choinga

I recently bought a Lindsey Boost Kit for my 951. It comes with a Bosch FPR that you use to replace the stock one since apparently it's not adjustable. My PO had actually done that already so as it turns out, I don't need to change the FPR. I have an aftermarket one with a guage on my rail.

Dave told me via email that I should just leave it on the car and make sure the pressure s set to 43 PSI when the car is idling and the vacuum hose is disconnected.

My question is - which hose and how do I adjust the PSI?? Should there be some kind of an adjustment screw on the FPR or do I need to look elsewhere?

Rock

That fuel pressure regulator is not adjustable. Theres no way to adjust it. It should be a 3bar regulator which puts out 3bars of pressure.

The vacuum line he is talking about is on a little nipple that connects to the fuel pressure regulator at the top.

V2Rocket

how big of injectors will the 3bar FPR support?

theedge

The regulator doesnt have a limit to the injectors in the way that you mean, it limits the flow of ANY injector. If you look at injectors at see 75lbs/h at 3 bar of pressure on the specs, thats what they put out. If you have "75lbs/h at 3 bar" injectors and your fuel pressure is 2.5 bar, then the injectors wont do their rated flow, theyll do less.

Any 3 bar will work with any set of injectors, just like any 2.5 bar regulator would too, youd just have to choose your injectors differently for a 2.5 bar regulator.

choinga

So, I'm even more confused now.

Are you saying that all I need to do is install the boost line and the PSI will jump to 43PSI? Right now at a cold start it idles at ~39PSI. I'm just confused I guess on if there's anything that I'll need to adjust after installing the boost line if the fuel pressure gauge doesn't jump to 43PSI?

V2Rocket

and what if the FPR's pressure setting is higher than the injector's specs?

choinga

per Dave's response to me that's not accurate. Apparently my FPR has a locknut screw you loosen on top then the inside screw turns clockwise to raise the pressure. You take the hose off and set then put thehose back on and the pressure should drop.

blown 944

I think what you mean is the PO has already installed an adjustable FPR??

If so there is a jamnut and allen or bolt head that you turn inward for more pressure and outward for less. Basically what he is telling you is to match what a 3bar regulator is set for with your already installed adjustable FPR

You remove the vacuum line that is attached to the FPR and plug it temporarily.

The regulator has nothing to do with how big of injectors can be supported. It is only a means of controlling pressure. The ECU,pump, and injectors are the determining items for tuning, the regulator only sets the pressure to be used w/i the tune.

blown 944

However, I should say that you can tune with an adjustable FPR but the tune may be off in areas and only good at WOT or visa versa.

The idea here is that the chip is built expecting (x) amount of FP,with (y) amount of injector and sends the proper signal to achieve the appropriate AFR. That is simplified but ......

V2Rocket

interesting.

anyone use the 3.8bar on pelican? part # 944-110-198-06-M14

theedge

If the regulator is higher, you get more flow.

Theres upper and lower limits to pressure, its usually best to stick to 3 bar and spec the injectors accordingly. Fuel pump flow is lower at higher pressure, and remember that when youre under boost the fuel pressure goes up. Its base pressure + boost pressure, so if the regulator is 40PSI then at 20PSI boost fuel pressure goes up to 60 PSI.

By upper and lower limits, I mean that too low of a fuel pressure then you can poor atomization of the fuel (this is 30PSI and lower I think) and too high and you run into pump issues depending on the pump, and fuel injectors can stick at high pressures.

Obviously this depends entirely on the setup and parts involved. Bosch 044 pumps can do high pressures, and it depends on the injectors. But not very many people use a 3.8 bar regulator.

jstand22

the 3.8bar regulators are for the 16V cars, never heard of anyone using one on a turbo, but I don't see why it wouldn't work.

blown 944

It would work however the injectors may not last as long.

I have myself ran some pretty significant FP (over 100 psi) and so far I havn't seen any troubles with the pump but I have had an issue with a set of injectors. I am unsure whether it was related or not but I can't rule it out.

After tuning on a 968 I realized that the FPR on that would be great for those who want to convert to E85 on a 951 b/c the pressure is perfect for a direct swap.