Injector Line Length - Equal or Not? January 03, 2011 09:05AM
I have seen in other motor sports this argument for both injector lines and headers. To make equal or not?

If you try to make all of the lines the same length, you will end up with multiple bends where you will get pressure drops, thus resulting in different flows per line. When fabricating the injector lines, do you calculate out your pressure drops due to the length of the line and the bends to try to get the same flow numbers per line? If you supply a constant pressure across the injector for a given period of time and this same pressure is constant for each injector, then the flow through the injector orifice should be the same regardless of the length of line.

Any dyno numbers or actual injector flow data to back up to go equal or not equal?

If you look at some of the engine photos in the For Sale tab, there are examples of both equal and not equal injector line length.

What is the opinion of the forum?

many thanks,

Grapes
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Re: Injector Line Length - Equal or Not? January 03, 2011 03:38PM
injector line length has to be the same length for the timing to be the same on all cylinders ...as with all mechanicl pumps the fuel is sent out at the same rate so th need to arrive at the proper time in the injection cycle so yes same length is the rule...IHSMOKE
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Re: Injector Line Length - Equal or Not? January 03, 2011 04:24PM
Flow at the injector is not a function of pressure. It's a function of volume. If the piston in the pump has no leakage past it, the fuel it pushes will flow out of the injector regardless of the length of the line or how many bends are in it, IN THEORY. The liquid fuel is not compressable, so what enters the line at the pump will come out the injector. In the real world, there may be microscopic air bubbles in the fuel, and slight leakage at the pump piston, which will reduce flow, so the least resistance in the line would be beneficial. It would also be easier on the pump, increasing it's longivity. Thats my opinion, and I'm stickin' to it.
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Re: Injector Line Length - Equal or Not? January 04, 2011 12:21AM
when i got my lines they were not bent,i bent them in the easiest way possible.they looked like big upside down "u's" of various lenghts and shapes.i did not notice any difference having them different lenghts or shapes.there is not any voids in the line so like toolz said the pump displaces "x" volume of fuel per plunger and thats what exits injector.
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Re: Injector Line Length - Equal or Not? January 04, 2011 02:45AM
The pressure inside the line is not at injecting pressure. If it was, the injector would stay open, pouring fuel into the cylinder constantly. When the pump sends the pressure pulse, it will take a millisecond for that pressure wave to reach the injector tip. If the lines are not equal length, the pressure wave will be ever so slightly different, affecting the individual cylinder timing.

If not, why would all the engine manufacturers waste time and money making the looped equal length lines standard?
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Re: Injector Line Length - Equal or Not? January 04, 2011 02:58AM
At high rpm and high fuel rate I doubt if there is a measurable difference.
Hand bent lines that vibrate all over the place are prone to breakage and look like junk.
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Re: Injector Line Length - Equal or Not? January 05, 2011 10:41AM
Listen to an old model 4020 DEERE 64 - 68 then listen to 69 - 72 you will have your answer
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