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 bethe 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 towhether 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


Right..

It's what Tracy should promote as the best performance per dollar when
using his EFI system.It would be much easier and lighter to build
than a turbo system, and in some ways would perform better than a
turbocharged side port engine.


Matt-

Well the HYTEK Data Acq module arrived all the way from Shanghi
DHL. I had no idea they were shipping it from Shanghi China when I ordered
it from an outfit in Toronto. They don't do credit cards so they
want me to mail a check which I will do. If I had to do it over
I would pay more and get one made and shipped from the states.

http://www.hytekautomation.com/

Basically all it is is a Microchip PIC 18F 4550 I/PT microcomputer.
That is a 44 pin surface mount flat pac with USB interface.
The 12 bit A to D is a Microchip MCP3208-C.
50,000 samples per second at 2.7 volt supply.
At a 5 volt supply it is 100,000 samples per second.

Don't try to take it apart as the circuit board can be easily
damaged.

More On this when I play with it a bit.

Paul Lamar



Now that's a cheap o-scope! Very cool for some projects.

If anything says it's "the cheapest" (or actually is the cheapest you
can find), it's from China..

It says 4.1V max input. I wonder how they handle over voltage.. How
easy is it to damage the input?


Matt-


I did not take any chances and hooked it up a 1.5 volt battery.
Unfortunately it does not appear to be working right as this is the
data it is saving. Should be a steady 1.5 volts.

I sent them email. We will see how long it takes.

----------------------------------------------

I got it working. It don't like only 125 samples per second for some strange
reason. Works fine at 500 samples per second and 1000 samples per second.
It will fill your hard disk lickity split.

Measures the battery voltage to .001 volt +/- .001 volt 1.659 Volts.

Paul Lamar


I wonder if they include a (software) FIFO buffer or how tough it
would be to write one for it.  Run it indefinitely until you meet a
particular condition and stop it - keeping only the buffer size as a
record.


Matt-