Much thanks for whoever posted that you can remove injector diffusers with a paperclip. I was sweating on replacing mine until I popped the first one out in 30 seconds!

How? There are three small holes, equi-distant from each other, on the body of the diffuser that a paperclip with a 1/4" long, 90 degree bend on it's end can snag and pull out.

Feel free to pop in and say "hi" if you're the mystery person. ~rich

 

I thought they just pop out. Why did it need a paper clip??? And would a pick work just as well???

 

Well, they can be brittle sometimes and are rather expensive to replace.

 

I shoulda clarified - the primary diffusers; Secondaries are easy once you have the UIM off. I was too lazy to remove the LIM to pop them out from beneath.

I'm sure a pick would work too but didn't have one with me. ~rich

 

heh i was thinking exhaust diffusers and was confused as hell. the intake "diffusers" are usually called "atomizers".

 

why were you removing these?

 

You got luckey....those things are so brittle when they are old.

I had to remove mine to clean my intake manifolds when I was cleaning them for the engine rebuild.

James

 

Yeah, they just pop right out. Haha, I thought you had some *ingenious* method for removing the exhaust diffusers, lol. That would be quite a feat to remove those with a paper-clip, lol...

But yeah, with the fuel-atomizers, just make sure you put them back...

 

I pulled my UIM to replace a leaky pulsation damper and found that one of diffusers was missing 1/4 of it's face. I'm gonna replace it (as you read this) this time but am thinking of removing the primary diffusers for good once I make some other mods. ~rich

 

Why? I thought they were kinda needed.

 

They are needed, from what other people say, for better fuel atomization especially at idle. Poor atomization is prolly cause the intake runners are so long / and the rather large intake port area.

I'm hoping that delaying injector opening time at low rpm's, reducing primary injector cycle, increasing rail pressure and bumping up idle rpm's a little that I'll be able to get rid of them.

In the meanwhile they're going back in. ~rich

 

But why are you taking them out? I didn't think they did anything bad that would cause you to want to get rid of them.

 

Weird theory, but unless you go with a standalone ecu, I don't think you can control injector timing with a stock ecu, at least I don't think. Please correct me if I'm wrong and tell me how.

 

you are correct carzy, the whole setup depends on a standalone. Which means it'll be summer before I have the extra money to buy what I need!

Sideways7: I'm guessing they help atomization for a smoother ride at lower engine speeds. At higher rpm's and faster intake velocity they become an obstacle to getting more air into the engine. Therefore - they gotta go. The higher rail pressure is to shoot the fuel harder out of the injectors improving atomization without intake restrictions.

~rich

 

I think you are going the wrong way again.

Even FD motors have them, and a FD motor will put out more power and suck more air in than any non turbo can be tuned to do.

The amount of drag that they induce is pretty small. Maybe if you were smoothing the entire length of the runners and removing the bolt re-enforcement; then you might be concerned with the minor amount of drag, but I wouldn’t.

Personally, I'd be more concerned with the drag from the re-enforcement bumps and cast runners then I would from something as small as the injector diffusers

 

If the factory had to make a choice between losing driveability for some higher RPM HP gains that only non-factory engine mods can utilize or a driveable car to please the mass markets which choice do you think they'll make? Somehow I don't think they would mass produce a car that idles at 1200 rpm and has little low end power. The factory fc3s was a compromise between racing and what regular people would buy to drive everyday.

You are absolutely right about intake manifold short-comings. Also been examining the LIM and the angles into the secondary ports are unacceptable. However, I'm not aware of any aftermarket alternatives. Been thinking of making a custom manifold but am not committed to dumping that much money / time in the car yet. ~rich

 

You just need to port and polish... Or extrude hone the whole intake as Icemark did. That seems the best, because it is a bitch to get into the runners.

The Extrude Honed intake takes out all the re-enforcement bumps, matches the runners, and enlarges and polishes the runners to a nice satin finish.

On the injector diffusers: I would probably leave in and dyno. Then if you are convinced there are gains removing them, dyno again after they have been removed.