Cylinder Head project !!!
Jun 14, 2007, 03:42 PM
#182
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yeah, if I recall correctly the WRX injectors that I purchased from a guy on NASIOC will flow 440cc, they are the stock injectors for his vehicle and everything is supposed to fit, maybe with a washer according to someone I talked to. the stock wrx injectors are light blue, not pink (those are for the STI, and don't fit our rail as far as I have been told
Injectors are rated at flow/minute at X pressure, three variables. you can use more fuel pressure to increase the amount of fuel at a certain duty cycle, to a point. With 440cc injectors Migue should be fine up to 300HP at 80%-90% duty cycle, and I haven't looked at the chart so that's a guess, with an adjustable fuel pressure system. That is a good injector size to meet his target of 250, if he goes over 50 he has at least a 15% margin before he needs to upgrade those injectors.
Just FYI
As the injector reaches it's maximum duty cycle at any fuel pressure the injector is held open constantly, and therefore can flow no more fuel at that pressure. The goal is to balance an injector with the available fuel pressure that will allow a 75% to 80% duty cycle at your HP rating.
the closer to the max duty cycle the more likely you will suffer fuel starvation because the time between opening and closing the injector is so small, fuel delivery is more and more difficult to increase unless pressure is added to assist the injectors. that's why you want a decent margin away from your duty cycle.
Injectors are rated at flow/minute at X pressure, three variables. you can use more fuel pressure to increase the amount of fuel at a certain duty cycle, to a point. With 440cc injectors Migue should be fine up to 300HP at 80%-90% duty cycle, and I haven't looked at the chart so that's a guess, with an adjustable fuel pressure system. That is a good injector size to meet his target of 250, if he goes over 50 he has at least a 15% margin before he needs to upgrade those injectors.
Just FYI
As the injector reaches it's maximum duty cycle at any fuel pressure the injector is held open constantly, and therefore can flow no more fuel at that pressure. The goal is to balance an injector with the available fuel pressure that will allow a 75% to 80% duty cycle at your HP rating.
the closer to the max duty cycle the more likely you will suffer fuel starvation because the time between opening and closing the injector is so small, fuel delivery is more and more difficult to increase unless pressure is added to assist the injectors. that's why you want a decent margin away from your duty cycle.
Last edited by DangerousDan; Jun 14, 2007 at 03:47 PM.
Jun 14, 2007, 04:48 PM
#183
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So in other words stock injectors will max out @ 200 Crank power but if you raise pressure changing the returnless system you might go up a little
Jun 14, 2007, 04:55 PM
#184
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yes, you should be able to push more fuel with the stock injectors, but I doubt it will cover what you are looking for. it looks like your calculator there will do the math for you
Jun 14, 2007, 10:06 PM
#186
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Ok here are some pics of the IM ported already I just got here and I am tired I will try to post tomorrow before and after IM runners . They port the **** out of it....
BTW it is not finished I still have to clean it up and ceramic coat it and then red painting.....
They matched the ports up to gasket and deeper in the manifold as they could...
BTW it is not finished I still have to clean it up and ceramic coat it and then red painting.....
They matched the ports up to gasket and deeper in the manifold as they could...
Last edited by migueralliart; Jun 14, 2007 at 10:10 PM.
Jun 14, 2007, 10:44 PM
#188
migue and dan, just so that I understand everything (thanks for your patience) that you are saying: with the stock fuel system, we are good for just a little over 200 atc safely, but thats kinda pushing it. If I understand things correctly, with a stock WRX injectors, he should be good for 300 hp. I apologize if this is a completely stupid question, but:
He's going to be running the smt-6. Will an FPR be necessary here, or is that all taken care of by the smt unit? - my understanding of this stuff is obviously very limited.
Migue, you suggested changing the returnless fuel system - I assume you mean going to a return system...? If so, were you just going to do the part from the OZ fuel pump, or did you have something else in mind?
Basically, I'm wondering what plans you had in mind exactly for delivering fuel safely. This is one thing that I just don't seem to completely understand. People start talking about duty cycles and something inside just cries a little heh.
The reason why I ask in such detail simply so that I'm able to wrap my brain around the whole thing. Again thanks as always for the patient answer.
He's going to be running the smt-6. Will an FPR be necessary here, or is that all taken care of by the smt unit? - my understanding of this stuff is obviously very limited.
Migue, you suggested changing the returnless fuel system - I assume you mean going to a return system...? If so, were you just going to do the part from the OZ fuel pump, or did you have something else in mind?
Basically, I'm wondering what plans you had in mind exactly for delivering fuel safely. This is one thing that I just don't seem to completely understand. People start talking about duty cycles and something inside just cries a little heh.
The reason why I ask in such detail simply so that I'm able to wrap my brain around the whole thing. Again thanks as always for the patient answer.
Jun 14, 2007, 10:52 PM
#189
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migue and dan, just so that I understand everything (thanks for your patience) that you are saying: with the stock fuel system, we are good for just a little over 200 atc safely, but thats kinda pushing it. If I understand things correctly, with a stock WRX injectors, he should be good for 300 hp. I apologize if this is a completely stupid question, but:
He's going to be running the smt-6. Will an FPR be necessary here, or is that all taken care of by the smt unit? - my understanding of this stuff is obviously very limited.
Migue, you suggested changing the returnless fuel system - I assume you mean going to a return system...? If so, were you just going to do the part from the OZ fuel pump, or did you have something else in mind?
Basically, I'm wondering what plans you had in mind exactly for delivering fuel safely. This is one thing that I just don't seem to completely understand. People start talking about duty cycles and something inside just cries a little heh.
The reason why I ask in such detail simply so that I'm able to wrap my brain around the whole thing. Again thanks as always for the patient answer.
He's going to be running the smt-6. Will an FPR be necessary here, or is that all taken care of by the smt unit? - my understanding of this stuff is obviously very limited.
Migue, you suggested changing the returnless fuel system - I assume you mean going to a return system...? If so, were you just going to do the part from the OZ fuel pump, or did you have something else in mind?
Basically, I'm wondering what plans you had in mind exactly for delivering fuel safely. This is one thing that I just don't seem to completely understand. People start talking about duty cycles and something inside just cries a little heh.
The reason why I ask in such detail simply so that I'm able to wrap my brain around the whole thing. Again thanks as always for the patient answer.
Jun 15, 2007, 04:42 AM
#191
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simplest way to put it:
duty cycle is the percentage of time the injectors remain open in a pulse. even wide open all the time the injectors will only flow what they can handle with the stock setup. the holes are only so big, as are the fuel passages.
you can change injectors, to get bigger holes and passages. you need to tune for the new injectors, but we can't flash the ECU so we have to tune the fuel itself with a piggyback.
if you add more fuel pressure, you can force more fuel through the injectors up to a point.
if you change injectors and add more pressure your fuel supply will increase even more.
stupid work.