Disclaimer: ABSOLUTELY NOT SELLING ANYTHING, INFO REQUEST ONLY

One of your members emailed me recently, inquiring if there was a Synchronic FPR model for the Impreza and requested that I post on this forum once available. If you haven't heard of it, Synchronic FPR is a new adjustable fuel pressure regulator that eliminates the use of a diaphragm and instead uses a piston in conjunction with an aerospace polymer seal. It is a dedicated 1:1 and 12:1 FPR in one, that is small enough to bolt directly onto the OEM fuel rail to replace the factory unit.

Unfortunately, we haven't been able to source an OEM FPR to take measurements. Could someone out there that has one of the factory units help out with a set of calipers and take some measurements? If we could start a thread that measures the various OEM FPRs on the various engine models, then it would be helpful for you guys to also cross reference which other aftermarket FPRs would bolt right on for the Impreza.

If you're up for it, here's what needs measuring. This is probably best done with digital calipers:

1) flange bolt hole inner diameter? Please note if this is oval or perfectly round. If oval, measure outermost arcs, and innermost arcs and take note of diameter of the oval.

2) O-ringed nipple outer diameter
3) O-ringed nipple depth
4) O-ring groove diameter
5) O-ring groove width
6) Distance from tip of nipple to where o-ring groove begins

Thank you and I know it is a lot to ask for a first post.

It is a dedicated 1:1 and 12:1 FPR in oneAre we talking about a FPR and RRFPR in one?

x99, yes, you can use it as a pure dedicated 1:1 adjustable FPR. Or you can also use it as a 12:1 that you can offset to kick in at later boost levels. Either way, it is very small and I'm theorizing bolts straight onto the Subaru distribution block.

FYI: Not all Imprezas have the same type of FPR.

FYI: Not all Imprezas have the same type of FPR.

Can you describe the main differences?

the difference is the way the fuel enters the regulator. WRX FPRs mate to the fuel rail. STi FPRs have a regular round fuel line inlet that mates to a hose.

?

Nothing but hose on all ports of my 2002 WRX FPR.

Same with friend's 2003.

I haven't seen it first hand but this is the diagram for an APS fuel rail install on a WRX.
http://www.airpowersystems.com.au/wrx/my01/fuel_systems/installation/frp_01_install2.gif
It shows one vacuum line and one fuel return. fuel from the rails comes in the port on the bottom.

The STi has one vacuum line, one fuel return (to tank) and one line coming from the factory fuel rails.


Am I wrong???

http://www.subaruparts.com/subaru.diag/5A/i050-103.gif
Part 22670 fpr mates to part 17533 rail.

No, I think I misunderstood what you were saying.

I haven't seen it first hand but this is the diagram for an APS fuel rail install on a WRX.
http://www.airpowersystems.com.au/wrx/my01/fuel_systems/installation/frp_01_install2.gif
It shows one vacuum line and one fuel return. fuel from the rails comes in the port on the bottom.

The STi has one vacuum line, one fuel return (to tank) and one line coming from the factory fuel rails.


Am I wrong???

http://www.subaruparts.com/subaru.diag/5A/i050-103.gif
Part 22670 fpr mates to part 17533 rail.

You are showing 2 pics of the wrx.

TMS

Here is the Sti.

http://i44.photobucket.com/albums/f1/mmurray75/fuelsystemdiag.jpg

http://i44.photobucket.com/albums/f1/mmurray75/fuelsystemdiaglist.jpg

TMS

Thanks for the clarification guys. Looks like we might have something for the WRX, but not the STi. I really don't understand why they would run two different part numbers for a similar config.

Does anyone have an OEM WRX unit that they can measure?

You are showing 2 pics of the wrx.

TMS
yep. I know what the STi looks like but I wanted to show two different sources I used for the WRX (never seen the WRX FPR in person) to show that it only has one fuel hose going to it. Thanks for the STi diagram. BTW it's missing the rubber seal between the intake tower (TGV) and fuel pipe (rail).

yep. I know what the STi looks like but I wanted to show two different sources I used for the WRX (never seen the WRX FPR in person) to show that it only has one fuel hose going to it. Thanks for the STi diagram. BTW it's missing the rubber seal between the intake tower (TGV) and fuel pipe (rail).

There are a couple of things that aren't quite right in that diagram. It is from the 04 FSM, maybe it is better in the 05 FSM.

TMS