Dinan Large Oil Cooler

The problem

The high oil temperature in 335 is well known problem with the 335i. When we started our research on the 335i performance upgrades we verified the oil temperature problem by performing several tests. All tests were performed at an ambient temperature of between 60-70 F and at the stock boost setting and on a car equipped with the factory oil cooler. Under steady state cruise the oil temp was 240F! When driven hard on a two lane road after 10 minutes the oil temp was between 290-300 F! At Thunder hill race track the engine oil temp pegged the gauge and the control system put the car into limp home mode after 3 laps! We were shocked because this was not even a hot summer day. We were convinced at this point that the car needed a more efficient oil cooler even with stock boost. In addition to the track day, we did some testing on the intercooler and radiator efficiency and found those to be well below standard. However the radiator and intercooler were not as bad as the oil cooler so we decided to concentrate on the oil cooler first.

We first looked at placement, as it is important that the oil cooler not be placed in front of the radiator and intercooler because the heat coming off the oil cooler would then put additional burden on the all ready marginal radiator and intercooler. Therefore it was decided to keep the oil cooler of to the side like the stock unit with separate inlet and outlet. Air flow through the oil cooler was as much a problem as the size of the oil cooler itself so improved ducting would be important to the design.

Design

For those looking to reduce oil temperatures problems Dinan is now introducing large oil cooler kits for the 335i coupe and sedans. This new oil cooler will mount in the same area as the stock oil cooler on both the coupe and sedan bumper style.

The Dinan large oil cooler is a prime example of quality engineering that Dinan is known for. The tolerances and fitment for the kit is quality that can only be found at the factory. The oil cooler is made from quality materials and uses the factory BMW thermostat housing for temperature control. Even the swaged and pressure tested lightweight oil hoses have chafe resistant sleeves to keep a clean look throughout the engine bay. Because the oil cooler sits on the lower passenger side of the bumper, the Dinan oil cooler is mounted on BMW factory bushings and has special swivel type mounts that allow it to be impact resistant to curbs and the factory fog light. Just in case.

This oil cooler has a capacity that is nearly double that of stock with a capacity of 19 oz. compared to the stock volume of only 9.5 oz. Dinan has added over 13 new cooling tubes over stock which equates to a cooling tube area of over 414 sq. inches compared to stock which is 112.5 sq. inches. This is an increase of cooling percentage by over 400%! For those that are running higher than stock boost, and even those running stock boost, will greatly benefit from the temperature control that the Dinan oil cooler provides.

Along with a larger cooler the intake and exhaust for the oil cooler was improved. Testing showed the mouth of brake duct was larger than the throat would flow. So the brake duct inlet was reduced to increase the inlet to the oil cooler. During the prototyping stages of the oil cooler, the throat size was increased in the duct to the oil cooler as well. Dinan used IR temperature guns to monitor the brake temperature recovery and matched both sides to within 5 degrees. This is import to prevent he brakes from being completely off balance, meaning that under hard use; the brakes would fade unevenly, allowing one side to pull harder than the other.

On the exit side of the oil cooler, there are specially designed louvers that were engineered for two specific reasons. The first reason is to increase air flow through the oil cooler the second reason was to reduce the amount of air going into the wheel well at high speed. This reduces lift in the front of the car at high speed improving handling.

This oil cooler design has been race proven in our Daytona prototype race cars for four years and has been very efficient.


Results

The Dinan oil cooler has been designed to have its own specially sized intake and outlet for the air that moves through the oil cooler. This is the only way that oil coolers, intercoolers, radiators any other type of heat exchangers can work effectively. Most oil coolers are used improperly by being placed in front of radiators which essentially moves hot air from the oil cooler to the radiator, consequently cooling the oil and raising the water temperature of the engine. This then makes the radiator less effective for cooling the engine.

All tests were performed at an ambient temperature of between 60-70 F and at the Dinan boost setting which is increased by 50% over stock. With the Dinan oil cooler the normal operating range is lowered to 210°F at light throttle cruise. Under hard driving on a two lane country road the temperature stays between 210- 226°F range. A race track test has not been performed as of yet but we expect dramatic improvements there as well. Even with the boost increase with the Dinan oil cooler, the average temperature drop in the engine is around 30°-70°F, which puts the car below the limp mode temperature and keeps the engine safer all year round, especially those in hotter climates. While most companies try to make parts that make your car go fast, Dinan also makes parts that make your car live longer.

comparison table and package pricing


Dinan Oil Cooler


Oil Cooler Kit with lightweight lines


Vent Size Comparison


Oil Cooler Size Comparison


Louver rear view


Front side installed

Contact your local authorized Dinan dealer or call us at 800-341-5480

This is what appears to be yet another excellent product from Dinan.

But I thought all new 335s came with a (second?) or revised oil cooler that prevented limp mode, etc.

Are 335s that are being built now, i.e. January, 2008 builds (or late 2007, Oct/Nov/Dec, 2007) still suffering from overheating and limp mode, in 70 degree weather?

Originally Posted by pilotman

This is what appears to be yet another excellent product from Dinan.

But I thought all new 335s came with a (second?) or revised oil cooler that prevented limp mode, etc.

Are 335s that are being built now, i.e. January, 2008 builds (or late 2007, Oct/Nov/Dec, 2007) still suffering from overheating and limp mode, in 70 degree weather?

Mine was built in late 2007 and the dealer retrofitted an oil cooler to counter my complaints, but with the addition of the cooler it still ran hot. 270+ degrees during street driving in 80ish degree weather. On the track instead of 3 laps I was able to get 5 laps before limp mode at Willow Springs International Raceway. It looks like Dinan came out with another kick ass product, too bad car is gone now.

-Jon

I have the stock oil cooler and have never had a problem - I also have the Dinan software installed and my temps are still normal, even under very spirited driving.

Stan and or Laszlo,

What I like about the Dinan software reflash is that its backed by a warranty. Can you guys tell me if a person would be able to get an extended warranty if the car has the DINAN reflash? Also, is the Dinan warranty exactly the same as the BMW warranty?

THANKS! I am very interested in this mod. (the reflash I mean)

Stan-

I see the prices on your website for the oil cooler ant then labor hours tagged as well (e.g. 10 hours for cars w/o stock oil cooler); do the prices include install or not?

Thanks!

Does the Dinan oil cooler come with a new thermostat? I have a factory oil cooler, and the cooler does not open until the oil reaches 250F. Normally, my temperatures on street are about 230-240F, and the cooler is cold to the touch, meaning that the thermostat is closed. How does the Dinan cooler then help to lower street temperatures to 210F?

Originally Posted by cramp

Stan and or Laszlo,

What I like about the Dinan software reflash is that its backed by a warranty. Can you guys tell me if a person would be able to get an extended warranty if the car has the DINAN reflash? Also, is the Dinan warranty exactly the same as the BMW warranty?

THANKS! I am very interested in this mod. (the reflash I mean)

+1

Originally Posted by cramp

Stan and or Laszlo,

What I like about the Dinan software reflash is that its backed by a warranty. Can you guys tell me if a person would be able to get an extended warranty if the car has the DINAN reflash? Also, is the Dinan warranty exactly the same as the BMW warranty?

THANKS! I am very interested in this mod. (the reflash I mean)

I don't know why this is such a hard thing for you people to figure out.

BMW provides a 4 year, 50,000 mile warranty. Dinan warranty "compliments" that if any of Dinan's modifications is the result of the warranty claim. Dinan warranty is only for 4 years, 50,000 miles.

Any sort of extended warranty isn't provided by BMW, even the 6 year, 100,000 CPO warranty. It is underwritten by a third party warranty company, BMW is just the middle man. Whether the third party extended warranty will cover your Dinan parts is entirely up to the third party extended warranty. Dinan's warranty does not cover any more past the 4 year, 50,000 miles originally guaranteed by Dinan.

No third party extended warranty that I've seen so far will cover parts that are not part of the original design of the vehicle. So if your engine should blow up due to the higher stress induced and can be directly attributed to Dinan parts, have fun fighting it out with the warranty company, and prepare to pony up for the cost of the repair.

The only question that remains, is how many people with third party piggy back systems will see 50,000 spirited miles before their engine goes kablooey.

Looking to buy an '08 335i coupe. Pretty pathetic that this thread even exists! Why can't BMW resolve this problem? What do you owners think of this? Okay with it because it is a BMW and you love the "feel" of the car? The technology exists to prevent this kind of stuff so, why is it an issue? Thanks.

Originally Posted by 800dog

Looking to buy an '08 335i coupe. Pretty pathetic that this thread even exists! Why can't BMW resolve this problem? What do you owners think of this? Okay with it because it is a BMW and you love the "feel" of the car? The technology exists to prevent this kind of stuff so, why is it an issue? Thanks.

You're assuming 240 degrees under normal operation is a problem (that's exactly what my car runs at). Can you prove that you won't be able to get 200k miles on the engine? Yes the dinan product lowers the temps but who is to say that running 20 or so degrees less is much better for the engine long term and worth probably close to 3000 dollars after labor for install. BMW warranties the engine so why would this have any affect on your purchase? They obviously are comfortable that the engine is fine at these temps and will stand behind the car through that warranty term. If your still concerned after the end of warranty, just buy an extented warranty (probably for less than the cost of that oil cooler). Just because a product is being offered doesn't automatically mean the factory system is flawed.

Originally Posted by The HACK

The only question that remains, is how many people with third party piggy back systems will see 50,000 spirited miles before their engine goes kablooey.

"kablooey"...what a great word, thanks, I'm going to use that more often in everday conversation.

Originally Posted by Craigito

You're assuming 240 degrees under normal operation is a problem (that's exactly what my car runs at). Can you prove that you won't be able to get 200k miles on the engine? Yes the dinan product lowers the temps but who is to say that running 20 or so degrees less is much better for the engine long term

I have to agree with this statement, to some degree.

Todays engines are designed to run at higher temps for various reasons that are probably only known to BMW engineers. For example, 260 or so might me ideal for burning off water and fuel in the oil. Oil viscosity is directly affected by temperature, so the oil recommended might be based on those temps being reached. Emissions is another reason. Cylinder head temperature affects the burn of the mixture, and in these engines I would bet that how the charge is burned is critical. Oil temperature can effect other systems that you do not intend to. One example I can think of is the oil-to-fuel heat exchanger on a 767. The oil cooler is actually cooled by fuel. This keeps oil temps within tolerance while heating the fuel. Without enough heat passing to the fuel at high altitudes, icing can occur in the fuel causing a flameout. I'm not saying this is the case with the 335, but just an example of how changing one variable COULD have unintended consequences.

So operating at continued low temps may not be the best thing for long term durability. It may not affect how the car runs runs day in and day out. But there is no way of knowing the long term effects without hundreds of thousands of miles of testing. (Something BMW does do during development.) Obviously you don't want a car to trigger limp mode after 3 laps on a race track. Especially a performance car like the the e9X. So I'm not saying there is not a problem with the factory design. You want a cooler that can handle extra heat and dissipate it efficiently enough to avoid excessive temps and limp mode. But running it continuously at low temps IMO is not the best solution either. If BMW designed their oil cooler to only be used above 240, there is probably some significance to that number. They could just as easily have used 230, or 210, or any other number.

Oh.... and one more good example. For some "old school" types (I'm dating myself now), back in the days of Late '80's performance revolution in the US, when everyone was modifying their "new" computer controlled, fuel injected Camaros and Mustangs, it became common knowledge that replacing a factory Ford 210 degree thermostat with a 180 degree unit was worth some horsepower. Of course some thought that if cooler is better, why not go with a 160 unit? But over time they were wondering why their car was running slower, and fouling spark plugs every 5000 miles. There is always a point of diminishing returns. Physics is always a balance of compromises. There is always a trade off for every gain.