Thinking about a TBI option

[dubya]

Holley's TBI page:
http://www.holley.com/types.asp?type=61

My question is why would Holley offer 4 different TBI systems rated solely on HP? Would a TBI itself meter the amount a fuel with the timing of the injector? In my head I imagine that once you calibrate the fuel pressure and injector timings you can make just about any combination work. Is there that much difference between the injector sizes? Aren't they interchangeable.

Sorry I know it's too many question and this board probably isn't the most appropriate

[shelby987]

From my crude understanding, it is based off of the capability of the computer, the size of the injectors (lbs/hr), I seem to remember reading that once the injector is pushing more than 60-70% of its max it actually becomes less efficient at fuel dispersion. Also, the throttle body blades themselves are different sizes (bigger engine, more cfm).
Likely, the designation is more for general guidelines....to base it off of cfm is not the best method, because most people will tend to lean toward bigger is better, and thats not how a fuel injection system works, it reads everything, and then makes the correct decision on how much fuel to deliver....i always thought of tbi as a smart carb, but my buddy prefers toilet bowl injection (step on the gas, and hear it flush)

[shelby987]

also, correct me if I am wrong, but if you are looking at this option, make sure you build the engine first, then install the tbi.....don't take a stock 350, put a 400hp rated tbi on it....and expect results....as far as power goes, people will disagree....but $$$ can often be spent in better places than on a $1,300 tbi setup....but for reliability, throttle response, mpg, and tune-a-bility its not a bad bang for your buck.
I would recommend (if you have a small block) look around for a used setup like this, or try to rig up your own.....people are always selling them on ebay....unless you have an inline 6....then you are on your own to figure it out!

[dubya]

Thanks - I built up a sbc400, and am running it with my stock 350 intake/carb. It runs like a champ, but was "thinking" about going a TBI route. You're right about the price tag stinking!!

[Jason915]

Just something to think about, in my experience the Holley Pro Injection is not easy to tune with the fuel mapping that it comes with the only way I would consider investing in one I would have to include the cost of the wide band O2 upgrade.