Worth 8 bucks?
 

http://cgi.ebay.com/ebaymotors/ws/eB...1902577&rd=1,1

is this worth the 8 bucks to add to my FMU?

with that background music on ebay, i would say no lol

its only 8 bucks, give it a try

I don't see why it won't work. You'll vortech will almost be like the BEGI unit without being able to adjust the base pressure. I'd say throw in the 12:1 disc, go to home depot racing and by the same fittings and a check valve and give it a whirl.

i use an MBC on mine unless you are running 300cc's I wouldnt ramp down the rate to much 12-1 isnt to bad. My setup essentialy delayed the ramp up until 1-2psi and then continued from there. For 8 bucks it is worth a shot but a MBC can do the same.

I thought it would work. I couldn't make it happen. Braineack tried too, and he couldn't get it to work right either.

IMO the problem is less of controlling pressure rise and more of controlling injector duty cycle.

thanx guys

can someone explane to me how this thing helps my fmu?? The fmu i have is 12:1 i was gonna change disks to 8:1.. with this bleeder valve i will be able to run my 12:1 disks, and adjust it to work with my setup??

i guess you could say im a bit unknoledeged in the FMU arena

i tried a pressure regulator to cap the amount of fuel pressure...this should work....looks to be straight off an old BEGi unit.

Drill and tap a hole in the body of the FMU/AFPR/Doodad that will take a hosebarb. Connect an MBC (ball and spring, not a bleeder) to the hosebarb and a check valve to the MBC. This will cause the AFPR to vent at a preset boost level, should stop fuel pressure from rising past a certain level. This should allow adjustment of base, rate of rise and maximum.

All theory. I was going to try it but sold my AFPR before I got around to it.

This is a good idea. I'm gonna try it.

it would be easier just to put one teed off the vacuum line...no drilling.

:dunno: Worth a shot I guess, but in my mind it won't work. I think all that will do is vent boost to atmosphere without affecting the pressure signal to the FMU. I would add a check valve between the tee and the mbc being used for the bleed.

i dont think the design of the vortech fmu will allow for drilling anyways....since the boost pressure pushes down on the diaphram. I might make myself another cheap little MBC and try it.

I thought we were talking about the BEGi FMU. The vortec SFMU has a simillar bleed to limit max pressure, like what we are discussing. Your idea is worth a shot, imo, especially before drilling.

Dunno, it's really the wrong solution to the ecu programming problem anyway.

The problem I think is that the boost pressure over runs the needle valve on the BEGI unit and fuel pressure continues to climb. Adding in the MBC as a relief valve should allow it to hit a set PSI and keep it there no matter how much boost you run or how quickly you get there. That way it shouldn't affect the rate of rise. Putting the relief valve BEFORE boost enters the AFPR will affect the rate of rise, similar to a restrictor.

I think bell should incorporate this into the design and give me a shiny new turbo kit for my idea! :)

but isn't that exactly how the BEGi fmu works....just using a bleed valve, not a MBC that pops open.

Except that it bleeds all the time, slowing the rate of rise. Putting the MBC in addition to the needle valve will pop when it hits say 10psi and will not go any higher. You'd have to use a good sized fitting. If an MBC can maintain XPSI for a wastegate it should work this way as well.

The needle valve doesn't bleed off the pressure fast enough. If it did the AFPR would never build any pressure and it wouldn't work.

Jay

magna are you running a 12:1 fmu??

Well on that regard, when the mbc "relief valve" pops open, wouldn't it just vent all the pressure in the FMU to atmosphere? Which would then drop you down to 0vac fuel pressure.

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 :)

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. ?

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

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?

im seeing a trip to ACE Hardware tomorrow.

At worst it won't work. At best I'll look like an internet god. Likely somewhere in between. :)

yes

I was under the impression that most guys were running 8:1 and that 12:1 was to much fuel...

He uses a safc to cut fuel.

bradley, you got a fuel pump right?

If you are running the OEM fuel pump, stay with the 12:1

I spent a little while thinking about this. Essentially the concept creates a rising rate fuel pressure regulator with 2 stages of rise. 2 stage linear, not progressive like I wrote in an earlier post. The first stage would be absolutely identical to a current FMU where the FMU builds fuel pressure with MAP linearly where the rate of fuel pressure rise is controlled by bleeding pressure to atmosphere at the needle valve. The second stage would start at the point when the pressure relief valve opens. When the prv opens, we can then vent additional pressure to atmosphere at a time determined by the prv's pop open point and a rate determined by the second needle valve.

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.

no i only have the stock pump...

80 psi is gonna limit you a 190hp migth help with headroom but for the time being you should be allright.

whats a safc?

im not lookin for that much power to start out with anyway

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

do you think this will be drivable magna, 12:1 fmu, no bleeder of any kind, 1.8 injectors, and stock fuel pump?

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.

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.

if not ill sell ya my safc for cheap and buy a MS.

magna says it will work, it will work :)

:yippee: just go with what you know it will work but i dont garuntee perfect that lies in your own redneck magic remember you can adjust the WI pressure to help alot. lemme know if you need some help i'll do what i can. heck might eeven get a wildhair take off work and drive over there never been that far west. :) lol

come on over buddy, i have a guest room, and the weather is beautiful in phoenix this time a year.. i will go to work every day, and u can just sit and work on my car all day!

you'll be able to make 170rwhp with 1.8 injectors and a 12:1 FMU on the stock FP. At least I was able to.

ok, so even if im running this smaller turbo? as long as it is capible of getting up to 8 psi and i can keep the a/f ratio right.. and keep it from spark knockin it should be able to put out 170?

it's really all in the math. 80psi of fuel and 265cc injectors = 198BHP

yeah but you have to be getting enough air in there to mix with all that fuel, doesnt the cfm capability of the turbo factor in there somewhere?

well, regardless if you are reaching 170rwhp at 4psi or 8psi, the injectors will be capable of supplying enough fuel.

true that.

ok.. so since my compressor is smaller than say the 15g turbo that comes with the greddy.. whats the real world differance.. will it just get to a point and stop making boost? like get up to psi, and not be able to do any more.. from what i can tell by looking at the map it should be at like 60 percent efficency at 6500rpm 8psi.... this sound about right.. ??

You will blow hotter air sooner like bripad. This is a trade off for your low end boost response at 230<- whp it shouldnt be alot of difference but the extra head room of the compressor does help not heat the air as much. For example my 16g had as much flow potential at 8 psi as the 15c at 15 psi but i only used so much of it.

so basicaly i will be pushin in hotter air at the same psi as the greddy compressor is, but should still be able to get the same flow as it does?

yeah as far as what your motor is ussing with crazzy ported heads and high dollar ignition shit you might use most of the available flow but i doubt it matter alot, just try to get it as cool as you can without bogging it on the low end.

yeah, i got no crazy ported heads or high dollar ignition... The way i see it, if the 2.0 engine on the eclipse ran with this turbo, why wouldnt my 1.6??

yeah youll be fine. stop worrying you might just surprise your self/us i did. :bigtu:

this is my daily driver, if it doesnt work, im up a creek hehehe No work tonite magna?

11pm-7am for a few months now. used to be 3pm-11pm better crew on third though.