A couple of $10 Free Scale pressure sensors came in.
If I get the data aq module today I will have some pressure
plots as a function of RPM and e-shaft angle by next week
from Marks Suspinski's P-port engine. We will monitor both
intake runners simultaneously because we can. They
should be 180 degrees out of phase. Sensor response time
is 1 millisecond so we will run the data aq at 2000 samples
per second or higher. We could go up to 32,000 samples per
second if we need to.

If the data aq does not arrive it will be  the week after.

Atmospheric pressure (15 psi absolute) is about 2 volts and it goes
up to 36 psi absolute to accommodate the P-port pressure waves.

Come to think about it Tracy may change the pressure sensor
according to  whether the engine is turbo or non turbo.
If it is a non turbo sensor the sensor will bottom out
at 15 psi. Not what one needs for a p-port engine.

For a p-port you need a turbo pressure sensor as the
the VE is about 120%. Much like a turbo engine.
On tune the intake manifold pressure of a p-port can
exceed atmospheric pressure by a considerable margin.
That is why you get 250 HP out of the engine.

Tracy, what pressure sensors does Mark have?
I cannot tell by looking at them as they are bolted
down and I cannot see the part numbers.

This could be part of the problem Mark is having
tuning the engine.

Mark, In case Tracy does not see this please call him and ask
what range of pressure sensor he installed in your computer.

Paul Lamar
Hi Paul,
Just working from memory but I believe Tracy's sensors are the same for
turbo or non-turbo. As I recall the paperwork says they're good for
upwards of 60 psi boost---for the daring few : ) The big difference
is that I've never heard Tracy claim ANYTHING about P ports....I think
his units are designed for use with normal, factory side ports. If
that's the case, the massive pressure fluctuations as a result
intake/exhaust "overlap" of P porting never occur at his sensors.
This may be the reason Tracy has no problems but P porters' do.
Does anyone have first hand knowledge of Tracy's engine?
Is it P ported???? Dave M

It is not p-ported and the throttle is up stream of the plenum so a sample
of the plenum pressure is sufficient for Tracy's configuration.

Paul Lamar


Tracy's system should function okay on a [RX8] P-Port engine if the throttle
is on the cold side of the plenum...  As has been mentioned before by
Paul, on a Renesis, this will even idle well.


Regards,

Matt-

I agree. Same as where a carb would be mounted :)

Paul Lamar