- I've seen the numbers for pressure at the injectors listed as anywhere from 3500psi to 19500psi - so, what's the REAL pressure the VP44 puts to the injectors?

 

When my injectors were set and tested, the spec was 308 bar, or in that neck of the woods. 1 bar (atmosphere) is roughly 14.7 psi, so that gives us just over 4500 psi.

 

...the Haynes manual indicates that pressures can exceed 17.5kpsi.....
4500 sounds more realistic!

 

300 bar- THat's just the oppening pressure. Peak injection pressure can go much higher.

 

I've read that it goes up to 15K or higher, but I don't understand, once the injector opens, how it can go up.....the injector should be bleeding of the excess pressure???shouldn't it???

I wonder if that is just "static" pressure under no load....that the VP is "capable" of producing...if the injector doesn't open???? Most high pressure fluid equipment I deal with is rated to max out at a little past 5000 psi, and the injector lines on my dodge do not look any more beefy than those.?

But there are some people on this site that know a lot about this VP44 injection system. They can chime in on it. Give you a better opinion?? I'm guessing most of the higher pressures nowadays have to do with the EPA and nothing else. You get a fairly atomized spray if you get close to 1500 psi, anything past that is just overkill. So I'm thinking it';s the instantaneous electronic "control" they want to have with everything......because they are trying sooooo haaaard to kill our fuel economy.

 

The pressure required to pop the injector may be 3500 psi, but remember that the holes on the injector tip never change size. In order to force more fuel through the holes in a given period of time requires more pressure.

 

Peak line pressures with the VP44 will exceed 15,000 psi.
Peak pressures are often 3-4 times higher than injector opening pressures. Electronic controls make the injection happen within a more precise time frame. Injection pressure has been gooing up with every injection pump change (higher still with HPCR) since the VE pump... it is emissions driven.

Raising injector opening pressure and increasing the "cam ramp angle" results in higher pressures and the injection sequence happens in a shorter time frame, reducing most tailpipe emissions. With VE pump technology, Hp would be severly limited without excessive smoke, because it would take too long (like 20 engine degrees) to inject all the fuel ness. to produce the higher hp.

Comment edited by Admin.

A typical injection line would be 6mm dia. with a 3mm hole for a 1.5mm wall thickness. Higher output systems will sometimes use a 2mm wall thickness. I'm not sure what the 03 and up systems use for wall thickness.