I will be using ID 1000 primaries and 2000 secondaries. I have the FFE cup things that they sit in (cant remember exactly what they're called)

Are diffusers recommended? I know they can break and damage the engine but im not sure if I should just leave them at this point

 

Most people say the spray pattern is good enough on the IDs not to need diffusers.

 

The spray pattern isn't the only factor, the diffuser creates a low pressure area downstream of itself which helps flash the fuel into vapor and improves the homogenization of the mixture.

 

At least for the primaries, it also stops the injector pattern before it can cross through the air stream like an air door. Having no diffuser on the primary should hurt airflow.

 

I've been thinking about this issue and I'd like to give 1 for vote for the diffusers not being that important relative to the risk of sucking one in and blowing a motor. Granted, that seems to happen rarely, so use your best judgment.

I haven't inspected the pattern on the ID injectors, but basically all the new style ones use a series of small holes to spray from the nozzle. On the old style injectors, it's one or maybe two bigger holes that need extra help to vaporize the fuel. Also, the air atomization ports help as well.

 

The o-ringed inserts are designed to be run without the diffusers. Don't use them. they become brittle, crack, and fall into the motor causing damage.

 

ID's have a significantly improved spray pattern than the common injectors we're used to seeing on our rotaries.

there is no need for the diffusers, and as Rotary Experiment Seven has said, you can't use them anyway.

I've seen ID 725 and ID1000's used as primaries and they hold a rock solid idle. Some people even use a much higher static fuel pressure.

 

I have seen a plastic diffuser fall into a 13B before. Nothing happened.

Timeline:
Tore it apart for rebuild, all diffusers were present.
Bolted it back together with its diffusers under the stock injectors.

Tore it apart over a year later because the owner then wanted to go single turbo, fancier seals, etc. Was still running fine.
Noted one diffuser was now gone. Engine had been running fine regardless.

This tells me that A. I dont think they have a huge effect on performance.
B. It clearly must have swallowed a diffuser while running. It kept running and did not cause damage. Nobody noticed until it was pulled apart one day.

 

You got lucky. I've seen at least 3 motors that chipped a seal when part of an injector diffuser fell into the motor.

 

I specifically asked full function about this, and they were definitive. Do not use the diffusers with the ID injectors.