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[Joseph Davis]

Holy technical fapping material.

http://automotivetestsolutions.com/pressuretransducersarticle.htm

[mrgreengenes]

great read!  too much caravan action tho.  Interesting to see the effects of cam timing on the curves.  It would be neat-o to have a pressure transducer in a fully running engine to measure combustion pressures and such... could be a better-than-knock-sensor ecu component, max efficient power at all throttle positions.

Phil

[92CXyD]

Bookmarked for reading when my brain stops hurting from reading a bunch of tech. for work. ;D

[kgx]

have you guys read the SAE paper on reading cylinder pressure by measuring the bending load on the intake valve face? interesting stuff.

[Joseph Davis]

have you guys read the SAE paper on reading cylinder pressure by measuring the bending load on the intake valve face? interesting stuff.

Fuck no, but I want to.

Have you read the stuff about inferring peak cylinder pressures and even knock based on residual 0-200 psi chamber pressures at BDC?

[7808]

was that on here that i seen these http://www.optrand.com/fliers/calplug_060201.pdf once ?  or somewhere else...

[Joseph Davis]

That's super sweet, but apparently they go for $950-1250.  Or did ten years ago, prices might have come down.

http://www.smokemup.com/bb/viewtopic.php?t=41&sid=2d398aa5a925d0e64e872a65d46bbda8

[Aero]

Using ion sensing is a pretty interesting too.
http://www.vehicular.isy.liu.se/~larer/Projects/main.html
http://delphi.com/manufacturers/auto/powertrain/gas/ignsys/ionized/

[kgx]

have you guys read the SAE paper on reading cylinder pressure by measuring the bending load on the intake valve face? interesting stuff.

Fuck no, but I want to.

mail sent. i threw in another i thought might be interesting..

[BoostedSchemes]

I am a fan of the ion sensing idea. BMW does this on the M5 V10.
Good ECU + abilitiy to monitor pressure within the cylinder = max power at all times, just lower power when pressure is reaching too high and enjoy teh powers.

[nock]

if you cut open a bosch knock sensor the quartz is a washer shape that is big enough for a head bolt. just get some copper washers for the wires, isolate it with phenolic washers, figure out someway to keep the oil off it, torque it down to the right preload, hook up a charge amp, and thats it. there is some stuff on the internet some were about how they used load sensing head bolts in natural gas compressor stations, the knock sensor idea is pretty much the same thing. next time i get a engine on the dyno i might fuck around with this a little, its way cheap, and it dosnt have the channel resonance to deal with like the "low cost" sensors.

[Joseph Davis]

Honestly, the Optrand Calplug or PSIplug itself looks like it's easy to fabricate if you can come up with a fixture, mill, miniature taps, etc.  The signal conditioner is minor electronics hobbyist stuff.  A quality transducer is a quality transducer, but you can source or snipe one off of eBay for cheap to a couple hundred.

[Adam Lofton]

Good stuff, I shot off some nut butter reading that. Have you guys read the article about the correlation between brake mean cylinder pressures and rod HIV? If the rod HIV is too high, it can actually make a window in the block. Hotrex will back me on this.  :yes:

[BoostedSchemes]

Ion sensing sexiness -


It's so accurate I like to make the little sound of the flame front advancing when I look at the picture.

[Adam Lofton]

Too bad carbon throws a wrench in the party. 

[92CXyD]

Too bad carbon throws a wrench in the party. 

What?

How?

[Joseph Davis]

It's so accurate I like to make the little sound of the flame front advancing when I look at the picture.

Yeah, but pressures aren't increasing with the flame front - that's just a fluke of resistance across the plug gap mid-reaction.  The burn will be mostly over before pressures come up significantly, with gasolines anyway.

[Adam Lofton]

Too bad carbon throws a wrench in the party. 

What?

How?

The carbon build-up on the plug throws off the resistance of the arc.

[kgx]

I am a fan of the ion sensing idea. BMW does this on the M5 V10.

the saab trionic ECUs have been doing it for over 10 years now too. i believe the honda passport/isuzu trooper uses an ion-sense setup as well, since they use delphi ion-sense coil on plug units.

they use the ion-sense as a cam position sensor as well. the ECU  batch fires the plugs during cranking and watches which cylinder's breakdown voltage spikes. it knows that was the plug that just fired, so then it knows which cylinder is next in line and goes full sequential injection and ignition. the trionic ECU only requires a 60-2 trigger wheel on the crank to run full sequential injection/ignition.

oh, and T5 and T7 suite are still freeware, afaik.

[nock]

Honestly, the Optrand Calplug or PSIplug itself looks like it's easy to fabricate if you can come up with a fixture, mill, miniature taps, etc.  The signal conditioner is minor electronics hobbyist stuff.  A quality transducer is a quality transducer, but you can source or snipe one off of eBay for cheap to a couple hundred.

the calplug stuff is nice for the money, the sensors are optical so the amp is built in, all you really need is labview or somthing.  most of the sensors for sale on ebay are to big to be flush mounted in a DOHC head.

a pressure sensing head bolt on the other hand is simple and would last pretty much forever. you would not see pressure in psi, and you may have to deal with torsional pressures from the timing belt, but i think that would be small and relatively constant compared to the combustion pressure. and, most importantly, no channel resonance, detonation can be seen clearly in every respect.

ion sensing looks great, but for some reason saab only thought it was good enough for misfire detection. i havent really looked into it, i wonder if you can see detonation on the pressure trace at all.

[BoostedSchemes]

tough guy i think you might be a retard, so unless someone confirms that, go fuck yourself

anyways, ion sensing is an awesome idea for preventing knock as opposed to detecting it - if its working right with an ecu that is capable of adjusting timing (hurr durr) you should never knock... it takes what, 1 millisecond after the spark to see if there is a spike in pressure (knock) and it takes at least a few more than that for the flame front start moving? I am just thinking of it using logs I have seen and videos of the combustion process.

also, pressure monitors - http://www.vems.hu/wiki/index.php?page=InCylinderPressure

also, "Ion sensing technology uses no sensor, but uses only the spark plugs as its 'sensors'. It constantly measures the resistance between the spark plug electrodes. At the onset of knock, before it is audible, ions are formed which change the resistance in the gap. The Ion Sensing system detects this, and can retard ignition before the knock actually occurs. This is a great system because it is impervious to engine noise, and less ignition retard cures knock before it occurs as compared to what's required to stop it after it occurs, due to hysteresis."

this is how I understand it - but if by the time the ions are formed early or whatever, is the knock already unstoppable and going to happen, before the adjustment is made? I guess a lot of this shit depends on super speedy ecus?

also, http://vvnet.fi/ville/ion/DIY-Ion-Sensing-2.pdf    - someone who actually put together a setup

[nock]

sweet, this thread isnt busted anymore. anyhow i dont know a whole hell of a lot about ion sensing, pressure changes the ionization current across the plug thats about it, ive never tried to mess with it because all the cars that i have looked at with ion sensing ALSO HAVE KNOCK SENSORS! so if you ignore all the manufactures product literature bullshit, what ever the fuck this shit dose, it dose not detect knock well enough for the OEM's to loose the knock sensor. and, the article you linked to also makes no attempt to detect knock either, or at least quantify it in some way. your other link just talks about some very expensive cylinder pressure sensors, you know, shit that actually works. mabye there is some new bullshit that dose detect knock effectively but i have not seen one yet.