One more comment on intake manifolds & race results.   Do not ignore the benefits of a really clean air inlet with ram air recovery BEFORE the manifold.   At 1125 ft  msl, 220 IAS, I saw manifold pressures around 31.8" Hg.  Ignore this factor and you throw away about 6% "free" horsepower.

 

Al,  I forgot to comment on your last note about your MAP tap in manifold.  I think it is highly possible you were seeing errors induced by air stream eddies or some other unpredictable factors caused by that location.   It is a challenge to get MAP measurements when you have no real plenum, only runners with high velocity air.

Tracy

 

I use the stock ports in the TWM throttle body.  I assumed they would know where to place the port to get a good measurement.

Where do you measure MAP on your system?  I can’t believe that you could see that kind of pressure at the engine end of a long intake tube.  But I remember once before when I was wrongJ.

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 ).

 

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.  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 : )

 

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.

 

Tracy

Tracy,
So, where's the correct location for the MAP port? 

Mark S.

Go up 6 paragraphs and read it again  : )

Tracy