I know quite a bit about computers, but nothing about the Arduino and its capabilities and need some sage advise.
MY PROJECT - Rotary engine compression tester
Mazda RX-7 and RX-8 rotary engines have two rotors, each with three lobes, and no pistons. A very good way to determine the 'health' of a rotary engine with a lot of mileage is to do a compression test using a specialized compression tester that tests the compression of each of the three lobe chambers separately.
A Mazda OEM Compression Tester costs about $1,800. Generic testers cost $325 (See the video at rotarycompressiontester.com for how it operates.)
A pressure transducer (connected to the compression tester) is screwed into a spark plug hole in the 1st rotor (the process is repeated for 2nd rotor) and the engine is rotated using the starter for a short period of time. The compression tester measures and stores the maximum readings of each of the three lobes and/or averages the readings (for each of the lobes) over some three to five revolutions.
If one of the lobes shows a significantly higher compression than the other two, this indicates a damaged apex seal between two of the lobes.
If the lobes show relatively equal but low overall compression, this indicates worn apex and side seals
PROPOSED PROJECT -
A pressure transducer would be connected through an ADC to an Arduino with a 4-line display.
The pressure transducer outputs 0.5V at 0-psi and 4.5V at 200 psi. Response time is about 1ms.
Engine cranking speed varies from 120 rpm to 300 rpm (2 to 5 revolutions per second) depending on engine temperature and battery condition.
The engine has a compression 'stroke' every revolution, so each compression stroke duration will be at least 200 milliseconds long in duration. The shape of the pressure curve would be approximately sinusoidal. Pressure transducer sampling could be done every 5-10 mSec.
'Good' or 'bad' results are dependent on both rotor pressures AND the cranking rpm.
(See chart at http://www.rx8help.com/img/compression_chart.png )
DEVICE OUTPUT -
At a minimum, the tester needs to calculate either highest pressure and/or average pressure for each of the three rotor lobes, and the average rpm. +/- 5% accuracy is probably good enough for both pressure and rpm. A 4-line 20-character display would be adequate.
Is this project feasible?
Thanks for your comments.