My design initially used a brass ball check valve. The problem with that check valve is that the crack pressure was too high. You see, we don't have all that much vacuum on this engine. At idle, the intake pulls -2.5 psi of vacuum. Refer to the attached image. This was taken by a fellow member, in gear, AC on, 74 degrees out. The hotter it gets, the less vacuum we have. 6inHg = -3 PSI. I also attached another image from another member that used a ScanGauge.Built my attempt at a fix, based mostly on this plan but ordering all parts but the throttle block from Amazon (I buy a lot of stuff from there). As an aside, the price for the valve cover was only $70 from the local dealership, which would have been a lot faster as they had both the valve cover and intake in stock. The intake was $470 though, so I had to wait for the other parts to get here.
I used all barbed connections. The downside is that at least between the throttle body spacer and the check valve, you need them clamped, since that'll be seeing some pressure.
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Detail shot of the nut - I only used the washer outside, based on the idea that that was the biggest sealing surface. I also went with a 1/4" to 3/8" adapter instead of the 1/4" to 1/4", so I had to step it back down before going to the angle, which also made my valve hang out a bit further - but there is plenty of room there for this. It makes me kind of surprised that they didn't go with the external valve, at least in the redesign - I wonder how much the warranty coverage cost them.
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Seems to work so far. I took it for a short drive tonight. Wife will use the car as normal tomorrow. It does seem a bit more peppy than the last time I drove it, which might have been due to lost boost from the intake valve failing first. Either that, or her car is just more peppy in general than my old winter beater...
Every resource I found on those 1/4" aluminum check valves (which are designed for fuel) indicated a -3 PSI crack pressure. The most difficult part of this project was finding a suitable check valve that would crack open at a similar pressure as the OEM check valve, which was barely under 0 PSI. The check valve I found (and linked in the original post) has a crack pressure of 1/2 PSI.
Produzione di articolo 100012%20LF - LEAD FREE PRODUCT - IN-LINE CHECK VALVE - Vendita di RUBINETTERIE BRESCIANE | www.bonominorthamerica.com
I spent many hours looking for this check valve. Your check valve cracks at too high a pressure and as a result, will direct too much (and in most cases, all) PCV gas through the turbo inlet.
I would strongly recommend revising your design to include the Bonomi check valve, unless you can find another one that cracks at a comparable pressure for a comparable price.
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