Car/Swap Background

So, MK2 supra eh?

I’ve had this car quite a while. At this point, I’m fortunate enough to have other cars, hobbies, family, and time to spend doing that stuff. So, this generally comes last. It has gone through a lot of stages, but here are some recent pictures with the last engine set-up. LS6/R154. I used an Advanced Adapters bellhousing for a Jeep/LS and some other goofy bits to make it all work. The swap carried over A/C, power steering, and working gauges. It has a Ford 8.8 IRS set-up that I designed and cool, 80s Recaro seats.

The car was fast but I never liked the rumbly-ness of the engine and wanted to get back to an inline 6. While an LS and R154 aren’t terribly heavy for their power outputs, they are still pretty heavy. So, I was hoping to get some weight out as well. I wanted to keep the car N/A just out of preference. Originally, I wanted to convert the car to a 2JZ and build and N/A motor but after some research on weights, I realized I wouldn’t get any weight out of the car. It seemed daunting to make much power N/A as well.

I had an M54 in my old E46 BMW and found it fast enough for a street car in the heavier E46. I figured it would work great in the lighter Mk2. A plus over the 2jz is the engine is alumninum. I weighed mine at 340lbs with accessories and no flywheel. I have an 8lb flywheel that will go with the motor so at most 360lbs in the car with the clutch and flywheel. The headers are smaller and lighter. I will run a set of S54 ITB’s and do some other mods to the engine.

The car weighed 2950lbs with the LS, some smaller 4 lug wheels, full tank, and a spare. I measured the LS6 engine at ~ 505lbs on my redneck game scale. This was complete with all accessories and clutch/flywheel.

BMW M5X series inline engines sit at a 30deg angle in their respective chassis. This would have required the engine to sit 1-2in further forward which would have made other parts of packaging a mess. So, I figured I’d rotate the motor upright. 12 deg would have been perfect but it didn’t work on the trans. More on that in a minute.

This meant I needed an adapter plate or bellhousing modifications to keep the transmission in the correct location. I couldn’t figure out a way to make this work with a BMW transmission that didn’t involve a lot of welding and machining so I started looking at other transmissions. A W58 seemed the easiest so I went with that.

Took a ton of measurements and modeled everything up. I found a full S54 CAD model online but it ended up being wrong in quite a few dimensions. Some internet deep dives and rock auto datasheets help me figure everything out for the . Single mass S52 clutch and flywheel fit a MK4 Supra. The input shaft length worked out perfect and a stock 2JZ pilot bearing should work. 7 degrees ended up being the best number to allow for starter clearance and bolt pattern stuff. This would fit great in the car.

This meant I would need a custom oil pan. Modeled all of that stuff, designed a pan, and had parts cut.

But, everything didn’t really work out how I wanted.

Insert, oil pan TED talk.

BMW engines have the oil pan hang below the crankshaft BC they are mounted at a 30deg angle in most of their cars. This makes things weird when you stand the engine upright, or in my case ~10 degrees. The pump is mounted off center so it sits parallel with the crank when installed at 30 degrees. This puts it above the the oil fill line. I originally designed a front sump pan but the pump and timing chain would have been completely submerged in oil which sketched me out because a) I expected this would aerate the oil and create pressure issues at high rpm/temp IE. track use and b) i didn't know how the pump/chain/engine would behave with extra oil aeration and I was concerned it may cause oil consumption or something basically, unknown unknowns.

Anyway, I re-designed the oil pan for rear sump that will still have the oil pump submerged most of the time but not the main supply of oil. I think this is how most track E36/E46 cars run because they typically run over-full to avoid pressure issues under cornering Gs. Those cars don’t have oil pressure problems.

The sump of the pan has no baffles but I believe I can run it complete full to the top of the sump. IDK if they are necessary. It has a small drain location from the main pan which should help act as an “upward baffle'“. This is how the S54 pan is done. I’m not sure how far the oil level is from the oil sump ceiling in those. I need to pull my other car apart and see. E46Ms don't have pressure issues so IDK, it felt like reasonable logic. It sits ~1/2in from the crank windage tray. I hope that will be enough to not lose power.

When I welded the pan, I had minor seeping that I could not resolve with my weld set-up. I had the same issue with the LS. The LS swap pan that I built wept a tiny amount of oil and would have paid almost anything to resolve it. So, I decided a giant machined section was worth it. I will still need a small burn/bend section for the sump but the interface areas. However, it should weld clean and seal nice because they're perfect 90s. This also makes the final weldment less prone to warping and sleek internally.

I redesigned everything, 3D printed a couple test pieces and sent it off to Protolabs be machined. I should see it in another couple of weeks. The sump is designed and in house as well.

Thanks for attending.

I’ll cover the headers and ITB’s next.