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Just the facts please ...
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1,030 Posts
Discussion Starter #1
While stuck in traffic, I came upon a couple of questions for those in the know for the SMT6 ...


Q1 ---
When using the secondary injector plate, all injectors are driven at once by a single wire. Does this mean that when they are fireing, injecting fuel, they pulse to deliver a set amount of fuel ... whether the cylinder is using it or not?

If thats true, would it be better to have the secondary injectors be the closest to the valves to prevent any fuel from pooling in the port area ... moving the stock injector wiring to the secondary plate and drive the ones in the stock location with the SMT6?


Q2 ---
Could the stock OEM injector drivers also drive the secondary ones, with the SMT6 stepping in to ground them out so they don't pulse at all or a given amount, depending on the SMT6 settings. You'd need a special box to take the SMT6 signal and convert it to a switchable ground .... Dennis?
 

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Final Fantasy 7=Teh Sex
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3,840 Posts
All injectors will either pulse on or off at the same time. I run my extra injectors off the secondary rail with no issues.

I can't answer the second question for you.
 

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Super Moderator
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12,635 Posts
There is a measurement called "tau". Tau is basically fuel resting against the intake valve when fuel is not being fired. This resting fuel helps to cool the valves down, especially in FI applications. I would not be concerned about using batch injection as it will help things for this reason.

It is normal for this to happen, as a matter of fact a few standalones actually have a tau map built in because once the intake valve rushes open then this resting fuel is pulled into the combustion chamber then that fuel is going to need to be replaced.

As for your second question, someone more experienced with the SMT will have to answer.
 

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Eldiablo owner
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306 Posts
nah, not a problem,
especially since the secondary injectors only open under boost (aka 3000 and + rpm and you have lots of air flow going in)
i seriously doubt you get fuel puddling

for the second question i would have to ask why? the smt-6 controls the injectors perectly while if you hook them up the way you think you want have any control over them since the stock injector are pulsed on the ground side
even if you would be poulsinbg the postive side with the smt-6 and some kind of inverter then you would be dealing with 2 different,talk about complication

BTW you actualyl havea switched ground output on the smt-6 it's the orange wire (aka the wire we use for the turbo box) but it's not mean to drive more then 100mA
 

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Registered
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1,115 Posts
Fuel puddling is not an issue using either Deniss' or Mahonroy's injector plate design. The injector angle is such that the fuel hits the valve instead of the head. Plus like was said the 2nd rail only fires under boost so the pressure helps atomize the fuel even further greatly reducing any chance of a puddle forming.
As for running the 2nd injectors off the OEM ECU do not try it as you'll burn out the OEM drivers. They are built for a certain ohm and amp rating and if you exceed that you'll burn them out rendering your OEM ECU as worthless.
 
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