24 hours of lemons build and VW VR6 swap.

[Rupunzell]

The more I've had to decompress from the race, the more I feel like the lockups were due to driver error versus the setup. I really only grabbed the wheel 3 times in ~100+ laps, and it was really, really wet and oily. It rained all weekend. Also the e30 lotus cortina's oil cooler fell off and I hit the oil patch before the yellow and red flag came out. That was a pretty spicy moment to instantly have 0 grip in T1 after the long straight. The car was easy to reel back in though.

I'm looking forward to the swap. We're planning to do some autoX and track days before registering for the race to work out some of the bugs. We don't *really* do lemons to be competitive, we do it because we like working on the car together. That's the real reason behind the oddball swap. If we really wanted to be competitive, we'd be doing a k20 swap like everyone else...no wait...we'd be driving an e36 but that's no fun...

We did LeMons as an experiment and learning experience. There is No Possible Way a PP race rotary can win at LeMons, the fuel consumption is absurd. Yes, the car is fast, real fast and reliable. Yet, that issue with fuel consumption makes the rotary powered X a no possible way winner.
By product of LeMons is enjoying the family of LeMons races and motorsports in a purity no other motorsports event can offer.
K20 swap might not be competitive at LeMons for much the same reasons. To win at LeMons is much about making laps, not just being fast. There have been entire NASCAR teams by day that have raced at LeMons just for fun.. There have been world class endurance drivers (24 hours of LeMans.. the real one) at LeMons racing ... for fun.. Take LeMons seriously, but never forget about the fun factor... as one of our drivers puts this.. Safe, Fun, maybe win..

Don't think those e36 are auto winners at LeMons, they have their share of serious failures from German electricals, to fragile gear boxes and more. e36 and Miata at LeMons work due to the Large user base and know-proven solutions to designed in/built in problems..

Reasons why the eye sore Miata does so well, their team is technically excellent, Good drives, Good race logistics, Excellent car prep and all No surprise given these folks do motorsports as their day job and more.. There are other teams like this at LeMons..

There have been factory sponsored teams from GM, Toyota and ... all learned lots about their products and the demands of endurance racing... which surprised them in many ways.


Bernice

 

[rozap]

Some cutting and welding happened. And now there are 6 pistons and 2.8 liters.

Axles fit. Shift linkage is long enough, so the box is now mounted. Next up is oil cooler and ducting to the secondary rad and oil cooler, and wiring harness. So really just a lot of fuel, water, brake fluid, electricity, air, and oil plumbing.

 

[Steve Thomas]

PP race rotary

Plenty of very successful endurance racing PP rotaries.

 

[Steve Hoelscher]

Plenty of very successful endurance racing PP rotaries.

Yes, but Lemons isn't ordinary endurance racing. You'll spend twice as much time in the pits refueling a PP rotary as you would with a typical piston engine car making similar power. Poor fuel economy and Lemons' refueling rules (No driver changes or any service work during refueling) is a time handicap that is difficult to overcome on track.

 

[Steve Thomas]

You'll spend twice as much time in the pits refueling a PP rotary as you would with a typical piston engine car making similar power.

That may be the experience so far in LeMons but - one of the advantages of the big PPs at the actul Le Mans was fuel efficiency... At the very big end of power, specific fuel consumption closes up between engine types. The answer for rotary engined LeMons is go bigger!

 

[rozap]

Fuel cell is in. Fuel pump and filter are mounted. AN lines are mostly done. Need to add another hole for the vent.

Started working on the oil cooler. It is mounted, and I think I'm going to relocate the oil filter as well, as it lands too close to the frame for comfort. We'll just make an aluminum plate that allows the oil to bypass it, and then do a remote filter in the cooler circuit. The VR6 weirdly uses a 3/4" 16TPI imperial size for the OEM oil cooler, meaning a generic mopar oil take off adapter for relocating it all will work, which is cheap.

Took a scan of the engine block using the old fashioned method of "stick a piece of paper on a dirty surface"

Then into CAD. The two holes will be 1/8NPT for oil temperature and pressure.

Also started the wiring harness. It's pretty simple because speeduino is simple. All the OEM fiat wiring has been removed at this point, and the OEM fiat dashboard will no longer work. So we're just going to run a small TFT display and integrate the shift lights into it. The STM32 which powers it just reads the from the serial interface on the speeduino to get the realtime data.

I've already been using this setup for several months in my VW bus with a subaru EJ20 and speeduino, and it has been great. We'll just reuse the same hardware and most of the code, but I'll modify the UI for racing.

Up at the in-law's place for Christmas so not a lot of progress, but plenty of time to update the build thread

 

[Dr.Jeff]

Love the VW powertrain swap! And all the creativity going on for everything else. Ignore any negative comments and press on with your own plans.

 

[rozap]

Not a ton of progress lately. Just getting little things put together. I've been moving slow the last couple weeks, the winter darkness destroys motivation.

Finally found an oil cooler inlet/outlet that fits

Relocated the oil filter

Removable firewall panel and mounted the fuse box. ECU will go next to the fuse box

First draft of the ECU enclosure. Changes need to be made, but nothing huge. Hopefully the next print works out.

Started assembling the dashboard readout

Out of town for the next week or so but hopefully I can pick up the pace a bit, otherwise it's not going to be ready for the next race. I also want to have time to at least do a track day or autocross to shake the car down.

 

[Dr.Jeff]

I'm using the same style oil cooler/filter block adapter. I have a temp sensor and the turbo oil feed in the two spare ports on it.

Make sure the ECU enclosure allows plenty of heat dissipation. They get pretty hot.

 

[Rupunzell]

I also want to have time to at least do a track day or autocross to shake the car down.

Will demand more than one track day ( many hours on track) to sort out this car due to the vast changes done to the car. Expect and plan of plenty of stuff to not work, bust and far more.

Autocross is not going to helpful as running the car on essentially a parking lot for a minute or two is not the same as racing the car on track hour after hour at higher speeds..

"What can possibly go wrong"
"LeMons is a situation you've brought to the track on your own"
~Jay Lamm


Bernice

 

[rozap]

Good point regarding the heat in the ECU. The OEM enclosures do usually have a heat sink. I'll add one.

Autocross and track days will help more than doing nothing

I'm going to try my best and learn as we go. It's not going to be dialed in for the next race, and it likely will never be perfectly dialed in, and that's fine. We're amateurs. Every race teaches us 100 new things. But I'm not going to skip races because it's not perfect, because then we'd never race.

 

[Rupunzell]

Autocross and track days will help more than doing nothing

I'm going to try my best and learn as we go. It's not going to be dialed in for the next race, and it likely will never be perfectly dialed in, and that's fine. We're amateurs. Every race teaches us 100 new things. But I'm not going to skip races because it's not perfect, because then we'd never race.

Take the car to an open off road space with a road as a possible place to test.. like Large Empty parking lots.. if possible.

One of the gifts of LeMons is learning, the entire event of LeMons is and could be about learning.. This is a significant aspect of LeMons and why LeMons has endured as the most popular form of endurance racing..

For some LeMons is the first time they put a wheel on a track, for others a thing to do away from their day job racing.. There have been entire NASCAR teams that have appeared at LeMons drivers, transporter and all for fun. There are drivers that have never put a wheel on a track to pro endurance drivers that have raced at 24 Hours of LeMons... the real deal Le Mons..

Bernice

 

[Dr.Jeff]

The OEM enclosures do usually have a heat sink. I'll add one.

Since you are 3D printing a custom enclosure see if you can make it so the heat sink constitutes one of the walls of the box. For example a aluminum plate creates/replaces the back wall. With the ECU mounted on the plate. That way the heat can transfer out externally from the enclosed box to dissipate through the surrounding air.

 

[rozap]

Yea I think that's a good plan. I have a big heatsink in a box of random bits and I think I'll make the lid of the enclosure encompass it.

 

[kmead]

Yea I think that's a good plan. I have a big heatsink in a box of random bits and I think I'll make the lid of the enclosure encompass it.

You will really want to mount the board to the heatsink side and of course not have it be the movable element…

 

[fastx19]

Hi Rozap. It is looking great! I think I saw a glimpse of a heat shield between the exhaust and radiators? That way when you pit the exhaust does not over heat your rads? Was that the thought there? You are doing a great job! Keep up the excellent work!

 

[rozap]

You will really want to mount the board to the heatsink side and of course not have it be the movable element…

This would be ideal, but it's not really possible with how the speeduino is laid out. The arduino is the only thing with the mounting holes, and the board with the injector drivers (which are the bits that actually could get hot) sits on top of it, with no mounting holes. So the enclosure needs to mount the arduino. I'm not really a fan of this arrangement, but it is what it is. If I wanted to change it, I could rework it because it's all open source, but I don't have the skills to do an all new layout of the board. I haven't gotten deep into hardware stuff...I stick to software.

Here's a picture that sort of shows what I mean. You can see the (much smaller) arduino board underneath the red board that sits on top it.

Hi Rozap. It is looking great! I think I saw a glimpse of a heat shield between the exhaust and radiators? That way when you pit the exhaust does not over heat your rads? Was that the thought there? You are doing a great job! Keep up the excellent work!

Yep, that's what that is for.

 

[Rupunzell]

This would be ideal, but it's not really possible with how the speeduino is laid out. The arduino is the only thing with the mounting holes, and the board with the injector drivers (which are the bits that actually could get hot) sits on top of it, with no mounting holes. So the enclosure needs to mount the arduino. I'm not really a fan of this arrangement, but it is what it is. If I wanted to change it, I could rework it because it's all open source, but I don't have the skills to do an all new layout of the board. I haven't gotten deep into hardware stuff...I stick to software.

Here's a picture that sort of shows what I mean. You can see the (much smaller) arduino board underneath the red board that sits on top it.
View attachment 80672


Yep, that's what that is for.

External heat sink is really needed for the power devices that drive the injectors. remainder of the circuitry should not be producing much if any heat. Given this fact, put the priority on applying the external heat sink on the injector power devices..
BTW, majority of oem engine ECUs are sealed. Granted, this is done using the metal (often aluminum) box as the heat spreading element. Keep in mind this is done to stop moisture intrusion which can be fatal to the electronics inside..


Bernice

 

[Rupunzell]

Curious, why not use the oem VW engine ecu & wiring harness ?

Bernice

 

[rozap]

The engine that was sitting in my garage for the last 10 years is a OBD1 coilpack AAA, produced between 93 and 94ish. Then they went OBD2, and then they switched to the AFP engine code around 2000 (which is DBW...). The hardware of all this stuff can mostly interchange, but the ECUs are all different, can be hard to track down, and vary between model and transmission and expect different bits and pieces to be present. So given that early AAA's are getting hard to find, the prevalence of the AFP in junkyards, the thought is that if we blow up the motor, we'd likely replace it with an AFP or even a 24v 3.2/3.6. That wouldn't require a new ECU or harness, "just" a new tune and minor wiring changes. Another benefit of keeping the ECU constant is we wouldn't need to make any changes to the telemetry or instrumentation.

The speeduino is a much simpler system, as they don't have to comply with any OBD or emissions regulation. So there's much less hardware (no MAF, no catalyst, no air pump, no EGR etc) to go wrong and it will not throw errors when that stuff isn't present.

The downside is obviously tuning is a whole can of worms. And I've heard that it's challenging to make as much power on an aftermarket ECU with a NA VR6 vs the OEM one because the OEM unit has slightly different fuel trims for different cylinders due to the different runner lengths. And we won't be running full sequential so we won't have that option even if we wanted to explore it.

There are positives on negatives on both sides of this but I think the ability to substitute different hardware without having to do major reworks of the rest of the system is the biggest plus and ultimately why I wanted to go this way.