RS4 to R8 dry sump oil system?

B6/7 S4/RS4
#1

I’m wondering if anyone has put the R8’s dry sump on an RS4. I believe that they are the same engine but the oiling system is different. Dry systems have shown to be a better option in yielding more horsepower. So a few questions:

Is this even possible?
Is there enough benefit to move to the dry sump in horsepower?
What would it take to make this conversion possible?

As the RS4s start to get up there in mileage and people look at rebuilding engines maybe this would be something to add to the engine?!?

#2

Need to see the lower bed plates on the R8 motor and a better understanding of their oiling system…this has been difficult information to come by.

#3

You can kinda see its possible but the amount of work and modifications would be prettty intensive. Would it make a big jump in power. NO. Appartently from whats been tested the RS4 and the R8 make almost the same amount of power. The sump is there to help in the agressive cornering ability of the RS4 and to help control oil temps better. It would be a cool talking point but performance wise there isnt a real gain there.

If you wanted to adding the JHM oil cooler is a good thing That seems to have made a big difference in guys oil temps and that will help keep the motor happy.

#4

I was looking at the difference in the power made the engines and I agree it wouldn’t make that big of a difference. If the swap was inexpensive and easy then it would be a no brainer but anything R8 is $$$. I also never saw JHM post anything up about doing this type of swap. I would have assumed they already had looked into it but I thought I’d post to see if anyone had attempted it.

#5

Does it though? Hasn’t Koolade tested his setup and showed on track it did not provide any additional cooling over stock?

#6

He thinks the proximity of our oil temp sensor to the oil pump might be affecting the oil temp readings. I think he said he’s going to tap in somewhere else on the block or use an existing hole to possibly get more accurate temp readings.

#7

This and there have been a few guys who saw nice temp drops recorded on the dash and followed up by there hard gauges.

Koolade knows his stuff so if he thinks or has seen otherwise I would want to read his thoughts. Two things about koolade. If he sees something wrong he will explain it very well and have a great solution for it.

#8

I don’t see the point of trying to make the RS4 a dry sump unless you are FlyingTomatoes trying to impress high school kids at car shows.

#9

So the oil temp issue…

Upgrading the heat exchanger made little to no effect on high-rpm oil temps. It did drop cruising and <6k rpm oil temps across the board, but not enough for me to recommend the upgrade. After looking at a torn apart BNS motor, I discovered the main oil pump feed is split between the oil cooler block (coolant fed) and the front heat exchanger. If you follow the path of the oil through the block, it has a straight-shot to the cooler block, but the lines for the front exchanger are perpendicular to the oil flow, thus the oil needs to take a hard 90deg cut. Considering fluid will take the path of least resistance, it made sense that at high rpm, the oil was moving straight through the oil block vs. the front cooler. This is where I left off a few years ago.

I finally picked up a block off plate for the cooler block in hopes to force the oil through the oil front cooler only. The risks are potentially lower oil pressure & over-cooling of the oil. On the track, there was (again) no difference. I discovered a small coolant leak that day , got burnt out, and put the car on time-out since April. Coolant leak is fixed and I’m driving the car again. I’ve noticed no difference since having the cooler block removed/blocked off.

I have an oil pressure gauge I’ve yet to install. The intent is to monitor pressure downstream of the oil cooler as a sanity check. That’s the next step.

Once the above checks out, I’ll then swap out the pressure gauge for a temp gauge. My latest theory is that the oil pump is generating all of this heat (not the motor), and the excess is dumped into the pan. Considering our temp sensor is also in the pan this could explain the high temps we see on the dash, while the oil the motor sees is actually being cooled properly (hence the additional temp gauge). I have no real info on our oil pump, so again, it’s just a theory, no data to support it.

My other theory is the built-in oil thermostat has a fail-safe that will bypass the coolers altogether and feed the motor directly under high rpm/temp conditions. This would also explain all the above, but I have no data to support it either.

In other threads, I’ve asked about the dry-sump on the R8 so I could hopefully learn more about the differences between our two oiling systems…there’s even less information about that though.

#10

Not many R8 owners test apart their engine blocks and reroute the lubrication

Koolade on another note why you sell that hood? Did that not help with your various temps?

#11

haha, sooooo true… I’d just be happy to see one torn apart. My best hope is that EvoMS does a tear-down on a V8 R8 prior to going FI, but I’m not holding my breath.

[quote=“sakimano,post:10,topic:8022”]
That was my old hood, it’s been passed around between a few friends, and I think it’s going to wind up on Ben’s car. I still have mine.

#12

koolade great post and info. Was there a drop in off power oil temps in the cool down drive. I would think from what Ive read or seen that is one of the spots people have seen the drops

#13

You got it. Shifting at 7k, I could keep my temps consistent around 240-250. If I use all the motor, I’ll see 285 and get it down to 230 on my cool down lap. The problem is around high RPM usage. I’d go so far as to say the OE unit would be sufficient for 99.9% of us if the internal flow issue is resolved.

Food for thought: Someone mentioned the RS5 (or B8.5 RS4, I don’t recall) motor has a variable-speed (or at least a high/low pressure) oiling system. Not sure if it’s due to design changes in the oil pump or the pressure regulator, but when I heard this, a huge flag went up…they did it for a reason.

#14

Lol

#15

Reason being lower parasitic losses. Many new cars have it, along with electric power steering for the same reason. A traditional oil pump where engine RPM dictates pressure is using too much energy most of the time in low load cruising conditions and fuel consumption is the enemy these days.

The oil pump itself will add very little heat to the oil, negligible really. It’s just pumping a liquid. The long hard trip through the engine is what heats it up.

I think your theory on the problem showing only at very high rpm is valid, the design is made to insure oil pressure at 8K first and cooling second. But in our admittedly rather cool climate I’ve not heard of oil temp issues on track, they go up to 120-125C on the Nurburgring. Did you log water temps by any chance? Dropping the water temp might be comparatively easy and help out the oil temp a bit.

#16

[quote=“JCviggen,post:15,topic:8022”]
Nay.

Clicky click
http://www.engineeringtoolbox.com/pumps-temperature-increase-d_313.html

[quote=“JCviggen,post:15,topic:8022”]
Water temp has never been a problem, and I live in the desert. As for the ring, you figure most guys are running 8-9 minute laps in their RS and hitting ~248-257F, that sounds about right, and then they have a few minutes to cool down before their next lap. Go out there for 20-30min straight and see what temps you’re hitting…

#17

Nay? I reckon that link supports my point about it being negligible. Fill in the numbers for engine oil in that formula and get back to me. Oil does have less than half the heat capacity of water and a higher viscosity but it’s going to be a small number at the end - not something you can hold responsible for noticeably increased sump temps.

[quote]Water temp has never been a problem, and I live in the desert.
[/quote]
It doesn’t need to be a problem, if you can lower it you will lower oil temps along with it without touching the oiling system. More often than not it’s the easiest way to get things down by 10C or so. But without knowing the water temp or even the coolant you use it’s just a suggestion really. Straight water with some water wetter is the best performing coolant and safer when spilled, but you may already have been using that.

[quote]As for the ring, you figure most guys are running 8-9 minute laps in their RS and hitting ~248-257F, that sounds about right, and then they have a few minutes to cool down before their next lap. Go out there for 20-30min straight and see what temps you’re hitting…
[/quote]
Possibly. When I go I’ll do a trackday where you can string together as many laps as you like without stopping and see what happens. But I strongly suspect it won’t change much after 1 lap based on previous experience with other cars. It’s a very high speed track which provides plenty of cooling for the car. E9x M3s can also hit 130-140C on track FWIW. With a quality xW40 oil I’d still be pretty comfortable with it, provided you change oil before and after.

#18

What you’re saying is true, but again water temp has never been a problem. Even at 285F oil temps.

[quote=“JCviggen,post:17,topic:8022”]
I already know what will happen. Based on my experience with this car, in worse environmental conditions. That’s pretty much what I’ve been sharing… If you’re there (the ring) for a private day and don’t have to wait in the queue for each lap, I’m guessing you’ll be short-shifting by the end of lap two. If your tires and/or brakes don’t give out before then. But by all means, go see for yourself and report back.

I’m saying this in the least-dickish way possible: If your oil temps in RS4 aren’t a problem, you’re probably not going fast enough…

#19

Fair enough koolade, I’m trying not to come across as obtuse - it’s just an interesting subject for me.

[quote]When you restrict fluid flow and increase pump pressure, where does the energy go…
[/quote]
Not arguing about where it goes, rather how much energy we’re talking about. The link you gave had 2 examples one where temp increase was 0.01 degree and the other 0.03C. We lack any numbers for the variables here but even multiplied by a hundred it doesn’t change the overheating issue.

[quote]What you’re saying is true, but again water temp has never been a problem. Even at 285F oil temps.
[/quote]
Appreciated, but if you want to work the problem of oil temps, stuff like a colder thermostat and different coolant can make a significant difference to the point that it may be the difference between “ok-ish” or “danger zone” oil temp. I figure it’s relevant when the problem is difficult to solve on the oil side. Provided there is room to drop the coolant temp without going too low but I’m pretty sure there is.

Definitely looking forward to try the car on track but it’ll be next year. I once tried a lap in the RS6 to get some pics of it and I backed off halfway in the lap already because of oil temp 140. That car went up 10C in oil every time I stepped on it for 3 seconds and took half a day to come back down. But the RS4 sans turbos is definitely a lot better and with the power band the way it is and the higher gears being pretty close together going fast does not require going to 8000rpm before every shift if that is the issue. Lots of people from RS246 track their car on smaller tracks and it seems to go well even with one of the aux rads deleted. Of course in ambient conditions that are more often below 20C than above where we’re at.