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At 11:52 AM 4/21/2004 -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 pressure at the engine end of a long intake
tube. But I remember once before when I was
wrong
J.
- 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.
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