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Digitizing D-jet

spock345

spock345

Well-known member
Joined
Nov 3, 2016
Location
Livermore, CA
I'd like to take my B20 back to some form of EFI after some experience with a rally this weekend. I've got the old D-jet setup complete on my workbench. I am looking at different technologies but would like something that is minimal fuss. I think the big sticking point where I am confused is the signal to time the injectors. I'm under the impression that with megasquirt and microsquirt a normal tach signal will work. Is this the case or should I really look at something more fine grained?

Also which platform should I look at being relatively new to this? I see a bunch of different options and am a bit lost.
 
A microsquirt box is so cheap. Avalanche performance used to make a b20 balancer to 36-1 edis adapter. Been a long time since I looked at a b20 fuel injected intake... I imagine there's a way to get a modern fuel injector in there.... but I am speaking from complete ignorance on that point.
 
If you want to look stock still (probably not a concern, but sometimes for some people it is) just gut your D-Jet case and put a MS inside.

Although I wouldn't continue using the D-Jet MAP sensor, they seem to be a bit flaky and imprecise 50 years later, run a hose to the MS MAP sensor.

Along with putting the MS inside the D-Jet case, this guy hid the moderni MAP sensor inside a gutted D-Jet MAP sensor body for uber-stealth:

That allows you to just plug your MS box into the existing harness. Of course, the harness is 50 years old as well, and quite often any running issues D-Jet is having is due to issues with the wiring, 50 years of being baked in oil in the engine compartment is hard on small thin wires.

The injectors are fine, and can work with MS. They're actually fairly large capacity, since D-Jet was limited to 50% duty cycle based on the way the electronics worked.

I think the distributor trigger switches are enough to get MS to work well enough, just use one of them and batch fire. D-Jet used two triggers and fired the injectors in pairs. But it really barely makes a difference to fire all the injectors at the same time, regardless of the engine position. That's the way LH2.4 worked, all 4 injectors were fired as a single batch. It barely matters at idle, and it doesn't matter at all at higher RPM's.

But if you ever wanted to add spark functionality to the computer as well - you'd need something far more precise like the trigger wheel mentioned by 740atl.
 
JohnMc said:
If you want to look stock still (probably not a concern, but sometimes for some people it is) just gut your D-Jet case and put a MS inside.

Although I wouldn't continue using the D-Jet MAP sensor, they seem to be a bit flaky and imprecise 50 years later, run a hose to the MS MAP sensor.

Along with putting the MS inside the D-Jet case, this guy hid the moderni MAP sensor inside a gutted D-Jet MAP sensor body for uber-stealth:

That allows you to just plug your MS box into the existing harness. Of course, the harness is 50 years old as well, and quite often any running issues D-Jet is having is due to issues with the wiring, 50 years of being baked in oil in the engine compartment is hard on small thin wires.

The injectors are fine, and can work with MS. They're actually fairly large capacity, since D-Jet was limited to 50% duty cycle based on the way the electronics worked.

I think the distributor trigger switches are enough to get MS to work well enough, just use one of them and batch fire. D-Jet used two triggers and fired the injectors in pairs. But it really barely makes a difference to fire all the injectors at the same time, regardless of the engine position. That's the way LH2.4 worked, all 4 injectors were fired as a single batch. It barely matters at idle, and it doesn't matter at all at higher RPM's.

But if you ever wanted to add spark functionality to the computer as well - you'd need something far more precise like the trigger wheel mentioned by 740atl.
Click to expand...
Thanks for the large writeup. I think I'll go grab a microsquirt ECU (maybe megasquirt if the need warrants it), re-use the d jet injectors, get a modern map sensor, use an actual IAC from a 240, and see what I can do with the distributor trigger points. I know 123 makes a distributor that has d jet trigger outputs, which is tempting.
 
hiperfauto said:
Kurt Incledon makes a "drop in" conversion kit for D-jet cars but his use of a stock distributor with a jury rigged pickup made me shy away from using it. He was local to us before moving to Florida and did a lot of his R&D on one of our customers cars.
Click to expand...
I was intrigued by that but am a bit put off with the distributor as well. Also their web site seems to be down.
 
OttoB said:
Solid shaft distributor
Lumination, Accuspark or similar trigger system
Datsun 260 fuel pressure regulator
EV1 injectors modified to hose connector
Mega or similar ecu
Click to expand...
Any idea on how to modify those injectors for hoses? I know earlier 240 ones fit in the holders.
 
Having been down the road already, same route you went, here's some feedback.
MS will indeed run from a tach signal for fuel, worked reasonably well, took some futzing around with the VR pots, filtering on the injector drivers to deal with some signal issues, but once that was resolved, it worked well. In my case I wanted something with more modern injectors, better spray pattern, so I took some k-jet bosses, trimmed them down, used an injector boss drill bit into them to take a standard Bosch style injector. From there I went with Hellcat injectors, dirt cheap on eBay, but they have a projected tip that sits nicely at the edge of the runner, like the stock d-jet stuff. A custom rail, AN plumbing, and a regulator up on the firewall rounded that out. In my case I'm also planning for future expansion of boost, so this was needed anyway. Redoing the system also really cleaned up the engine bay over the stock rail setup.

For a crank trigger, I went with the CAS adapter from Josh, got the original prototype for the B20's prior to him releasing them to the wild. Gives me the capacity for sequential, though I didn't go that route just yet, way more involved than I had time for. Going with the CAS allows for spark control and wasted spark as well, a welcome change.

Hopefully that gives you a little insight?
 
gsellstr said:
Having been down the road already, same route you went, here's some feedback.
MS will indeed run from a tach signal for fuel, worked reasonably well, took some futzing around with the VR pots, filtering on the injector drivers to deal with some signal issues, but once that was resolved, it worked well. In my case I wanted something with more modern injectors, better spray pattern, so I took some k-jet bosses, trimmed them down, used an injector boss drill bit into them to take a standard Bosch style injector. From there I went with Hellcat injectors, dirt cheap on eBay, but they have a projected tip that sits nicely at the edge of the runner, like the stock d-jet stuff. A custom rail, AN plumbing, and a regulator up on the firewall rounded that out. In my case I'm also planning for future expansion of boost, so this was needed anyway. Redoing the system also really cleaned up the engine bay over the stock rail setup.

For a crank trigger, I went with the CAS adapter from Josh, got the original prototype for the B20's prior to him releasing them to the wild. Gives me the capacity for sequential, though I didn't go that route just yet, way more involved than I had time for. Going with the CAS allows for spark control and wasted spark as well, a welcome change.

Hopefully that gives you a little insight?
Click to expand...
Yep, that helps a lot.
 
From my experience….

Ms1 on a locked dizzy, pertronix, single coil running MSnS, d-jet injectors. Cool. Worked. Made it to the grocery store, gas station, etc, but timing control was about as good as the springs in the old distributor.

36-1 ms1, ls coils in wasted spark… much more control, less drift, not as afraid to use all the timing.

36-1, ms2, ls wasted spark. Yes. But ok, there’s more that can be done to improve.

Dsm cas, ms2 ls sequential coil, sequential injection. Ok, well 25-30 mpg ain’t bad round town on 950cc injectors, and 20psi on cast pistons ain’t bad… 7500+cast pistons+22-24psi+1/8 mile autocross course.. and only cracking a ring land… not a bad Sunday.
 
www.fiveomotorsport.com

High-Resistance-12 Ohms, Hose-Type Fuel Injector, Jaguar, BMW, Porsche, VW

<style>#html-body [data-pb-style=EA7D797]{justify-content:flex-start;display:flex;flex-direction:column;background-position:left top;background-size:cover;background-repeat:no-repeat;background-attachment:scroll}</style><div data-content-type="row" data-appearance="contained"...
www.fiveomotorsport.com www.fiveomotorsport.com

Or these?
 
cwdodson88 said:
From my experience….

Ms1 on a locked dizzy, pertronix, single coil running MSnS, d-jet injectors. Cool. Worked. Made it to the grocery store, gas station, etc, but timing control was about as good as the springs in the old distributor.

36-1 ms1, ls coils in wasted spark… much more control, less drift, not as afraid to use all the timing.

36-1, ms2, ls wasted spark. Yes. But ok, there’s more that can be done to improve.

Dsm cas, ms2 ls sequential coil, sequential injection. Ok, well 25-30 mpg ain’t bad round town on 950cc injectors, and 20psi on cast pistons ain’t bad… 7500+cast pistons+22-24psi+1/8 mile autocross course.. and only cracking a ring land… not a bad Sunday.
Click to expand...
For an initial attempt I am thinking of just using whatever stock advance curve the distributor has to start with. The goal is just a decent NA driver.

OttoB said:
www.fiveomotorsport.com

High-Resistance-12 Ohms, Hose-Type Fuel Injector, Jaguar, BMW, Porsche, VW

<style>#html-body [data-pb-style=EA7D797]{justify-content:flex-start;display:flex;flex-direction:column;background-position:left top;background-size:cover;background-repeat:no-repeat;background-attachment:scroll}</style><div data-content-type="row" data-appearance="contained"...
www.fiveomotorsport.com www.fiveomotorsport.com

Or these?
Click to expand...
Now those seem like an intriguing option. I'll probably look to those if the stock injectors give me issues.
 
WillettRun? said:
I did a B20 on MaxxECU Mini. Put normal injectors/welded bungs on the intake manifold. Mitsu CAS and it works pretty good.
Click to expand...
Thanks, that is another option to look at. At this point though I am leaning towards microsquirt due to cost and the limited nature of my current goals. Although I bet I'll be down the same road as cwdodson.
 
cwdodson88 said:
From my experience….

Ms1 on a locked dizzy, pertronix, single coil running MSnS, d-jet injectors. Cool. Worked. Made it to the grocery store, gas station, etc, but timing control was about as good as the springs in the old distributor.

36-1 ms1, ls coils in wasted spark… much more control, less drift, not as afraid to use all the timing.

36-1, ms2, ls wasted spark. Yes. But ok, there’s more that can be done to improve.

Dsm cas, ms2 ls sequential coil, sequential injection. Ok, well 25-30 mpg ain’t bad round town on 950cc injectors, and 20psi on cast pistons ain’t bad… 7500+cast pistons+22-24psi+1/8 mile autocross course.. and only cracking a ring land… not a bad Sunday.
Click to expand...
What did you do to lock the distributor? Tack welds on the advance weights? I've got a 009 with out any play in the shaft but a messed up advance system I could use as fodder.
 
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