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BASSr
09-16-2006, 07:11 AM
OK, I looked around the website and could not find the specifics on how fuel injectors are rated? (i.e. stock bosch are 29.8 lbs).

This has to be tied into the fuel pressure regulator/fuel rail. Can anyone give me a quick laymans explanation?

Bruce

kenmosher
09-16-2006, 09:58 AM
Basically, they are rated at a standard pressure (usually 3 BAR or 43 psi).

That only tells part of the tale though ... just because they are the same at that flow doesn't mean they are DYNAMICALLY flowing the same, control fuel spray the same, have the same range of pressure, etc.

The newest generation injectors from Delphi, Siemens/MotoTron/Edge, Bosch have greater dynamic range of pressure and still have an excellent spray pattern, linear response, and fast low pulse width response.

Some of the older "ball" design injectors (older Rochesters, MSD50s, etc.) will lock up under pressure, piddle fuel at low pulse widths and not adjust much beyond their rated static pressure.

BASSr
09-16-2006, 10:21 AM
Basically, they are rated at a standard pressure (usually 3 BAR or 43 psi).

That only tells part of the tale though ... just because they are the same at that flow doesn't mean they are DYNAMICALLY flowing the same, control fuel spray the same, have the same range of pressure, etc.

The newest generation injectors from Delphi, Siemens/MotoTron/Edge, Bosch have greater dynamic range of pressure and still have an excellent spray pattern, linear response, and fast low pulse width response.

Some of the older "ball" design injectors (older Rochesters, MSD50s, etc.) will lock up under pressure, piddle fuel at low pulse widths and not adjust much beyond their rated static pressure.
Ken,

With the older "ball" style, is that why you someyimes run a little rough at idle or low RPM?

Bruce

kenmosher
09-17-2006, 09:35 AM
The "ball" style uses a different seal design that hinges around a little thing that looks like ball (instead of a pintle or a disc).

They are cheap to make and are OK as along as you stay within their pressure limitations. You usually find a lot of variations between individual units (which is why it pays to have that style flowed and matched) and they really get sloppy at higher pressures or extended duty cycles.

They sometimes may leak down a little (which can cause rough cold running).