Hi guys,

I own a set of RC 750cc injectors (SH4-750) for my AP1 supercharged.
I sent them to flow testing and cleaning. Before sending them, I saw that one of them (the third) did not look like the others: the "diffuser" which has 3 holes seems to have the center part missing. You can see it by zooming in the picture:


The following picture shows the injectors being flow tested, and you can see on the right that this injector number 3 has a "single spray" shape, where the others have a "3 sprays" shape.




My question is: how important is the spray shape ? I am taking a risk to use this injector in my F20C with 10psi supercharger ?? (on pump fuel "SP98" in France, equals to your 93Oct)

Thanks for your help!

 

The diffuser is rather important because it's job is to atomize the fuel and allow it to mix with the incoming air better. Whether it is enough to actually cause a large issue is debatable, but it's probably best to replace that injector to prevent any issue. It could save a major headache in the future

 

Thanks for your first answer. I understand the "atomization problem"...
Here is the video of the flow test, where you can really see the shape of the 4 sprays.
(test is done before cleaning, and flow results are not ideal: near 10% gap between the 1 and 2 ... we'll se after cleaning)

 

I have the same type of injector tester and it differs a lot between the tubes, I think it's mostly because of the fuel rail.
To get good comparable data you should test each injector in all four tubes at least 3-4 times and then take an average of all runs.
Check minimum pulse width and also compare how the spray pattern look down there, at higher pw I'm not sure how much difference you would notice.
If it was me though I would just go for a new set of Bosch injectors instead either way.
You don't want to cheap out on a critical component like this, I bet you will notice a big improvement on how the engine runs.

 

What Bosch injectors are you talking about ? (if you have a link)
If I have to change injectors, I would like to go for 1000cc to be ready for E85 conversion. I understood that ID1050X is the best solution, but it has a cost...

 

I guess any Bosch EV14 injector from a reputable source, like these for example https://www.finjector.com/eng/ev14_1...r-p-450768-187
I got a set of ID1050X myself but would never buy anything from Injector Dynamics again, their quality control and customer service is a complete joke.

 

I am very surprised by your experience with ID. I thought it was the most reputable injector maker ?!
ID1050X has a major reputation here on s2ki. Being like 40% more expensive than the EV14 you show, I don't know if I have to be safe and spend money on the ID, or if the EV14 is good enough (quality, reliability...)

 

Your link really makesd me hesitate: it provides the set of flow matched EV14 for 340€ delivered in France
Best price I find for ID1050X is around 520€.

It is really difficult to know if the quality difference is worth the money

And how do you know that the set on your link fits the AP1 ?? (length, O-ring sizes, connector ...)

 

I guess even the "best" fails sometimes. I also paid the premium just to be safe, but clearly this is not the case with ID.
I got pretty lucky and found the fault before mounting though, otherwise I might have sprayed down the engine with fuel and if really unlucky burnt it down.

The injector I linked to is the same size as the ID1050X but it has no top or bottom adapter.
If I remember correctly pre facelift has 11mm top and those thick spacers on the bottom, you can get those separately from many places or maybe from same place in a ready package.
https://www.finjector.com/eng/bottom..._injectors-219
https://www.finjector.com/eng/adapte...diam_11_mm-217
It might be even cheaper from some french store, I mostly linked to finjector for their great assortment and that they also seem very trustworthy.
I'm not using my ID adapters so I can check the lengths on them later for reference if you want.

 

The quality is good enough for Bosh Motorsport to have them listed in their catalog, which no other aftermarket injector company can claim. The customer service is as good as you will find anywhere, I have the two customer service reps sitting directly behind me. Sounds like a situation where you were told something you didn't want to hear. Feel free to email me and explain the situation though

Stuart@t1racedevelopment.com