im currently building an engine up from various diffrent bit and pieces.
originally was built for twin carbs but i have converted it to efi.
one of the last things i need is a set of injectors but im not sure which ones i should be going for as i dont play with efi that much!!

most injectors come with sizes eg 380cc,440cc or colours eg red,green.
is there a rule i should be using??regaurds to the power i want to be getting??

are the colours all the same or can you get 380reds and 400reds or are all colurs the same size??
are some injectors better than others??eg spray pattern etc

any help greatly appreciated

 

What engine are you building? Zetec or CVH?

I would say you'd be ok getting a set from a similarly sized normally aspirated engine, so if your building a 1600 CVH the a set from a 1600/1800 Zetec would be ok, but if i'm wrong then someone else will be along to correct me

What management are you using, as you might be better off using the injectors that your choice of management used?

 

its not a cvh or a zetec! its a mix of bits !
its a turbo'd engine but that shouldnt make a diffrence to injectors should it??
im using adaptronic management. not sure if there is a type of injector they recomend??

 

Turbo makes all the difference! You'll need one that will flow enough fuel for the boost/power you want to make, so its very important to get the correct ones. N/A ones usually do not have enough capacity for turbo'd engines.

Plus they need to be the correct impedance, high or low, for your management.

I do not have a turbo'd engine so cannot recommend any injectors, but someone else will be able to help

 

so i need turbo specific injectors

 

No, you need injectors that will flow enough fuel to make the correct ratio of fuel/air for your engine to consume. If you can work out how much air your engine is going to swallow, you can make a judgement based on that iirc

 

think im going to find a set of injectors from another turbo'd car of around the same power iv set it to run in with until its all fitted and running and then change them when i turn the power up and work out my a/f/r's

 

With decent mapping you can go bigger without problem, colour doesn't on bosch injectors mean a thing, just more like a common way to distinguish for cossie people.
They don't need to be turbo injectors, if needing high impedance you can use low with a resistor in each earth line to give you more choice.
Work out your bhp then size accordingly, there's loads of tripe about about siemens being superior, but 4 years on I'm still waiting to see evidence, indeed watching spray patterns I don't see a major difference, and where I've known people switch from bosch to siemens there doesn't appear to be any difference.
Take the injector flow in cc/min divide by 5 then multiply by the number of cylinders this will give you the bhp potential of the injectors.
Get the injectors you want to use cleaned ultrasonically BEFORE using, this will in general drop the flow rate to what it should be but they will be all balanced then, and you will be assured of decent spray patterns as well.
If one is flowing slightly less put this nearest the water pump end of the engine, one flowing slightly more at the opposite end.
I for example run "greys" or 0 280 150 403 injectors at 300bhp, and have emissions of 0.97% CO with 137ppm, with 200k MILES on the engine but then mine was mapped by someone who knows what he is doing, despite some claiming it's been cleaned up for mot, the very low ppm show this is not the case, it runs 100% perfect can crack 40mpg as well.
tabetha
tabetha

 

ok thanks for the advise il do some sums and work out what size injectors i should be looking at.

also i know you shouldnt run injectors at 100% and that iddeally they should be at 80-90% .
but is it ok to run them at say 30- 50%???

 

Ideally keep to 80% or below duty cycle, they will be perfectly ok at lower duties this is what happens when just poodling around, that said some are better at lower duty cycles than others, greys are fine for example, my cos is clean as a whistle even when doing low rpm/duty, 1% engine 99% mapper ability imo.
tabetha

 

You dont need resistors with high impedance injectors..

 

thats why he said "if needeing high impedance" ie you need high impedance for your ecu, and you use low, then you can use resistors with the lows.

 

I can see now that that was originaly said could be taken the other way but there wasnt a single mention about the ECU just injectors !

 

The thread title "injector question" gave me a clue that it was about injectors and not ecu's.
tabetha