I don't know for sure. I guess it depends on how sensitive the MBC is. If the MBC is set to open at 8psi, will it close at 7.5psi? Will it open and close instantaniously?
That's why someone needs to try :) |
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I don't know, but wouldn't think the resultant ocillation in fuel pressure would be very fun. Maybe a simple pop vent to atmosphere isn't correct for the application. It would have to be coupled with a second bleed. So the resultant would be a pressure rise with boost that progressively reduces its rate of rise. So then there would be two additional adjustments: the pressure to begin the venting event, and the rate of bleed at the vent. Now it should work. ?
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I wonder if a smaller diameter outlet on the MBC would help relieve some pressure...just not all, like the BEGi unit's small port
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I'm thinking something along the lines of a mbc that vents through a needle valve instead of a standard port. Then you could control the pressure dump pretty precisely. Whatchya think?
Originally Posted by braineack
(Post 68969)
I wonder if a smaller diameter outlet on the MBC would help relieve some pressure...just not all, like the BEGi unit's small port
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im seeing a trip to ACE Hardware tomorrow.
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At worst it won't work. At best I'll look like an internet god. Likely somewhere in between. :)
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Originally Posted by adbradley
(Post 68893)
magna are you running a 12:1 fmu??
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Originally Posted by magnamx-5
(Post 68998)
yes
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Originally Posted by adbradley
(Post 69031)
I was under the impression that most guys were running 8:1 and that 12:1 was to much fuel...
bradley, you got a fuel pump right? |
If you are running the OEM fuel pump, stay with the 12:1
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Originally Posted by Ben
(Post 68972)
I'm thinking something along the lines of a mbc that vents through a needle valve instead of a standard port. Then you could control the pressure dump pretty precisely. Whatchya think?
So let us assume that we set our stage 1 needle valve bleed to rise fuel pressure at the rate of 8 psi to every 1 psi of boost pressure. Let us then assume we set our pressure relief to open after 4 psi of boost pressure, and we set our second needle valve to increase fuel pressure at the rate of 3 psi to every 1 psi of boost with any boost over 4 psi Result of above assumptions: 1 psi boost pressure --> +8 psi fuel pressure 2 psi boost pressure --> +16 psi fuel pressure 3 psi boost pressure --> +24 psi fuel pressure 4 psi boost pressure --> +32 psi fuel pressure STAGE 2: 5 psi boost pressure --> +35 psi fuel pressure 6 psi boost pressure --> +38 psi fuel pressure 12 psi boost pressure --> +56 psi fuel pressure http://img413.imageshack.us/img413/3396/fmumodlx8.png Bear in mind my assumed rates are arbitrary, so observe the data as conceptual/hypothetical, but not necessarily correct for the application. |
i got the safc after trying to run some 460's for all my dyno runs so far i haven't had one. it did help me on top end and driveability though. just not with the 460's. i first stated doing the mbc fmu tweak with my low impedance 305's that i ran for a while and it slowed the fp ramp up becouse my injectors where doing silly things being the wrong impedance and all on boost transition.
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no i only have the stock pump...
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80 psi is gonna limit you a 190hp migth help with headroom but for the time being you should be allright.
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whats a safc?
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im not lookin for that much power to start out with anyway
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Safc is an Air fuel controller it plugs in between the ecu and afm and tweaks the signal +-50% not the best but for 200 bucks it aint bad i am probably gonna get MS if i cant hit 300whp on stock ecu. if not some nos then MS and 350+whp hopefully. Good luck man
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do you think this will be drivable magna, 12:1 fmu, no bleeder of any kind, 1.8 injectors, and stock fuel pump?
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oh yeah that is what i had for my first setup. minus 1.8 injectors but the 1.8's made driveability better esp on real hot days.
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I wouldn't assume you'll get 80psi out of the pump until you confirm it with a pressure gauge while driving. The pump out of my 93 would only give me 65-70psi under boost.
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