Series vs. parallel oil cooling
Yes sorry, on the FC a stacked plate style oil cooler is used. I may use two of them if needed when I revert back to pump gas, but between the ducting and the efficiency I have no real worries about my oil cooling.
Joined: Mar 2001
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From: https://www2.mazda.com/en/100th/
you can see the radiator and oil cooler are side by side.
BTW - I can probably cover the stock oil cooler with new 120mm fans for $30. Experience with computer electronics says that the fans do not tolerate any amount of contamination with anything. Dust, moisture, anything...
BTW - I can probably cover the stock oil cooler with new 120mm fans for $30. Experience with computer electronics says that the fans do not tolerate any amount of contamination with anything. Dust, moisture, anything...
a lot of the 60's mercedes sedans are like this, and yes it has an FC sized oil cooler for the engine.
toyota had a turbo celica at the historics one year, and it had the radiator next to the IC.
...and looking at it, the Porsche cooler looks a lot like a bar and plate cooler in design with large tanks and many short tubes, while the Mazda coolers force everything to go through two or three very long tubes... in each direction.
So, I can see how Mazda coolers in series can cause restriction and not the other ones.
I'm not impressed by engineering degrees, I'm impressed by real-world evaluations. What works on paper never seems to pan out in the real world...
So, I can see how Mazda coolers in series can cause restriction and not the other ones.
I'm not impressed by engineering degrees, I'm impressed by real-world evaluations. What works on paper never seems to pan out in the real world...
But if it makes you feel better, own a road race FC that we run enduros with. So i think i know enough about oil cooling in the "Real World" to be part of the discussion.
Further, half of earning an engineering degree is lab time where the "on-paper" is directly related to physical tests and results. Thus creating EXPERIENCE as part of mathematical capability. When an degreed engineer looks at a fairly straighforward problem like this they can anticipate the relative results WITHOUT doing anything on paper, and consistently be correct. Because, not only have i done the calculations thousands of times but i have seen how the calculations ACTUALLY correspond with "Real World" results...
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Old [Sch|F]ool
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From: Cleveland, Ohio, USA
I have, but I've also run into plenty of "Ivory Tower" engineers who don't seem to want to believe that their on-paper theory might not be taking all factors into account.
Old Rotary Dog
Joined: Feb 2003
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From: Durham, NC
Good discussion, and definitely topical for me.
I'm running Paul Ober's old track car. NA FC, stock internals. It came with dual FC oil coolers plumbed in series. From what I recall, the thermostats have been removed. One of the coolers is in the stock position while other sits behind the nose (like Dan Lemon's old E-Prod car) and has its own ducting cut into the bumper region.
Here's the problem - I have *too* much cooling. In a summer HPDE at VIR (paddock temps in the mid 90's), my oil temps (measured at the pedestal) rarely exceed 160F. I have to tape over one of the nose openings in order to get things up to 180 (see picture).
So before I would get into comparisons about serial v. parallel in terms of cooling efficiency, I would instead look at the ducting first. It seems that even serial setups with enough ducting can be more than sufficient (at least for my car).
The oil pressure discussion is probably more important here. My pressures are slightly lower than I would like (definitely not the 100psi that Chris mentions) so I am considering gong to a parallel setup this year and see if that has any significant impact.
-b
I'm running Paul Ober's old track car. NA FC, stock internals. It came with dual FC oil coolers plumbed in series. From what I recall, the thermostats have been removed. One of the coolers is in the stock position while other sits behind the nose (like Dan Lemon's old E-Prod car) and has its own ducting cut into the bumper region.
Here's the problem - I have *too* much cooling. In a summer HPDE at VIR (paddock temps in the mid 90's), my oil temps (measured at the pedestal) rarely exceed 160F. I have to tape over one of the nose openings in order to get things up to 180 (see picture).
So before I would get into comparisons about serial v. parallel in terms of cooling efficiency, I would instead look at the ducting first. It seems that even serial setups with enough ducting can be more than sufficient (at least for my car).
The oil pressure discussion is probably more important here. My pressures are slightly lower than I would like (definitely not the 100psi that Chris mentions) so I am considering gong to a parallel setup this year and see if that has any significant impact.
-b
Been here since dirt...
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From: AZ
Honestly , I think that dual coolers is overkill and that it might need a better location or fan, or both. I trashed the stock sytem on my FC and redid it with a Taurus fan that was including the oil cooler in the airflow. And I have a hard time getting enough temp, even in 98 deg days.
Lot of air and a good cololer with the T-stat replaced with a plug.
GD
Lot of air and a good cololer with the T-stat replaced with a plug.
GD
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Old [Sch|F]ool
Joined: May 2001
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From: Cleveland, Ohio, USA
Honestly , I think that dual coolers is overkill and that it might need a better location or fan, or both. I trashed the stock sytem on my FC and redid it with a Taurus fan that was including the oil cooler in the airflow. And I have a hard time getting enough temp, even in 98 deg days.
Lot of air and a good cololer with the T-stat replaced with a plug.
GD
Lot of air and a good cololer with the T-stat replaced with a plug.
GD
You also have an FC engine bay, meaning you don't have an engine 1/4" away from your fan to block the airflow. I didn't have an oil temp gauge before relocating the hood latch, but coolant temps dropped from ~190-200 on the highway to ~170. Amazing what helping the air out of the engine bay will do for radiator efficiency. Didn't help the rallycross temps all that much.
I did a little shopping and with the cheapest fittings I could find (not sure I like that) it's still going to run me about $180 just in plumbing to add the second oil cooler. A couple 10AN-18mm adapters, five straight -10, one 90 degree -10, two Ys, and a few feet of hose. Adds up quick, doesn't it? Sad thing is, the only pieces I could conceivably make (18mm adapters) are the cheapest individual components at $7 per so it doesn't even make sense to do that.
edit - I just realized that I don't need six ends, I need EIGHT. D'oh, that makes it worse!
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Old [Sch|F]ool
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From: Cleveland, Ohio, USA
I have to make the car go faster so it will run cooler.
I know I can out-drag modified Evos on the straights, the only problem is that the pesky course designers rarely install any straights
Honestly , I think that dual coolers is overkill and that it might need a better location or fan, or both. I trashed the stock sytem on my FC and redid it with a Taurus fan that was including the oil cooler in the airflow. And I have a hard time getting enough temp, even in 98 deg days.
Lot of air and a good cololer with the T-stat replaced with a plug.
GD
Lot of air and a good cololer with the T-stat replaced with a plug.
GD
"Elusive, not deceptive!”
Joined: May 2007
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From: Slidell, LA
Never tried fans, but I really pay attention to oil cooling. Coming from an air/oil cooled Porsche background, I have seen some pretty extreme oil cooler setups.
Oil cooler in 911 Turbo Race car, its fairly large and does its job perfectly-
I have had no real issues running oil coolers in series, but I can see how others have.
Oil cooler in 911 Turbo Race car, its fairly large and does its job perfectly-
I have had no real issues running oil coolers in series, but I can see how others have.
Peejay, try not to use 90º fittings if you can. Straights and 45ºs flow much better.
Also consider lowering viscosity to the point of having 10 psi /1000 rpm. This increases flow at the bearings and moves through the cooler faster also.
Barry
Joined: Mar 2001
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From: https://www2.mazda.com/en/100th/
the oil cooler setup i arrived at with mine seems to work really well.
the car came with an FC cooler shoved in the nose, they welded tabs on the round cross bar and just let the cooler hang out. since this is ugly, and i intend to park the car, and probably put it into the weeds too, i wanted the cooler out of the way.
after many hours of trying to get the FC cooler and hoses to fit, i think i found the perfect solution.
i used a gsl-se cooler, came core size, different hoses and mountings. the cooler is actually bolted to the radiator panels, and sits horizontally behind the round cross bar. i added a little duct, actually right now its a cereal box, to go between the undertray and the cooler, and it works great. plus its totally out of the way.
Rotary Freak
Joined: Jul 2003
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From: Oakville, Ontario
jgrewe nailed it.
Personal experience is this - Customer's ITS road race car came in a couple years ago with a series setup. Comes in for engine management install and tuning. We cover that part. Car makes great power but oil pressure is lower than I'd like to see. We're seeing only about 70 psi WOT 3k+ RPM. Ideally, I'd want to see 100+. Tell owner this, they run it anyway, with no changes. They had bought the car already built as it sits, and, I think, convinced there is not an issue.
I'm asked to drive the car in a couple regionals that year and the car performs very well. However, oil and water temps are fairly high (230-ish), and oil pressure during extended running is no more than 70 psi. I think perhaps the engine has a stock FC pressure regulator in it, and recommend they have the regulators swapped out for Mazdaspeed or REW regulators.
Week after I win a couple races with it, the owners call me. The engine is locked up. They bring it down to me and we tear it down together. Front main is seized, noticeable wear on all other bearings. Oil pump is broken. One of the rotors is in 4 pieces. It's a TII pump FWIW. I build them a new engine with the typical ITS setup. New TII pump, REW regulator, Mazdaspeed open e-shaft jets, race bearings, etc.
Start the engine in the car with the old series setup and immediately have lower than expected oil pressure. Pressure on first start (cold oil) at idle is around 70 psi. We should be seeing 100+. As the oil temp comes up, the pressure goes down. To around 25 psi at idle. We're still seeing a max of 70 psi with warm oil at 3k+.
I'm thinking one or both of the coolers is clogged. I send them out for ultrasonic cleaning. No change. I bypass one of them and run the engine with just one cooler. With one cooler we have 100+ on cold start, comes down to around 60 at idle, and 100-110 warm at 3k+. Good! So the other cooler is bad right? Nope. Plumb that one in by itself and the results are repeated. With just a single cooler, either one of them, the pressure is good. Plumb them in series and we loose 30+ psi at 3k+ with warm oil!
One other thing we found while experimenting was that one of the coolers still had the thermostat bypass while the other had it removed and the bypass blocked. With relatively cold oil (the working thermostat bypassing), we would see good oil pressure at 3k+. Once the oil warmed, and the thermostat closed, the pressure at 3k+ dropped.
Working backwards, I think we answered the question of "how the hell did the oil pump break"? Without a pressure gauge on the line at the front cover outlet I can't say for sure, but I would have to guess that with the huge restriction obviously imposed by the series setup, that we would be bumping the pressure setting of the front regulator and working the heck out of the oil pump to do so.
Personal experience is this - Customer's ITS road race car came in a couple years ago with a series setup. Comes in for engine management install and tuning. We cover that part. Car makes great power but oil pressure is lower than I'd like to see. We're seeing only about 70 psi WOT 3k+ RPM. Ideally, I'd want to see 100+. Tell owner this, they run it anyway, with no changes. They had bought the car already built as it sits, and, I think, convinced there is not an issue.
I'm asked to drive the car in a couple regionals that year and the car performs very well. However, oil and water temps are fairly high (230-ish), and oil pressure during extended running is no more than 70 psi. I think perhaps the engine has a stock FC pressure regulator in it, and recommend they have the regulators swapped out for Mazdaspeed or REW regulators.
Week after I win a couple races with it, the owners call me. The engine is locked up. They bring it down to me and we tear it down together. Front main is seized, noticeable wear on all other bearings. Oil pump is broken. One of the rotors is in 4 pieces. It's a TII pump FWIW. I build them a new engine with the typical ITS setup. New TII pump, REW regulator, Mazdaspeed open e-shaft jets, race bearings, etc.
Start the engine in the car with the old series setup and immediately have lower than expected oil pressure. Pressure on first start (cold oil) at idle is around 70 psi. We should be seeing 100+. As the oil temp comes up, the pressure goes down. To around 25 psi at idle. We're still seeing a max of 70 psi with warm oil at 3k+.
I'm thinking one or both of the coolers is clogged. I send them out for ultrasonic cleaning. No change. I bypass one of them and run the engine with just one cooler. With one cooler we have 100+ on cold start, comes down to around 60 at idle, and 100-110 warm at 3k+. Good! So the other cooler is bad right? Nope. Plumb that one in by itself and the results are repeated. With just a single cooler, either one of them, the pressure is good. Plumb them in series and we loose 30+ psi at 3k+ with warm oil!
One other thing we found while experimenting was that one of the coolers still had the thermostat bypass while the other had it removed and the bypass blocked. With relatively cold oil (the working thermostat bypassing), we would see good oil pressure at 3k+. Once the oil warmed, and the thermostat closed, the pressure at 3k+ dropped.
Working backwards, I think we answered the question of "how the hell did the oil pump break"? Without a pressure gauge on the line at the front cover outlet I can't say for sure, but I would have to guess that with the huge restriction obviously imposed by the series setup, that we would be bumping the pressure setting of the front regulator and working the heck out of the oil pump to do so.
I strongly recommend 2 FC coolers in parallel. It is cheap and effective.
Eric
@ Barry, I don't want to quote that big pic again. At first read about the oil only really being hot for the first three inches fo that cooler it sounded like it made sense. But after thinking about it for a second it seems to me that side tank is just acting like an extension of the hose that is bringing the oil. The oil that travels to the far end of the tank before it runs through the core would only lose temp like it was moving through an aluminum tube. No?
It would be very interesting to hit various parts of the cooler with an IR thermometer to see what it says.
It would be very interesting to hit various parts of the cooler with an IR thermometer to see what it says.
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Old [Sch|F]ool
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From: Cleveland, Ohio, USA
Also consider lowering viscosity to the point of having 10 psi /1000 rpm. This increases flow at the bearings and moves through the cooler faster also.
Barry[/B][/COLOR]
Barry[/B][/COLOR]
Although really, if I'm seeing upwards of 10k at times, I'm not running enough pressure by that logic.
I'm going to attempt running Mobil 5W30 this year instead of Valvoline 20W50. I think I've solved my oil pressure issues with the RX-8 front cover gasket. (It just plain works)
"Elusive, not deceptive!”
Joined: May 2007
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From: Slidell, LA
PS- looks like you are having great fun with the rallycross.
Barry
Decent Quality AN fittings are certainly not cheap. My cost for the parts to make the lines was well of $300. I dont think it is any cheaper to do dual coolers vs one big one unless you allready have two FC coolers that are clean and in good condition. Cleaning for me was 125 per cooler. I had to buy a total of 3 because one had an unrepairable leak...
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Old [Sch|F]ool
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From: Cleveland, Ohio, USA
It's one of those back burner "that'd be cool" things to have, like a proper loop line arrangement, but the reality is that I need to keep things simple so I don't have to engineer new parts every time I have a failure of some type. Rerouting the oil arrangement is low on the ease/benefit scale.
I have tried several different oil cooler configurations on my 13B PP road racer, and for the last several years I have had very good luck with two stock coolers plumbed in series. I get pretty decent airflow at road racing speeds. One cooler was not quite enough, so I went to two coolers. Per race engineer expert Carroll Smith's writings, I plumbed them in parallel, and my oil was still on the hot side. I finally took my InfraRed Pyrometer and checked the temps, and one was hot and the other was cool! I then replumbed them in series, and it has kept my oil cool for several years of road racing.
I just started co-driving a friends Toyota truck in Rallycross, so I now know the format of your runs. I think one cooler with electric fans would be the way to go. I know the computer fans are the right dimension, but I don't think they would flow enough CFM of air for you. What about a fan from the car's heater system? don't they have about a 4" outlet size? They have much higher CFM than a computer fan.
I just started co-driving a friends Toyota truck in Rallycross, so I now know the format of your runs. I think one cooler with electric fans would be the way to go. I know the computer fans are the right dimension, but I don't think they would flow enough CFM of air for you. What about a fan from the car's heater system? don't they have about a 4" outlet size? They have much higher CFM than a computer fan.
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Old [Sch|F]ool
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From: Cleveland, Ohio, USA
I have tried several different oil cooler configurations on my 13B PP road racer, and for the last several years I have had very good luck with two stock coolers plumbed in series. I get pretty decent airflow at road racing speeds. One cooler was not quite enough, so I went to two coolers. Per race engineer expert Carroll Smith's writings, I plumbed them in parallel, and my oil was still on the hot side. I finally took my InfraRed Pyrometer and checked the temps, and one was hot and the other was cool! I then replumbed them in series, and it has kept my oil cool for several years of road racing.
Your experiences are part of where I got the idea that parallel wasn't as good as series for really getting the temps down.
I just started co-driving a friends Toyota truck in Rallycross, so I now know the format of your runs. I think one cooler with electric fans would be the way to go.
I remember some guys from around your parts came up here in 2009 with their green 2002.I was poking around at the car and I noticed that while I had the top of the oil cooler well ducted, the bottom had a large area where air could flow right under it, so I'm going to pay closer attention to that first.
I'm also going to (as soon as I can round up another person to push my car into the shop!) see about fitting a Neon radiator in the nose. It's a single row radiator, pin-mounted, and the automatic models had an option for two very beefy large fans. It will require an FC water outlet and some water bleeds, since the radiator has no provision for a cap. But, I also can lay the radiator down so that air can get OUT of it.
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I have tried several different oil cooler configurations on my 13B PP road racer, and for the last several years I have had very good luck with two stock coolers plumbed in series. I get pretty decent airflow at road racing speeds. One cooler was not quite enough, so I went to two coolers. Per race engineer expert Carroll Smith's writings, I plumbed them in parallel, and my oil was still on the hot side. I finally took my InfraRed Pyrometer and checked the temps, and one was hot and the other was cool! I then replumbed them in series, and it has kept my oil cool for several years of road racing.
As a mechanical engineer with experience in fluid flow and heat transfer I maintain a properly configured and installed parallel system will out-perform an in-series system.