Miata Mailing List: March 1997, Message #52
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   From: (none)

Subject: Question to Autorotor owners...

   Date: (none)



RE:  Fuel pressure



With the boost/vacuum signal tube disconnected for the FPR (@ atmos. 

pressure) what fuel pressure do you run?



For the past year, I've toyed around with the fuel pressure regulator.  

I've experimented with pressures from 45psi to 55psi.  Under certain 

conditions (temp, humidity, lunar events, etc,.) the fuel pressure got 

stuck momentarily at around 60psi, causing a temporary lean condition 

(bogging), before shooting up to it's usual nice and rich 115psi at full 

boost of 11-12psi (with larger injectors, that is)



The solution was that I could not open the throttle quickly (boost would 

rise before the fuel pressure could catch up) otherwise I would suffer 

an annoying fuel pressure lag, especially at 2-3k rpm.



Recently I've played around with even higher off boost fuel pressures.  

I found a suprisingly high pressure of 60psi to feel very very nice.  No 

bogging and more low end/midrange torque with marginal decrease in fuel 

economy.  Needless to say, I'm not going back to the recommended 

pressures of 45-50psi.



NOTE:  When I adjusted the off boost fuel pressures by the center 

locking nut, I also had to adjust the bleeder valve in order to still 

maintain the appropriate fuel pressures at boost.



>From experience with all of the Bell systems, this small problems seems 

to manifest itself more with the autorotor and aerodyne due to the fact 

it achieves 5-7psi at low rpms instantly whereas the turbo spools up 

gradually allowing the fuel pressure to follow.  Anyone else share this 

opinion?



I know all these problems with be resolved with Bill's ECU, but until 

then, what are you guys doing?



Comments??



Regards,



Shiv