Quote:
Originally Posted by Lowspeed Lowside
OK, maybe a $5 headset is a little too lowtech. But parts for a device with 192 khz DAC and ADC (which gives us about 5 microseconds resolution)
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I think the 192 khz is likely overkill after all. Our cheap tablet-PC should be able to convert digital-to-analog and vice versa at 48 khz with the integrated chip, as even the most inexpensive sound chips for $2.36 are capable of doing this, and we can pulse the injector several times to tweak the amount of fuel we inject to a very high degree. I read somewhere that fuel flow during the first and last 1.5 microseconds is only about 1/3 of the maximum rate.
Piezo-electric pressure sensors (e.g. SENSOR,PIEZO FILM VIB TAB MASS 25x13mm,ANALOG~70VDC,50mV/g) are less than $2.50/piece, so we could attach several sensors at different locations on the engine, which should give us a better 'picture' of what's going on. Maybe it's even possible to activate the sound chip's 2-channel ADC converter (stereo) to effectively double the resolution.
There are several 7-inch tablet-PCs with VIA VM8650 800 MHz processors for less than $100 shipped, an appropriate fuel injector and pump should be less than $50.
At less than $200 this setup is within our budget and allows us to choose a trade-off between (possibly drastic) reduced engine-life and (possibly dramatic) increased engine-power. Considering the experiences of other members with carbed turbos, at less than $100 additional cost, I think fuel injection should not really be considered optional anymore.
Setting up a fuel injection system as described above might be useful to members who do not desire to turbocharge their Ninjettes, so this actually deserves another thread. Attaching a couple of sensors and monitoring the engine is non-invasive, so the monitoring software can be engineered and tested without removing or replacing any components required for the normal functioning of our Ninjettes, and we don't have to wait until the winter season.
Side-note:
One advantage of turbocharging over supercharging is that we essentially get two different machines in one: below 8000rpm we'd have a Ninjette-sheep and above 8000rpm we'd have a Ninjette-wolf.
