Paul,

I'm not sure the plenum is the problem as there is a serious MAP
mismatch even at idle.  If it was a plenum flow problem, shouldn't it
be minimal at idle and worsen as RPM increases?  I could verify this
theory by test running it without the plenum.

I still suspect I'm getting some serious leakage somewhere in the
intake, most likely through the slide throttle.  I plan on testing it
with a shop vac and a Uni-syn.  I'll hook the shop vac to one runner
outlet and then check for leakage on the other two; then repeat for
each of the three runners.  Then I will check the flow through each at
idle setting to see how well they match, or not.

Mark


 From what I can see from this picture it looks like the plenum.

The engine appears to need a lot of air even at idle.

Get up on something high and take a picture looking down on the current
plenum. What are the dimension of the plenum?

There is a huge difference in the amount of air the back rotor is
getting compared to the other 2. We are talking 20% here. I don't think
it is leakage through the slide throttle. The rear rotor is doing a lot
of extra work. No telling what will improve when this is fixed. The BSFC
could get significantly better as well as the power. The rear rotor is
running leaner as Tracy averages the air getting in the engine. The
front rotor is running richer. If you have EGT's let us know what they
are saying.

The non symmetry of the plenum could be affecting the tuning of each
intake pipe. A higher data sample rate will give us better info on that.

Just take the plenum off and run it with the data acq still connected.

Here is what Mark Suspinski plenum looked like and we were getting equal
pressure in both rotors.

Paul Lamar

Paul,

I don't have the plenum dims handy.  I will have to wait until next
weekend to measure it.

Mark

Taps on the way.

Paul Lamar