injector size?

[bentvalves]

s15 tubby, tomei cams, z32 maf, 3 in tbe, powerfc....I know 550's will supply that turbo with enough fuel at 18 psi, but was thinking of going bigger for future upgrades.

If I went with 680's or 750's would I be able to control those injectors down low and on idle well, or would it be a tradeoff to some extent? I dont want a car that gets 17mpg light cruising/partial throttle.

suggestions?

[Bwana]

I use 660's in the MG. They're bigger than I need, but I've had no problem with the idle and I get about 30 mpg on the hwy (2100 lb car).

[bentvalves]

what are you using for managment, and what turbo?

sounds like I may be going with bigger than what I need.

[Kouks]

With proper tuning, you shouldnt have any trouble with even 850cc injectors if tuned correctly. A competent tuner shouldnt have problems making them idle correctly.

And still get good gas milage. I have a formula for selecting injector size if you want it, that way you can get as small as possible (if you want).

Lemme know, Ill find the thread and post it.

[float_6969]

The PFC should be able to control those injectors. As was stated earlier, how much power do you think you might be making?

[sideways danny]

a lot depends on the spray pattern, I've heard of people having trouble with 660s before because the nozzle wasn't very good but 720s were easy enough to sort out

[float_6969]

That is very true. The kind of injector and effect the spray pattern very much.

Here is a link to a HP vs. Injector comparison.http://www.sdsefi.com/techffhp.htm

[bentvalves]

thats what I should have mentioned before......these bigger injectors will have problem atomizing the fuel properly at lower duty cycles, no?

I dont want the smallest possible to get me by, in that case 550's would do. Im planning ahead thats all, but shooting for 280 - 300 wheel with my current setup.

[float_6969]

The 550's should support those power levels no problem At 100% duty cycle, they're good for about 380HP. At 300HP they're only at about 80% duty cycle.