Everything about CB Performance Black Box

[daos]

why not just call CB and get your info from the horse’s mouth. they don’t bite.

[Rob Combs]

One thing that I noticed early on but did not fully consider with the Black Box is the potential for MAP sensor skew.

Mine sits at 93 kpa at atmospheric pressure, sitting on my desk on a power supply. Never gave it much thought, but the other day while I was reconfiguring my timing table to take advantage of lower manifold pressures I'm seeing (BB software packages seem to bottom out around 60 kpa; I'm idling at ~35 indicated, it finally dawned on me to check the local atmospheric pressure, convert that reading to kpa, and compare. My sensor appears to be skewed 8 kpa low, at least at ambient pressure. This might just be normal tolerances in the MAP sensors themselves, and to me it's not worth fixating or chasing down a root cause since I can program around it.

If my logic is not failing me, and I assume the sensor skew is constant (it might not be), this means transitions need to happen a little earlier because actual pressure is a bit higher than indicated pressure. It won't matter as much just off idle and at low pressures because the engine will probably tolerate more error in that range as long as you're not running it on the bleeding edge. But it might matter at the higher/full-load pressures when the engine isn't quite as tolerant to too much advance.

For this reason I programmed mine to start phasing out vacuum advance a little earlier, closer to 70 kpa to compensate for the sensor skew.

You all might already know this, and I might be slow on the uptake, but another handy thing available to anyone with Excel is to duplicate your timing table (yes, it's time consuming). You can then "heat map" your table to give colors to cell values so you can easily see any outlier cells that don't make sense, or to see stark changes in timing between adjacent cells and determine if those stark changes make sense or might cause problems. I find this super convenient when changing values, as you can also copy your table before you make changes, and create a separate "delta" table to map the differences before to after using very simple formulas, and heat map those changes to see if you've done anything truly drastic and if it still makes sense. This really highlights your changes in an easy to interpret way.

This beats the hell out of trying to focus on 441 cells in a tiny table in a small window on your laptop. You can also create a 3D chart of your table, complete with heat mapping, if you so desire.

Just a few tips for those who find the graphical approach more intuitive to interpret.

Hope these observations help someone along the way...

[piledriver]

Microsquirt and a VW 4 post coil, GM 3 bar external map sensor. Fully programmable ignition , add you can add
injectors if desired. Main unit is ~$350 with a 1M harness, it can mount on the fan housing or firewall, all components automotive rated.
VW 4 tower coils are available anywhere.(you want the one with the aluminum heat sink/ignitor module built in)

The Tunerstudio and megalogvier software is quite excellent and free to use with a couple missing features, for ignition only you wont miss the autotune (fuel only, with a wideband) The logging software will allow you to offline tune mased on logged data.(given a wideband O2)

There are many trigger setups out there, or you can roll your own.

I run a $6 steel toothed wheel on some 3/8" brass tubing... inside a mostly gutted 009 can and a $8 sensor module I made myself from an ATS667 from Digikey. The wheel has a tiny bit of weld for a missing tooth. (the sensor doesnt like a missing tooth but with one filled in works past 15K, 36 tooth wheel)

The best distributor is no distributor but one that's just there to run the toothed wheel is pretty reliable.

I have run MS2 or MS3 for about 15 years now, >10 years with this setup, the car is a daily and I have a ~50 mile commute each way.

I have also run a VR sensor aimed at the flywheel, but that requires a flywheel with no extra holes in the disk vent hole or plate bolt hole radii. (a hole is the same as a tooth to vr and most hall sensors)
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Current daily driver---73 Square, 1.8L T4, MS3+MS3X/sequential w/LS2 coils 80 miles/day.

[jimmyhoffa]

Speaking of enhancing the topic at hand which none of the last 6 posts did in the slightest, here is the IGBT in the Black Box responsible for coil driving. It is automotive-specific in ways that fit the bill perfectly and CB uses the genuine ST Micro brand one instead of some knock-off copy.

Look up the .PDF datasheet for the ST Microelectronics GP18N40LZ and you'll find what current it is capable of reliably sinking, and you can use that to ensure what the Ohm coil you'd be able to run if you desire a specific one. I know the manual tells you when you buy a BB, but maybe you want to push it. That IGBT in the picture has the job of grounding the negative side of the coil to charge it for the dwell decided by the CB Black Box brains, and then releasing that connection to ground to fire the coil.

Nothing revolutionary but nice to see well-specified genuine components. I was rooting around in there trying to figure out why my BB is chronically unreliable and hypersensitive to mag pickup spacing, but I think I'm done here and I'll run my Daytona TCS-1 with a Ford TFI or my "Dumb" MSD box.
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1974 Chenowth 2RL #1244 Street Legal
My other car isn't ridiculous.

[oprn]

Looks like our aviation friend gave up and went away. If he is running an automotive engine he is also operating in the Experimental class. As such there are no certification requirements for either the engine or the systems attached it therefore there is no liability attached to advice given him. It's his butt in the seat, his funeral if it goes left.

An aircraft engine is for all practical purposes a STATIONARY engine. It will not likely be operating below 75% of full throttle except for taxiing on the ground. As such I am not convinced there is any advantage to having a vacuum input for part throttle advance. It will never be running at a load where it would be an advantage except on the ground.

Historically certified aircraft engines didn't even have a mechanical advance.

I think our aviation friend is way overthinking this.
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Our cars get old, we get old but driving an old VW never gets old!

[58 Plastic Tub]

I have a couple of Black Boxes modified to drive twin-spark. It seemed to be the easiest and best way to light two fires at exactly the same time when I was putting together a twin-spark 2276 about a decade ago. Mario Velotta added a second coil driver to a pair of BBs (one was a spare) and I used a single comp-u-fire pickup and a Datsun twin-plug cap and rotor in a modified and locked out 009. It was the shizzle, and looked the part with a bundle o' snakes distributor cap front and center.

It was also a complicated Rube Goldberg arrangement that eventually let me down, when 1000 mi. from home, the comp-u-fire module loosened up and started shaking around and giving me horrible spark scatter. Until then, it had performed amazingly well. In the end, the entire thing was brought down by the complexity of the entire conceit.

The failure had nothing to do with the BB or its modifications, which is my point in posting. This thread was already going when I decided to use the BB for spark control, and when there was the (unfounded, as it turned out) concerns about firing while cranking, etc. The electronics of the thing performed flawlessly in a pretty hostile environment for the entirety of the time I ran it (3 years, if memory serves).

It uses manifold vacuum instead of a TPS for load calculations. I'd rather it used a TPS, and I'm sure there's probably a way to get it done, but the vacuum signal at least worked, which is more than I was ever able to say about an 034 (or Unilite) vacuum canister advance.

The rest of this nonsense is just a pissing match over grudges from another time and place, or guys who feel the need to record every random thought they have as it occurs to them.

I've lurked here for a long time, and posted sparingly. I appreciate the contributions of guys who forget more before they get out of bed in the morning than I'll ever know in my life -- but a ton of space is used in nonproductive ways by a few guys bent on having their say on every conceivable topic.

This one is about the Black Box. It's a zillion pages long, and probably never going to be read its entirety by anybody. You're shouting into the void, gentlemen.
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Stan Galat
"A single point in isolation is a reference point. Two points is a line. Three points is a trend. Trends don't lie."

[jimmyhoffa]

[58 Plastic Tub]

I’m not sure what Mario used or did, Jim, but it worked great.

It took him a while to figure it out — but once he did, it was reported to be not overly complicated. I do know the first one was a bit expensive (because of the research involved), but the second one was very inexpensive to have done.

Both of them are sitting in my stash, likely to never be used again. The entire project was straight up to see if I could do it, and to provide a diversion from the pressure of running a business. The project failed in the end (by not producing the desired result) — but it was a success, insomuch as I learned a ton and was amused and occupied mentally in the process.

It really was stupid-cool… but in the end, mostly just stupid.
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Stan Galat
"A single point in isolation is a reference point. Two points is a line. Three points is a trend. Trends don't lie."

[Dauz]

I've had the same technology in CBs "digital" distributor. Although I had wound up leveraging one of the default tunes, the timing table was easy to work with. MAP input worked perfect. Disabling the mechanical advance was a breeze.

[GreeneHoosier]

Black Box Newbie, here! It is an AMR500 equipped 1641 with a locked out 009 and accufire electronic ignition. The instructions, I think I am reading the right one, say to connect the wire from pin 10 to "input from points, electronic module or Hall effect module" This would be the black wire from the distributor/accufire?

I am using this diagram. Grounding pins 3 and 6. Pin 2 to + side of coil. Pin 7 to negative side of coil, and if correct pin 10 to black wire from accufire.

So now, the red from accufire goes to coil, but the black wire from accufire no longer goes to the coil it goes to pin 10?

Here is a pic of the diagram I am using and a pic of my modest little Super. Thanks!

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1974 Super Beetle
40 Years VW enthusiast!

[Rob Combs]

I’m not familiar with accufire but if it’s a two-wire device I think you’re on the right track.

[GreeneHoosier]

Thanks for the reply! I am reasonably certain also, but I don’t want to fry anything by doing it incorrectly. I am sure a black box veteran will chime in soon! Thanks again!
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1974 Super Beetle
40 Years VW enthusiast!

[Rob Combs]

[Lo Cash John]

[Rob Combs]

I'll let you know John

Got a mockup started with my spare crank and flywheel shimmed up to control end float to about .010" riding in two main bearings in my less-than-perfect spare case. That should keep the crank sensor from inadvertently hitting the magnets.

Should receive an extra alternator stand later today for something to bolt the crank sensor bracket to. Bracket will be made from some cheap aluminum bar stock sourced from Lowes. Crude but simple and easy. I don't have machine tools or a 3-D printer to fabricate stuff like this.

I've made a crude crank sensor out of two reed switches and a cheap circuit board building kit - one switch is NC and one NO so we can test the logic both ways with an oscilloscope. Can run my black box in my office if I can remember the password to the computer where my black box files are stored.

Can spin it up by the crank bolt, or if necessary the gland nut, with a drill and some socket adapters.

Should have a working prototype sometime late next week.

Stay tuned...

[Rob Combs]

Ok so the initial mockup is complete, albeit a little crude.

Simple on/off signal picked up on the continuity scale of my meter picks it up every time the magnet passes, 2x per crank revolution.

Now I need to find a few minutes to bring my Black Box inside, add a wire to the desktop harness to monitor points feed, and see if it registers RPM properly when I spin the crank.

More to follow.

[raygreenwood]

[Lo Cash John]

NICE!!!!!!
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www.LoCashRacing.org
More brains than bucks...Believe it or not!!

If you actually drive your VW, you need www.AirMapp.com

My boss told me I need to work on my mutli-tasking. So now when I use the bathroom at work I surf The Samba on my iPhone.

[Rob Combs]

It almost works

Spinning it over ~ 60 RPM with a cordless drill I get this:
(not a typo and not 600 RPM, my drill maxes out at 450 in low gear)

I thought it was due to noise coming through my power supply, and I guess it could still be, but would the scope pattern square waves look clean like this:

Interestingly, I only drop from ~ 13.8v to ~ 10v when the magnet passes by. This is with the scope positive terminal connected to the desktop power supply (13.8v) and the negative backprobed into terminal 7 at the Black Box, which is the points input connection.

#7 at BB also connected to one leg of the N/C reed switch while the other leg is connected to the power supply negative. With switch N/C and one leg of the switch connected to power supply negative, the #7 terminal circuit should be shorted to ground for all intents and purposes (just like when the points are closed), and I should get 0v and a pulse of something > 0v when the magnet passes by and opens the circuit (like when the points open). But I seem to be getting the opposite. I can't wrap my head around why this is happening.

The power supply works fine for programming the BB, but connected to this noisy power supply, I have no idea how it's reacting or what it might be doing internally.

It just feels like there may not be enough current flowing through the circuit or too noisy a DC input, to make this thing work. I may try this scheme connected to a real battery and see what I end up with. Really don't expect a different result though.

In the meantime can anyone see something I'm missing?

[Lo Cash John]

I would try a manual toggle switch in place of the reed switch to verify your circuit does function and the BB can reed a simple ground reference with an interrupt to trigger the coil.

Once you know that works, verify your NC reed switch is in fact normal closed. Also, does it have a maximum cycle rate?

And I absolutely would do all testing with a large battery in the circuit or powering the circuit entirely. AC ripple from the power supply could be triggering the BB but not show on the scope perhaps? The battery will help cancel the ripple.

As a test, you could run three back to back tests:
fixed RPM
Power supply only
Power supply with large battery
Battery only
_________________
www.LoCashRacing.org
More brains than bucks...Believe it or not!!

If you actually drive your VW, you need www.AirMapp.com

My boss told me I need to work on my mutli-tasking. So now when I use the bathroom at work I surf The Samba on my iPhone.