fuleinjection 460/514 Who

[Mr.Fixit]

Coyled,

Thanks for the offer, but I really don't work on cobras anymore as I left the industry a couple years ago. Kisler is the setup I worked with that had the speed pro CPU. I have done two of them. I got them to work fine, it just took a lot of time and data logging to get the airflow and fuel maps anywhere near reality. Yes, the injectors are near the intake valve, but that is of little consequence. The butterflies are very near the intake valve too, and the injectors need to be below them. On sprint cars with the non-CPU controlled version of the same injection, fuel makes it to the top of the tall stacks anyway. The air column pulses back and forth in a compression wave and the vaporized fuel migrates up the stack. I believe Kinsler gets their castings from Hilborn anyway, I may be mistaken. I found the carabine controller a lot more user friendly, it was easier to tune and made all the power of the speedpro. It also doesn't need an O2 sensor, crank trigger, or MAP sensor. Or a laptop CPU to tune it.

The low rpm throttle response improvement can be had on motors with big cams, due to their low rpm air velocity, booster signal is weak with a carb. FI shoots the gas out so that's not an issue, but this is not very important because it only happens at the rpm's that are too low for your cam to be making any power. You can get a wild motor to idle at a lower rpm with FI, but who cares? Individual stack FI gets a really touchy throttle, because they have 8 throttle blades which are much larger diameter than the 4 in a carb. So a small % of throttle opening has a much larger change in airflow. (It has nothing at all to do with the injector being nearer the intake valve)

BiB,
TBI injection often runs a throttle body much larger than the carb it replaces, so as to minimise the venturi effect of the throttle body. It is THE restriction on the induction. If you go to too big a carb, the velocity through the carb drops and so does booster signal, so the motor runs like crap until it has a bunch of RPM. Not an issue when the gas is shot out, only when it is sucked out. You may have the qrong floats in your demon becaus ethere are a wide variety of racing applications, and there is not one correct part for all of them, you need the road race floats according to the description of the problem you gave.