Al

I measure it at the dynamic/plenum chamber, just under the throttle body.

Tracy

Hum-m-m.   That’s about equivalent to me measuring it in the air plenum before the TB.  It would be very interesting to know what it is on yours about 4” from the intake port.  Then there is the whole question of ‘which’ MAP pressure the EC-2 should be interpreting – or maybe it doesn’t matter. . .

Al

 

Before the TB?   I don't follow you.  Ideally, that would be true at WOT only, but it would be a fairly useless figure.  And it would definitely matter to the EC2 if you tried to measure MAP there  (i.e.,  Would Not Work ).

Just meant equivalent at WOT, before pressure drop in tubes (my TB is like a 5” long tube)

 

At one time I did measure the MAP at the far end of the small (primary) runners and found a .8" Hg drop at WOT compared to dynamic chamber reading. 

 

At what RPM? This is really what I was after; a feel for the pressure drop due to flow losses, and trying to understand the nearly 4” Hg drop from atmospheric that I measured at 6000 rpm.  I am pulling both ports through a 1.75” dia, 5” long TB barrel, and maybe a bit of loss in the inlet plenum; but not likely that could account for such a large loss.  As you suggested, it must have something to do with the placement of the measurement port.  I may call the guy at TWM and see what his thoughts are.

  

 I expected this drop.  For reasons of not wanting to enter a prolonged and fruitless discussion on rotary engine manifold design, I will not explain why this drop is desirable : )

Oh; come on – gives us the 25 words or less version – well; maybe 50 words. We promise no prolonged and fruitless discussion.

 

But my main point was that you can get about 2" of MAP increase from ram air recovery (at ~200 mph),  REGARDLESS OF WHERE you measure it.

I’m going for that.  I’ve got that ram scoop sticking right out there, and no air filter to reduce it.

 

Al