Begi Fmu

[wallace]

I just scored a BEGI RRR, the rate of gain is adjustable and so is the point at which the gain starts (onset). I have +40% injectors and a stock '90 T1 SBEC. My question is can I use a lower fuel pressure to match the older injector size up to the 1 Bar Map's limit (~14 psi) and then have the RRR come on and use it to tune the fuel from there? Has anyone done this? I have a wideband to monitor with. Thanks.

[wallace]

I just re-read the instructions, the onset of gain is a fuel pressure adjustment not a boost level adjustment...oops.

[Wink]

I think the one you purchased is the one for adding turbo to a N/A motor. I'd honestly suggest taking that back for a refund or selling it to someone else. I hope you purchased it for a great price. I only say this because you could have purchased a custom 3 bar calibration for the price of a new BEGI FMU these days. But if you wish to "Gus" your setup, just get the FMU with the adjustable rate of gain. You don't need the adjustable onset for a motor that actually has the calibration for up to a certain amount of boost already.

Before my Shadow had it's engine fire, I was just going to install larger injectors with a lower base fuel pressure and get a cheap used OBX FMU and put a needle valve and a check valve on the vacuum line to make it adjustable.

Wink

[2.216VTurbo]

'Back in the day' like 5-6 years ago, I had pretty good luck with the adjustable regulator on the fuel rail to set a low initial pressure, then a Cartech (is BEGI the same?) RRR to crank up pressure under boost, combined with a set of +40's. Kind of low tech these days but it got me to 272WHP. Yeah pathetic by todays standards I know...:o

[wallace]

I think I've got the onset of gain figured out. It's just an extra feature that allows the rate of gain to start at a preset pressure at zero inches vacuum. I'm with you on the calibration. I have one ordered but based on feedback on the vendor it will be quite a while before I get my cal. So, I'm trying to figure out how to calculate what my pressures should be at x amount of boost. Does anyone have any pointers they could give me? I read the Dodge garage writeup about RRR's and I downloaded the program to calculate hp vs injector size and I can't put it all together. I just need a little more direction I'm slow. Thanks.

[2.216VTurbo]

I think I've got the onset of gain figured out. It's just an extra feature that allows the rate of gain to start at a preset pressure at zero inches vacuum. I'm with you on the calibration. I have one ordered but based on feedback on the vendor it will be quite a while before I get my cal. So, I'm trying to figure out how to calculate what my pressures should be at x amount of boost. Does anyone have any pointers they could give me? I read the Dodge garage writeup about RRR's and I downloaded the program to calculate hp vs injector size and I can't put it all together. I just need a little more direction I'm slow. Thanks.


Zero inches of vacuum-or sooner. I used that center screw to cure a little preboost stumble that I always suspected was a lean condition at throttle tip in.

As far as settings you just kind of have to mess with it until your AF gauge is happy at WOT. Remember to restrict the amount of total signal coming into the reg so that the needle valve bleed will function properly. Hooking a temporary diagnostic type FP gauge to the Schrader valve and viewing while under boost helped a bunch while I was making changes. Don't worry about the math, just make it run as lean as you dare under cruise with a low intial FP, then four lights worth of pig-rich under WOT to keep all the hot parts happy:thumb: IIRC correctly running a 2.5 on a 2.2 computer I needed like 36 intital and 92 total at 18-19 psi boost. YMMV

[wallace]

When you say to restrict the inlet, do you mean just a plastic vacuum line restrictor? I think I understand that part. If I read your post correctly you had almost 3 to 1 gain on the regulator. OK, what I'm trying to come up with is a baseline on the rate of gain for the the regulator to get me close. The combo is new and I have no test data to start with. I have an lm1 to tune the afr with. I'm using a 2.5l engine with '90 SBEC for same engine. I'm guessing that 20 p.s.i. of boost would get 230-240 fwhp? I can list supporting mods if that will help with this #. If I use that and the base for the stock injector of 34.85 @ 55 p.s.i. I would set the base fuel pressure for the 53 @ ~24 p.s.i., correct? so at 20 lbs of boost the fp would be 44 p.s.i. To baseline it would I just adjust the reg so that the injector matched to target hp at 20 p.s.i.....plus a little for safety. I won't attempt to start at 20 p.s.i., initially the plan is to just let the wastegate run off of the compressor outlet so I'm expecting 7-10 p.s.i. Thanks alot.