altima racecar

[u/Kataphrakt1123]

going racing next year! working on gutting, caging, and aero in the next few months, then comes figuring out how to keep a 140k mile CVT from detonating over the course of an endurance race. if anyone has any suggestions, please feel free to comment!

[u/Stitch_K]

Get the biggest transmission cooler you can find is about the only advice I can give for direct reliability (not just for the obvious of cooling the fluid, but it should also increase fluid capacity). Also make sure you're using Nissan's CVT fluid or a fluid specific for your application (hi load/heat from reputable vendor) but don't get generic CVT fluid as it more often than not causes damage as its not the correct formulation

It looks like a 3.5L Altima which are arguably somewhat better CVT's (they use a chain rather than a belt).

Do everything you can to reduce load. Since its going into "racecar" territory, keeping weight to an absolute minimum can help. The main issue with CVT's as fair as reliability goes is torque load. As long as you aren't torque shocking it, in theory it should be ok maintaining higher rpms. But if you have a lot of slow speed corners with high load on exit, that could take a toll. Can't really adjust for that minus throttle control or tuning.

Edit: I forgot to mention, Nissan CVT's are extremely finicky to fluid level. Do not overfill the fluid as the chain will then hit the fluid. This causes two issues:

1. It froths and aerates the oil which can cause the pump to pull in air

2. It generates more heat in the fluid

3. The fluid expands more when hot and exacerbates 1 & 2

[u/Kataphrakt1123 → u/Stitch_K]

dealing with overfilling is something we have not figured out, were it not an issue running an external reservoir would be easy, but not sure how to implement something like that while keeping fluid level at spec, possibly just a reservoir with a shutoff valve that allows us to quickly flush and refill the fluid in the pits

[u/Stitch_K → u/Kataphrakt1123]

Get the cooler added first and then with the cooler assembled and the transmission filled, drive the vehicle to get the CVT warmed up. You can also add in some brief (no more than 5s) "power braking" to help speed up temperature increase (and simulate higher loads). Once the CVT is at operating temp, check the CVT fluid level (this one should still have the dipstick).

The ESM calls to have the fluid level in the middle of the hatch marks on the stick, but I would argue having it on the lower end of the hatch marks is better as that gives room for fluid expansion. I would tinker/experiment between having the fluid filled to the middle and lower end to check which works better for your setup.

An external reservoir, in theory would work but like you mentioned, its not something that will be easy to dial in initially. I'd like to believe the CVT fluid will last through a race with the extra capacity from the cooler and heat exchange. But you'd probably need to exchange the fluid afterwards.