gbarron

Anyone had any experience installing an S2 (80-86) fuel pump on a S4 car? Looking at the specs the only difference between the pumps is about 13 PSI (S2 model 017 listed at 45 PSI and S4 model 045 at 58 PSI), flow rates are almost identical. Any thoughts?

mark kibort

i wonder how i get 70+psi with my S4 pump?

mk

FlyingDog

Those numbers are not for the pump. Either pump will easily push over 100psi.

Lizard928

Glenn, the pump from your 86 will work in your S4 without an issue.

mark kibort

so, the pump is rated at some type of flow rate at 45 or 58psi or something like that?

thanks

Mk

gbarron

Mark, I got those specs from a spreadsheet I found on the web, it lists all the Bosch Fuel Pumps by P/N and then gives the specs for each one (min/max pressure, flow rates, voltage, amperage draw, etc.). It's a good piece of information, you can compare all the pumps Bosch manufactures.

That said, I referenced the SM last night and found the testing specs for the fuel pump. The 87- model years test spec is 46 PSI (3.2 Bar) whereas the 80-86 spec is 34 PSI (2.4 Bar). I was concerned that the replacement pump I have is rated at a maximum 45 PSI (as per the spreadsheet) and was wondering if anyone out there had installed one and if it had worked okay?

FlyingDog

80-86 L and LH-jet fuel systems are 36psi without vacuum reference and ~30psi with vacuum reference. 87+ fuel systems are 55psi without vacuum reference and ~47psi with vacuum. Either pump will push well in excess of 100psi and possibly up to 200psi. Some 928M, Murf, and Keel supercharged cars use pressures this high on the stock pumps.

IIRC, Tony H. has posted the peak pressure/flow specs for standard Bosch pumps and upgraded pumps. You can find a lot of pump info searching the Rennlist 928 forum.

gbarron

If these pumps are interchangable with no effect on the fuel injection system then why did Porsche make the change in 87-88, and again in 89?

jpitman2

I had an S4 pump on a Kjet car for 5+ years in 120F temps delivering 75psi.......I work on the basis that if the pump will mate to the fittings and its built for injection, it should do the job.
jp 83 Euro S AT 51k