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Date: Fri Aug 9 00:20:49 1991   
To: (z-car list)
Subject:  Holly Pro-jection system arrives

My Holly TBI fuel injection finally arrived today from Summit.  They
had backordered it (translate:  They don't stock it and have to have
it drop-shipped.)

The first impression is that they paid more attention to the packaging 
than they did the unit.  The packaging is top-drawer with separate
compartments for each component and the injector assembly in its own 
naccel.  They should have put the effort into the product.  The fit and
finish is typical of what we've come to expect from American companies
and illustrates why the Japanese own the manufacturing segment of our
economy.  Very little of the die casting flash was trimmed.  One  hunk of
flash blocked the throttle from fully opening.   Apparent design changes
were accomplished by drilling random holes through casting bosses obviously
meant for something else.  Several VERY thin metal membranes were removed
that were left from the intersection of 2 machined passages.  These would
have eventually cracked off and entered the engine.  A couple of hours with a
die grinder and some fine burrs cleaned things up but I should *NOT* have
to do this.

The control box is all analog and is the ultimate in simplicity.  It's 
inputs are throttle position from a pot, water jacket temperature and
a tach signal.  There are adjustments on the box for idle, midrange, WOT,
"choke" and acceleration enrichment.  The "choke" pot really does nothing
regarding enriching the mixture and instead sets a temperature setpoint 
for dropping the fast idle.  Which brings up an interesting "feature".
The throttle body contains a standard high idle solonoid that jacks up
the idle speed when the engine is cold.  What it does NOT do is jack up
the idle when the air conditioner turns on.  The manual makes special note
that the control unit does not support that mode of operation which is
stupid.  2 diodes and the solonoid can be triggered by either the control
box or the A/C.  This mod is already in place.

The  injectors look a lot like standard TBI injectors except that  they're
just enough smaller that standard ones won't fit.  A GM-style TBI fuel
pump comes with the kit that must be installed near the tank.  A return 
line is necessary (no problem on the Z) for the bleed-type pressure regulator.
A large fuel filter that looks strangely like the one on 75 and above Z 
injection systems is  included.

The electrical connectors are those first rate units that use the little
green silicone rubber gaskets on each pin (who makes these things, anyway?)
All wires are contained in split corrugated tube.  Cable ties are included
but fuel line is not.  Strange.

I pretty much spent the evening going through the system, measuring every-
thing (electrical and mechanical) and cleaning up the mechanical 
fubars.  I'd consider this to be essential to anyone buying such a kit.

I'll post more details after the installation is complete.  My impression
is at this point neutral.  The mechanical sloppiness is disappointing but
not totally unexpected.  This seems to be the modus oprandi of any 
company that Colt Industries (the owner of Holly) buys.  Sad.  I hope
it works better than it looks.    we'll see.


Date: Sun Aug 11 03:17:32 1991   
To: (z-car list)
Subject:  Pro-jection update

Well guys.  The Pro-jection system is in!
drove over from Athens today and helped with the task (and we enjoyed some
of my world famous Bar-B-Que to boot :-)  A million thanks, Jialin.  

The short review:  It works.  Pretty well right out of the box too.
The time constants for acceleration and cranking enrichment, idle mix
and a few other things, being designed for a V-8, are a bit off for
the datsun.  The throttle bores are over 2" in diameter each which means
that when the plates open, LOTS of air moves.  With a small engine,
a whole lot of acceleration is required to avoid bogging.  With the 
holly carb, I had to add the high capacity accelerator pump, use the fastest
cam and open the spray nozzles way up so I'm not surprised at the 
Pro-jection system performance.  The range of adjustments is just too 
narrow.  I had to lower the fuel pressure several PSI to permit the
mixture pots to have any effect.  This made the acceleration enrichment 
too small.  I'm going to consult with Holly tech support on monday.  I 
hope schematics are available.  If not, we'll just spend a bit of time
with the scope and figure out where the mods need to be made.  The control
box is dirt-simple, consisting of a number of analog op-amp function 
generators and some timing circuitry.

The accelerator and starting enrichment (too much) are the only 2 
performance complaints I have.  The car mortally flys compared to the
carburator on the same manifold.  Despite the engine only being a tired
260, I could fairly easily pull away from Jialin's 280 when we were 
testing tonite.  One of the most gratifying improvements is the 
instantaneous throttle response.  Anyone who has a stock Z knows of the
sluggish response to stabbing the throttle - especially on the 
fuel injected cars that try to keep the eco-nazis at bay even during
transient conditions.  I hate to use an overworked cliche but the throttle
does feel like a rheostat.  More opening, more power.

This system has cured a second problem.  With the carb, the engine would
detonate rather heavily under WOT conditions.  I now know that it was
probably leaning out on the secondaries despite the high capacity 
fuel pump.  Damn, I hate carburators.  With this unit, the engine pulls 
strongly right up to 7000 rpm.  Making a VERY rough estimate of mileage
by watching how many miles I traveled before the gas gauge came off the 
full peg, the mileage should be >20 mpg.  I'll update the net as I 
gain more experience.  I REALLY look forward to the improved hot 
weather performance.

All that good stuff said, I cannot recommend  this kit to anyone who does
not have a VERY well equipped shop.  I had to remove a LOT of metal from
the intake manifold to make it match the throttle bores.  Holly tries to 
make this thing be a one-part-fits-all.   Unfortunately, one part fits all
poorly.  The mounting holes aligned  up properly but the throttle bores
were greatly offset from where the 390 CFM 4 barrel was.  I also had to
add helicoils to the intake manifold because the countersunk allenhead
bolts supplied were too short to pass through and accept nuts.  Minor 
problem but a killer if you don't have helicoil tools.  

Another problem is that this unit is about 1/2" taller than the old 4-barrel.
That means that my Moroso air cleaner won't fit.  I'm going to have to do some
serious jerry-rigging to solve this problem.  I suspect that my answer is
going to be to remove the intake manifold and mill it on a slight angle so
that the whole assembly sits lower in the engine bay.

I think I mentioned it in the last  update but another SERIOUS problem 
has to do with Holly's quality control.  The throttle body was designed
for a stepping motor idle speed control though they do not support one
now.  That means there is a LARGE passageway cast just below the 
throttle plates.  After the bores are bored, there is only a tiny sliver
of metal between the bores and this passage.  Unfortunately these 
slivers are necessary to seal the throttle plates at idle.  My solution 
involved die grinding the slivers down until what remained had at least 0.5 mm
thickness and then backing them up with epoxee.  A number of 1/16" holes
drilled about gave the epoxee something to bite into.  A bit of pocket-
knife machining broght the epoxee back into round where the throttle 
plates would seal.

Other minor problems included a large hunk of casting flash keeping the 
throttle from opening fully.  I had to trim that down and remove some
extraneous tabs on the throttle lever in order that it would clear the 
manifold.  None of these problems are fatal but they do require time and
skill to remedy.  

Probably my biggest bitch is Holly's typically totally shitty documentation.
It's written for the complete moron.  It's a Heathkit-style stick-this-wire
in-that-socket  step by step that gives no explaination for what you're doing
or why.  The "theory of operation" takes all of 2 paragraphs.  No schematic
is supplied.  Crude pictorials with NO wire labels are all that's available.
I've often wondered why high performance magazines tend to read the same
way they did 20 years ago with practically no technical content.  This 
kind of crap is probably one reason.  The manufactures give the customer
no information so the customer remains ignorant.  Pedantic things like
labeling the acceleration enrichment adjustment pot "accelerator pump"
and the cold start enrichment "choke" are really pissers.  At least the
hardware works.

2 full  12 hour days.  That's a lot of work for what is supposed to be
a bolt-on replacement.

This stuff is just begging for a microprocessor.  That's probably going
to be the next step.  I'm so interested in TBI because it is perfect
for my turbo motors.  The holly casting is pretty nice other than the 
quality problems.  A little bit of bit-shuffling will really 
fix things up.  Meanwhile, I'm going to make the analog box work completely
right.  I'll keep the list posted.


Date: Tue Aug 13 08:10:30 1991   
To: (z-car list)
Subject:  Pro-jection daily update

Another day of tuning is under my belt.  For a Z application, the system
has one major problem - it is calibrated for a V-8.  When I get the fuel
pressure set so that the WOT pot will bring the mixture in, the idle
is too rich.  Clean the idle up and the acceleration enrichment is too
little.  I've settled on a setting where there is only a slight bog
right off idle but very clean everywhere else.  If Holly can't give me
some technical details on the control box, I'll just reverse engineer it.

Today was a 90+ degree scorcher.  It would have had the carburator drooling
all over itself.  Not a problem from the injection system.  What a pleasure
to not have that worry!

I've learned a couple of things about details.  One has to do with throttle
geometry.  I was having a real problem with transitioning off idle.  
A major factor was the fact that the butterflys are so large in the Pro-
jection system that they suffer a lot of vacuum resistance.  This manifests
itself as added force needed to open the throttle that goes away once
the throttle cracks a bit and dumps manifold vacuum.  The result can be
a snap action that makes it almost impossible to ease into the gas.

I knew all of this.  What I did not realize was how sensitive this problem
is to small throttle geometry errors.  The throttle is actuated by a 
home-made cable system.  I developed it from a teflon coated Honda 
motorcycle clutch cable.  Very slick and very reliable with over 5 years
of use on it.  There is a spherical (Heim) joint on each end for pivots.

Moving the cable from the old carb to the injector resulted in the idle
position being a bit past perpendicular.  In other words, the throttle
had to move a bit before the lever axis and the cable formed a 90 degree
angle.  The lever at a 90 degree angle gives the most mechanical advantage.
Herein lies the problem.  With this geometry, the maximum mechanical 
advantage was realized just about the time the vacuum force was being broken.
The lessened vacuum force combined with the favorable leverage made the
throttle leap across that point.

Tonight I cut the braket and rewelded it so that the 90 degree angle 
occures at idle.  The best mechanical advantage is available 
when it's needed the most - right off idle.  By the time the vacuum dump
happens, the mechanical advantage is headed way down.  The change could
not have amounted to more than a quarter of an inch.  What a difference it
made!  Not only does the throttle now open smooth, the apparent bog is gone.
I believe what was happening was that the throttle snapped open enough to
dump vacuum but not enough to develop an acceleration enrichment 
signal.  They obviously take a derivative of the throttle position voltage
to do the acceleration enrichment and the small but fast movement probably
did not exceed the threshold.

Even though is is a major improvement, I'm not satisfied.  I ordered a
gear blank from Boston Gear today.  I'm going to machine a quadratic
cam on it and use it to actuate the throttle according to a square law
response.   This will produce a roughly linear air flow vs accelerator 
movement response.  This idea is not new - BMW did it with cams and 
levers on my 635CSI.  But I'm doing it simpler.  A quadratic cam that
the throttle cable pulls against is much simpler than the BMW rube 
goldberg arrangement.

Stay tuned.  I'll be digging into the electronics in a couple of days.


Date: Wed Aug 14 07:56:36 1991   
To: (z-car list)
Subject: Re: Holley Injection system

	You'll have to pardon my ignorance, but I am curious about what
	you started with and what you use the car for.

	What is the configuration of the Z engine.  Was it mostly stock?
	Do you have a bigger cam, lifters, headers?  Apparently, it was
	carberated before you started, but did you have a stock intake?

This is a 75 280 2+2.  Red, of course :-)  This is a classic "sleeper"
"portch" and 'Vette killer.  The current engine is from a 260Z and is
simply a "runner" while I repair the turbo motor.  The 260 engine 
had been converted from sidedraft carbs to a small Holly using a
Cartech kit.  The Cartech kit consists of a manifold that bolts to the old
manifolds in place of the old carbs.  Even the small 390CFM carb is 
too big for this engine so it was probably never really right.  A
hundred thousand miles of wear meant it was garbage.

	What is the configuration of the Z engine.  Was it mostly stock?
	Do you have a bigger cam, lifters, headers?  Apparently, it was
	carberated before you started, but did you have a stock intake?

The engine has the mildest Racer brown cam, small headers, my custom
3" exhaust and MSD ignition.

	Does the kit come with a new intake manifold with injector ports,
	or is it throttle body injection?

This is a bolt-on replacement TBI system to replace holly carbs.  It looks
a lot like OEM TBI systems.

	Also, you might want to comment on what the difference is between this 
	injection and the injection system that comes with the stock Z cars. 

Because the Holly system makes no attempt at smog compliance (though It
will meet the idle sniff test), it is capable of better  performance 
than the stock system.  The controller box contains adjustment pots for
idle, midrange, WOT, acceleration enrichment and cold enrichment. 
Thus, you can (and must) tune the engine while you drive.  The stock
280Z system does several things better, most notably in the area of 
pathological conditons such as stabbing the throttle at 1500 RPM in high
gear.  At the present state of development the Pro-jection system 
will sputter.  The stock system obviously had to maintain control in 
order to meet smog specs.

On the other  hand, the Pro-jection throttle response is instantaneous
and it makes significantly more power than stock if for no other 
reason than the throttle bores look like sewer pipes and the mixture 
can be tuned rich enough for power.

I view the non-turbo motor as a development mule.  My real interest is
designing a digital control for the TBI for turbocharging.  the 
injectors can flow enough fuel to feed a 400 hp turbo motor.  The proper
engine for this Z is a Turbo Tom's based turbocharged engine that 
makes an estimated 400 hp at between 25 and 30 psi boost.  TT's kit 
uses a Holly, thus the interest in bolt-on replacements.  TBIs
have some real advantages for high boost turbomotors.  The cooling
effect of the gas being injected upstream of the turbo helps 
control detonation.  The mixing action of the turbine obviates any advantage
a port injection system might have.

If the non-turbocharged engine works out as well as it looks like it will,
I may make some manifolds and offer a kit.  The CarTech jerryrig is really
poor.  It would be substantially cheaper than port injection systems such as 
the Haltech.  I'm also going to try to collaborate with Turbo Tom to offer an 
electronically controlled turbo kit.  I say "try" because Tom is somewhat 
difficult to work with and is afraid of electronics.  Nontheless I have  
his interest.  He has gone to the trouble of having intake and exhaust 
manifolds cast to fit a turbocharger and so has the slickest Z kit available.

Speaking of Haltech, I today initiated becomming a dealer for them.
Anyone interested?

	Is this a street machine or are you breeding it for racing?  Any
	guesses on how much power increase you have gained over the stock

As I said above, it's a street machine designed to slay yuppy playtoys :-)
The absolute very best ones are the 928 drivers.  The Portch is 
invariably a manhood substitute and it almost drives 'em to the 
edge of suicide to have an at this point somewhat ratty looking old 
Z blow 'em away.  My best run to date has been 155 on the radar gun at 
10 psi of boost.  Unfortunately on that same run the water 
injection system failed and I chipped a piston which is why the engine is on 
the stand instead of in the car.  I'm going to have to break 
200 mph to get the occasional Calloway 'Vette.  My calculations 
indicate that 400 hp is going to be kinda marginal so I may 
have to go up a bit on power.  My limiting
factor has been pistons.  I'm using Datsun racing cast pistons.  Forged
pistons are getting hard to get, though a conversation today with
Wiesco was promising.  I may have to pay custom charges but so it goes.

BTW, I spent the entire day on the phone with performance electronics 
vendors.  I'll have some real goodies to add to the resource list 
as soon as I get time to key it in.

Stay tuned.

Date: Fri Aug 30 22:19:03 1991   
To: (z-car list)
Subject:  Anybody out there? (and fuel injection update)

Yoo Hoo, anybody out there?  The silence on this list is deafening :-)
Whatsamatter, everybody too busy driving to type?

Anyway, now for a fuel injection update.  I've had the Holly Pro-jection
system installed for about 3 weeks now and have it in a useable state.
My 3 week impressions are that it basically works, though I consider it
an incomplete job.  It badly needs an air temperature sensor.  I have to
tweak the mixture when the air temp changes significantly.  The other
major problem regards the inability to lean the power range out enough
and the inability to get enough acceleration enrichment.  Both are 
symptoms of the unit being designed for a larger engine.  It *REALLY*
needs either an airflow sensor or a manifold vacuum sensor.
Throttle position alone really is not enough input.  Finally, its 
startup algorithm, which involves shooting a rather massive quantity of
fuel unrelated in rate to cranking RPMs, easily floods the engine.   It
has an "anti-flood" mode that is invoked when the throttle is held 
wide open.  I've found that if I press the throttle wide open half
a second after hitting "start", the engine fires real clean.

Mechanically, the excessive vacuum force on the throttle plates
that I mentioned before had become terminally annoying.  I've orderd
a gear blank from which I'm going to machine a square root throttle
pulley to solve the problem.

Other than that, I like the system.  This little 260 engine makes
gobs of power, much more than a 280 and it has excellent throttle
response.  Mileage is less than I'd hoped for but I blame this on
the too rich WOT and the lack of richness on acceleration which means
more throttle is needed to get power.  It is definitely not a set-it-
and-forget-it system but it DOES beat the holly carb.  With a bit more
work it will be a very good system.

I did find out that the black box is made by MSD ignitions.  I have totally
failed in my attempts to reach Holly for technical information.  Their
phone numbers are always busy.  Even a couple of hours of demon dialing
did not get me through.  I'm going to be contacting MSD to see if they'll
supply some information.  

As I mentioned before, my main interest is building a digital controller
for this unit.  It looks like the task will be fairly easy.  I have 
a fancy digital storage scope on order and when it gets here, the reverse
engineering will begin in earnest :-)

BTW, I just got a HUGE package from HKS.  Gawd what a collection of 
goodies.  More later.  I've also found an inexpensive source of 
intercoolers if anyone else is interested in turbocharging.


From: John De Armond
X-Source: The Hotrod Mailing list
Date: Apr 1992
Subject: Re: FI

>did i hear you mention a while ago that your pro-jection 2 is on a
>six?  Perhaps thats why it floods the thing-- isn't it meant for a
>small eight?  my 350 needs all the fuel it can get on cold starts-- i
>have never been able to flood it.  I could see the pro-jection 4 being
>too much for anything where CID<=350...

Yes.  A 2800 cc engine.  However because of the terrible intake
manifold design, it also takes a BUNCH of gas to start.  When I
had the 390 cfm holly on it, it required full hard choke (choke spring
wound up so the butterfly is tightly closed) if it cooled any at all.

The problem with the Pro-jection is it has no idea how hot the engine is.
The temperature sensor only serves to turn the "choke" off.  It gets
the same shot whether the engine is just barely warm or scorching hot.
I've found that if I hold the throttle wide open, triggering the
"flood clearing" mode, it starts OK.  They knew of the problem as
evidenced by them including the flood clearing mode.  But they let it


From: emory!!gallant (Robert Gallant)
X-Source: The Hotrod Mailing list
Date: Jul 1993
Subject: Pro-Jection
X-Sequence: 5757

I just talked to an engineer at Holley.  They are currently working
on a computer for the projection that will be digital.  It can be
programed with a pc AND/OR with a few trim pots.  The system will use
a few more sensors including MAP for forced induction systems.

They expect about another year before its on the market.


[ *Sputter*!  A YEAR!  Whathehell are they doing, making their chips by hand?
If I'm lucky and have the time, I'll have my digital controller prototype
on my Projection in 2 weeks.  Three or 4 weeks for the snazzy user
interface program on the PC and I'm done.  This ain't rocket science.

While I'm talking about the Projection, I flowed the injectors last
night.  Each injector flows 89 lbs/hr on gasoline at 23 psi pressure.
Looks like those big Mazda injectors I reported on earlier earlier
would be good replacements.  Last time I checked, Holly wants almost
$200 for each injector!  Oh, while I was disassembling the throttle
body last night, I noticed the throttle shaft is already worn out.
This system's barely been on the car 2 years.  Trash!  JGD.]

From: emory!!gallant (Robert Gallant)
X-Source: The Hotrod Mailing list
Date: Jul 1993
Subject: Re: Pro-Jection
X-Sequence: 5766

On 13 Jul 93 23:50, hotrod wrote:

>[ *Sputter*!  A YEAR!  Whathehell are they doing, making their chips by hand?
>If I'm lucky and have the time, I'll have my digital controller prototype
>on my Projection in 2 weeks.  Three or 4 weeks for the snazzy user

Great!  What about the rest of us :-)!!!!

[The whole purpose of this exercize is a system anyone can build.  That
implies a series of articles in the mag :-)  JGD]

>While I'm talking about the Projection, I flowed the injectors last
>night.  Each injector flows 89 lbs/hr on gasoline at 23 psi pressure.

Do you run with the pressure this high?

[Apparently.  I just twiddled the pressure as another tuning adjustment
until I got decent throttle response with the tuning pots off their stops.
I'd never measured the pressure before.  That's what the regulator
regulated at on the bench.  JGD]

>Looks like those big Mazda injectors I reported on earlier earlier
>would be good replacements.  Last time I checked, Holly wants almost

Would you use the mazda injectors in the throttlebody?

[ I'd drill the manifold under the throttle body and install them there.
The Z will be perfect for that application since the original manifold
was set up for two SU carbs.  JGD]

I took a look at the intake manifold (since it is off of the car).
The injectors spray onto what looks like a plastic disk with holes drilled
in it.  The disk is in the center of the intake runner.

Any idea what this is?  If I remember correctly the pictures John sent
me of the injectors firing, was a nice spray??


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