E46 M3 C&R Oil Cooler

[sdwz_m3]

I would definitely give this feedback to BW and that's an ECS-esque pack job IMO.

I'm primarily interested in the actual cooling ability--if it's better than stock, with an essentially stock fitment as you've mentioned, I'm in. The weight savings claim, while problematic in that it doesn't appear to be accurate, isn't such a big deal for me.

On a side note, I asked my dealer about the stock cooler availability and they told me that the new part number is 17-21-8-854-480, on order from the supplier but no ETA.

Shoot, I wish I would've known that last week haha. I thought they were discontinuing all manufacturing. If anyone wants to ship me a new oem cooler when released, I'll be happy to continue my testing

I'd imagine a new cooler from BMW will be at a close price point of the C&R.

[Feffman]

My $0.02 spewing. 😎 I went with a Fluidyne stacked plate oil cooler as stacked plated are more efficient at cooling if a little heavier than a tube & fin design. It fits nicely into the original location, but required (with all the racing mods) a simple fabricated bracket for each side. As for C&R, I run their radiator. This has been a very effective combination of cooling.

Feff

[sdwz_m3]

I've collected data from the weekend, and have tried to compare it to the best of my abilities to my past data.  I will be going out again next month and should have some more comparison data. In the meantime, refer to the attached chart for what my car read (again, this is from OEM sensors, through CAN bus).

I did not see a large reduction in cooling temps. What I did see, and what isn't shown, is the drop in temperature on the cool down lap. From finishing my last hot lap, and coming back into the paddock, oil temps dropped to ~220.

I will reach out to BW to try to understand how they collected their info, and why my results weren't as positive as I'd hoped for.

[bigjae46]

I've collected data from the weekend, and have tried to compare it to the best of my abilities to my past data. I will be going out again next month and should have some more comparison data. In the meantime, refer to the attached chart for what my car read (again, this is from OEM sensors, through CAN bus).

I did not see a large reduction in cooling temps. What I did see, and what isn't shown, is the drop in temperature on the cool down lap. From finishing my last hot lap, and coming back into the paddock, oil temps dropped to ~220.

I will reach out to BW to try to understand how they collected their info, and why my results weren't as positive as I'd hoped for.

I think that is going to be in line with the results you should expect - not so much a drop in peak numbers but a quicker drop when cooling down.

Your biggest limitation is the airflow on the backside of the oil cooler. The beat up OE oil cooler probably generated a decent low pressure region behind the cooler because it was clogged. The C&R is probably creating a higher pressure zone behind the cooler since it is not full of stuff with bent fins. My theory is the airflow on the backside must be controlled and vented to a low pressure region - probably under the car would be the closest source of low pressure air flow.

I've been studying this so I am making an informed decision as I look to lower peak oil temps. I'm leaning towards installing a non-M radiator with a large oil cooler on the backside of the radiator then duct it through the hood. How the ducting is designed is important in achieving a sufficient low pressure region behind the coolers. A stacked setup will typically yield more efficient use of cooling air and the ducting should improve the pressure differential to increase airflow and cooling. It seems that bigger or more radiators will not necessarily result in lower peak temps or will be inefficient from a cooling vs drag ratio.

I haven't tested any of this so I'm only youtube trained thus far. So take it for what its worth. But I wouldn't be concerned with the data you collected. 240's is still really good...and some heat in the oil isn't a bad thing. I really don't get concerned until I see 275 and higher.

[sdwz_m3]

Agreed. I'd like to figure out a way to vent the air behind the cooler, and not have to add the weight of an aluminum skid plate.

This data is without a splitter; I've heard that the addition of aero can have differing temps from that of a stock-bodied car. I also wanted to collect the data to help others make an informed decision, as there isn't a whole lot of info on this specific cooler.

[0-60motorsports]

I just switched back to the OE Oil cooler as I think the BW oil cooler was causing heat soak in traffic and causing for me to run much higher oil temps. Once i would move of course the temps would drop but then that IS the point of a racing oil cooler, it cools while you are moving.

Someone needs to make a better "street" version as in not too big and thick so as to prevent heat soak in traffic.

Before you all even think it or don't think it Bahrain has constant 120-125f days and high humidity and when stuck in traffic the actual ambient temps can be much higher than 125f (due to cars around you and small country running ACs all day. If you havent been to Bahrain/UAE/Saudi/Qatar in summer.....Well the you will never know LOL

[CrisSilberGrau]

Agreed. I'd like to figure out a way to vent the air behind the cooler, and not have to add the weight of an aluminum skid plate.

This data is without a splitter; I've heard that the addition of aero can have differing temps from that of a stock-bodied car. I also wanted to collect the data to help others make an informed decision, as there isn't a whole lot of info on this specific cooler.

Then create similar ducting to the pow3r motorsport skid plate byjust cutting up the oem plastic body panel, I see no downside to this. Perhaps this will give way to some fabrication DIY. I like the pow3r motorsport option because it's literally on the floor, weight +\- 10lbs or near as makes no difference and the ability to go full race splitter down the line. The smooth front flat bottom can also give way to some aero DIY on the suspension arms in the wheel well (dreaming now but still).

It's wild just how good he OEM stuff is when considered as a complete working package. I dont think I've seen this on many other car makes and models....

[Bry5on]

I think that is going to be in line with the results you should expect - not so much a drop in peak numbers but a quicker drop when cooling down.

Your biggest limitation is the airflow on the backside of the oil cooler. The beat up OE oil cooler probably generated a decent low pressure region behind the cooler because it was clogged. The C&R is probably creating a higher pressure zone behind the cooler since it is not full of stuff with bent fins. My theory is the airflow on the backside must be controlled and vented to a low pressure region - probably under the car would be the closest source of low pressure air flow.

I've been studying this so I am making an informed decision as I look to lower peak oil temps. I'm leaning towards installing a non-M radiator with a large oil cooler on the backside of the radiator then duct it through the hood. How the ducting is designed is important in achieving a sufficient low pressure region behind the coolers. A stacked setup will typically yield more efficient use of cooling air and the ducting should improve the pressure differential to increase airflow and cooling. It seems that bigger or more radiators will not necessarily result in lower peak temps or will be inefficient from a cooling vs drag ratio.

I haven't tested any of this so I'm only youtube trained thus far. So take it for what it’s worth. But I wouldn't be concerned with the data you collected. 240's is still really good...and some heat in the oil isn't a bad thing. I really don't get concerned until I see 275 and higher.

You might also consider doing a horizontal oil cooler in front of the radiator that ducts downward under the car at speed and upward from convection at a stop, like all of the new M cars. This would help cooling but hurt downforce and might be a quicker/easier solution than ducting upward. The non-m radiator does seem like a much better option than the M radiator with the added bonus of running a proper OEM ducted electric fan shroud from the 330i.

I’d certainly be interested in duplicating this on my car as well - but I have to use the non-m undertray unfortunately because I use the ZHP front bumper.

[Altaran]

You might also consider doing a horizontal oil cooler in front of the radiator that ducts downward under the car at speed and upward from convection at a stop, like all of the new M cars. This would help cooling but hurt downforce and might be a quicker/easier solution than ducting upward. The non-m radiator does seem like a much better option than the M radiator with the added bonus of running a proper OEM ducted electric fan shroud from the 330i.

I'd certainly be interested in duplicating this on my car as well - but I have to use the non-m undertray unfortunately because I use the ZHP front bumper.

Before this I would convert to a water intercooler and an oil cooler delete. The water cooling circuit has the extra capacity. The you can lower the radiator and have a lower center of gravity. Probably no weight savings as the extra intercooler is not weight free.

For now I run a DO88 oil cooler and I have little negative effects, only that its slightly heavier than stock due to the extra capacity. Together with the oil thermostat delete temps are well within acceptable range.

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[bigjae46]

You might also consider doing a horizontal oil cooler in front of the radiator that ducts downward under the car at speed and upward from convection at a stop, like all of the new M cars. This would help cooling but hurt downforce and might be a quicker/easier solution than ducting upward. The non-m radiator does seem like a much better option than the M radiator with the added bonus of running a proper OEM ducted electric fan shroud from the 330i.

I’d certainly be interested in duplicating this on my car as well - but I have to use the non-m undertray unfortunately because I use the ZHP front bumper.

Stacking the coolers reduces the overall drag by reducing the surface area. Separating the coolers will increase overall drag. When stacked, you maximize the use of the cooling air by placing the hotter radiator on the backside. This also helps warm up the oil faster at start up. For me, this could fix three issues - lack of cooling, a long time to warm up, and adds front downforce while reducing overall drag.

Of course, venting the radiator out of the hood can screw up the airflow up and over the car.

[sdwz_m3]

To update and close this thread, I've reached out to BW with my results. In regards to cooling, the data C&R collected between their graphed coolers were bench lab tests (not hooked up to an engine), and specifically measured heat dissipation with flow. To increase the flow, BW recommended their oil diverter valve in order to maximize the effectiveness of the oil cooler. BW believes that I wasn't pushing the cooling system hard enough both in oil temp & oil flow rate to actually see a noticeable difference between these coolers. 240F is relatively low, and their concerns begin when oil temp reaches 290F.

In regards to the weight, they admitted a probable mistake of comparing the C&R to the OEM cooler, while they should have compared it to a competitor. They mentioned they'd update the listing, but I haven't seen the change at the time of writing this post.

In summary, running the stock oil cooler will be sufficient for most individuals (even if it appears to be gunked up). If needing a replacement, I'd recommend finding another OEM cooler in decent shape in lieu of upgrading; although I can say that the C&R cooler is made well, and should last for a long time.