Flat Spots in Rising Rate FPR's
Discussion
Think this is my first post for a year and haven't driven the 350i for even longer than that.
Anyway, last time I drove it it was suffering from severe fuel starvation. Would either start and run faultlessly, or start and barely run at all. Fuel pressure regulator?
Spoke to an engineer about fitting a rising rate jobby - but he recommended against it because of the difficulty in removing flat spots when the cars are on the rolling road, and he added they sometimes can't be removed altogether (he actually fits a particular brand of these himself, then does rolling road tuning, by the way). He just recommended fitting a standard one instead.
Just wondered what other peoples opinions were and how long it can take set one up with the car on the rollers.
Thanks
Anyway, last time I drove it it was suffering from severe fuel starvation. Would either start and run faultlessly, or start and barely run at all. Fuel pressure regulator?
Spoke to an engineer about fitting a rising rate jobby - but he recommended against it because of the difficulty in removing flat spots when the cars are on the rolling road, and he added they sometimes can't be removed altogether (he actually fits a particular brand of these himself, then does rolling road tuning, by the way). He just recommended fitting a standard one instead.
Just wondered what other peoples opinions were and how long it can take set one up with the car on the rollers.
Thanks
I had one on mine when I bought it last Sept, Webber one. I had it tuned recently and they took it off and put a standard one back on. It was set up then, timing etc(not on a rolling road mind you) running 97 ron unleaded and it feels a bit quicker and more responsive on the standard regulator. I will try the rising rate one back on at some time, (next time I get it tuned and checked) just as a comparison. 
The one fitted to Wyn's car was fitted and setup by Tower View in London. The car was supposed to be more responsive and have a little more get up and go with the adjustable fitted but in my opinion it caused no end of fuelling issues.
I took it back several times to the boys at Tower but every time I felt that it still wan't quite right.
In my opinion stick with the normal one (in my experience).
MikeB
I took it back several times to the boys at Tower but every time I felt that it still wan't quite right.
In my opinion stick with the normal one (in my experience).
MikeB
I could maybe see a reason for using a rising rate regulator on a mechanical injection system, like the 280 because its injectors are designed to flow over a wide pressure range.
Wierd stuff happens to fluid flows if you change the pressure. I cannot imagine that the injectors on a 350, which are designed to work at a single pressure would be matched to within even 20 percent flow if you changed the pressure by a similar amount. More likely you'll get a few cylinders running much leaner, and a few running much richer.
I think all the car makers have now realised that variable pressure injectors are just not viable, at least I don't know of any cars using them.
- jim
Wierd stuff happens to fluid flows if you change the pressure. I cannot imagine that the injectors on a 350, which are designed to work at a single pressure would be matched to within even 20 percent flow if you changed the pressure by a similar amount. More likely you'll get a few cylinders running much leaner, and a few running much richer.
I think all the car makers have now realised that variable pressure injectors are just not viable, at least I don't know of any cars using them.
- jim
jchase said:
Wierd stuff happens to fluid flows if you change the pressure.
Jim, weird stuff used to happen with fuel regulators at TVR. Rather than go the rising rate regulator option, they acheived greater pressure in the fuel system by partially compressing the regulator in a vice.
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