200+Hz air valve? - Page 1
Forum section: electronics / general

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: May 21, 2023, 06:54:08 pm
content: I'm looking for a way to get an air valve to respond extremely fast. For use in car engine crankcase evacuation, using the venturi vacuum in the exhaust, PLUS short scavenging pulses that should give me even more vacuum, but for those I would need an extremely fast acting valve, 200Hz is just so it reacts to each cylinder's full cycle but in reality it would need to be around 10x faster to react to the actual pulse itself.it's gonna go on a 1/2" pipe fitting, for a very rough flow estimate.I presume a mechanical valve is out of the question, I was thinking of maybe a pressure sensor and a fast acting solenoid. It would have to be able to handle around 200C temps, and the pressure sensor would need to handle basically fire, and also frequent backfires which are explosions in the exhaust.Does it sound like a feasible setup?

author: joeqsmith
author_rank: Super Contributor
timestamp: May 21, 2023, 07:52:49 pm
content: Why not just pump it out like is normally done?

author: PlainName
author_rank: Super Contributor
timestamp: May 21, 2023, 09:03:48 pm
content: QuoteCan you explain further? Shouldn't there be the reverse too, to let the air back in?

author: Benta
author_rank: Super Contributor
timestamp: May 21, 2023, 11:45:32 pm
content: How old is your engine? I haven't seen wet sumps since at least 40 years ("the crankcase has the oil sloshing around it").And the compression (say 10 bar) plus combustion pressure (much more) compared to perhaps 0.2 bar of vacuum during intake is a problem?Wow! Talk about microscopic optimization (popularly: "quantum leap"). Put that "improved" engine on a dyno and you'll see... nothing. Same with fuel consumption.

author: joeqsmith
author_rank: Super Contributor
timestamp: May 22, 2023, 12:21:47 am
content: Quote from: ELS122 on May 21, 2023, 08:08:24 pmElectric pump with a total loss system but the motors are small and they are only ran a short distance. Looks like some are using belt drive.https://www.starvacuumpumps.com/products/STR.09.04.000

author: joeqsmith
author_rank: Super Contributor
timestamp: May 22, 2023, 12:43:30 am
content: The great George Bryce talks about the history and whys

author: Haenk
author_rank: Super Contributor
timestamp: May 22, 2023, 08:42:40 am
content: "aerodynamic drag"Any idea about the loss you are talking about? 1/10000th of total motor power?I assume the best option is to hone your motor, new sealing rings and low viscosity motor oil. For another PS or two, polish out your exhaust manifold.If allowed, straightpipe & cat delete.If going crazy, add (larger) turbo and/or compressor.And somewhat older Germans know another trick: Adding a foxtail to your antenna adds another PS.

author: AVGresponding
author_rank: Super Contributor
timestamp: May 22, 2023, 11:49:55 am
content: Quote from: Haenk on May 22, 2023, 08:42:40 amIn fact aerodynamic drag in the crankcase, known as windage, is a serious loss, and much effort goes into minimising it.I recommend you to watch the recent Engineering Explained video on the new Corvette C8 Z-06 engine.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: May 22, 2023, 02:46:32 pm
content: I personally think this quest is silly, but if you really are going to pursue it a mechanical solution seems best. Unless your engine is exotic enough to have variable valve timing the required openings and closings of the valves are fixed relative to crankcase rotation so a rotating disk on the crank with appropriately placed ports would do the job. If you felt that transport times forced timing changes as a function of rpm a much slower responding servo changing the disk angle relative to the crank would do the job.