EFI Boxer

Status update.

I've been a little preoccupied with various projects (too many at once), but I've made some progress.

Scoops

I think I've basically gotten to the end of my skill and/or patience with the scoops, but they're primered and ready for paint. I may do another version with a carbon fiber skin to give them more strength and less likely to warp from sitting in the sun (not sure that's an actual problem yet). Even if I skin them, I'll still paint them satin black – so you'd never know.

Trumpets / Filters

I am currently experimenting with black trumpets. I tried a few different materials, and it's down to black or polished aluminum. Still deciding.

I also 3D printed aluminum top plates to replace the plastic prototypes. I polished the outsides (the part you see), and added rubber trim which seals against the aluminum brackets mounted to the engine lid. I added UNI coarse filters; which are kept in place with stainless steel mesh. The filter is a high-flow layer that is typically part of three layers (coarse inner, fine outer). I don't expect it will have a dramatic impact on air flow, but I'd like to do some dyno tests to see for sure. Sacrificing a few HP for some basic filtration might a good trade-off. Also curious how much the filters want to get sucked into the trumpet. I may need to put a support under the filter (maybe more steel mesh, or just a laser cut large "grid"). I might just hit them with a leaf blower to see how solid they are (off the car, of course).

Side note, the little nub sticking out on the RH side (between cylinders 1 and 2) is the air temp sensor.

Ps. ignore the exhaust area. Different project

Wiring

I am pretty sure I want to redo the wiring harness now that I've lived with it for a bit and made some tweaks. I also want to make engine removal more straightforward with larger milspec connectors at various middle points rather than having the entire harness connected at the ECU. I am still deciding whether I want to tidy up the injector / ignition wires using something like what was used on the TR (essentially a little rail that attaches directly to the injectors), or leave the wires exposed. Either way, I don't love how I routed everything down the LH side (it's bulkier / messier than I expected), so I may replicate the original routing where some of the wires cross over the bell housing.

BBLM Inspiration / Project Reflection

This is my best attempt to combine the various LM generations. The exterior is Series 1 pre-silhouette (the scoops), and the engine itself is a little bit more like the Series 2/3 cars with the trumpets. For me, I'm pretty happy with how things are turning out. I really tried to be respectful to the history of the Boxer, while incorporating EFI. I don't see myself making dramatic changes to the EFI / ITB design moving forward. Mostly cleanup / beautification.

Next Steps

Other than painting the scoops, I think I am will leave everything as is for a little bit so I can make more progress on the other projects. That'll give me some time to think about any changes to the wiring routing, settle on black vs polished trumpets, etc.. I also want to dyno the car once the radiator swap is complete. I know the car sounds better and has much better throttle response. Not sure what the actual HP/torque numbers will be though. The head simply doesn't flow great (inlets are 35mm choke points), and the cams are too mild, so there's only so much EFI and ITBs can do. A lot of potential though.

Image Unavailable, Please Login

Image Unavailable, Please Login

Image Unavailable, Please Login

 

Thanks Peter, I appreciate that. It's taken almost a year to get here, but it seems I'm in the final stretch to wrapping this EFI/ITB conversion up.

 

Thank you. It's been a ton of work, but I don't regret it at all, and I feel like I mostly achieved the look I was going for (reminiscent of the BBLM). I'm glad I went with vertical trumpets.

So far, very satisfied with how it runs. Starts right up, idles well, and throttle response is much improved. The sound is killer. I'm also glad that I ran it for a bit after converting to EFI, and before starting the ITB work. The car was better with EFI, but this is much better. Some of that might have been due to a poorly setup CIS / mechanical ignition. My advance was all rusted, and the springs / arms were basically stuck. My guess is that higher RPM had horribly retarded timing, even though idle was fine.

Once I do the radiator swap, I'll dyno the car. Very curious to see those numbers.

 

I am curious what the effect of the larger throttle bodies have as well. It'd be great if EFI + ITB was all it took, but my suspicion is that I'm just north of 300HP. I used 42mm throttle bodies, and the trumpets flare out to 70mm openings. That should address the restrictions from the stock dual throttle bodies and narrow runners. At the end of the day though, the head port is what it is. My manifolds loft from a round 42mm to an oblong 35mm at the head (shown below); which I did intentionally to allow plenty of material for porting (if I go that route). The oblong 35mm is probably more like an equivalent 32mm round.

If I go down the engine work path (which was my original plan), I figured I'd do a bunch of work at once – replaced valves, ported heads, higher compression, proper cams (somewhere between stock BB and P6?), and maybe even a lighter crank / lighter rods. It's my understanding that the BBLM cars had close to 500 HP in some cases, with essentially the same upgrades (although P6 cams seem a little much for the road, but I'd defer to someone with experience with those cams on that recommendation). If I could get to ~400 HP, I'd be happy, so maybe the mods above are overkill. Honestly, my biggest hesitation on the additional work is the downtime of the car. I really like driving the car, and having it out of town for months just sounds like a bummer.


Image Unavailable, Please Login

 

I've lost track how many times I've almost purchased a 355 for exactly that reason!

 

Status update. Mostly refining / beautification / optimization.

Air Filters

I revised the design to include a "support" under the foam filter (somewhat out of paranoia that the filter could get pulled into the trumpet). The pattern is based on the pattern ITG uses inside their sausage filters (except I filleted my edges). It's 1mm laser cut aluminum that I cleaned up a bit. On top of that is the UNI foam filter (30 PPI), then the stainless screen (69% open area). The top edge of the top plate has a neoprene rubber that seals up against the scoop base. I also added reflective aluminum / fiberglass to the bottom of the scoop base; which the trumpet plate seals up against. I swapped the M5 bolts for M5 clevis pins to make removal easier and less likelihood of nuts backing themselves off and falling onto the engine. Also, they're aesthetically cleaner on top.

I'm pretty content with this setup. Intake temps are only slightly above ambient, and it feels / looks solid. Obviously, this is more restrictive than open trumpets, but I think it's probably worth it. When I dyno the car, I might run it without the filters to see how much it really makes a difference.


Image Unavailable, Please Login

Wiring Harness 2.0

I was fortunate enough that I could reuse the wiring harness I made for the EFI swap with only a few minor tweaks to get running with ITBs. One thing I didn't account for in the initial harness though, was engine removal. The current harness would be a PITA, and would require disconnecting pretty much every sensor, injector, and ignition coil, then snaking the harness away from the engine. So, I'm creating a new harness that aesthetically lends itself to the ITB setup, but also makes engine out service a lot easier.

Basically, I am adding a breakout box using 26 way autosport connectors. Simply disconnect from the breakout box, and drape over top of the engine. No need to disconnect each sensor / actuator. Also, I am working on a design based on Paul's earlier recommendation to incorporate some kind of cover over the wiring (a la 512TR and 512M). On those cars, the "cover" is pretty clever in that the injector connectors are integrated into the cover itself, so the injector connector itself becomes the mounting mechanism. I am doing something similar, but it will include the coil wiring as well, and it will use generic EV1 connectors. You can see the design below. Not sure if you can tell, but the EV1 connector slots in from the bottom, and then a plate slides in to keep the EV1 connector in place. I did a few test fitments, and it works really well.

I angled the front and rounded the edges to resemble the valve cover (as opposed to the TR/M version that is basically a long rectangle). Also, 24 x 22 AWG Tefzel wires wrapped in Raychem is only 8mm OD, so the "conduit" doesn't actually have to be that large (even for so many wires).

The rest of the sensors will get their own harness; which will follow a similar path as the stock setup (basically, a "U" shape around the block). This will also use an autosport connector (I think I can get away with a 19-way).

This should tidy up the engine bay a lot – especially down the LH side as that has become a bit of a mess of multiple large diameter Raychem harnesses. That will all-but go away with this change.


Image Unavailable, Please Login


Image Unavailable, Please Login
Image Unavailable, Please Login

Image Unavailable, Please Login

 

Status update.

Wiring Harness / AS Breakouts / Wiring Cover

I've deconstructed the harnesses I originally created for the EFI swap, and mostly finished the new breakout harnesses for each bank's ignition / injection. These resemble the TR style, where the harness comes through the middle of the bank and then splits off. Probably easier to tell how it works from the pictures. One key difference is that mine houses the injectors and the coil wiring. Since the injectors are sequential, they each need their own wires. So there's a total of 24 wires in each bank harness (two for each injector, two for each coil).

Image Unavailable, Please Login

The ign/inj harnesses then run along the throttle bodies through p-clips, and connect to AS breakouts; which then connect to the ECU/PDM. I'm working on a bracket design for the AS connectors that I plan to zinc plate / yellow chromate. The 1-6 bank snakes over the bell housing similar to how the old spark plug wires did. Same as all the other wiring I've done, it's Tefzel with Raychem, Kapton tape, heat shrink labels, high quality barrel terminals (requires $$ tools), and braided sleeve to pretty it up.

The AS breakout harnesses are quick disconnects. You simply drape the harnesses back over the engine, and you can take the engine out without having to disconnect any of the sensors / injectors / ignition coils.

I've been experimenting with the wiring cover. It's just unfinished plastic at the moment, so I can test out ideas quickly. You can see though, that it covers all the wiring for the injectors and ignition coils. It works well too, as it's easy to remove and service. Now I just need to settle on the aesthetic.

Overall, I really like the cleanliness. This setup removes a lot of the harness clutter going down the LH side. The injector / coil areas is just cleaner as well. Not to mention this makes servicing a lot easier. AS connectors cost a small fortune, but I think they're probably worth it.

Fuel Rail

I had Jenvey make new fuel rails without any zinc plating. These are slightly longer to align better with the wiring covers. I then Cerakote them in "Black Velvet". Leaning towards Cerakoting the wiring cover in Black Velvet as well, so they match. The end result should have a similar aesthetic to the TR.

Image Unavailable, Please Login

Vacuum Hose

I usually try to turn a blind eye to the grittiness of the engine (which will get addressed during the rebuild), but the filthy vacuum hose to the brake booster was just irking me. I went with a M10x3.5 black cloth braided hose from NewCo. I was able to cut it a little longer, and have it loop over the fuel rail. I think it looks much better.

Image Unavailable, Please Login

Throttle Lever

I finally got around to swapping out the plastic bushing for the actual Ferrari part. I threw it in the freezer the night before. It slid right in to the lever and stayed in place once it warmed up. Honestly, I can't tell any difference in pedal feel with the metal one vs the plastic bushing I 3D printed, but this seems more "pro".

I could maybe design a "prettier" version of this throttle lever, but it's just a throttle lever after all.

Image Unavailable, Please Login

Scoops

I intentionally ignored these for a little bit, as I wanted to see how they held up to the stresses of opening / closing the engine lid, weather, engine heat, etc.. I noticed a crack forming on one of the seams that I only "plastic welded" one side – which I believe came from the stress of closing the engine lid. The seams where I welded both sides were holding up fine (I intentionally varied the ways I did it to see what was necessary).

To solve for it, I re-welded the seam (and any other one-sided weld seams), and coated the inside of the scoops with epoxy resin – the same stuff used with carbon fiber, just without the CF. This created a strong and flexible layer that has held up well for the last month. Short of putting an actual CF layer (either inside or outside), I think this is a good option. I am going to run with this for another few weeks before doing the final primer / paint.

 

Status update.

It's been a few months, with somewhat slow progress on the EFI due to working on other projects (exhaust, BBS wheels, custom shocks, cooling upgrades, etc.). I've made some progress though, so I figured I'd share where I'm at.

Breakout / Junction Box Wiring

I've mostly finished this work. There are three new harnesses:

1. Bank 1 injectors / coils.
2. Bank 2 injectors / coils.
3. All other sensors / actuators on top of the engine (crank position, cam position, coolant temp, IACV, air temp, knock sensors, etc.)

The harnesses meet where the old distributor cap was – essentially replacing the spark plug wires (bank 1 literally uses the old p-clips as it crosses over the bell housing). Now, to prep for engine out, all you have to do is disconnect the three autosport connectors, drape the harnesses over the top of the engine, and you're good to go. Each harness is using Tefzel wiring with Raychem heat shrink, and then flex wrapped (just for aesthetics). Still some more work to do, but it's close.

Side note, I'm working on a custom top heat shield, which is why that's missing. You can see the quad exhaust in there too.

Image Unavailable, Please Login

Return of the Aluminum Trumpets

I originally started with aluminum, then went to plastic (ASA-CF) when I added the filter. After living with it for a bit, I realized a few things:

1. The induction sound was quieter. Partly due to the plastic absorbing some of the "bark", partly due to the foam filter.
2. The filter was restricting airflow at high RPM.
3. I prefer the look of the aluminum.

So with all that, I decided to find a way to go back to the aluminum. I removed the filter, but left the stainless mesh. I also redesigned the filter "housing" to appear taller buy introducing a "skirt" that goes around the trumpet bellmouth. The end result looks a lot more like the BBLM, has the nice aluminum aesthetic, has a louder induction noise, and doesn't restrict airflow nearly as much (technically, the mesh on the bellmouth radius is disrupting flow, but I'm not too worried about that). If I bring back the foam filter, it'd likely be in the scoop where there's a lot more surface area / volume to work with.

Also, I had this filter housing CNC instead of 3D printed. This allowed me to do it all one in piece.

This is technically version 3 with many many revisions in-between. I'm going to live with this for a bit, but I'm hoping this is "final". I should really do a recording of this because I think it sounds awesome.

Image Unavailable, Please Login

Tuning / Cooling

At this point, I'm not sure there's much to be gained from street tuning. One thing I found helpful is flooring it from a 5th gear rolling start. The RPM rises very slowly, so you spend enough time in each throttle % / RPM cell to trust the lambda value with less issue of the value being more "transitional".

Also, with my cooling issues resolved (combination of new radiator, thermostat delete, and electric water pump), I feel very comfortable getting back on the dyno to see what this new setup got me without upgrading internals. I have to imagine that this setup is near the absolute limit of what it achievable naturally aspirated without upgrading internals (or at least porting heads). So anything beyond this is going to have to come from internal work. Personally, I'm most excited for cams since there's an audible aspect to that too.

 

I'll take a look. In hindsight it seems kind of obvious, but I'm not sure there's any filter that can be as a "cap" to the trumpet that would would be effective as a filter and still flow enough CFM. Ie, a foam filter in a dome shape could work, but that's not how I was using it. Less about the material choice, and more about the surface area.

I'm considering re-introducing the foam filters (the same material used in ITG and UNI filters), but within scoop. There's much more space to play with in the scoop, and you wouldn't even see it.

For now, I'm just going to run without a filter (just the SS mesh). Obviously this has some negatives as well...

 

Yeah, I should have gone with a similar solution. If I bring back the filters, I'll do something similar. A lot less complexity trying to balance form/function.

 

I'm actually pretty impressed the cars have even 320hp considering the head flow, low compression, and such mild cams. They really went overboard detuning these engines. No surprise there is a such a considerable HP jump when you start tweaking things.