[E90convert]

Hey everyone,

Can anyone share what their DCT oil temps were on track? Other conditions would be helpful too like ambient temp, modifications, tire compound, and driver skill.

I am trying to gauge if I need to upgrade the DCT oil cooler to avoid overcooking it and having to change it more often.

(I did search, but could not find anything decent).

Thanks!

[M1500Z]

I got you (sort of). I'm running a stock drivetrain M2 Comp—stock tune, cooling package, even exhaust. I don't remember if the DCT coolers are the same on the N55 cars or not.

In my reading, it seems the more common issue is to have DCT oil starvation with higher grip tires—moving to a deeper sump with a better positioned pickup seems to resolve this.

Here's a screenshot of my Aim data from a hot session at COTA where ambient temps were just shy of 100ºF.

In this image, Gear T in the 3rd section is DCT temp.

[E90convert]

Thanks for the track data, pretty stable! 230F is great for performance driving. It looks like the comp got a slightly bigger DCT cooler. Probably because of the added 40hp.

Engine oil seems pretty stable too! Under 260F? That’s great for a stock car.

[ZM2]

Another approach is running the M2 racing larger DCT pan and the stock DCT cooler. I did that bc I needed to change my DCT oil & filters anyways, and to still give as much air to the radiator as possible.

DCT temps stay 215-220F on average, with 239F as the peak I’ve seen. And, I’m tuned to 480whp/540wftlbs.

[E90convert]

Thanks. I have a 3-day at mid-Ohio coming up in 10 days. I’ll be taking data logs of all the temps and will report back.

[E90convert]

Through the morning and into the afternoon on day 1. Temps seem to sit in the 200-210F range. Pretty ideal in my opinion. Oil is running warm enough to optimize efficiency, but not too hot to break down additives.

Engine oil is about 230F. Ambient is 65F and full sun. Really got some more aggressive laps in this last session and saw nearly 150F on the IAT on the long straight. Need an intercooler for sure.

[sly1types]

Mine will hit 260F at the end of a session. This is even with fresh fluid/filters. I have the bimmerworld kit that allows an extra liter via a dry break connection.

My car is a M3 with 540/550 at the tire on 305 slicks. I haven't ran into starvation issues even at 1.5Gs.

[ZM2]

Originally Posted by sly1types

Mine will hit 260F at the end of a session. This is even with fresh fluid/filters. I have the bimmerworld kit that allows an extra liter via a dry break connection.

My car is a M3 with 540/550 at the tire on 305 slicks. I haven't ran into starvation issues even at 1.5Gs.

That’s pretty close to when the DCT will go into limp mode (~270F) and put the car in neutral and disengage the clutches with no drive while you’re on track.

And once you find a place to stop, it’ll put the car in Park and you can’t do anything until DCT temps drop.

Ask me how I know…DCT cooler line thermostat failure. $125 part and a wasted weekend.

[E90convert]

Originally Posted by sly1types

Mine will hit 260F at the end of a session. This is even with fresh fluid/filters. I have the bimmerworld kit that allows an extra liter via a dry break connection.

My car is a M3 with 540/550 at the tire on 305 slicks. I haven't ran into starvation issues even at 1.5Gs.

I'm impressed the transmission is holding up to those loads. That is a lot of power and grip! Really important to keep the fluid as cool as possible for that.