EFI Boxer

There's been no shortage of restomods in recent years (eg, Singer), but I didn't really get the EFI bug until seeing the Mototechnique David Lee Dino and 388. The BBi seems like an ideal candidate for this style of treatment. CIS is clever, but it feels like it's neither better than the carbs before it, nor EFI after it. Also, with EFI, I am unblocked from having engine work done (eg, proper cams). I'm not going for crazy power here, just my "ideal" incarnation of the car.

A few self imposed rules / restrictions:

• Nothing destructive. While reversing would be laborious, it could be done.
• Motorsport quality.
• Where possible, opt for period-correct aesthetic (eg, yellow zinc plated steel vs carbon fiber).
• Isolated to the engine bay (eg, no plans to control windows with an ECU).
• Don't overdo it on the sensors.
  
• Where possible, DIY in my very modest garage.
• Pragmatism and iteration. I don't want the car off the road for a year at a time. I want to drive it!

Here are the bullet points of the design:

• v1 is to keep the original plenum designs (no ITBs... yet).
• EFI injectors in the same holes as the CIS injectors (requires custom injector "carriers").
• Custom fuel rails (hard to find cylinder spacing for popular straight 6 engines).
• Repurpose OE ignition timing sensor (12 tooth gear in distributor) as crank sensor (REF).
• Distributor rotor and cap replaced with magnetic hall sensor for cylinder 1 timing (SYNC).
• "Pencil" style bike ignition coils (Hyabusa).
• Motec M150 ECU.
• Motorsport wiring (milspec Tefzel, raychem heat shrink, etc.).
• Lambda and knock sensors for each bank (allows for real-time fuel / ignition trimming).

I am currently transitioning out of the planning phase, and into the prototyping phase. The wiring harness is almost complete. After experimenting with different Chinese knock-off injectors and coils, I have the OEM versions on the way (Bosch / Denso, respectively). I drilled the first fuel rail over the weekend, and the fuel rail mounting brackets arrive tomorrow (SendCutSend). I 3D printed the distributor cap and the injector carriers (both PET-CF). Lambda (O2) sensors have been mounted, and ready for the CAN bus wiring.

Yesterday, I was able to piggy-back off the OE reluctance sensor (distributor) and read the RPM in the ECU. Combined with the MAP sensor (pulling from the plenum), you have the two most important ingredients for batch injection. The cam sensor is necessary for sequential injection and ignition.

If all goes well, I plan on doing a batch injection test this weekend (maybe next).

While I know some will see this as blasphemy (I can respect that), I hope there's someone out there who finds this as cool / exciting as I do. In the end, this is going to be a lot of work, and a lot of money, but I am optimistic that the results will be worth it. I've attached a few pics of the progress.

I'll post more as I make notable progress.


Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login

 

As I've gotten into this, I've had to resist the temptation to "sensor all the things". The Motec dealer threw a laundry list of sensor recommendations at me. Not really sure where the line is. Here's what I currently have planned:

- MAP
- Crank (OE reluctance sensor on distributor)
- Cam (magnetic Hall effect)
- Coolant temp (replaces CIS temp sensor)
- Fuel pressure gauge (taps into pressure regulator)
- Knock 1 (RH bank)
- Lambda 1 (RH bank)
- Knock 2 (LH bank)
- Lambda 2 (LH bank)

Similar to what I am doing with the OE dizzy sensor, I can piggy-back off other existing sensors too (eg, oil temp, oil pressure, etc.). I think I am mostly interested in monitoring things that alter the fuel map during operation.

Thoughts?

 

That's a good point. There are ways to program different fuel maps based on different fuel types, or simply adjust based on a sensor (aside from the knock / lambda trimming). I live in Miami, where ethanol free gasoline is often used for boats – so it's quite easy to find. They refer to it as "rec 90". But outside of Miami, most gasoline has varying levels of ethanol.

 

Definitely don't want to blow up an engine to find out where it knocks! The Motec M150 can monitor 4 different frequencies (per sensor). It's my understanding that there's a formula that can be used to get your ballpark frequency, and then you bracket around that until you do get a knock event:

Knock frequency (kHz) = 1800 / (3.14 x Piston Dia (mm))

For 82mm, you'd get 7k. I planned on including 14k in the bracket as well, as I understand the 2nd order frequency can sometimes have less noise (in this case, 14k).

All that said, I figured I'd set the timing to the factory specs (at least to start). I'm not looking to go crazy here on squeezing out every morsel of ignition timing.

So you have it running, even though you never fully "tuned" it?

 

Thanks Greg. Nice to see this subject is getting some interest! I will definitely post updates.

Yes, I looked into a few of them. You might find this video interesting. Some are disqualified due to the requirements of 12 cylinders (eg, Holley). For simple batch injection, you could run pretty much any ECU, as you could split a 4 cylinder signal into 12 (all cylinders pulse at the same time, which isn't too different than CIS). In that case, I'd at least run as a V6 so you could have separate banks. Anyway, things get more complicated if you want 12 cylinder sequential injection / ignition, volumetric efficiency based mapping, high quality enclosures (Motec is a magnesium enclosure, and the "marine" version is IP67 rated), real-time fuel trimming, logging, etc.. Then there's the software side of things. There was also the factor that I felt if I were to ever sell the car (no plans!), then the Motec brand would have larger appeal / higher resale value (which might be baseless). Lastly, I'd be remiss if I didn't admit to having been at least a little swayed by the fact that Mototechnique used Motec in their Dino and 388 projects. All that said, I spoke with a Motec dealer about the project in detail before actually committing.

I will say, it hasn't been all moonlight and roses with Motec though. The assumption is that you are either a motorsport team, or a tuner that does this for a living. It's expected that you already know how all this works. Whereas companies like Haltech are far more approachable. That said, I don't regret the decision to go with Motec at all, but it means I have had to rely more on my dealer for pointers (which is by-design, I think). I have learned a lot from the HP Academy videos as well; which has an entire course dedicated to Motec.

So short answer, Motec is pretty amazing, but there are others that do a fine job.

 

IMO, EFI simplifies things; while also enabling better performance (eg, not having to worry about intake reversion). Not to mention, EFI can also handle ignition. I personally think the aesthetics are cleaner with EFI too.

To each their own, though. Ironically, I don't think I would do this if there weren't already so many owners passionate in preserving these cars in their original state.

 

Had some time over the last few days to poke at this a bit more. Removed the 7-12 bank CIS mixture control unit / fuel distributor, and air filter. Wired up the MAP sensor, fuel pressure sensor, O2 sensor and CAN bus – so I'm all set on sensors (previously wired up the crank sensor). I also test fit the injectors, the 3D printed injector carriers, the fuel rail, and the fuel rail brackets. There's just barely enough room for the injectors; which is a balancing act trying to get as close to the head as possible. The 3D scans really helped, as there isn't a ton of wiggle room with this design and things seem to be fitting as expected / hoped. An M14 to 6AN adapter converts the existing fuel line from the pump / accumulator / filter. A custom bracket allows me to attach the fuel rail to the head. Exiting the fuel pressure regulator is a 6AN to 3/8 barb; which reuses the original return line.

This is going to stay a giant bird's nest while I'm in the proof-of-concept phase. There are so many variables, and areas I could be wrong. I don't want to commit to anything until I know it's working (especially if I need to put CIS back in for some reason). The next step is wire up the injectors, and pressure test the fuel system. If that goes well, I can try firing it up! The crazy thing is that cylinders 1-6 will still be CIS; with 7-12 being EFI. Betcha that's never been done! If this proof of concept works, I'll start to clean up the wires, mount the ECU, swap cylinders 1-6 for EFI, etc.. I have a few ideas for the air filter, but haven't settled on anything yet. Once fuel is taken care of, I'll start swapping the Dinoplex / coil / distributor with coil-on-plug.

Lots of work left to do.

Image Unavailable, Please Login


Image Unavailable, Please Login


Image Unavailable, Please Login

Image Unavailable, Please Login


Image Unavailable, Please Login

 

Thanks Peter! Something similar was my original plan. Essentially, "pass-through" the old unit (with the plate removed). I had planned to put the ECU where the Dinoplex is as well. As things started to progress though, I increasingly felt that I wanted to see more of the engine; which is covered by so much of the CIS and intake ducting. With CIS removed, you can actually see the valve covers. In the end, I think it's probably more a matter of preference, and someone who wanted to add EFI while maintaining a near-stock appearance could totally do it. At one point, I even considered running individual fuel lines to each cylinder to mimic the look of CIS using these injector adapters.

To be honest, I think I'm just rationalizing an eventual switch to ITBs...

Image Unavailable, Please Login

 

My suspicion is that the stock plenums / throttle bodies are okay for mild performance improvements over stock, but would eventually become a bottleneck if other things were done (eg, cams, head porting, etc.). Time on a dyno will confirm.

There are two reasons I didn't just go straight for the ITBs:

1. I wanted to be iterative (both effort and cost). ITBs would require custom manifolds, etc..
2. I've heard from some tuning pros (including my Motec dealer) that tuning ITBs can be difficult. There are tricks, but simple manifold pressure from plenums is much simpler.

Basically, walking before I run.

He did mention to me that he felt Ferrari was far too conservative, and that you can reprofile the BBi cams without interfering with CIS. I didn't get the sense that you'd have BB performance though. Need him to confirm that.

Agreed. And aesthetics, personally. The BBi plenums don't look bad, but 12 tall velocity stacks!?

I don't believe so, especially if you use the available clearance for longer velocity stacks.

Thanks. Pressure testing the fuel system tomorrow!

 

It runs!

Yesterday, I pressure test the system by jumping the fuel pump relay like you would for a CIS test. I checked for leaks while adjusting the regulator to ~45psi and monitored the pressure on the laptop. The fuel rail started to lift from the cylinder 7 injector, but that was easy enough to cure by adding another bracket (3 total). I blocked off the shared fuel line between the two WURs, and tested pressure for bank 1 as well. All good, so I called it a night.

Today, after a few triple checks, I turned the key, and it fired right up! Idle was smooth. Basically, the combination of a MAP sensor and RPM, basic info about the injectors and engine displacement were all it took to have it "just work". I can hear vacuum leaks coming from the new injector carriers; which should be easy enough to cure by bumping the diameter out so the o-ring has a tighter seal.

Next up is to fully remove CIS from bank 2 (I left the WUR, aux air valve, cold start injector), and do some cleanup before moving on to bank 1. Once I have both banks running batch injection EFI, I'll move on to coil-on-plug ignition (likely going with the Hyabusa coils). Then I'll mount the ECU / relays / fuses, and finalize the wiring (cut to final length, re-pin the connectors, heat shrink with DR25, and label). Still a lot of work left to do, but for me at least, today was a really big milestone.

A few side notes:

- I experimented with "low profile" EV1 connectors that came with white pigtails. They seem to work well, so I'll re-pin these (remove the white pigtails) and likely add 90 deg boots so the wires don't stick out so far.

- I was curious if the spark wires would interfere with the injector signals since they are so close. Didn't appear to be an issue. Somewhat moot since I plan on switching to COP.


Image Unavailable, Please Login

 

Because I was unsure I'd be able to pull this off, and I might have to go back to CIS. But, now that I know it works, I feel confident that I can commit and take it all out.

Yes, zip ties just to test how many and where I wanted to place the brackets. I didn't want to drill into the rail only to change my mind on placement. Same idea though! See attached CAD / photos. My original thought was that two brackets would get the job done, but I'm leaning towards three now (although, that could have been because zip ties are not exactly the same as bolts...).

Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login