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Where To Place Fuel Injectors?

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Old 12-24-2004, 08:54 AM
  #11  
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Wouldnt the extra length of runner cause the injector to spray late? Shouldnt they inject earlier to compensate for the time the fuel charge needs to travel the length of the runner?
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Old 12-24-2004, 10:14 AM
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That would be compensated for during tunning.



You would get the fuel there when the motor needs it. If you had a map with all the injectors spraying directly into the irons and then changed the injector placement then i'd imagine youd create a problem if you used the same map.
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Old 12-24-2004, 03:29 PM
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I have the AEM ECU and can set-up additional injectors and change firing times, so tuning shouldn't be a problem, as long as I take enough time for the trial and error approach. The best of both worlds makes a lot of sense to me and was my initial preference, although I have to admit the 787B paper had me in doubt.
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Old 12-29-2004, 05:24 AM
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Maybe something or nothing (sorry for not knowing the correct names!!).

I have a modded FD with two extra injectors in the 'elbow' of Panspeed make, just before the 'butterfly thingys' . These point at an angle of roughly 45 deg. towards the front rotor, now my motor has just (for the second time) 'blew' the rear rotor, within a 1000 miles.

The tuner im using ( it was on a Rolling Road at the time) is suggesting that the injectors may be to close to the chambers and as they are injecting towards the front this 'may' be running the fuel lean to the back.



Sounds possible'ish or does it??? before i spend on an alternative what do you think??



J.
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Old 12-29-2004, 09:16 AM
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I don't really understand what you are trying to say. The tuner hopefully uses a wideband where he can monitor the fuel needs of your engine. You can get readings that are to lean if you run overly rich when you have fuel drop out, but that wouldn't blow your engine.



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Old 12-29-2004, 09:44 AM
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Well, again only from what im being told but, Mr Tuner also tells me the 'knock sence thing' only see's the front rotor which at time of problem was fine.He did not see this coming and was in the seat at the time with lap-top in hand.....

As mentioned if you look down from the top of the engine the extra injectors point almost directly at the nearest to the front butterfly inlet......so 'could' this mean the rear most would not benefit!!! may sound dum but if there's not enough time for the extra fuel to 'mix' properly or even-out could this happen.





Im struggling with the idea as it is a Panspeed item, and i cant see them flogging something that dont work proper.



Thanks for the reply anyway, as you can see im new to all this.
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Old 12-29-2004, 10:55 AM
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YES, it is possible your running your rear rotor lean because bad fuel distribution due to the Panspeed TB elbow with extra injectors. The only way to know for sure is to run two seperate Lamda (wide band O2) sensor in each rotors exhaust runners or two seperate EGT sensors. At the very least swap the knock sensor to the rear rotor, as this almost always seems to be the rotor that lets go first.



~Mike..........
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Old 12-30-2004, 03:34 AM
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Thanks Mike ideas sound good...ill give them a try.
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Old 01-07-2005, 11:56 AM
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Notice the fuel is sprayed at the inlet of the intake runners
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Old 01-07-2005, 12:56 PM
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If you placed your primaries far from the port, you idle, throttle response, and gas mileage will suffer do to fuel drop out and "wetting" of your manifold runners.
These statements match with my experience as well. I mounted 4 injectors up high in the runners (see below), and tried to use them in place of the stock injector locations. I could not get decent idle/low rpm operation with the primaries in that location. I suspect at idle the low airflow, large runner area, and injector firing against the opposite wall ended up resulting in the fuel wetting out the manifold.



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