ok i was reading the haynes man. s4 press. reg. is 28 s5 is 21 can use s4 secondary fuel rail (for more press. ) on the s5 TII intake w/o major prob. it looks like it will fit

 

The S4/S5 pressure regulators work the same; the main difference is the S4 regs are threaded in. If you can get it to bolt onto the S5 TII UIM, it should be fine. Also, make sure the fuel lines are still routed so the regulator is on the return side.

A lot of people interchange rails with custom builds. I've used S5 NA rails on a S4 NA block with no problem.

 

Ditch whatever your reading and download the Factory Service Manual from this site and read the Fuel and Emissions Section. What your reading is B.S.

Talking about the thread owner.

Series four and series five pressures are about the same if not the same. Hell, even a non turbo series four has the same pressure, at idle, as a turob car and the same can be said if the vacuum line is removed from the FPR with key to ON.

Plus, I can put pressure on a non turbo FPR and get a result of 50psi when 10psi is applied to the FPR *vacuum* port on it.

Series five at idle is the first jpg.(idle vacuum)

Series five with just the key to ON is the second jpg (atmospheric pressure)

Series four is the same thing. Turbo or non turbo. Same thing. Alike. Like Dittos. Two peas in a pod, thing. Same 'ole, same 'ole.

The second two jpgs are NON TURBO figures. Same 'ole same 'ole.

 

thx i'll read the FSM

 

you will need/want to use washers under the mounts for the fuel rail so it tightens down correctly. other than that, it bolts right in.

 

Yo. I was just trying to disabuse the thread owner from thinking that the change in rails was going to do squat for pressure.

 

lol. i was merely stating that they will fit with the spacers. i didnt say it would be a good/bad idea to do so or if it would be worthwhile.