your idle characteristics? Does it idle rough due to the pulse width? Also, has anyone run 8 smaller injectors rather than the larger ones? If so, does anyone know who makes the intake manifold for them?

 

Large injectors; ie 500cc + will idle better if run richer. What I mean is as you get bigger in injector sizes, the larger pulse width will be need to idle smooth thus making the A/F greater at idle. I think that's how it's explained. Say for instance, 440cc injectors will idle smooth at 850 rpm and 14.5:1 A/F, 530cc injectors will idle smooth at 850 rpm and 14:1 A/F, 578cc injectors(which is what I have) will idle smooth at 850 rpm and 13.5:1 A/F(I keep mine around 12.9 though), 750cc injectors will idle smooth at 850 rpm and 12.5:1 A/F, etc. What I mean by idling smooth is that the engine won't sit there and oscillate or the rpms won't go up and down. It will stay within 25 or so rpm of 850 rpm. This is how mine idles with my 578cc injectors, 850 rpm and very smooth.

 

Isn't that too rich of an idle run the chance of washing oil away from cylinder walls at idle?

 

We aren't talking about dumping a lot of fuel in here like 9:1 A/F, just richening it enough to control a smooth idle. Even 10:1 or 11:1 A/F may be a little too rich for idle but I still don't think it would be enough to wash the oil off the cylinder walls.

 

The reason it idles better when rich with larger injectors is due to the fact thsat if the pulse width is too small the spray pattern sucks. Think of a injector as a garden sprayer. You want the fuel to mist. If you don't open the sprayer enough the patten of the mist is cappy, drips a little bit and doesn't ionize as well. If you don't get a good pray from the injectors, it doesn't mix properly with the air and doesn't combust at optinal time.

 

so does anyone know anyone who has made there own intake manifold to accommodate additional smaller injectors?

 

gotcha

Well, doesnt fuel economy at idle count?

just kidding

 

I was running the 1600cc injectors at about 950rpm's at 13:1a/f and no problems with the idle at all

 

There wasa guy that made a plate to go between the intake and head and had 4 additional injectors. I believe he was using stock injectors in the manifold and supplementing fuel with the 4 additionals.

There was a thread on the set up then a while later they were in the For Sale section.

 

This should be an option if you dont' have a reliable aftermarket ems like AEM. If you have a reliable ems don't bother. Good injectors are so cheap these days. I have 4x1000cc injectors and the engine still idle well.