BEGi FMU parts?
 

Trying to get this 89 S4 with Stage 1 928 Motorsports kit properly sorted...before I tune it correctly with bigger injectors n' all.

So many issues on this S4 from all paid shop labor. Flappy vacuum was mixed with the BOV so that neither worked. Rear upper control arms upside down. Cam gears are completely shiny (through the breather holes) and the tension warning system (stock tensioner until I pull the radiator and supercharger) is wired to ground, etc. etc.


Anyhu, the FMU was leaking air and obviously wasn't working when the PO's shop installed it. With no boost reference they just adjusted the base pressure to 80 psi! Amazingly, the LH compensated and it runs kind of normally. I was shocked today when I slapped a fuel pressure gauge on the fuel rail.


Anyone know of a source for the diaphragm? BEGi appears to have been absorbed by MaxG. I emailed them (and 928 Motorsports).
https://www.maxgms.com/collections/f...sure-regulator

They offer a rebuild service on their web site but all I want is the diaphragm. I may just make one.
https://www.carburettorshop.com/cont...e-per-cm2.html

https://cimg4.ibsrv.net/gimg/rennlis...8e1c131719.jpg

https://cimg2.ibsrv.net/gimg/rennlis...0c0f7d5fde.jpg

https://cimg8.ibsrv.net/gimg/rennlis...d57ffd1458.jpg

You need to discard that car- it has no jump post cover !

Looks a bit like the motor that used to be featured on Carl's website if I recall correctly- what is your target for this car by the time you have finished "Porkenising" it- 500 bhp/torque?

The diaphragm looks as though it could be made from a sheet of appropriate rubber given your talents but I would have thought your first objective would be to dump that dinosaur era accessory albeit I believe they work surprisingly well. I see a new Porken supercharged chip [the Porkeniser] on the near horizon- :roflmao:

Nothing says pride in craftsmanship like zip ties as hose clamps.

I see a vacuum line running to the brake booster connection. Can't miss that bright red hose... Is that a reference for fuel pressure? If so, that's a poor place to connect. I'm not familiar with this unit so have no insight beyond amateur visual cues.

Doesn't fit with the intake tube :p

It makes a lot of power right now after some fixes but I am hoping for 400-ish Dynojets to start. I have already shamed some Teslas and a new 911. :D

That is probably what I will do. It is just 1/32 rubber diaphragm stuff. It does not come in contact with gasoline.

I want to get the kit working as originally delivered before changing... mostly everything. Might go with a billet compressor wheel but I don't plan on moving to stage two anytime soon.

All my hoes gotta make that money! Self learning Stage One EZK-S chip is already for sale (EZK-B). Made a nice difference right away and only rarely shows new knocks. (Much much safer than the stock EZK chip the kit uses. This chip should be standard issue!)

The silicone hose has to go. It pops off easily.

I think so too. The FMU should be sharing off of the FPR and damper lines.

The Blow Off Valve was T-ed off the line to the flappy. (It must have looked like a manifold connection to the shop.) Further, the T was connected to the wrong port on the flappy solenoid so it never could purge vacuum. Both the flappy and BOV were always partially open and the stored vacuum was always leaking out. Dyno graph supplied by the shop clearly shows no second flappy peak.

All lot of the mistakes seem to me as if they were done because it would look nicer to plumb it that way.

IMO those BEGI units are junk. We played with those back in the day and gave up since they were never consistent and eventually failed.

Do yourself a favor and get a Vortech FMU.

Or better yet, slap in some larger injectors and properly tune the fuel map eliminating the BEGI all together.

Ken, search the Twin Screw thread. There are a couple posts about BEGI Diaphragm’s and I think they were sourced from Corky Bell at least that’s where I got mine :thumbup:
​​

That was the first thought I had too, but when I looked at the photos of the one Ken is working on, it is a different design from the one that was on Rocket. Corky Bell still may be able to help him with parts though.

https://rennlist.com/forums/928-foru...ml#post2636490

I ordered some 1/32 silicone diaphragm stuff (red = faster)

https://www.mcmaster.com/diaphragm-r...hickness~1-32/

https://www.mcmaster.com/mvC/Content...4593952111.png

That is the plan once I get it running properly and re-dyno'ed.

What is the current fashion in (low-boost) injector size?

Will read through that thread. 2005!!!

I am going to cut out a diaphragm from sturdier reinforced silicone sheet. Should be here tomorrow!

Thanks for the link! The parts blow-up shows what I suspected: the small washer which presses down on the spring is missing.

Good thing I ordered a 12" x 12" sheet because the fuel side gasket/diaphragm is bad too.

Bad thing: there is a bushing around the newer design piston which, of course, fell out as I held it over the side of the engine. It clanked and did not fall on the ground. If I can't find it with my usb camera later today I may follow the signs and get a Vortech. :banghead:

Could not find the bushing...ugh :icon501:

Fortunately, it measures out to 5/16 ID x 7/16 OD x 1/2 tall, a common bronze bushing size.

Should be able to source it locally tomorrow and get it back together for the weekend... but it is forecast to close to 110F here so I can't drive it because the cooling fans are inadequate. :D

The Murf928 kits run the green Bosch 42lb injectors. Just be careful where you buy those, a lot of counterfeit ones out there.

@Lizard928 has run larger injectors by Siemens, but I don't know the exact model.

Really no harm in going bigger.

We may have a couple Murf928 intercoolers that would fit all the same. I'm not a fan of non-intercooled boost, no matter how low the boost is.

Ken,
Use the Siemens Deka IV 60# injectors. Do not get the offshore units!!! make sure they are genuine siemens!
They work perfectly down to 1.5mS and all their specs are readily available.

Ditch that BEGI and purchase a new factory fit FPR from Roger, he has aftermarket units that work awesome and are much cheaper. They just tune it for those injectors.