turbo and WOT injector

[Buchholz, Steven]

Why must we get so excited here?  We are trying to work through this, and I
think that there are valid points made by a number of people.  Sure, you
have built a system with a pulsed injection add on which works to augment a
stock non-turbo CIS, it works and looks pretty cool ... but honestly, how
much of an expert does that make you?  How many examples of your system
currently exist and how many cumulative miles have you logged?  I know that
from my point of view I tend to think of myself as Scott J does himself ...
I certainly would never claim to be an expert on the subject.  All I know is
what I've seen, and in my mind there is plenty of evidence that the back
cylinders of the I-5 turbos have a tendency to run lean, even on stock cars.
(BTW, yes, I do have a car that runs above 7psi boost and over 5k RPM ...
but it came from the factory that way ... so you don't need to listen to me
either ;-)

I don't think that everybody is discussing using the CSI as that 6th
injector ... AAMOF in my post I clearly stated otherwise.  There are issues
with the mounting location of the CSI as well as the fact that the CSI was
not designed to do much more than provide a bit of extra fuel to get the
engine started.  I think the product I saw installed on another urq was
called a microfueler, or something like that.  The injector was a standard
pulsed injector mounted in the air path leading to the intake manifold. It
certainly seems to me that this location would tend to cause the fuel to mix
with the air, and be directed by the air as it flowed into the intake
manifold.  While it may be true that since the fuel droplets will have more
inertia than the air they will have more of a problem making the sharper
bend to the front cylinders ... but that is exactly the situation we're
trying to address with the air.  This would tend to richen the rearmost
cylinders more than the front.  This certainly seems to me to address the
concern more than simply adding injectors that squirt the same amount of
additional fuel to the front as well as the rear cylinders.  Remember this
part of the thread is predicated on the assertion that the rear cylinders
run leaner on the engines which feed the intake manifold as the WX and MC
engnies do ... this premise has not been proven, so you can feel free to
dismiss it.  

The interesting thing is that on the DIY-EFI list the thought of an injector
mounted in the intake tract has come up as a means to provide additional
cooling of the intake charge.  If you mounted an injector at the inlet to
the intercooler you should notice better vaporization of the fuel and
cooling of the intake charge as well.  This would also at least in part
address the "inertia" issue raised before ...

It sure seems to me that unless we have a situation where we could determine
the mixture in each cylinder like an EGT or ION monitoring system (like the
Saab Trionic) all of the discussion here is little more than speculation.  I
for one happen to find this sort of discussion useful and somewhat enjoyable
though.  I am contemplating mounting individual EGT probes in my 2-piece EM
... perhaps when that is done I'll be able to speak a bit more
authoritatively ...

Steve Buchholz
San Jose, CA (USA)

>    Man, this is really getting good!  Tell you what, untill 
> you can build a car that actually runs above 7 psi and 5k 
> RPM, I will not differ to your opinions or advice.
>    Ask any engineer??  How about an Audi engineer who 
> implemented 5 CIS injectors all delivering the same amount of 
> fuel to each cylinder.  You are actually implying that a 
> "6th" injector is the right way to do this?  In reality you 
> are suggesting that an injector be placed directly above the 
> #1 intake runner spraying at 40+ psi pressure directly down 
> into it-and you imply that that is a better solution for 
> correct dist. of fuel to each cylinder??  Have you taken into 
> consideration the higer mass and thus intertia of fuel?  Are 
> you really implying the fuel is going to react in the same 
> way as almost weightless air?