MSefi.com read only forum (Jan.15,2018)

I'm hitting 80% duty cycle currently with my 440cc @3bar injectors and need to upgrade. This is at 11psi boost and the only things keeping me from hitting 1 bar+ are the injectors.

The injector sizing calculator shows that 300 crank HP at 3bar fuel pressure for a turbo would require 650cc injectors. I don't know that I'll hit 300HP, but the other option would be 550cc injectors and those wouldn't leave me much wiggle room. (note, I want to stick with hi-imp). The MegaLogViewer HP calculator is showing 220-230 crank HP at the moment.

Right now my idle pulse widths are 1.6-1.7ms. I'm able to reach a decent idle, but I'm worried what 650cc injectors are going to do. Has anyone "been there done that" and can offer tips/advice?

Cheers,
nick

Err... nobody has attempted using injectors this large on a smaller turbo engine? The folks at RC Injectors are confident that they'll work without a second thought - "with a properly tuned stand-alone".

I'd love to hear from someone who has tried it with MS?

I'm running 440cc injectors on a 2.4L motor. It works fine.
With E85, I'm exceeding 100% duty cycle, so I know I need to upgrade.
Trucks like mine seem to run fine in the 550-560cc/min range. By my calculations, that's the safe limit for idle resolution.

In practicality, however, you may be able to go higher. If you're at a lower fuel pressure, you'll have a little more resolution.

RC Engineering makes great stuff, but there are so many OEM injectors that could possibly meet your needs for about 25% of the cost, I like to go searching before buying new...

You should be fine. I'm running 788cc injectors on a 1.8 engine and have been for 6+ months. You might have to bump up your idle a bit (I idle at around 900-1000 rpm) but other than that you should be ok.

I'm running 1000's on a 1.9. It idles funny, but that is caused by the cams, not the injectors.

a friend of mine had 900cc/min injectors on a mr2 turbo he built that was running a haltek and a t66 turbo. this was on a 3sgte which is 2.0l. it ran fine and idled perfect at 800rpm. i myself have 780cc/min injectors on my 7mgte currently wit hthe stock ecu using a maft to compensate for the increase in size. my car idles perfect too. id say go at leas 750cc so your a lil over what you think the max goal is in case you end up with room to grow.