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. John Date: Sun Aug 11 03:17:32 1991 To: (z-car list) Subject: Pro-jection update Well guys. The Pro-jection system is in! Jialin@dogwood.botany.uga.edu 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. John 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. John 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 engine? 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. John 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. John From: jgd (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 pass. John From: emory!oasys.dt.navy.mil!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. Rob gallant@oasys.dt.navy.mil ------- [ *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. Grrrr. 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!oasys.dt.navy.mil!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?? Later Rob gallant@oasys.dt.navy.mil |