Injectors

[jpetrovic]

Well im thinking about changeing out my injectors.
i have some 315cc volvo injectors, im Not planing on doing anything except a Msd blaster coil later on.
i dont know what the accord injector specs are soo... will these work? will they give me a little more power? will i flood the engine, or will thes even pump enough fuel?

[3rd Party]

the injectors won't put anymore fuel into the cylinders than what the computer's wired to put into the cylinders. you could have 550cc injectors in your Accord and they'll only be at like 20% duty cycle 'cause your computer's only telling them to work at 20% usage, or 75% if they were stock injectors. in order to really benefit from bigger injectors is if you've got a cam, with injectors, and some sort of kit that allows you to plug and play with the computer for tuning on timing, injector pulse, et cetera. so save your money for now duder, buy stuff that the motor can use without needing computer tuning software, blah blah

[jpetrovic]

well i have the Injectors, they are about a yr old (from my brothers volvo)and i was thinking of switchin out the old accord injectors. or should i just clean them ? :dunno:

[3rd Party]

that's really your call man, if you've got reason to believe that your Accord injectors are crap and aren't working as good as they should be, then by all means try out the Volvo injectors. but if it isn't broken, don't fix it...something i always hated hearing, but it's true. the best you can do i guess is just hold onto them for later...you never know when they could come into use.

[AccordB20A]

it will make the engine run rich, stock injectors are like what 240cc, when they are at say 20% duty cycle it runs okay but 20% duty cycle on a 315cc injector will be more than the 240cc
theres not really any benefit from running your car rich

[3rd Party]

it will make the engine run rich, stock injectors are like what 240cc, when they are at say 20% duty cycle it runs okay but 20% duty cycle on a 315cc injector will be more than the 240cc
theres not really any benefit from running your car rich

well, i meant that the 240cc injectors are probably run at more than 40% duty cycle because that's what the computer's programmed to do...so lets say you have the 315cc injectors, yes...i didn't even think about the fact that it'll run the 315cc injectors at the same usage as the stock since it's thinking it's still using 240cc injectors making the car run rich. BUT, maybe then you could advance the timing? compensate for the rich fuel mixture? haha...i don't know, i'm blabbering.

[jpetrovic]

ohh, ehh, i guess i'll clean them out, Thanks for the Advice :D i read a post about useing seafoam? any effective? any ideas?

"if it isn't broken don't fix it" Yeah, lol i know what ur saying man,
i have one injector leaking the slightest bit, soo i decided to changer or clean them out as
i replaced all of the O rings thats how the changeing the injectors idea came into play.

[3rd Party]

it's effective from what i hear, but i've never tried it on a fuel injected motor...a guy who lives close to me with a third gen uses it on his carb'd '86 and it works like a dream apparently.

[jpetrovic]

hmm so i guess i'll just soak them for a bit?
any ideas on how long?

[3rd Party]

from what i hear, the seafoam shit's run through your car by adding it into your gas tank. but don't quote me on that since i've never used it, like i said....i've just heard people talk about it.

[Rendon LX-i]

A little over kill bro...If your nothing doing boost or high hp a20 theres no need for nothing over the stock 240. then you would need to control em some how so. So Safc is what you would have to get. Or just Replace a the injectors. get a set at a jy

[3rd Party]

A little over kill bro...If your nothing doing boost or high hp a20 theres no need for nothing over the stock 240. then you would need to control em some how so. So Safc is what you would have to get. Or just Replace a the injectors. get a set at a jy

heh, that's what i was saying...you'd really need some sort of engine management to really use the injectors to their potential. on top of the fact that you really wouldn't need'em until serious modifications such as mild aggressive cam, head work, blah blah

[Rendon LX-i]

yup....i didnt even understand what i wrote. sorry bout the that. But Basicly going to need a some serious mods to run that high of injector. Pointless otherwise

[alberto]

Hell this was help full 4 me 2 thank's guy's.

[zilog357]

The behavior of using bigger or smaller injectors will always be unpredictable. That is why it is a good idea to have some kind of system management (a piggyback will suffice) to adjust it to its optimum level.

If your stock injectors are 240cc, that mean that they will spray a maximum (100% duty) of 240cc of fuel per minute, at certain pressure (40-60 psi) on the fuel rail. The thing is that the factor "time" also comes into the scene.

The ecu is programmed to inject fuel, based on injector time opening in microseconds (uS) and milliseconds (mS), so, if the 315cc Volvo injectors have the exact same characteristics (electrical resistance and mechanical resistance of the closing spring), the the mixture will definitively be richer. In the same line, then a 450cc or a 550cc injectors will flood the engine.

Injector duty is not automatically corrected by the ecu as it has no way of really knowing how much fuel it is spraying. That is supposed to be a constant for the ecu and not a variable. The only thing that it can do, and only to some extent, is trying to correct by seeing the O2 sensor reading when at closed loop, but again, it is based on table of constants and it is not completely dynamic.

Summarizing, the number in "cc" (Cubic Centimeters) per minute, or "lb/hr" (Pounds per Hour) is a measurement of injector flow capacity that will depend on:

1 - Fuel rail pressure
2 - Injector coil resistance
3 - Injector opening time (commanded by the ecu)
4 - Last but not least, circuit voltage (yes, 13.5 volts will inject slightly more than 12.5 volts).

For the last one, the ecu has a table for "trying" to compensate for voltage variations.

A final note, remember that power is dependent on air too. So injecting more fuel, making it richer, will lower the AFR (Air Fuel Ratio) and if it is not lower than 11:1, what you can do to take advantage of that is:

1 - Ensure the maximum input of air (high flow filter maybe) and very important, the cooler the air the better because of its greater oxygen concentration.

2 - Increase a bit the ignition timing (maybe 2-5 degrees) to take advantage of allowable extra compression for the extra fuel. Yes, extra fuel will greatly avoid detonations.

The only problem with the second is that if you do it globally (at the distributor), it won't be optimal, like it would be by reprogramming the ecu, advancing it only at the needed points in the ignition map.

Well, sorry guys for the long post.

Regards,

Richard