Restrictor for BEGi FMU
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Joined: May 2005
Posts: 80,552
Total Cats: 4,368
From: Chantilly, VA
Anyone have the restrictor for the vacuum line that comes with a new BEGi unit? I threw mine on today but I couldn't lower it past a 9:1 rise. I'm looking for a 6:1-7:1 rise, so I need to throw one in.
On a sidenote: I tested my Vortech FMu today. I have the 6:1 disc installed (measurements confirmed). It acts just like a 8:1 disc. at 5psi it reaches 80psi of fuel and at 10psi it reaches 125psi of fuel. This is why when I calculated and installed a 8:1 disc I was overfueled on the dyno, dipping well below 10:1 AFR. I'm sure it was acting more like a 10:1 disc or something. Right now I'm reading pretty good AFRs, which makes sense, cuase I wanted a 8:1 rise to begin with.
On a sidenote: I tested my Vortech FMu today. I have the 6:1 disc installed (measurements confirmed). It acts just like a 8:1 disc. at 5psi it reaches 80psi of fuel and at 10psi it reaches 125psi of fuel. This is why when I calculated and installed a 8:1 disc I was overfueled on the dyno, dipping well below 10:1 AFR. I'm sure it was acting more like a 10:1 disc or something. Right now I'm reading pretty good AFRs, which makes sense, cuase I wanted a 8:1 rise to begin with.
jayc72's calculation looks right, base is 36 psi, but that's at what..20 inches of vacuum? So you hit 0 vacuum/boost, you have 50 psi of fuel pressure, plus another 6*5 = 80 psi of fuel pressure. The Vortech doesn't do anything until you get on boost.
FM suggests the base pressure of 50 PSI base for their systems, and nothing you can do about that if using the supplied Vortech. For my 8 PSI Greddy I prefer about 48 PSI base and capped at around 94 PSI using the stock 1.6 injectors. By seat of the pants tuning those pressures seem to give the best throttle response and crispness. Your pressures may vary and the Pierberg/BEGi combination permists tinkering for your optimal adjustments.
Everyone here is a smart SOB
Thread Starter
Joined: May 2005
Posts: 80,552
Total Cats: 4,368
From: Chantilly, VA
Weasel made a good point about me reading 36psi at 20 ~Hg. At 0 ~Hg. at the FPR i'm at 48psi which calculates out correctly, and makes a bit of sense.
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StratoBlue1109
Miata parts for sale/trade
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Sep 30, 2018 01:09 PM







yes, correct, i was at around 48psi at 0 ~hg. So it is working as advertised. silly me!
