Twin injector system?

[frederic.breitwieser]

Barrett,

>Low RPM/daily driving tends to be a bit rough with large injectors in a
>hi-hp engine, and then upper RPM lean out-out performance driving gets
>to be a problem. My idea was to try and get the injectors to take up

Yes, this is exactly the issue with high HP engines at idle in regards to the 
injectors (that and the timing, runners, etc are usually way off, geared for 
higher RPMs).  This is the approach I will be finalizing on my Buick V6.

>it. My engine is supercharged (via Carroll Supercharging/Paxton SN-89
>blower). Just searching for the best of both worlds, and electronics is

Good choice in unit... I believe that one goes up to the 15psi range, if my 
memory is working this morning.  A lot of the smaller Paxtons weese at the 
higher RPMs and still blow about 7-8 PSI.  I've always prefered superchargers 
for low-end torque (as they are already spinning), and turbos for higher RPM 
use.  Of course different products, combinations, and application yield 
different results.

>the only way to get there from here. Problem is, I am a mechanic not an
>EE... :) or should that be an :(
>I've got lots of feasable ideas, just no way to impliment them on my
>own.

You and me both.  To be honest with you Barrett, it only takes some 
perserverence (if I could spell) and a few dollars in tools.  I made my 
aluminum intake manifold using nothing but hand tools.  All of the holes were 
drilled using a variable speed drill, then ground out using my father's dremel 
and appropriate grinding bits.  The cuts were even stranger - I made a simple 
miter box that my sawzall attaches too, and cuts through at a reasonably 
straight line.  I had to grind the edges straight, but it worked in the end.  
I had the sawzall and the hand drill, so I made do.  Recently, I bought a 
drill press because hand drilling is the worst if you want straight holes :)

Most of my experiments were lame, without controls, but illustrated to me how 
things really work, and what happens when I changed certain aspects of the 
system, then I started making parts.  I have an advantage as I have several 
friends who work in various aspects of the automotive industry, so I do have 
access to neat toys that make it easier to make, test and debug a system.

>the polution laws they are tied down. With my way, the
>pollution/performance problem is nill, and performance is greatly

This is also true - emmissions will always be a problem, and continue to get 
worse.  Using two smaller injectors per cylinder allow you to run a little 
lean at cruise, but when the power is applied, thwap - lots of available fuel.
 The other advantage I see is redundancy.  Lets say one injector on rail one 
starts to get messed up (i.e. not flow well), the second injector can be 
pulsed to compensate and still give great street performance.  Of course, this 
is nothing more than a programming exercise (smile). yeha, right.

>Also on my wish list is a variable length plenum/runner design,
>electronically controlled of course. maybe I should go back to school
>for my EE degree? <smiles>

Through my intake manifold experiments, I found that the length of the runners 
is not that important compared to other parameters, assuming its a dry 
manifold, not a wet one (i.e. TBI or carbeurator).  The runners on my intake 
are approximately 15" each, and bend around much like the newer TBI systems on 
Camaros, Corvettes, and Trans-Ams.  Like the Accell TPI system.  TPI, TBI, I 
keep mixing them up (I hate acronyms).  Anyhoo, I didn't see much of a 
difference on the dyno power wise with different length runners, but I did see 
more consistancy in HP and torque by using longer runners. But, the longer 
runners, under high boost, add to a slight appearance of "turbo lag", which is 
not really the turbo's fault, just the fact that it has to pressurize the 
entire intake manifold - longer runners mean more space, means it takes 
slightly longer to pressurize them.  Its easier to cool of a 8'x8' room with 
an air conditioner than to cool off a 20'x20' room with the same air 
conditioner.  The analogy crosses over to blowers and runner length.

Variable length runners is an interesting idea, and probably not that 
difficult to achieve - but then you will have a complex valving system that 
can leak, resulting in less performance.

The "ultimate" solution, one that I and a friend applied for a patent on 
(expensive process, but worth it), is to vary the timing relationship of the 
Cam/Crank across the RPM band.  By adjusting the cam for low-RPM the engine 
grunts off the line with reasonable, near-stump pulling power.  At higher 
RPMs, the cam is rotated slightly out of phase with the crank, thus making it 
breath extremely well at higher RPMs as well.  Thus, the power band of a 
particular engine widens, creating better performance throughout.

Patent attorneys, even if they are "best friends", are not cheap :)

Now, back to the dual injector system.  I believe you are right in your 
thinking, and have been testing such a thing.  My current system runs 40lb 
injectors in squential mode, and the second pair of injectors (also 40lb) in 
batch mode.  The haltech system I have/used can't manage dual injectors 
individually for each cylinder, so I cheated by firing the second ones of the 
pairs as batch.  A six Mosfets and six diodes to protect against injector coil 
kickback and that's it.

Ideally, I'd like to have two 40lb injectors for 93/94 octane, and one 
injector for an isopropyl/distilled water mix.  Boost this :)