20B Cooling Setups & Results

[Antoine]

Upgrading my cooling system has been on my mind for too long...I've been through one too many HOT & HUMID summers here in Japan...I'm seriously thinking about upgrading my stock setup when I take the Cosmo out of hibernation.

I'd love to know what sort of cooling setup everyone is running and how it's performing...

- Are you guys sporting 2 or 3 core Alumi rads?

- Built in Tranny cooler or separate?

- Stock or Electric Fan?

- How about your oil coolers?

- Upgraded Hoses & Lines?

I want a versatile trouble-free setup that can normalize temps during summer traffic and handle high-load mountain runs as well as the occasional circuit / track run...

One concern I have with a heavy-duty cooling setup is running too cool in Fall, Winter & Early Spring...What do you guys think?

Any feedback would be greatly appreciated, thanks!

 

[Cams]

Hi Antoine.
Hope Grant does not mind but here's his how to list from his excellent site www.eunos.com.au Near the bottom of the list he has some cooling projects he has done. This is the link. http://www.eunos.com.au/data/howto/cosmo/index.html
Cheers Darryl

 

[rodneooo]

This is the setup i have on my 13b. id run it exactly the same on a 20b. (maybe a slightly fatter rad or twin pass if pumping serious HP)

-50 somethign mm alum rad (not sure on cores or passes) (10in & 16in thermo fans mounted flush on core with shroud & clutch fan)
-pwr tranny cooler with new lines (mounted onto the a/c condenser) one of the largest they make
- Pwr core intercooler (approx 70mm thick, as wide as poss and tall as poss core is approx 350w x 600h, custom tanks with inlets right at the bottom where direct airflow through front bar is)
- Aftermarket oil cooler mounted where tranny cooler used to be (about the same size as the factory oil cooler, no thermostat, inline before the factory one, custom lines made to suit)
- Factory oil cooler with thermostat

This setup has been nothing but reliable, always run <90c with factory mazda thermostats. Never overheated on the hottest of days even with aircon on in traffic. (thermos are on with a/c)
u wont have any problems with it running too cool if your thermostats are good. if your car takes longer than 1 minute for the temp guage to start moving, or if it sits below 1/2 then u gotta change the gauge sender or get new thermostats. i was suprised how much quicker my car warmed up with new thermostats.

The bread winner was the twin oil coolers.

Also keep all the factory undertray and shrouding & clutch fan.


the only thing i can complain of is slight boiling sometimes after shutdown. an ewp would solve that no dramas with the after shutdown circulation. even just 1 min would be sweet.

 

[Antoine]

Thanks for the tip, Darryl!

Grant's site is a great resource indeed...I hadn't been there in a while...Thanks for the reminder!

I've considered going with electric fans but after I went to that 20th anniversary meeting in Yokohama...I noticed everyone was running the stock belt driven fan...Even the modded ECs...It's hard to beat the simplicity, dependability and effectiveness of that big fan and shroud.

 

[Antoine]

Wow...Thanks for describing your setup in detail, rodneooo!

Glad to know it's holding up for you even with the aircon on in traffic...Got a few initial questions...

- So you're running two thermo fans mounted directly on the back of your radiator moving air along with the stock fan and shroud?

- What sort of lines are you using...What are the most durable type of lines (steel braided)?

- What kind of aftermarket oil cooler are you using?

- Do you have any mesh / screen installed to protect the coolers for rocks etc?

- Does the stock water pump suffer from cavitation? Have you thought of porting / smoothing the internals?

- Are all PWR products made in Australia? How does their quality, design and durability compare to other well known brands?

Thanks again!

 

[magnumP5]

Even though I don't have a 20B, or even a Cosmo for that matter the same principles apply to all rotaries. rodneooo is pretty much on target, but I wanted to add my own $.02.

Radiator: Thicker is not always better. Look into a good quality, multi-core, multi-pass aluminum unit. PWR is good, but expensive. Koyo also makes some good units as well. They may even have a direct replacement.

Engine fan: The reason you see a lot of stock fans is because they are very good. Their speed changes with engine speed and they're shrouded to make sure not air escapes by the radiator. If you REALLY want an electric fan find the biggest one you can get (16+ inches) that moves the most amount of air with the lowest possible amperage-draw (I have a 16" Zirgo unit that supposedly flows 3000 CFM at 20 amps). A shroud is a must. Definitely do not look to an eletric fan as a power-adder.

Oil cooler: Stock is pretty much best. I know PWR makes some ($$$) but I do not believe they come with a thermostat and are not drop-in. I would only bother replacing lines and fittings if yours are leaking, worn, etc. There's no cooling benefit from new lines otherwise.

Water pump: I do know the higher-revving 13B's do experience cavitation at sustained RPM (ask me how I know). I don't think you'll have this problem so just ensure everything is working properly and there are no leaks, etc. Slowing down the water pump will require underdriving other components so it's probably not worth it to you.

Transmission cooler: Unfortunately I really don't know much in this area. You can probably upgrade the existing cooler (if it has one) but more than likely everything will be custom. Always use a thermostat for best performance.

Intercooler. As with the radiator stick with a good quality unit PWR (again $$$) or whatever. I'd try to stick with something that is a replacement for stock so you don't run into pressure drop issues, which will affect how the car drives. Again, bigger does not always mean better!

Other than that, as rodneooo said, make sure all the factory undertray pieces are still there and in good shape. A lot of parts have rubber or foam seals around them so make sure that's all still there and providing a good seal.

 

[Antoine]

Thanks for chiming in, magnumP5...I really appreciate your input!

Radiator: There used to be several aftermarket options from high-end brands such as ARC but most are no longer available...Looks like RE-Amemiya still offers an aluminium replacement radiator for the EC but it's quite expensive and I'm not sure it's even 3 core (might be 2 core)...Plus while it says the core has been proven via the GT series, I have no idea about the design and quality of the unit... http://www.re-amemiya.co.jp/commodity/?pid=7a5c6a82&scd=5310

Koyo only offers one replacement choice made of copper and even though it's not a high-end alumi unit...It IS very affordable... http://www.amazon.co.jp/KOYO-コーヨー-レーシングラジエター-ユーノスコスモ-KA061227/dp/B004X0Z5RQ

If I can't source a replacement, I'll have to get one "order-made" as they say in Japan...Either via a big-name like ARC (probably too expensive anyway) or via a local source.

To be continued...

Engine fan: For now, I plan on keeping the stock setup and seeing how an upgraded radiator performs...Thanks for the additional advice though about running electric fans!

Oil cooler: Seems like several EC owners have had great success adding an aftermarket oil cooler inline with the stock one...While the stock one may perform well, I've seen my oil temps easily rise when scaling Mountain roads which in Japan can involve lots of hairpins and steep grades...The next question is, sourcing a high-quality cooler for my application and budget.

Water pump: I see...Yeah, cavitation seems like more of a concern for heavily modified / raced rotaries.

Transmission cooler: Found an example of an upgraded setup here... http://minkara.carview.co.jp/userid/208466/car/98037/438282/parts.aspx

The SERCK-SPEED cooler looks like a really nice unit but I'm not sure where it was sourced...Like the oil cooler, I'll have to source a high-quality unit for my application and budget.

Intercooler: I'm not planning on upgrading the intercooler just yet (depends on fundage) but I appreciate the advice on size...As with all my upgrades, I'd like them to remain effective if I increase power levels in the future...ARC used to offer a direct replacement intercooler...When I'm ready to upgrade, I may try to source a high-end order-made core and get the rest custom fabricated..?..We'll see!

Undertray: Keep it stock and fully functioning...Got it!

 

[rodneooo]

Wow...Thanks for describing your setup in detail, rodneooo!
no worries, glad to share
Glad to know it's holding up for you even with the aircon on in traffic...Got a few initial questions...

- So you're running two thermo fans mounted directly on the back of your radiator moving air along with the stock fan and shroud?
correct!
- What sort of lines are you using...What are the most durable type of lines (steel braided)?
for the tranny cooler im running braided lines, i had this from the setup in my previous car so i just reused them, was made by a workshop in sydney, if i could do it again id just use rubber oil lines, the braid can get abit frayed after time and can cut you and they stand out alot more in the engine bay, im trying to keep everything factory looking. rubber will do just fine. I had braided for the oil cooler lines too from the old setup, but i mounted in a different location this time so i had rubber oil lines made to suit from pirtek (a hose and fitting specialist in oz)

- What kind of aftermarket oil cooler are you using?
im not sure exactly what brand it is, however it is fairly thick and robust with large threaded fittings. its not thin and bendable like the cheaper ones are. very dense fins aswell

- Do you have any mesh / screen installed to protect the coolers for rocks etc?
no i dont, however the oil cooler is mounted fairly deep in the wheel well, basically flush with the plastic (iv also cut some holes to allow the air to pass through, nothing on the intercooler either.

- Does the stock water pump suffer from cavitation? Have you thought of porting / smoothing the internals?
not that im aware of, for a street car i wouldnt be too concerned with cavitation, just make sure the system is bled properly and it should be fine
- Are all PWR products made in Australia? How does their quality, design and durability compare to other well known brands?
iv heard mixed reviews with PWR in regards to their rads and heard of very bad customer service. never had a drama with my intercooler though.

Thanks again!

 

[Antoine]

Thanks for the responses, Rodney...Much appreciated!

I want to keep a clean look as well...I like the brushed and polished metal look over chrome.

Interesting point about steel braided lines...Perhaps rubber makes more sense.

 

[Berty]

I've been meaning to reply to this thread for a while but I have been getting sidetracked.

I trialed a number of set-ups over the years and was largely unhappy with all of them for some reason or another. Here are my experiences

-A single 16" fan, not matter what its rating is will never be enough. For the JC Cosmo aircon to work, you need a minimum of two fans. With the single, large fan, I would get 'hot air-con'. You MUST have two fans - one that triggers when the AC is active and another that comes on at a certain temp.

-Shrouds are a must. I have a massive aftermarket radiator and the un-shrouded electric fan did nothing.

-Get a proper temp gauge. After the mid-line, the next two lines on the factory temp gauge represent a 20 degree increase in temp!!!

-The clutch fan is awesome. As others have said, the choice to go to electric fan should not be made based on power-adding.

-The twin turbo's generate most of your heat. If you are going to rebuild them, ceramic coat the housings and dump pipe. The under-bonnet temp difference is huge as a result.

-There is a coolant nipple on the rear iron. If this is leaking it will introduce air-bubbles into the system and cause over-heats.

-The factory oil cooler is huge and awesome. Only change this as a last resort.

-The auto cooler is not as great. Change this for a unit with a thermo fan built onto it.

-The Carbing cooling plate is over-priced but it does work. If you can find one cheap, grab it.

Here is my advice;

-Copper or Aluminum radiator - at least twin past. Don't worry about the auto's heat exchanger.

-Clutch Fan with the thermo fan replaced with a higher rated SPAL unit. 12 to 14 inch.

-Ceramic coating of the turbo housings and dump pipe

-Ensure all under-trays are in good nic.

-Big fat intercooler

-Leave the factory oil cooler alone

-B&M Auto cooler with built in thermo fan.

-Ensure that there are no pressure leaks in the system - especially from the rear iron area which is susceptible.

Here is what I am running now...

-Twin electric fans from a BA Turbo falcon. Fan one turns on with air-con, fan two comes on at 85 degrees. Temps never exceed 90 degrees.
-Twin pass allow radiator (58mm thick)
-RX7 Reverse V-Mount cooler
-Stock oil cooler

This has been the best set-up yet. PLUS I run a single turbo and everything is heat-wrapped. You'd be surprised at how much heat that gets rid of compared to the twins. Hope that helps.

 

[Antoine]

Thanks for all that info, Berty...Much appreciated!

• You MUST have two fans - one that triggers when the AC is active and another that comes on at a certain temp.
  

Not sure if I will run fans initially, but if I do...I'll be sure to run two!

• Shrouds are a must. I have a massive aftermarket radiator and the un-shrouded electric fan did nothing.

I've realized this...No matter the fan type, size or use case...An effective shroud is critical in all cases.

• Get a proper temp gauge. After the mid-line, the next two lines on the factory temp gauge represent a 20 degree increase in temp!!!

I'm currently running an OLED Defi gauge with sensors reporting both Oil and Water Temp.

• The clutch fan is awesome. As others have said, the choice to go to electric fan should not be made based on power-adding.

What do you think about running the clutch fan AND two electric fans?

• The twin turbo's generate most of your heat. If you are going to rebuild them, ceramic coat the housings and dump pipe. The under-bonnet temp difference is huge as a result.

Great advice...I hadn't thought about that but it makes a lot of sense...I often leave the hood open after driving to release the heat...I would like to find a way to vent the heat out...Possibly with super subtle hood vents or some other stealthy way.

I saw this custom vent at the 20th Anniversary Meetup...I really like how it looks...







As for the Stock Turbos...I'd like to get them upgraded someday (like what http://bnrsupercars.com offers) and that would be a good time to get housing and exhaust ceramic coated!

• There is a coolant nipple on the rear iron. If this is leaking it will introduce air-bubbles into the system and cause over-heats.

Noted...Thanks!

• The factory oil cooler is huge and awesome. Only change this as a last resort.

I would like to see lower oil temps when in traffic and taking on intense mountain roads...I'm seriously thinking of adding an additional cooler in-line with the stock one...Maybe one with its own fan and shroud.

• The auto cooler is not as great. Change this for a unit with a thermo fan built onto it.

Noted...Planning on it!

• The Carbing cooling plate is over-priced but it does work. If you can find one cheap, grab it.

I've thought about getting one for a long time...If they are still in stock, I'm going to get one! Carbing products are beautifully made, love my front strut bar!

Here is my advice;

• Copper or Aluminum radiator - at least twin past. Don't worry about the auto's heat exchanger.

In Japan, they use the term "cores" (2 core is standard...3 core is beefy)...What exactly does "twin pass" mean?

• Clutch Fan with the thermo fan replaced with a higher rated SPAL unit. 12 to 14 inch.

As previously mentioned...What are your thoughts on running the stock clutch fan AND two radiator fans?

• Ceramic coating of the turbo housings and dump pipe

Noted!

• Ensure all under-trays are in good nic.

Noted!

• Big fat intercooler

In the plans...Maybe not in Stage 1 of cooling upgrades but definitely in the pipeline!

• Leave the factory oil cooler alone

Will do...Most likely adding a second cooler as backup!

• B&M Auto cooler with built in thermo fan.

Being in Japan, I'm going to have to see what the best options are for my budget.

• Ensure that there are no pressure leaks in the system - especially from the rear iron area which is susceptible.

Noted...Will do!

Here is what I am running now...

• Twin electric fans from a BA Turbo falcon. Fan one turns on with air-con, fan two comes on at 85 degrees. Temps never exceed 90 degrees.
  
• Twin pass allow radiator (58mm thick)
  
• RX7 Reverse V-Mount cooler
  
• Stock oil cooler
  

"Temps never exceed 90 degrees." That's my goal and it would be a major relief not to worry about temps, especially in summer!

 

[Cams]

Hi Antoine
Any chance of seeing your defi set up in action. Have liked the look of these units.
Darryl

 

[rodneooo]

Love that bonnet vent! very subtle and doesnt ruin the cosmos smooth lines. It even curves with the end of the bonnet, nice touch. may need something like that to suck out some heat later on down the track.

PS: i think i may have been abit too excited in my intercooler measurments. Its more like 450x450x70.

 

[cosmojc]

Hi Antoine,

I have always thought that the Cosmo bonnet needs that vent to let the heat out. Ive seen overhead pictures of that car for some time - I think its the one that has the really smick well installed aftermarket sunroof too! (?). I've toyed with the idea of a vent from a Mercedes - most of them have such a vent. I do hate the Cosmo badge on the front bumper tho - particularly as those badges are colour coded to the OEM paint and that badge is clearly off a yellow car!!

Also, I noticed you mention BNR upgraded Turbos. He does a good job from all reports and it would be fun to do BUT - you then take yourself into the realms of sorting out other issues eg you will probably/possibly need to do an aftermarket computer, installation, tuning and unforeseen "collateral" bother tinkering expense and possibly unreliability untill (if ever), it is "sorted" bigger turbos may also mean you need bigger injectors, fuel pumps .............................? and it can go on and on. If you can do most of the work yourself, have a garage, a surplus bank balance and want to tinker and play with enigmas in ridddles when stuff stops working or causes other problems - go for it! It will be awesome.

If not.......................................... and you a coward like me - what I did was mild upgrades eg big intercooler for Cosmo, hiflow second turbo, (it is possible), RE amemiaya computer, hi flow air filter, custom 3" exhaust. So far touch wood - it is working with most other components being OEM eg gearbox, engine ports, fuel pump etc etc.

BTW if you do need to take your turbo's off - YOU MUST check the OEM manifold for cracking in the centre. They are prone to it! BEFORE you reinstall you can prevent cracking simply by drilling the outer (not the centre two) 4 manifold bolt holes bigger by 1mm each - it just allows better for the expansion under the extreme Cosmo turbo heat! I also had my manifold ceramic coated. The new one isnt - anecdotally, I dont think there is a big difference BUT I'd do it again if I had thought of it at the time - anything to reduce Cosmo engine bay heat!!

Kramer
PS - how was your birthday?

 

[Antoine]

Hi Antoine
Any chance of seeing your defi set up in action. Have liked the look of these units.
Darryl

Sure...I realize I never took video of my Defi setup in action...I do have pics with comments though (taken from my thread)...

Shot from the driver's seat...Here you can see the Defi-Link Display partially mounted...The plan is to find a way to have it sit inside the ashtray allowing for the pop-open top to function like stock...It's a really cool idea and very "stealth" but it's also proving to be quite difficult...The Pro Audio guy is currently working up a plan to make it work...Stay Tuned

You can also see a preview of the custom Defi/Blitz glovebox setup...Although the current setup is super sweet...There are still some details I'd like to workout before giving the (thumb)...Notice the Defi & Blitz units are slightly angled towards the driver for easy viewing and access...(2thumbs)

Sorry about the fuzziness...I didn't want to use flash ...Here is a close up of the Defi-Link Display in action...So far I've got Water & Oil Temp sensors hooked up...I really like this unit...It's very easy to read day or night and the info it provides is invaluable!

The new Amemiya/Defi setup came out really nice...I can imagine it being a Mazdaspeed factory option from the Dealer back in the day...Plus it's great knowing what the twins are up to at any time...(boobs)

 

[Antoine]

Love that bonnet vent! very subtle and doesnt ruin the cosmos smooth lines. It even curves with the end of the bonnet, nice touch. may need something like that to suck out some heat later on down the track.

PS: i think i may have been abit too excited in my intercooler measurments. Its more like 450x450x70.

I wonder what car that vent is from..? I didn't have a chance to ask the owner...Wish I had!

Thanks for the update on your intercooler measurements..

 

[Antoine]

Hi Antoine,

I have always thought that the Cosmo bonnet needs that vent to let the heat out. Ive seen overhead pictures of that car for some time - I think its the one that has the really smick well installed aftermarket sunroof too! (?). I've toyed with the idea of a vent from a Mercedes - most of them have such a vent. I do hate the Cosmo badge on the front bumper tho - particularly as those badges are colour coded to the OEM paint and that badge is clearly off a yellow car!!

Yes, that's the one!



So you think the vent is from a Benz? Sure?

Also, I noticed you mention BNR upgraded Turbos. He does a good job from all reports and it would be fun to do BUT - you then take yourself into the realms of sorting out other issues eg you will probably/possibly need to do an aftermarket computer, installation, tuning and unforeseen "collateral" bother tinkering expense and possibly unreliability untill (if ever), it is "sorted" bigger turbos may also mean you need bigger injectors, fuel pumps .............................? and it can go on and on. If you can do most of the work yourself, have a garage, a surplus bank balance and want to tinker and play with enigmas in ridddles when stuff stops working or causes other problems - go for it! It will be awesome.

I hear ya...I wouldn't venture down the path of upgraded turbos without first assuming I will need to upgrade other related systems like fuel and ecu etc.

If not.......................................... and you a coward like me - what I did was mild upgrades eg big intercooler for Cosmo, hiflow second turbo, (it is possible), RE amemiaya computer, hi flow air filter, custom 3" exhaust. So far touch wood - it is working with most other components being OEM eg gearbox, engine ports, fuel pump etc etc.

I wouldn't call it cowardly...Just sensible...lol...Beyond that is simply "hardcore"...How do you like the RE Amemiya upgrade and how do you think it would compare to going with a professionally tuned piggy-back...I would like to optimize performance without loosing streetability and durability. I believe RE Amemiya still offers their ECU upgrade for the Cosmo (unconfirmed). Unless I'm mistaken, the advantage of a piggy back would be that it can be tailor-tuned for my exact setup but there is the disadvantage of added complexity etc.

Have you had your current setup on the dyno?

BTW if you do need to take your turbo's off - YOU MUST check the OEM manifold for cracking in the centre. They are prone to it! BEFORE you reinstall you can prevent cracking simply by drilling the outer (not the centre two) 4 manifold bolt holes bigger by 1mm each - it just allows better for the expansion under the extreme Cosmo turbo heat! I also had my manifold ceramic coated. The new one isnt - anecdotally, I dont think there is a big difference BUT I'd do it again if I had thought of it at the time - anything to reduce Cosmo engine bay heat!!

Thanks for the heads up!

 

[Antoine]

Well after some initial research as to what's available / possible in Japan...I'm thinking...

- Replace Radiator -

• 3-Core
• Aluminum
• Local Custom Job

- Add an additional Oil Cooler -

• Blitz Type RS

or

• HKS Type S

or

• Setrab

- Replace Tranny Cooler -

• Blitz ATF Cooler

or

• HKS A/T Cooler

- Replace Hoses -

I'm also thinking of a silicone setup like the one shown below...






- Additional Parts -

• Carbing Cooling Plate (if still available)

* I might upgrade the intercooler at a later stage...Depends on the budget!