plastex

Ok, I was just wondering what the fuel damper does?, and why do we need 2 fuel pressure regulators?

Also, if I go to one of the adjustable FPR, then do I need to buy 2 of them?

Thanks,
Oscar

plastex

Anybody?

hacker-pschorr

My first thought is, what are you trying to do? Why are you going to an adjustable FPR? What have you upgraded on the engine to need this?

Jadz928

You only need 1 AFPR and the other 2 can be dampers. The dampers balance out the system, rail to rail (left & right)
The front damper is necessary. One of the FPRs can be removed IF you install a damper instead. Or no rear damper and the FPR centered between the rails.
What YM is your 928? Your need for an AFPR is unknown because most stock 928s don't need added FP. Usually it's a bandaid fix for something else wrong, ie bum fuel pump or clogged filter.
Some cars, like the fixed fuel map Euro sometimes need a bump in FP to avoid lean conditions. This was the case with mine. I added a AFPR after making sure everything else fuel related was up to snuff. So my Euro was naturally a little lean.

plastex

I was looking into this because at some point this winter I am going to go with a Megasquirt system, and will eventually add a S/C at some point. Other cars I have worked on have had only one FPR. When I did the Megasquirt to my 911 Turbo I used an accel Adj rate FPR and it worked fine. At some point I will buy one of the Adj FPR and didn't know if I would have to have one for each side?

Thanks,
Oscar

hacker-pschorr

Ok, to swap down to a single FPR most people buy a used S4 dampner to replace one of the regulators.
You then have to re-do the plumbing from the single FPR to the return line but that is not a big deal.

Flint

Don't suppose you (or anyone) have pictures?

123quattro

If you are converting to megasquirt why would you want an adjustable fuel pressure regulator? Just adjust the cells in the map where you need more fuel. It's much more precise that applying a single gain to your entire system.

hacker-pschorr

Of what?

Unless he wants a higher base line. The stock FP on an L-Jet car is low by today's standards.

I'm running over 100psi on my 81 when under boost.

Jadz928

Here's what I did to plumb a single AFPR sans rear damper. The fuel feed hose hooks up directly to the elbow at the bottom of the reg.

toofast928

L Jet right?
Been their, done that. PM me with any Q.
The fuel dampner is a "shock absouber" for the fuel system. It quiets pulse noise from the fuel pump. For a SC set up it becomes a restriction.
Tony

Flint

Ahhh, interesting... My AFPR looks a little different, but I imagine it could be made to work the same way. When I bought it I also bought an 24 damper but it doesn't have the same fittings.

Alas, but I hijack...

mark kibort

Ive done this a few time. You only need one fuel regulator and just take the other regulator, that already has the return line and clamp the end shut! then, just attach the stock return line to it. If it leaks, it doesnt matter, its pointing to where it would go anyway. But, you get the idea. That eliminates the need for any new parts or fittings. the RRFR just replaces the one fuel reg. Nothing else needs to be done. Now, you have control of the system fuel pressure.
Did this exact thing on my two Ljet system cars (and Scots currently) and i worked all the way to near 300rwhp.

mk

123quattro

The problem with upping the pressure is it really starts working the fuel pump hard and decreasing it's efficiency.

hacker-pschorr

We are talking about fuel here.........did you bump your head this morning?

If he is serious about these mods a new fuel pump better be on the short list. Even a stock S4 pump is rated to handle 50-70 percent more then an L-Jet car and is also a direct bolt in.