Injector Code Comparison

I pulled apart four injectors from a scrap motor that chucked a rod bearing at 300,000 miles. They were mixed codes. I pulled apart a BB, C, D, and G from the same motor.



As you can see, the C, D, and G, all from Italy, have shorter springs that were about the same length and paired holes for the return passage, but only one connected to the upper part of the injector. The Italian injectors also had two additional holes in the spring seat and had 12 pt lower bodies. The C and D used the same pintle holders. The main difference was that the BB spring and pintle seat used a greater angle.

All of the pintles had the same body diameter and length, but the BB had the smallest tip, then the C, while the D and G had the same tip diameter.

It would appear that the differences in the injectors are limited to a few thou on only a few dimensions. The sealing angles of the British made BB injector appear to be more desireable, since it looks to be more tolerant to wear.

I applaud the effort, but unfortunately very little of that really matters. What really matters with the injectors is the pop pressure (which can be measured and adjusted) and the size/shape of the pintle and nozzle, which is very difficult to quantify. Moreover, the interaction of the injector with the fuel is important and difficult to determine. A larger orifice may allow faster injection of a large volume of fuel, but atomize it more poorly and not function well at all at lower fuel flows.

The difference in spring length is of interest. The shorter spring will take more force to open the same distance as the longer one at the same seat pressure. In theory this should affect the spray pattern as the pintles will be at different position, but I shape of the pintle would also have a factor on how much force is applied on the spring. Which may amount to very little in overall performance, but when trying to get fleet emissions and mileage up for a company that sells a lot of pickups any improvement is a big plus.

I mic'd out the pintles and openings, so I'll put that in a table and post it.

I'd still like to know the basis for the BB code's popularity.... do rebuilt C or D injectors have any difference? Why was the G code used for factory turbos? Surely there is an explanation.

Subscribed to this one. I'd also be interested in knowing. Some guys will swear by one code...then another guy will swear just as strongly by a different code. I guess as long as we're swearing by them instead of at them its all good

Appreciate the "one-stop-shopping" picture on the injectors, BDCarillio. I don't claim to know why the BBs are "better." Reliability is but one criteria but there could be flow rate differences as well as pop pressure. I seem to remember seeing a pop pressure difference between the BB and the one of the others (the G???). I put Brit Made BBs in mine back in the late '90s and when I tested them in 2010, they still popped right at spec and made a perfect pattern. jaluhn83 is right, though. Matching the injector characteristics to the application and power output is what it's all about. One size doesn't fit all.

BBs (lucas/delphi) became popular because nothing else was available for awhile. They also seem to maintain a good spray pattern for much longer than the stanadyne injectors.

Black dawg said:

BBs (lucas/delphi) became popular because nothing else was available for awhile. They also seem to maintain a good spray pattern for much longer than the stanadyne injectors.

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The angles on the pintle support that idea. For what its worth, the BB I took apart was Cav brand from England.

BDCarrillo said:

The angles on the pintle support that idea. For what its worth, the BB I took apart was Cav brand from England.

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from what I have seen, the lucas/cav/delphi injectors are the same.

One advantage might be that a longer spring wouldn't fatigue as quickly when subjected to the same stress over the service life of the injector. Not sure if it would make a noticeable difference, but could it?

Black dawg said:

from what I have seen, the lucas/cav/delphi injectors are the same.

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Delphi bought the IDI rights from lucas/cav, just had a chat with my local pump shop. He is of the mind that any of them are good if maintained and serviced reasonably.