Model 3 Tearing it Up at the Track

[Zerosport]

Cooling hasn't been an issue with the Model 3, which really surprised me. But I've run it hard for multiple full sessions on 100+ degree days in the high altitude desert in UT.

For reference, a few years back Acura brought out a couple of their then-unreleased NSXs for testing. They blocked off their section of the track from spectators, but couldn't hide the fact that the cars broke down multiple times that day from overheating. It's just a brutal environment, so I'm pretty confident the Model 3 holds up.

We'll see as the car gets faster. IMO the biggest factor is power reduction from drop in SOC.

 

[mcbarnet007]

Cooling hasn't been an issue with the Model 3, which really surprised me. But I've run it hard for multiple full sessions on 100+ degree days in the high altitude desert in UT.

For reference, a few years back Acura brought out a couple of their then-unreleased NSXs for testing. They blocked off their section of the track from spectators, but couldn't hide the fact that the cars broke down multiple times that day from overheating. It's just a brutal environment, so I'm pretty confident the Model 3 holds up.

We'll see as the car gets faster. IMO the biggest factor is power reduction from drop in SOC.

I guess it depends on the track and average speed. I have power loss after two hot laps at Laguna Seca and Buttonwillow. I guess since your car is now 500lb lighter than stock, the drive train holds up better?

Yeah, power reduction from SoC drop is very noticeable once it goes below 50%. When it gets to 25%, it feels like you've lost 100hp.

 

[Zerosport]

So are Essex making the brackets and hats to adapt their calipers and rotors to the Model 3?

How come Essex list the CP9561 as having a piston area of 50.1cm2, whereas AP Racing list that caliper as having 58.6cm2?
CP9561 Family - 58.6cm² Piston Area | AP Racing

Which brake kit are you going to use?

Correct, but more to it than just brackets and hats. Piston sizes have to be adjusted to match clamping force relative to the Model 3's master cylinder. I'll be using the 9660 or 9668.

 

[Dangerous Fish]

So are Essex making the brackets and hats to adapt their calipers and rotors to the Model 3?

How come Essex list the CP9561 as having a piston area of 50.1cm2, whereas AP Racing list that caliper as having 58.6cm2?
CP9561 Family - 58.6cm² Piston Area | AP Racing

Which brake kit are you going to use?

So trying to answer my own question, I think Essex have a typo on their website, as the URL for that page refers to CP9562, so I think they are using the 9562 caliper but have incorrectly put 9562 in the product description. Maybe I'll win a free BBK for pointing this out?

 

[Zerosport]

I guess it depends on the track and average speed. I have power loss after two hot laps at Laguna Seca and Buttonwillow. I guess since your car is now 500lb lighter than stock, the drive train holds up better?

Yeah, power reduction from SoC drop is very noticeable once it goes below 50%. When it gets to 25%, it feels like you've lost 100hp.

Yeah, good point. Power loss is noticeable after 2 hot laps for me as well. Though I'm usually not starting at 100% SOC. And at 1700+ wh/mi the car gets below 75% pretty quickly, which is where power drop starts to kick in. Mountain Pass did some good dyno tests on this which you might have already seen. So you're probably right, and I'm not noticing because I'm not getting the "OMG everything's too hot" alerts like you usually see in most cars, and attributing loss to falling SOC. More testing and engineering will be needed to sort out.

 

[mcbarnet007]

Yeah, good point. Power loss is noticeable after 2 hot laps for me as well. Though I'm usually not starting at 100% SOC. And at 1700+ wh/mi the car gets below 75% pretty quickly, which is where power drop starts to kick in. Mountain Pass did some good dyno tests on this which you might have already seen. So you're probably right, and I'm not noticing because I'm not getting the "OMG everything's too hot" alerts like you usually see in most cars, and attributing loss to falling SOC. More testing and engineering will be needed to sort out.

I always try to start at 100% so it's apparent to me.

If you're logging the CAN, it maybe useful to see which component temperature is correlating to power loss. I've heard many theory that it's not the battery but the motor or inverter temp that's limiting performance.

 

[Mash]

Yeah, good point. Power loss is noticeable after 2 hot laps for me as well. Though I'm usually not starting at 100% SOC. And at 1700+ wh/mi the car gets below 75% pretty quickly, which is where power drop starts to kick in. Mountain Pass did some good dyno tests on this which you might have already seen. So you're probably right, and I'm not noticing because I'm not getting the "OMG everything's too hot" alerts like you usually see in most cars, and attributing loss to falling SOC. More testing and engineering will be needed to sort out.

If you ditch plastic frunk, open up front grill to scoop more air and make a new box for the cooler - you have a space to put much larger cooler vs stock. This can potentially eliminate overheating and you can use this box to collect pressure for brakes cooling. For your level of changes that shouldn't be a big deal. Next step would be changing coolant pumps to higher pressure ones.

Fighting SOC is hard - that's a whole new battery pack and that is going to be expensive r&d, unless you're going to buy existing ones. Lower capacity, but higher current chemistry might compensate itself since you're going to be losing less on internal voltage drop. It's just going to cost a lot.

I would start from collecting logs and checking what actually limits you. If temperature - check cooler temperature. If it's too hot - make it larger and send more air flow. If it's not too hot, but coolant is hot at the exit - change pumps (or add boosters), change lines to higher pressure, make them thicker to drop less pressure. If it's not a temperature - look at 10-20C rated cells, but check your budget limits, I guess.

Luckily we have tons of CAN data now to study the subject.

 

[MagnusMako]

I saw this on Facebook group. Justin claims he can get CF trunk lid for $1300 if he can get 5 orders or more. Weight 6lb. Maybe it's something you can consider.

"Justin Hagan it's more expensive than that. But even cheap just for looks CF trunks are. If we can get 5 they'll be around $1300.
So weight savings and they look cool. The guy doing then even has different CF weave. But these are full dry carbon fiber trunks and gooda. No gel coat or fiber glass bs.

Justin Hagan http://www.marshcomposites.com/

Here is the company. My friends shop has installed a number of his parts on their customers and own WRXs. Quality is A+++
"

I'd like to see what it looks like on the car but count me in on a group buy at that price for a full CB lid. I didn't see any examples on his site with the 3 and as the 3's tail-lights are partially integrated with the trunk lid, it'd be good to know those are still kept in tact.

Also, @Zerosport have you gotten any 1/4 mile times yet? I know you did a 0-60 run on Dragy which was very impressive with your 2.74 time (1' rollout), I can only imagine if you're pushing close to 11 seconds or maybe even sub 11's now.

 

[Dangerous Fish]

Another possibility for carbon trunk lids? COMING SOON: Tesla Model 3 Carbon Fiber Trunk - Maier Electric Vehicles

 

[MasterC17]

Another possibility for carbon trunk lids? COMING SOON: Tesla Model 3 Carbon Fiber Trunk - Maier Electric Vehicles

FWIW, the stock trunk is not that heavy. I've held one (stripped) and it was surprisingly light; I see UP quoted about 26lbs which sounds right. With some cutting in the right places the stock trunk could be made lighter.

There are definitely cheaper/better places to save on weight, I think the main one being all the heavy glass at the top of the car. Replacing that will help lower the center of gravity even further and probably save a few hundred pounds.

At the end of the day, when you figure the powertrain weighs 1,500lbs+, compared to roughly ~600lbs in an ICE, the fact that the Model 3 isn't heavier is pretty impressive! A BMW F80 M3 is about 3,600lbs, and that's with a carbon fiber roof!

 

[Dangerous Fish]

I wouldn't consider a CF trunk lid myself. Agree that it's not enough gain in real terms.
It's yet another situation (for track driving/racing at least) where you could probably argue the money would be better spent on a few sessions with a really good driver coach.

 

[SD_Engnr]

Another possibility for carbon trunk lids? COMING SOON: Tesla Model 3 Carbon Fiber Trunk - Maier Electric Vehicles

I saw the prototype at Laguna Seca. It is quite nice looking, and looked high quality.

I'd consider a CF rear deck lid if it allowed for an adjustable/replaceable rear spoiler.

 

[Mash]

FWIW, the stock trunk is not that heavy. I've held one (stripped) and it was surprisingly light; I see UP quoted about 26lbs which sounds right. With some cutting in the right places the stock trunk could be made lighter.

There are definitely cheaper/better places to save on weight, I think the main one being all the heavy glass at the top of the car. Replacing that will help lower the center of gravity even further and probably save a few hundred pounds.

At the end of the day, when you figure the powertrain weighs 1,500lbs+, compared to roughly ~600lbs in an ICE, the fact that the Model 3 isn't heavier is pretty impressive! A BMW F80 M3 is about 3,600lbs, and that's with a carbon fiber roof!

It's very possible that after removing glass roof and bringing rigidity back to stock you won't gain anything there as well. Glass there is not just for fun - it's an important element of structure.

 

[MasterC17]

It's very possible that after removing glass roof and bringing rigidity back to stock you won't gain anything there as well. Glass there is not just for fun - it's an important element of structure.

True, but a cage such as in this case will resolve the structure concern while also allowing for a much lighter weight material as a replacement (carbon fiber/lexan/etc).

 

[Mash]

True, but a cage such as in this case will resolve the structure concern while also allowing for a much lighter weight material as a replacement (carbon fiber/lexan/etc).

That is right, if welded cage is required and it's properly installed, glass won't be bearing any structural rigidity and can be easily substituted by thin lexan sheets. But, cage is certainly heavier than glass.

 

[JayAreOhhh]

As a Shifter Kart racer, this is awesome to see. Looking forward to seeing more! If you're ever in Az for a track day let me know, I'd love to check it out. Post race beers on me!

 

[MagnusMako]

Yeah that's a good idea. A few people have been asking about acceleration - we plan to run some data and post up another video soon.

Any updates on this or other progress on your build?

 

[Zerosport]

Lots to share since my last update. Trying to decide if it'd be better to just do a full build thread or not. But for now I'll just share some highlights:

Dropped battery and removed glass in prep for cage welding-

 

[Zerosport]

Floor is extremely thin. Added extra reinforcement to the baseplate to spread the load in case of a rollover event, so the tube is less likely to puncture into the battery-

 

[Zerosport]

Cleaning off sound deadening from floor-

Welding-

Cage and rough-fit seat before adding harness bar-

Test fitting seat-

Custom seat mount & harness hardpoints-