Additional Oil Cooler

[bz888]

I am thinking of installing a second oil cooler behind the passenger side blade on my V8. I'm certain the the V10 has two of them. One behind each side blade. Can someone confirm?

I really want to keep engine oil temps down as much as possible, especially on the track. High oil temps means the block is hot and heat soaked. Which in turn forces the ECU to limit timing advance and reduce power. We have seen this occur on the dyno.

Anyone added an oil cooler? Any ideas?

[R8SAUDI]

i don't think you need to do that in your v8.
v10 engine it's a must so Audi make it as a stander.
unless you add supercharger to your car...

[desperado]

Here are some random facts and rumours which bear on your question...

I don't know about the V10, but the V8 has an engine oil cooler inside the LH side blade, and a transmission oil cooler inside the RH blade.

I believe the engine oil cooler is a oil-to-water cooler, so adding an additional one will just take heat out of the oil and put it into the cooling water. That heat still has to be rejected through the same size radiators in the front of the car. So there would be zero net increase in cooling capacity.

I have heard, but not verified, that some models of Audi cars have an optional heavy duty cooling package which is installed at the factory on cars destined for certain markets. I believe the TT is one of these, and that TTs built for certain countries (such as Saudi Arabia) come with extra cooling capacity over NA or EU vehicles. I'm guessing this includes either larger or additional water radiators.

I don't know if such an option is available for the R8. It would be interesting to see an original window sticker from a car originally delivered in one of those markets, as it should show up in the detailed listing!

Adding an air-to-oil cooler behind the side blade would pull additional heat out of the oil, but would also put that heat right back into the engine compartment. So not the most ideal setup, either.

Conclusion: you would get the most bang for your buck by improving the existing water radiator cooling system. An easy place to start is with the coolant itself. There are some products advertised for racers which make fairly impressive claims, including additives such as Red Line WaterWetter and complete coolant replacements such as Evans Waterless. Here is a listing of some of these products.

[Europrice]

The V8 has a cooler back by the engine, in front of it and off to the side, however the V10 appears to have a bolt-on cooler on the block (correct me if I am wrong) and adds a secondary on the left sideblade. The second cooler has a built in thermostat and bolt/o-ring style fittings. From what I can tell the V8 cooler constantly has oil running through it, the V10 block mounted unit is the same way and then when the thermostat opens on the secondary cooler in the sideblade oil flows through until the thermostat closes.

Not sure if you would want to go aftermarket or not, but remember you have to keep the dry sump system in mind. The V10 system from what I can tell goes:

When thermostat closed:
Reservoir > Pump/Motor (including filter and primary cooler) > Secondary Cooler Thermostat (Bypasses Cooler) > Reservoir

When thermostat open:
Reservoir > Pump/Motor (including filter and primary cooler) > Secondary Cooler Thermostat > Cooler > Reservoir

Now maybe someone can correct me if this isn't right, but the diagrams aren't great and I don't have a V10 study guide here.

So you would need to get a thermostat that can not just open and close but also let oil bypass the extra cooler completely back to the reservoir. So I would think you would want to get the oil line from the V8 standard cooler here:



Run that to your thermostat (which needs a bypass back to your reservoir), to the cooler and finally cooler to your reservoir. You just always somehow have to have oil flowing back to your reservoir.

Too bad these cars don't have a traditional spin on filter because a sandwich plate would make this much easier.

Maybe I've made this too complex, but I think this is the only way to do this.

Cheers,

[Europrice]

Desperado-
You are correct, the primary coolers on both cars also have coolant running through them. These are actually dual purpose, in old Audi/VW applications we used to call them oil heaters. Their cooling capacity is nowhere near what a genuine oil cooler can do, however they do in fact heat the oil during warm up. Coolant heats up much faster than the oil and we all know that oil has a sweet spot for it's lubricating abilities that is far warmer than ambient temps. The coolant heats the oil up during warm up and draws heat out once up to temp.

Now the reason I say that these aren't as effective as a traditional oil cooler is that you are making a warm to hot liquid take heat away from another hot liquid. The traditional style cooler gets loads of fresh relatively cool air through it when moving and will get more heat out of the oil than the coolant style coolers.

The heat that comes out of the oil into the engine bay isn't likely going to be all that detrimental to anything. Audi/Lambo both use the secondary cooler that same way and it's definitely got a purpose for hard use or in extremely hot climates. As you mention in loads of Audi/VW products they have high temp climate product, different radiators, additional radiators, more powerful fans, bumper grilles with more cutouts, etc.

The thing is to monitor oil temps with the stock V8 system and if you are really cooking the oil on track it's time for a secondary cooler. If you are never running the oil into higher temp zones it's not worth it, thermostat will never open, secondary cooler will never get used. Also too low a thermostat is bad for any motor, oil not up to temp that is being overcooled is a nono!

[desperado]

Alexander, thanks for all the additional info. bz888 now has a lot of good information to consider!

[Bodhii]

Great stuff. guys!

.

[Yspokes]

On another note, I have actually used both Redline's Water Wetter and Evans coolant, and both work as advertised.

I have seen results from Water Wetter at the race track in my own car reduce overall coolant temps by 10 degrees on a 100 degree + day with no thermostat change.

The Evans coolant works quite well too. The only way I could really test it was to do a "before and after" test with my OTC Tech II and record knock sensor and coolant temp data during actual racing conditions. What I found was that even though the coolant temps were not down, it dissipated heat through the radiator much more rapidly than factory coolant. With "DexCool" installed from the factory (red coolant) the block would eventually heat soak and the knock sensors would go off, limiting timing advance. With the Evans coolant installed, temps would stay consistent, heat soak was kept to a minimum, and the knock sensor activity was kept to a minimum also.

The downside of Evans coolant, is that the cooling system must be completely flushed of any old coolant, and water before the new installation is done, as the Evans coolant is not compatible with water (it comes with a sticker warning service personnel not to add water to the cooling system). The upside, besides being very effective, is that it is a food grade liquid, and will not harm the environment, children, or small animals.

[bz888]

Hmmm, lots of info guys!! Thanks! Need to speak to my Mechanics and digest a little...

[desperado]

The additional interesting claim of the Evans is that, unlike water with water wetter added, it is also effective as an antifreeze.