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-   -   Restrictor for BEGi FMU (https://www.miataturbo.net/diy-turbo-discussion-14/restrictor-begi-fmu-4803/)

Braineack 09-21-2006 02:46 PM

Restrictor for BEGi FMU
 
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.

Stripes 09-21-2006 02:52 PM

I had the same problem you are having. I used an inch of plastic hose off of a wd40 can. Worked perfectly.

Braineack 09-21-2006 02:56 PM

you smart son of a bitch! I gotta try that. Good thing this is an easy swap out.

Pop VII 09-21-2006 03:39 PM

Also have it here in my BEGi pages: http://bellsouthpwp.net/P/o/PopVII/BEGi%20AFPR.htm

Braineack 09-21-2006 03:43 PM

Another example of me not reading very good. I've looked over your pages many a times.

Stripes 09-21-2006 03:46 PM

Now he's not going to think I'm a smart son of a bitch.

jayc72 09-21-2006 03:54 PM

6:1 ratio should take you to 80PSI at 5psi of boost shouldn't it?

50psi (base) + 30psi (5*6) = 80PSI

8:1 Would be 90PSI
10:1 would be 100PSI

Right?

Braineack 09-21-2006 04:09 PM

my base is 36psi (OEM). 8 x 5 + 36 = 76psi

iWeasel410 09-21-2006 04:11 PM

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.

Braineack 09-21-2006 04:14 PM

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

Braineack 09-21-2006 04:54 PM

Corky's sending me his restrictor along with one of those small fittings, but i'll try the spray tube trick in the meantime.

jayc72 09-21-2006 05:02 PM

I'm going to try using another needle valve since I'll have a spare when I get my rebuild kit. Should allow me to bleed off boost and slow the rate of rise.

Pop VII 09-21-2006 08:51 PM


Originally Posted by jayc72 (Post 45737)
6:1 ratio should take you to 80PSI at 5psi of boost shouldn't it? ... 50psi (base) + 30psi (5*6) = 80PSI ... Right?

Not unless you are using an adjustable afpr such as the BEGi or Vortech Super FMU which can raise the base pressure to 50 PSI at atmosphere and the ability to cap the pressure at desired top boost level. The Pierberg gives me the pressure I need and the BEGi permits me to adjust how much I wish to use.

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:bigtu: :bigtu:

Braineack 09-21-2006 10:13 PM

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.

Stephanie Turner 09-21-2006 11:24 PM


Originally Posted by jayc72 (Post 45767)
I'm going to try using another needle valve since I'll have a spare when I get my rebuild kit. Should allow me to bleed off boost and slow the rate of rise.

Some needle valves are interchangeable, some are not. The thread size is 10-32.
Stephanie

jayc72 09-21-2006 11:34 PM

Thanks Stephanie, I'll make sure that I'm careful! :)


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