3.5bar vs 5.0bar

[grannyknot]

Hi guys,
Starting a list of all the ins and outs of an S54 swap and the first one is I have a 3.5 bar fuel pump installed in the car now, S54 uses a 5.0 bar pump.
Can I get away with using the lower pressure pump and what be consequences if I tried it?
Thanks,
Chris

[FredK]

What pump are you using right now?

Pumps are rated by flow rate at a given fuel system pressure. Not all fuel pumps are created equal: some can flow nearly the same fuel at higher pressures, and some can't. There's a lot of aftermarket pumps that are fine with either 3.5 or 5.0 bar.

Like would an M42 stock fuel pump work? Some of them might work fine, but if you can't deliver sufficient fuel, your engine can lean out and cause engine damage. Like am I certain that an M42 pump would cause engine damage? No, but it's a cheap thing to address.

The system pressure, of course, is regulated by the fuel pump regulator.

[grannyknot]

I'm using both the fuel pumps from a 1987 M6, an in tank lifter pump and the bigger one with separate fuel filter just outside the tank.

[FredK]

Gotcha. I am sure you can reuse the in-tank lift pump. As for the high pressure pump, it appears to be a Bosch 69418 pump. I believe it can operate at 5 bar, but information on it is a bit sparse.

If it were me, I would reuse the stock lift pump and feed a brand new and quite affordable inline pump like a Walbro GSL392, a 255 liter/hr pump.

[grannyknot]

Thank you, that`s good info, I was mostly worried about having open the tank up and start screwing around trying to get a different pump to fit in there.

[The Dark Side of Will]

Doing an S54 swap on an E24?

[grannyknot]

Doing an S54 swap on an E24?

Well I hope I don't get kicked off the forum but I'm planning on putting the S54 into a 1972 Datsun 240z, I have an S38B35 in the 240z at the moment which is wonderful but after I started reading up on the s54 it was pretty obvious that it really is the ultimate straight six.

[ThatM20Guy]

That will be a pretty killer build. One of my favorite cars of the era and a great motor!