacuum starts to became a noteable thing from around 3500rpm and up and it goes bad as 15kpa at 5700rpm. Boost is too dimishing above like 5000rpm as soon as it hits 75kpa. There is noise in the boost and pedal sensor signals so they aren't too accurate. Averaging gets boost value close enough to 80kpa to be accepted as healthy system. No noise in vacuum signal though.

So what I did not measure by doing it this way is how much there is vacuum before throttle valve and how much mina gallery etc intakepipe couldhelp in this.
I can publish megasquirt log file if someone is interested in. You need a software to read it.

It would be cool to measure now how much elbow porting makes difference and if not or not completely then move further. Extensive measurements I would say.

Vacuum values are all absolute.

 

Good info! Thanks for sharing.

 

Also check the intercooler pump is opperating.