m42 overheating during HPDE track sessions

[Asbradley21]

So I've begun to more actively do HPDE's in my m42. During each 20 minute session after a few laps the temp needle will hit the 3/4 mark and stay there. I already use the lower temp thermostat. The car does not overheat in normal use, just on the track when it gets pushed hard continuously. What do I do? Do I need a new radiator? Should I convert to an e-fan? Do I need a mishimoto radiator? If so, which?

Thanks in advance
-Austin

[bmwm42]

Stock cooling sucks I switched to using an m20 radiator no issue this far with cooling no matter what I do

[Asbradley21]

Where did you put the expansion tank? How did you mount it?

[KenC]

A new stock M42 radiator will probably help.

What are track temps?

[bmwm42]

Expansion task mounted ok drivers side fender wall just like a normal m20

[u3b3rg33k]

since when is hitting the 3/4 mark overheating?

[Asbradley21]

A new stock M42 radiator will probably help.

What are track temps?

What do you mean when you say track temp? Actual surface temp? That would be pretty high I guess as it's Alabama/Georgia and summer where ambient temps can be in the high 90's.

since when is hitting the 3/4 mark overheating?

Since m42 heads have a tendency towards cracking if overheated. I don't want to risk that I've already had it happen once.

[u3b3rg33k]

Then I'm on board with a system (radiator) upgrade. Mine might make it up to the halfway mark on a warm day at the track (sits @ just over 1/4 with where I put the needle after reassembly).

[KenC]

How old is your current radiator?
Is this a track car that you can remove the AC condenser from?

With ambient temps in the 90s, it's probably 100+ on the actual track. Not surprising that there's elevated water temps when you're racing.

[Asbradley21]

Current radiator is the original I believe. Right now I think I'm going to go with a full overhaul with a mishimoto rad, zionsville shroud and expansion tank, and spal 16in fan.
This set up, the zionsville shroud looks amazing.

I'd rather leave the AC there as currently this is my DD until I get a new DD in the next couple of weeks and I tend to drive it to the track.

[u3b3rg33k]

Seems odd to me they'd block so much of it off in that manner. the way VW set up radiators on the old rabbits made more sense - electric puller, and some rubber one way check flaps. if you're driving, you get unencumbered flow, if the fan is on, then the flaps prevent wasteful recirculation.

[Dj Buttchug]

thermostat delete mod. get on it

[gearheadE30]

I was having issues with a hydrolock of sorts at the tstat, and drilling a hole at the top of it (some come this way) seemed to solve the issue.

[Ryann]

Seems odd to me they'd block so much of it off in that manner. the way VW set up radiators on the old rabbits made more sense - electric puller, and some rubber one way check flaps. if you're driving, you get unencumbered flow, if the fan is on, then the flaps prevent wasteful recirculation.

I appreciate this post, agreed.

OP I see an m44 e-fan conversion in your future, possibly with a simple low-speed relay jumper from pin 30 to 87 while on the track.

[Ian Bowers]

How old is your radiator? When is the last time you flushed the system? I've taken my M42 out to multiple drift events on skidpad and fulltrack in 107* weather, and it never went past 1/2 way. Stock Radiator, distilled water only.