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Hi,
I'm running 30# injectors @ 50psi with a sn2000 paxton with no FMU with timing at 4 degrees.
Is this normal? Do most of you supercharger stangers out there run with such retarded timing and high fuel pressure? I'm about to go to an MSD 6BTM. I just wanted to make sure my car doesn't have any other issues.
Thanks,
p51302
I run a base fuel pressure around 55 to 60 psi. With 20 psi of boost, the injector will see 70 psi of fuel pressure. Haven't had any problems.
Have you had the car tuned by a shop or used a wide band oxygen sensor? Running that high a base fuel pressure is going to make your 30lb injectors act like 37.5 lb injectors. If you back pressure down to 40 again your car will run a lot leaner than it is now (and that may not be safe).
Timing depends on what your engine likes. 4 degrees is not a lot of timing.
Concerning, an air/fuel ratio guage, does that mean I need to weld in a new bung into the tail pipe? I keep seeing kits where they say they use the existing bung. How does that work? Doesn't the computer need to have both o2 sending input to it?
If I have to get a bung welded in, where does it get welded into? In the cross over section in the h-pipe? Does the location matter?
Thanks,
p51302
4 degrees of timing that thing must feel like a Escort. Put the fuel pressure back to stock area 38-40psi and if your only running 5-psi set the timing to 10 degrees. If you run at least 91 octane and your total timing will be 26ish you will be ok. Just keep things soft till you get a BTM or move to bigger injectors. Nothing listed on parts installed but I hope you replaced the fuel pump 190lph or larger.
Pulling one O2 out of the loop will probably flip a check engine light but it will still run okay just getting info from one of the two sensors, it copies the KAM info to the non-functioning side. Many wideband O2 controllers have an output to replace the oem sensor output, just have to splice the controller output into your harness.
I agree on bumping timing slightly but I'd sneek up on it 2 degrees at a time, no need to go at it all at once from 4 to 10. Iron heads?
I also agree on reducing fuel pressure slightly, maybe back it down to 45 psi or so. You should know that eventually, running 50 psi, your O2 sensors will tell the computer to cut back the fuel in all modes of operation including WOT at some point.
Running 50 lbs of fuel pressure will not necessarily make your car run rich. It depends on what else has been done to the car. With a proper tune running extra fuel pressure will make an injector that is too small work just fine. Unless you know what tuning has been done you can not assume that the extra fuel pressure is causing a rich condition and -worse yet- if you back it down and it needs the pressure to maintain a proper air/fuel you will go lean and could burn up the engine.