As the title states. I know there is the sticky but I dont want to upgrade to a 30# if a bigger one will do. I rather spend the few extra bucks then get new injectors later. I want to leave room for improvment. Is there a minimum that they should be ran at? Since 80% is max there has to be a minimum. Im doing a H/C swap and some spray down the road but I think its going to be direct port so injector size should not matter w/ that anywyays? correct? --Ryan

 

yes there is a minimum, if you go too big the injector has to work out of efficiency range and it wont idle for ****....the 30lber's are a good way to go if you're just doin H/C.....injectors only factor in to a dry shot.... wet and D/P ( as long as it's a wet DP) just needs a good fuel pump

 

Well thank you Brad. I should have just PM you

 

As said above, to big of an injector for your application will give you problems. At idle you will have poor resolution which will give you problems. However if you go slightly larger you will be ok. Just don't buy a 90lb injector when you only need a 30lb.

 

Well 30 lbs it is then. I am going w/ a set of 5.3 heads and FM12 cam plus spray down the road. I just want to make sure everything will be kosher.

 

hmm maybe i should steal your ideas lol, follow you from board to board!

 

get off my back lol

 

if you're going cam and spray, go 42s. the minimal pulse width is the real determining factor for 'too big.' figure out what's your idling pulse width with the cam in it, and find the bigest injector which minimum pluse width is smaller than your idling pulse width. so if you idle at 2.5ms on stockers, don't put in anything bigger unless they can do a lower minimal pulse width.
svo42s are awesome because they can go down to 0.9ms. that means even with a huge cam and fairly low idle rpm you are still way within range.

 

The oe PCM uses saturation injectors instead of peak hold...

I run four 160lb hr injectors on the DSM.. Its a peak hold system on the OE or the AEM PCM..

When they are too big you will have a hard time getting a good idle.. The saturation type injector is even more limited in how short of a pulse width it can accurately meter out fuel..

 

actually he's stealing mine anyway, so go ahead...heads are in the garage, nitrous sytem is 80% complete, hopefully I'll have some numbers by next month

 

actually he's stealing mine anyway, so go ahead...

 

Brad, You are my hero!

 

...

 

"svo42s are awesome because they can go down to 0.9ms. that means even with a huge cam and fairly low idle rpm you are still way within range."

redhardsupra

I recently installed the svo 42's and used your IFR table.

I had 2002 Z06 injectors so I used the 2002 Z06 file which has 1.261 as the minimum injector pulsewidth. I also used the Z06 settings for short pulse adder, offset vs. volts vs. KPA and default inj. pulsewidth.

Do you change anything except IFR when going svo 42's ?

Thanks

 

no, IFR is all i change

 

take if from a guy that had to deal with the minimum pulse width bs, dont use big racetronix injectors unless you make killer power/go with forced induction. like marcin said, 42# fords are the way to go

 

i know it sounds silly, but how could i know what size of injector do i need ?
i've been searching everywhere .. i already know the calculator , but am still confused , what if i changed the fuel pump to a higher pressure one , does it ganna change the injectors size i should use ,

guys i need ur help for a better understanding for the ls1 fuel system , if u have any web sites or any other ls1tech threads ill be thankful , or at least u can answer my above question,

 

there are non adjustable regulators on our system, i have a 255 lph pump and i get 62 psi at idle and 59 at wot so that wont change injector size much at all.

 

it's a question of balance. on one side, you have the maximum power/capacity, on the other you have low rpm idle and general drivability.
obvieously the higher the capacity, the less resolution you got (since you're regulating it with the usual 5 or 12 volts).
so the way i do it:
figure out what power you plan to make: let's say you're making 450rwhp on heads/cam and that puts you about 75-85% injector duty cycle (weather dependent), on svo42's then you picked a good injector powerwise.
part two is drivability. let it warm up fully, let it idle and see if your injector pulse width @ idle is higher than the minimum pulse width of the injector. if it is higher, then great, you got yourself a good setup. if it isn't, then up the rpms until the injectors reach that minimum pulsewidth.
that's why for racecars you just put the biggest ones you can and don't worry. if you have to idle at 2000rpm, oh well. for streetcars, that's unacceptable, that's why you have to participate in this balancing act.

whoever tells you that 42s are too big, they're full of ****. they're still baby injectors, and they idle perfect on our setups. if you're going serious FI or with a lot of dry spray, then you wanna go beyond. for most cam only, cam+spray, head+cam combos, 42s are perfect. beyond that point, it really depends how radical you wanna get.

 

Are you guys using LS-1 edit or HP tuner?

Where are you getting the tables from?


Thanks
Andrew