D-valves from DI to IDI?

[TurboDerv]

Hey,

I have a question about using delivery valves from a DI pump/head, on an IDI application, which is whether or not they will work.  Also, does anyone know the difference between them, and if they are different, how functionally are they different?  Thanks!

[QuickTD]

Delivery valves are "tuned" to the length of the lines and the amount of pressure that a particular system develops. IDI delivery valves are just simple check valves that have a piston with a certain "retraction volume". They are designed to remove a precise volume of fuel from the line at the end of delivery to prevent secondary injection due to pressure reflections in the injection line. Due to the higher injection pressures encountered in the DI engine, retraction volume alone is often not sufficient to dampen the pressure wave that is created when the injector closes. DI injectors have an either a return flow restriction or a constant pressure valve in the retraction piston to help dampen the pressure wave.

 I'm sure that either type would allow the engine to run, but it's a case of horses for courses. I would guess that the IDI delivery valves would be a better match for the IDI injectors and lines.

[2383 GTD]

Well written QuickTD.  I can add some of my experience using both types of D-valves.  The quick version of it is, in general, use the D-valve that came with your engine.  It is also possible to use D-valves from one IDI engine to another, provided the injector type, and injector line lengths are about the same.  

However, when using DI D-valves on an IDI, in my experience, resulted in a completely non-running engine.  The valves were slightly longer, leaked a bit when sitting without injector lines, and were brand new.  Whilst cranking, fuel would shoot out in a slightly greater quantity (not measured, just observed the quality) with less force (also qualitative).  In addition, when the lines were in place, "zero" fuel was injected.