Cooling Question

dogbone wrote

Unfortunately, on this platform, there are no magical solutions to the engine overheating.

I think it’s less magical and more “no easy” solutions. What has been tried is largely just the iterations of the same things over and over expecting different results.

There’s nothing inherently disqualifying about the S65 that requires it to overheat even when supercharged, on slicks, with aero.

Just the systems employed are largely poorly executed as a true system. Mostly a bunch of 80% efforts across each component in the system (airflow dictation, radiator placement, pressure restrictions, water circulation, ambient under hood temps, etc).

Hood vents and radiator core upgrades definitely is no holy grail though! That’s for sure.

DRLane wrote

I think it’s less magical and more “no easy” solutions. What has been tried is largely just the iterations of the same things over and over expecting different results.

There’s nothing inherently disqualifying about the S65 that requires it to overheat even when supercharged, on slicks, with aero.

Just the systems employed are largely poorly executed as a true system. Mostly a bunch of 80% efforts across each component in the system (airflow dictation, radiator placement, pressure restrictions, water circulation, ambient under hood temps, etc).

Hood vents and radiator core upgrades definitely is no holy grail though! That’s for sure.

Your coolers and an undertray sounds like the plan for now lol

Let me know!! 😎

Undertray and the oil cooler ducting is important! I ran for years without the oil cooler duct (didn't realize it was missing). When I did my metal undertray the mech realized the duct was missing and we replaced it. Instantly saw 8-10C reduction in oil temps especially at cruising speeds.

Finally got around to ordering stuff. Coolers coming in from DRLane (do88 oil, power steering, and csf radiator). Also ordered an oil diverter valve and I’m putting on the OEM undertray. Also going to use redline water wetter.

Since temps have risen in my area (90-100 degrees F), my long commute home with my shortened diff (80mph at 4k rpm) has driven my oil temps up in the 240s which gives me low hopes for a track day in its current state. Will report back results as soon as everything is installed.

Narvin wrote

Finally got around to ordering stuff. Coolers coming in from DRLane (do88 oil, power steering, and csf radiator). Also ordered an oil diverter valve and I’m putting on the OEM undertray. Also going to use redline water wetter.

Since temps have risen in my area (90-100 degrees F), my long commute home with my shortened diff (80mph at 4k rpm) has driven my oil temps up in the 240s which gives me low hopes for a track day in its current state. Will report back results as soon as everything is installed.

nice, just don't run full distilled and RWW as RWW is meant to flushed more often than regular fluid and honestly quiet often lol.

For me to avoid doing it so often, i run a mix.

70% distilled, 30% coolant, 1 bottle of RWW.

I have everything installed
Initial impression is that it absolutely helped. The gauge is no longer near 3rd mark at all.

Went with 25% super water wetter, 75% bmw coolant/distilled water 50/50 mix
Csf radiator
Do88 oil cooler
Vac oil diverter valve

When it’s cool (70s). temps are under 210

At 95, dash shows around 215-220.

Startup only takes an extra 5-8 minutes so it’s really no big deal. I just keep it under 3K rpm

Odd thing was that it took almost 10.5L to fill the car back up before the sensor said the level was fine. I did drain the oil overnight including from the cooler lines and the oil filter housing.

I’ll have more accurate data to report soon because I now have an awron gauge to monitor water vs oil temp

Narvin wrote

Odd thing was that it took almost 10.5L to fill the car back up before the sensor said the level was fine. I did drain the oil overnight including from the cooler lines and the oil filter housing.

dima had this issue to, i told him its either his voltage regular or his battery, bro finally replace his battery and it read fine again lol.

Narvin wrote

Startup only takes an extra 5-8 minutes so it’s really no big deal. I just keep it under 3K rpm

What are the ambient temps where you live?

Redd wrote

What are the ambient temps where you live?

90-100 in the summer


Here’s temps after warming up and idling for 25 mins. I don’t have any control data to compare it to. Any thoughts? (It was 95 outside at the time

Narvin wrote

I do have hood vents already. However, I currently am running no undertray

My stock oil cooler and radiator have 160K miles on it and are original.. they’re pretty much due for maintenance

are these track spec vents that have been epoxied on under the hood?

This is an interesting thread, I'm in a similar situation. I have a SC'd e90 m3 DCT that I want to run cooler. I have a larger DCT fluid pan waiting to go on and was planning on the 3 vent track spec hood louver setup. my next step was going to be a larger oil cooler or radiator, but now maybe I should consider doing the trans cooler first?

Oreo Cat wrote

This is an interesting thread, I'm in a similar situation. I have a SC'd e90 m3 DCT that I want to run cooler. I have a larger DCT fluid pan waiting to go on and was planning on the 3 vent track spec hood louver setup. my next step was going to be a larger oil cooler or radiator, but now maybe I should consider doing the trans cooler first?

Yes the vents are epoxied under the hood. They are puretech Sweden vents. The track spec hood vents were a little too aggressive and big for me.

I personally didn’t have any trans issues before I got my do88 dct cooler. I just had the bigger pan. To be honest I just thought it looked great and I got a good deal.

Attached below are photos of temps now cruising to work. I have a 3.85 differential and this was at 85mph around 4k rpm. 70 degree ambient temp. I saw it touch 199 a few times when I let off to 3200ish rpm.

I’m running liquimoly 10w60. I found that my dashboard gauge closely followed the oil temps vs radiator.

Overall pretty happy with the results! I doubt it’s as good as other people’s systems but it has significantly brought down my car’s temps

oof chill with the speeding there bud... 148ftlbs of torque is a monster.

omgzirra_exe wrote

oof chill with the speeding there bud... 148ftlbs of torque is a monster.

I was like 25% throttle aite my boi 😂

I just did the VAC oil diverter valve and it's made a world of difference in terms of oil temps, at least on the street. I'm also convinced my oil thermostat wasn't opening up all the way either, but I'm hitting Big Willow on Wednesday and I'll see what the temps look like during the sessions.

SunnyD wrote

I just did the VAC oil diverter valve and it's made a world of difference in terms of oil temps, at least on the street. I'm also convinced my oil thermostat wasn't opening up all the way either, but I'm hitting Big Willow on Wednesday and I'll see what the temps look like during the sessions.

How much longer did it take to warm up from cold start?

Redd wrote

How much longer did it take to warm up from cold start?

Cold start, ambient 68° out, maybe 10 mins longer than before.

SunnyD wrote

I just did the VAC oil diverter valve and it's made a world of difference in terms of oil temps, at least on the street. I'm also convinced my oil thermostat wasn't opening up all the way either, but I'm hitting Big Willow on Wednesday and I'll see what the temps look like during the sessions.

Im also interested in going this direction…please keep us posted on the results.

I know this is an old thread, but I found it while looking into cooling upgrades for my own car, and felt I had to weigh in on something for those of us whose track cars are primarily street cars.

In street use, most wear occurs in the time between a cold startup and when the engine reaches operating temp. That's when oil viscosity is highest, clearances are furthest from their happy zones, and fuel and combustion byproducts are contaminating the oil at the highest rate. Any mod that increases warmup times will by definition extend that period of highest wear.

On a track-only car, that's probably a non-issue and well worth it if the mod substantially helps control high temps.

For a street car that only does a few events a year, it's hard to imagine how you could reduce high-temp wear by enough to make up for taking longer to get up to temp after every cold start. That's not a short-term issue unless you do a lot of short trips. But it could be an issue long-term. That's one main reason why our coolers have thermostats in the first place.

I'm still learning, but all the expert advice I've seen on addressing cooling issues seems to converge on taking things generally in this order:

1. Airflow
2. Also airflow
3. Still airflow
4. Coolant/oil flow rates
5. Radiator sizes
6. Airflow again, because you messed with it by upsizing your radiators
7. Everything else

Hence, the importance of keeping the factory panels, ducts, and seals in place.

I like roastbeef's advice to start with the basics. Also SunnyD's thought that maybe an aged thermostat might not be opening all the way; that's got me wanting to replace that part preventatively.

Newer cars have grille openings and ducts that open and close with temp. Maybe that's a thing to look into fabbing up, if it doesn't already exist? E.g., 3D-print some motorized grilles for the TrackSpec vents and wire them up to a switch or thermistor via a relay or something. Spitballing here.

One small thing I do: Whenever I wash my car, once I'm done with the painted surfaces, I make it a point to spray all the leftover wash soap in my foam gun onto the radiators, let it dwell, and then rinse thoroughly. No idea how much that helps, but it's gotta be better than nothing, right?

IamFODI wrote

In street use, most wear occurs in the time between a cold startup and when the engine reaches operating temp.

I think your initial premise is flawed.
The cold startup wear occurs for a much shorter period of time, definitely not all the way up to operating temp.

I wouldn't recommend the oil diverter valve to anyone that drives their car in the winter in states above FL/TX.

Here in South FL, it doesn't seem to make much of a difference in warm up 90% of the year.

tdott wrote

I think your initial premise is flawed.
The cold startup wear occurs for a much shorter period of time, definitely not all the way up to operating temp.

AFAIK wear starts really high and then exponentially decays until it stabilizes at a low level. So yeah, it's not like wear is high until operating temp and then falls off. It's much lower near the end of the warmup.

The point is, if you extend your warmup time, the slope is more gradual, so there's more area under the curve. Does that make sense?

tdott wrote

I wouldn't recommend the oil diverter valve to anyone that drives their car in the winter in states above FL/TX.

Here in South FL, it doesn't seem to make much of a difference in warm up 90% of the year.

I can see that.

I'd still want to try basically everything before deleting the thermostat regardless of climate. It really is best to get out of that cold running regime ASAP. But, if the mod doesn't make much difference to warmup times in your climate zone, then obviously there's that much less risk (and more gain if it really does help lower peak temps).

I've been doing research and brainstorming for my E46 and what I've learned is differential air pressure is the key to get flow across the radiator. It is possible if you can improve air flow through the radiator that you can run a smaller radiator core.

Most of the solutions I've seen is bigger radiator, more air TO the radiator. Not through.

I think you can solve overheating issues if you can duct the back of the radiator somewhere. Requires tilting the radiator forward which would be very tricky for this platform. A more efficient backside duct can be designed the more the radiator can be pushed forward and tilted.

For my E46, I also plan to use a full face oil cooler on the back of the radiator. This will warm up the oil much faster and be more efficient in terms of cooling and aerodynamics.