Can you have too big of a Injector?
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Can you have too big of a Injector?
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
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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
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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.
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#8
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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.
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.
#9
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..
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..
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"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
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
#17
Originally Posted by Classic
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.
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,
#19
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Originally Posted by FiveSevenEagle
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,
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,
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.