At 03:01 PM 4/22/2004 -0400, you wrote:

 
 

 

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 pressessure 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 measuriuring it in the air plenum before the TB.  It would be very interesting to know what it is on yours about 4â€Â? from the intakee port.  Then there is the whole question of ‘whihich’ MAP pressure the EC-2 should be interpreting âg – 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
Sorry, I missed that... that's where I put mine. 

Mark