what size injectors does mercedes uses?

[jstrat85]

does any body know what size injectors mercedes uses on there 1996 c220? and also if i do bigger injectors what size should i do them??? :(

[jnenad16]

the stock ones are around 22lb/hr. 24lb/h would be a great upgrade for the stock or lighly modded engine. my brand of choice would be accel.

nenad

[Ashkan's C280]

what would happen if he got 60 lb injectors?

[jnolte]

Originally posted by Ashkan's C280
what would happen if he got 60 lb injectors?

is this a joke?

[Ashkan's C280]

i meant there is only a certain amount of fuel an engine needs, and having bigger injectors would just dump more fuel in, so what would happen, and its not a joke, flame if you want, I really don't know, that is why I asked........

[jnenad16]

amongst many things, the engine would die as soon as it starts, would not be able to run it, the O2 sensors would die, plus the catalytics would most likely melt, thus causing damage to the undercarriage as well.

nenad

[Ashkan's C280]

but why, I mean wouldn't you need a bigger fuel pump to handle all the fuel being put in, and if it didn't have the need wouldn't it just not do anything, I suppose my real question is why would having more fuel sent in fuck everything up

[Ashkan's C280]

well I guess if your air fuel ration would make the engine die, but wouldn't the engine only send the right amount of fuel into the engine anyway, I mean don't know a whole lot about fuel systems, but why would your cats melt if your engine would die right away?

[jnenad16]

the O2 sensors can only regulate the AF ratio so much, everything over 25% variations over the 14.7 air to fuel ratio can not be regulated by the O2 sensors and the engine will run very rough, and during this time the cat will get severely damaged, possibly melt. with extremely oversides injectors, the AFR will be very rich, and the O2 sensors wont be able to correct it. example, I had the 24lb injectors on my C280, and the car ran fine, but before I installed those, I had the 30lb ones and the car ran like shit, it even stalled after 10min of driving, so I had to replace them with smaller ones(24lb).

nenad

[Ashkan's C280]

but I mean what if you were making a ton of hp like 450 for example would you be able to run 60 then? or what if you were running 510 like that benzmac c55? would it work then

[c280nz]

Originally posted by Ashkan's C280
but I mean what if you were making a ton of hp like 450 for example would you be able to run 60 then? or what if you were running 510 like that benzmac c55? would it work then
your car would not run, as the ecu would open the injectors dump way to much fuel in, sence that it all wasnt burnt and try and open them for a shorter cycle, and then sence that fuel wasnt burnt aswell, then probebly shut off; or melt your exaust in the process.
the smaller adjustment in injector cycle would be out of the range of adjustments for the ecu and thus engine light/shutdown / limp mode etc.
if the car was capable of 550-hp then it would burn all the fuel thus no problem. although this in itself would require other things to be changed. as to generate this sort of hp in a small capacity engine would require higher compression/ high boost and thus require more fuel.
i cant really explain it well in words and cant be bothered thinking.
hopefully sum1 else will explain clearer :-?

[jstrat85]

allright guys i did a turbo kit on my car and i was thinking about putting bigger injectors so, when i do run more boost. what size should i use???

[jnenad16]

Originally posted by jstrat85
allright guys i did a turbo kit on my car and i was thinking about putting bigger injectors so, when i do run more boost. what size should i use???
whats the year and model of you car?

[98c43amg]

Originally posted by jstrat85
allright guys i did a turbo kit on my car and i was thinking about putting bigger injectors so, when i do run more boost. what size should i use???

jstrat85, the guy that did my engine swap runs 65lb. (click here) (http://www.club202.com/forums/showthread.php?s=&postid=64697#post64697) on his custom built single turbo (used to be dual) 3.5L in his C36. Standalone engine mgmt tho.

[Under Pressure]

Originally posted by jstrat85
allright guys i did a turbo kit on my car and i was thinking about putting bigger injectors so, when i do run more boost. what size should i use???

I have an idea. First, lets get the fact I am not an engine expert and really don't know too much about injectors. But here is my idea:

Since you turbo C220 is very much like the C230 Kompressors, why dont you get injectors from a C230 Kompressor and use those (assuming they are different).

I mean look at the picture, the C220 and C230K are both Mercedes four cylinders, and I believe are the same block. The only difference being 0.1L of displacement more on the C230K.

As far as the method of forced induction, your car probably does not care, for fuel issues, whether it induction comes from a supercharger (via the C230K) or from your aftermarket turbo system. And I believe the C230K makes around 5.5psi, just like your turbo kit.

So maybe you can use injectors of a C230K.

[VIP_MBZ]

Originally posted by Ashkan's C280
well I guess if your air fuel ration would make the engine die, but wouldn't the engine only send the right amount of fuel into the engine anyway,

The way a modern electronic fuel injection system works is that there is a base map in the engine control module. This ECM takes input from a number of different sensors in the system, including the air flow meter, map sensor, and cam/crank position sensor. It then references a predetermined map, which tells the injector driver how long the pulse width will be. The pulse width basically refers to how long the injector will remain open. This is relevant since injectors are described as a flow rate over time.

When the engine actually is running, the oxygen sensor will try to roughly figure out how rich or lean the mixture was based on the content of the exhaust. From the readings of the o2 sensor(s), the computer will produce a "learned" map, which has up to maybe 10-15% correction over the base map. This compensates for fuel quality, elevation, air density, inconsistencies in the fuel system, etc. Some cars spend the first few days after the computer has lost power to relearn this optimized map, whereas some other cars (I think MBZ included) learn constantly.

A change in fuel injectors to a higher flow rate will mean that for the same pulse width, there is more fuel delivered. This means that the base map is now far too rich, since the pulse width was originally calibrated for a slower flowing injector. While the O2 sensor can compensate for small changes, it will not be able to compensate for something as significant as an injector change.

The solution is to run either any number of piggyback computers to fool the ECM into thinking less fuel is necessary (thus reducing the pulse width for any given point in the map), reducing the fuel pressure across the board using a fuel pressure regulator (though the downfall is that you can affect the spray pattern of the injector), or by completely replacing or reprogramming the ECM.

Hope this helps,

-Ray

[Ashkan's C280]

it does help, thank you

[jnenad16]

I couldnt have said it better myself.

nenad