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Porschefile Porschefile is offline
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Join Date: Jun 2004
Location: Austin, TX
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Originally posted by WydRyd
What type of injectors are the 951/944Turbo units? High or low impedance? That's what I'm using in my setup. Recommended by Protomotive because of their excellent atomization. They are over-driven, so they can support higher power levels in a 3.3.
What type of EFI or fuel injection are you running again Merv (sorry, bad memory)? You know, the 951 stock 37lb injectors are what I had when I first bought my Carrera (has a "quasi" Protomotive stage 3 setup). Personally, IMO these injectors are too small for the 400+rwhp level, at least if you want to keep the injector duty cycles under 80% for longevity reasons. The only reason I've been able to figure that Todd prefers to go this route on a setup around the 400hp level is due to the atomization and the fact that they might provide better drivability with the stock 3.2's Motronic (if that's what you are using; I am) as opposed to some significantly larger injectors. Though, typically most injectors tend to wear out much faster and can sometimes fail completely when running over 80% duty cycle for extended lengths of time. 37# is about equal to a 370-400cc injector. Running higher fuel pressures (depending on the exact type of injector) can increase this output a bit, though ultimately it's a bandaid. If you happen to have an aftermarket EFI, most modern EFI systems have much more advanced tuning capabilities and can be tuned very well for significantly larger injectors. My rule of thumb is to always go a little larger than your planned max hp level so you leave yourself a little bit of room and keep the duty cycles lower. Despite what some might say, you can tune some fairly large injectors to still provide good drivability with a good aftermarket EFI. I've seen and had friends that have tuned significantly larger injectors around the 800-1000cc range on various Nissans, Toyotas, and other cars using good quality aftermarket EFI like Autronic, DTA, Motec, etc. One other issue though is impedance differences as high impedance injectors typically don't get as large as some of the low impedance ones can. Though, many modern aftermarket EFI systems are capable of using either high or low impedance injectors. Anyways, sorry to get OT, I just figured this info might be good to post.
Old 12-01-2006, 10:56 AM
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