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03-21-2006, 10:01 AM | #1 |
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Modded injectors - Help me pick which injector to install into which cyl
I just got my results form Witch Hunter last night. I have done some searching and I cant decide where I want to install these injectors. Some say that 2 and 4 should get the highest others say 3 and 4. Can anybody recommend how I should install them? I assume that Cyl 4 will get the highest flowing injector and Cyl 1 will get the lowest flowing injector but nothing is set in stone. From there I really dont know what to believe.
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03-21-2006, 10:19 AM | #2 |
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804 in #4, (drivers side rear) 798 in #3 (passenger side rear)
790 and 792 in the front holes. Larry |
03-21-2006, 10:37 AM | #3 |
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Thats exactly what I would do.
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03-21-2006, 11:18 AM | #4 | |
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But I don't understand why you would do this. 3 and 2 are the cyl with the dogleg exhaust ports. Wouldn't you want the highest flowing there? TMS |
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03-21-2006, 11:23 AM | #5 |
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I have been under the impression that 3 and 4 ran the hottest and were typically the ones that failed.
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03-21-2006, 11:40 AM | #6 |
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I think most here believe that Cyl #4 runs leanest (based on EGT measurements) and is most prone to knock. It seems strange that FHI engineers haven't ever noticed that and fixed it by now. Unless it's intentional.
Subaru's modern ECUs certainly have the processing power and memory to detect knock and adjust spark advance on an individual cylinder basis. Yet they don't do this. Instead, they still seem to use the process laid out in FHI's patent US 4,726,339, which essentially says:
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03-21-2006, 11:48 AM | #7 |
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4 is the closest on the fuel bank. it gets the MOST fuel, more fuel, higher egt's
3 is the leanest, thats why it fails. 1-2 fall in the middle i think. Corrrect me if im wrong, but I think thats correct. |
03-21-2006, 11:59 AM | #8 |
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more fuel = lower EGTs.
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03-21-2006, 12:14 PM | #9 | |||
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Quote:
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03-21-2006, 12:18 PM | #10 |
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Guys,
First, keep in mind that this is on an STI NOT a WRX. I know that there are a number of differences between the two. Second, are we all on the same page as far as cyl numbers go: ____ Bulk head ____ 3-----------------4 top center of motor 1-----------------2 ___ Front of car ___ IS THIS CORRECT? Jon [in CT], Are you saying that the factory knock sensor is monitoring Cyl 4? Hmmm... |
03-21-2006, 12:21 PM | #11 |
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The subaru is not that much different than most V8's it is very common for engines to run hotter in the rear most cylinders due to coolant flow considerations. If you study the layout of the subaru flat 4 you will see that rear of engine block does not get as much cooling as the front cylinders.
As far as the knock detection, Jon, you make an interesting point there, but if properly biased you would get all 4 cylinders having the same sensitivity to knock so I'm not sure it would change knock correction significantly unless #4 was so far off the mark that it would not knock at all when the others were in serious trouble. Larry |
03-21-2006, 12:25 PM | #12 |
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It would appear that I am hearing this:
804cc in Cyl 4 798cc in Cyl 3 792cc in Cyl 2 790cc in Cyl 1 Would a 1.7% difference really mean a whole lot on a car thats not tuned anywhere near the ragged edge? |
03-21-2006, 12:53 PM | #13 |
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03-21-2006, 12:54 PM | #14 |
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