Installation of ATR/AMW oil cooler

[CB72]

Given that my NSX overheats on warm track days, I decided to install an oil cooler.
I had postponed this decision for a long time as I'm not a fan of changing the oil feed system to the engine.
Instead of spending many hours trying to decide who to engineer the system, I went for the ATR oil cooler.
ATR (@austrian type-R) took over the design from AMW and I was quite impressed by the overall quality.
Fitting the oil cooler takes quite some time as the space is very limited to fit the large AN 10 fittings.
I took the opportunity to fit an oil temperature gauge that I must still finalize.
Driving back home, I noticed that there is a small oil pressure drop from my normal maximum 6kg to 5.5 kg per square centimeter.
Not to worry I suppose?
Here are a few pictures:

 

[CB72]

I went for a longer test yesterday after installing the oil temperature gauge.
At an ambient 25°C the oil stabilized at 95°C but the oil pressure never rose above 4.5 kg/cm square versus 6 kg previously without the oil cooler.
I now understand why Juha drills a couple of holes in the ramp of the sandwich plate.
It provides an alternate path for the oil under pressure thus reducing the efforts of the oil pump.
The question is how many holes?
3 with a diameter of 6 mm as shown here ( http://www.nsxprime.com/forum/showt...-Nsx/page2?highlight=oil+cooler+pressure+drop) or 2 of 6.5 mm or only 1 of 8 mm.
If any hydraulic expert has a sound advice, I'm all ears!

 

[RYU]

i'm not sure if i'll be of help here but in the interest of trying to help...

I noticed a good bump of oil pressure after changing to the Toda oil pump gear in a new OEM housing. If memory serves, my idle is consistent around 20-25psi and roughly about 80+psi (100psi?) during normal and track driving. Oil pressure hasn't really been a problem with my side mount oil cooler. Keep in mind, my oil cooler is super old and was put together with parts. For example i'm using a discontinued billet SOS sandwich plate AN10.

Also in terms of temps, i'm convinced a good radiator helps keep oil temps down. In the hottest of hottest track days my oil has never gotten above 255F. This was about 110-115F ambient at Thermal Raceway in Palm Springs, CA. I'm not a fan of removing the factory oil to water cooler. Are you still running that?

 

[CB72]

i'm not sure if i'll be of help here but in the interest of trying to help...

I noticed a good bump of oil pressure after changing to the Toda oil pump gear in a new OEM housing. If memory serves, my idle is consistent around 20-25psi and roughly about 80+psi (100psi?) during normal and track driving. Oil pressure hasn't really been a problem with my side mount oil cooler. Keep in mind, my oil cooler is super old and was put together with parts. For example i'm using a discontinued billet SOS sandwich plate AN10.

Also in terms of temps, i'm convinced a good radiator helps keep oil temps down. In the hottest of hottest track days my oil has never gotten above 255F. This was about 110-115F ambient at Thermal Raceway in Palm Springs, CA. I'm not a fan of removing the factory oil to water cooler. Are you still running that?

I'm surprised to see that your oil pressure is that high with the oil cooler in place?
Do you remember if there were any holes in the ramp of the sandwich plate?
I followed your build with great interest but the main difference with my configuration is the fact that I have a turbo with a water to air intercooler radiator that sits right in front of the engine radiator.
My radiator is already a special one from Driving Ambition.
Coming back to the holes in the sandwich plate, I remember that the resistance to oil flow through a hole increases as the square of it's velocity.
This means that through carefull dimensioning of the hole it should be possible to increase the oil flow to the radiator at high revs i.e. with more oil pressure when it's really needed.
The open question is still: how many holes?
My gut feeling is that the surface of the holes beeing equal the more the holes the quicker the pressure must increase to push the oil through them?
Maybe [MENTION=32623]Mac Attack or [MENTION=4799]DDozier[/MENTION] can help out?

 

[RYU]

Unfortunately I don't recall any holes drilled into the sandwich plate. It was simply just too long ago and if I did look at it was for a mere few seconds.

What kind of coolant temps do you average? What's your peak ECT on a hot track day?

 

[CB72]

Unfortunately I don't recall any holes drilled into the sandwich plate. It was simply just too long ago and if I did look at it was for a mere few seconds.

What kind of coolant temps do you average? What's your peak ECT on a hot track day?

I got a reply from Juha ( [MENTION=22066]Operator[/MENTION]) who recommends 2 each 1/4 inch holes in the sandwich plate.
The only indication of my coolant temperature is from the OEM ECT ...
It stays very stable until I start pushing really hard on a hot track day and then it just moves upwards.
By slowing down with very little throtlle it will come back to normal but I know it's useless to go back on track.
My local mechanic who works on rally cars recommends putting an inline electric pump in the coolant circuit?
This option was also recommended in those days by DAL racing BTW.
I wonder if anyone uses this setup these days?

 

[RYU]

In my experience my OEM gauge stays dead solid. Once it starts creeping up after the tick mark right below the halfway (if memory serves) you're already over 210-220F and climbing quickly. Someone please correct me on that. There was a post here on prime. I'm now running 100% digital gauges so my gut feeling is you're running hot ECTs. I noticed after I cooled down my ECTs my oil temps also went lower significantly.

 

[RYU]

I found it. I was a bit off in my estimate. Where is your OEM gauge based on the scaling here?

http://www.nsxprime.com/forum/showt...uge-accuracy?p=1937644&viewfull=1#post1937644

 

[CB72]

I found it. I was a bit off in my estimate. Where is your OEM gauge based on the scaling here?

http://www.nsxprime.com/forum/showt...uge-accuracy?p=1937644&viewfull=1#post1937644

I'm just below the middle line mark ( graduated in °C)
My ECT has always been at this level since I bought the car 20 years ago.
DAL racing mentionned that the cooling on their racing NSX was border line and I'm encountering the same issue on hot track days.
Don't forget that my turbo setup delivers a lot of power ( way more than my previous CTSC supercharger for sure).
With an average efficiency of 20% one must get rid of the remaining 80% of heat generated...
Given the mid-engine configuration of the NSX it's a real challenge!

 

[Mac Attack]

I went for a longer test yesterday after installing the oil temperature gauge.
At an ambient 25°C the oil stabilized at 95°C but the oil pressure never rose above 4.5 kg/cm square versus 6 kg previously without the oil cooler.
I now understand why Juha drills a couple of holes in the ramp of the sandwich plate.
It provides an alternate path for the oil under pressure thus reducing the efforts of the oil pump.
The question is how many holes?
3 with a diameter of 6 mm as shown here ( http://www.nsxprime.com/forum/showt...-Nsx/page2?highlight=oil+cooler+pressure+drop) or 2 of 6.5 mm or only 1 of 8 mm.
If any hydraulic expert has a sound advice, I'm all ears!

First, unless others tell you exactly where they are measuring pressure and temperature and what kind of oil viscosity they are using, please be aware that you can have very different observations and behaviors. Some people tap into oil pressure at the OEM location in the heads or right at the pump discharge since there's a nice threaded port right there. Others take temperature in the oil pan or somewhere in those sandwich filter adapters pre- or post-extra cooler.

The OEM oil pump has a spring-loaded relief valve that begins to bypass oil around 6000 RPM on a stock engine, stock pump. That's why the pump pressure doesn't increase above 6k RPM and even drops when VTEC is engaged and sending extra oil to the heads (opens up another parallel flow path that drops the resistance). If you add resistance anywhere downstream of the oil pump then the oil will take the path of least resistance and flow through the bypass valve and back to the pump suction at a slower engine speed, say 5500 RPM (just a guess depending on the added resistance for example). Therefore, if you run a real thick oil or add significant resistance like an oil cooler, then you will decrease oil pressure and even worse, decrease oil flow at high RPMs than what the OEM engineers intended. Add that to the fact that you are increasing main and rod bearing loads with the extra turbocharged power at those high engine speeds and you have reduced the margin before you lose the hydrodynamic oil wedge and wipe a bearing. I haven't tested the limits so I don't know how much margin there is because there are a lot of variables, but I don't want to test those limits!

We can get into relief valve shims, different gears, modified housing, modified oil pickup, etc, but you need to look at this as a whole package. Just changing one thing drastically like adding a restrictive cooler can reduce OEM design margin when you're pushing the limits on the track and ruin your day.

In hindsight, I would have recommended adding the temperature gauge first before adding the cooler to see if you really need it. Depending on the oil you use, I probably would have sacrificed slightly higher than optimal oil temperatures than using an extra restrictive oil cooler like this.

Adding the bypass holes will bring your oil pressures back closer to OEM, but then you're just bypassing the oil cooler you installed. You can start with the two 1/4" holes in the sandwich adapter and then monitor the effect it had on lowering your oil pressure and increasing your oil temperature. Then consider adding a third hole if you still want to reduce the pressure drop and can live with a higher oil temperature.

Where are you measuring oil temperature? Can you shorten the rear-most hose about an inch to give more clearance to the upper A-arm? It doesn't look like you can rotate it anymore as it is due to how it's routed in the fenderwell. It will probably be fine if your suspension was at full droop in the pictures, but I personally don't like to see such little clearance on sensitive lines like oil, fuel, coolant, and brake fluids.

 

[Mac Attack]

Oh, one more thing:

At 6k RPM, a stock NSX oil pump in new condition is flowing 18 gallons per minute. You have two 90 degree forged 10AN fittings on the oil cooler ends. Each 90 degree 10 AN forged fitting at 18 gpm has roughly four times the pressure drop compared to a 10AN bent tube style fitting. Therefore, just replacing those two fittings with slightly taller bent tubes will give you back I'm guessing around 0.5-0.8 kg/cm^2.

It's cheap to swap out those two fittings. It looks like you might have the space to do it too if you can shift the cooler over a bit more.

https://www.xrp.com/portfolio/flow-comparison-90%CB%9A-bent-tube-and-90%CB%9A-forged-adapter-fittings/

I would try to change those two fittings before drilling holes in the adapter plate. Than you can also shorten that one oil line at the same time :wink:

 

[CB72]

Oh, one more thing:

At 6k RPM, a stock NSX oil pump in new condition is flowing 18 gallons per minute. You have two 90 degree forged 10AN fittings on the oil cooler ends. Each 90 degree 10 AN forged fitting at 18 gpm has roughly four times the pressure drop compared to a 10AN bent tube style fitting. Therefore, just replacing those two fittings with slightly taller bent tubes will give you back I'm guessing around 0.5-0.8 kg/cm^2.

It's cheap to swap out those two fittings. It looks like you might have the space to do it too if you can shift the cooler over a bit more.

https://www.xrp.com/portfolio/flow-comparison-90%CB%9A-bent-tube-and-90%CB%9A-forged-adapter-fittings/

I would try to change those two fittings before drilling holes in the adapter plate. Than you can also shorten that one oil line at the same time :wink:

You have clearly underlined the concerns I have following the modifications of the oiling system on my NSX...
I have now drilled two 6.5 mm holes in the sandwich plate to somewhat shunt the oil cooler and thus raise the oil pressure.
It's definitely working with high rev pressures around the 5kg/cm^2 mark with the oil at 95°C using Motul 300V competition 15W/50.
One thing for sure: the oil radiator is pulling a lot of calories out of the engine judging by the temperature of the quarter panel after a quick run (which was the initial goal BTW).
Clearly the 90° bends going into the radiator are not ideal but there is not enough space with the current radiator to use more rounded bends...
I could of course use a slightly smaller radiator but does that affect the pressure drop?
What about using a separate oil line running direcly from the oil sump through an electric pump?
For your information the oil temperature sensor is bolted to the sandwich plate and the oil lines don't touch the suspension at all.

 

[Mac Attack]

You have clearly underlined the concerns I have following the modifications of the oiling system on my NSX...
I have now drilled two 6.5 mm holes in the sandwich plate to somewhat shunt the oil cooler and thus raise the oil pressure.
It's definitely working with high rev pressures around the 5kg/cm^2 mark with the oil at 95°C using Motul 300V competition 15W/50.
One thing for sure: the oil radiator is pulling a lot of calories out of the engine judging by the temperature of the quarter panel after a quick run (which was the initial goal BTW).
Clearly the 90° bends going into the radiator are not ideal but there is not enough space with the current radiator to use more rounded bends...
I could of course use a slightly smaller radiator but does that affect the pressure drop?
What about using a separate oil line running direcly from the oil sump through an electric pump?
For your information the oil temperature sensor is bolted to the sandwich plate and the oil lines don't touch the suspension at all.

Glad to hear the lines clear - It's always hard to tell from pictures. It's also hard to tell how much space you have available on the oil cooler and trying to squeeze in new fittings. Those rounded 10 AN fittings are pretty cheap and just a tad taller than what you use now. Maybe purchase two of them and see if you have enough space if you rotate the entire cooler at an angle? It would be a lot cheaper than buying a smaller oil cooler, which leads me to...

In general (because it all depends how two different oil coolers are made), a smaller oil cooler will have less pressure drop but it will also have less heat transfer. So, I wouldn't switch to a smaller oil cooler yet.

I'm not familiar with the sandwich plates but from your 95C temperature it sounds like you're measuring it after the cooler. That's pretty low and combined with that heavy 15W-50 oil you run, I still say I would get rid of the oil cooler.

As far as adding a supplemental oil pump and circuit taking suction from the pan, running it through a cooler and back into the pan, that could work. It would take some experimentation determining the pickup and discharge locations (with baffles) so it doesn't interfere with the pickup for your engine (locally depress flow taking into account vehicle accelerations, etc). You'd also have to determine a good flow rate for heat transfer (at least 5 gallons per minute), take into consideration the extra volume of oil in the system so it doesn't sit too high and interfere with the crankshaft (foam the oil), etc. Sometimes, it's best to keep it simple so there's not many failure points (oil lines and fittings). This gentleman had a nice oil setup on his car, but IIRC, it burned due to an oil leak fire and was salvaged:
http://www.mscperformance.com/Thermalpg2.html

Maybe contact Juha again and ask what oil weight he used together with his cooler. In the case of the NSX engine that we don't clearly understand the oiling limitations or have a good database on what clearly works and what doesn't, good to get other peoples experience. I would still try to change the fittings and maybe go to a 40wt oil at the most.

 

[CB72]

I'm not familiar with the sandwich plates but from your 95C temperature it sounds like you're measuring it after the cooler. That's pretty low and combined with that heavy 15W-50 oil you run, I still say I would get rid of the oil cooler.

I believe that the 95°C reading is related to the water temperature as it's measured just below the OEM water to oil heat exchanger.
You mentionned another possible location for the oil temp.sensor?
Where is it exactly?
Does it also have an NPT thread?
Coming back to the AN 10 90° bends, I will investigate drilling holes in the body to pull the oil lines through?

 

[Mac Attack]

I believe that the 95°C reading is related to the water temperature as it's measured just below the OEM water to oil heat exchanger.
You mentionned another possible location for the oil temp.sensor?
Where is it exactly?
Does it also have an NPT thread?
Coming back to the AN 10 90° bends, I will investigate drilling holes in the body to pull the oil lines through?

You can add a bung to the oil pan for a temperature sensor, but you can also add it to the oil pump discharge as that is the hottest the oil will get after it is discharged from the engine and the pump has added heat to the oil due to the pump inefficiency. If you look at the engine from the rear, that is the bolt on the oil pump housing pointing to the back. According to this it is an 18mm bolt (Item 7 - Make sure you buy another crush washer if you remove to inspect the thread):
https://www.acurapartswarehouse.com/parts-list/2005-acura-nsx--2dr_nsx_t-ka6mt/engine/oil_pump.html?Diagram=1311110&PartNumbers=15100-PR7-J21

Ideally, you want to know the temperature before the cooler and after the cooler so you know ultimately how hot the oil is getting (for oil degradation), and also how cool it is to know the properties needed to support the crank and piston rod loads. If you are measuring after the oil cooler, you're right that it is the engine coolant temperature because the "cooler" design also acts as a heater to quickly warm up the oil when cold and regulate the temperature. 95 C oil temp sounds about right because the oil "cooler" is the last thing the engine coolant sees before it goes back up front to the radiator if I remember correctly (and is why I guessed you were measuring it post-cooler).

I wouldn't make holes in the body to pass the lines through because first, I just don't recommend making holes in general if you can avoid it, and also because I think the holes you're talking about would be through some of the seam welds which would weaken that area. I think if you buy one of those rounded fittings and physically compare to what you have now you might be able to make it work with a little adjustment to the oil cooler mounts (the fitting sizes aren't that much different). But, you know better on how much space is there than I do.

Did you ask Juha what oil he runs with his turbo setup and oil cooler? I think he's using 15W-40 oil from the US. Years ago he was helping me select oils with the best Timken wear results through his independent testing. Really, he's probably the best person to give you advice on this setup. Good luck!

 

[CB72]

You can add a bung to the oil pan for a temperature sensor, but you can also add it to the oil pump discharge as that is the hottest the oil will get after it is discharged from the engine and the pump has added heat to the oil due to the pump inefficiency. If you look at the engine from the rear, that is the bolt on the oil pump housing pointing to the back. According to this it is an 18mm bolt (Item 7 - Make sure you buy another crush washer if you remove to inspect the thread):
https://www.acurapartswarehouse.com/parts-list/2005-acura-nsx--2dr_nsx_t-ka6mt/engine/oil_pump.html?Diagram=1311110&PartNumbers=15100-PR7-J21

Ideally, you want to know the temperature before the cooler and after the cooler so you know ultimately how hot the oil is getting (for oil degradation), and also how cool it is to know the properties needed to support the crank and piston rod loads. If you are measuring after the oil cooler, you're right that it is the engine coolant temperature because the "cooler" design also acts as a heater to quickly warm up the oil when cold and regulate the temperature. 95 C oil temp sounds about right because the oil "cooler" is the last thing the engine coolant sees before it goes back up front to the radiator if I remember correctly (and is why I guessed you were measuring it post-cooler).

I wouldn't make holes in the body to pass the lines through because first, I just don't recommend making holes in general if you can avoid it, and also because I think the holes you're talking about would be through some of the seam welds which would weaken that area. I think if you buy one of those rounded fittings and physically compare to what you have now you might be able to make it work with a little adjustment to the oil cooler mounts (the fitting sizes aren't that much different). But, you know better on how much space is there than I do.

Did you ask Juha what oil he runs with his turbo setup and oil cooler? I think he's using 15W-40 oil from the US. Years ago he was helping me select oils with the best Timken wear results through his independent testing. Really, he's probably the best person to give you advice on this setup. Good luck!

I've decided to give it a try with smooth 90° AN 10 bends by tilting the radiator sideways in order to decrease the oil pressure drop.
At the same time, I will delete the carbon fiber air duct to both keep it simple and on top to reduce the cooling effect.
The reason for this is that I believe I don't need much extra engine cooling and I don't want a massive amount of hot air in the rear quarter as that's where my intake air filter is positionned!

 

[CB72]

Since my last post, I looked into the " Building a 50k$ track tool to beat the 500k$ track tools" thread from [MENTION=26776]1K2GO[/MENTION].
His car uses an oil cooler developped by Shad that looks almost identical to the AMW model including the sharp 90° bends in and out of the radiator.
http://www.nsxprime.com/forum/showth...+pressure+drop
The picture is on post #134 .
I'd be very gratefull to get [MENTION=26776]1K2GO[/MENTION] oil pressure readings?
Update:
I went for a ride this afternoon to determine the effects of the holes in the sandwich plate.
The practice confirms the theory: there is far less oil going through the radiator and the rear quarter is now only warm close to the radiator whereas previously the whole body piece was really hot.
It also fixes the oil pressure issue as at 3k rpm the pressure is at 4 kg/cm^2 to raise at 5.5 kg at 6 K rpm just like without the cooler.
These measurements done at 90°C oil temperature.
Idle as usual at 2 kg/cm^2.
Final test to be done on track on a warm day but it looks very promissing!