DIY Ultimate CVT Cooler with pics

[ThatWhiteFK7]

I ended up just adding an extra half quart for starters to be safe. But still started the car to allow Transmission fluid to fill the hoses and cooler.

Basically I added half a quart. Started the car. Shifted from P,R,N,D,N,R,P while allowing 3-5, seconds between each shift.

Then turned the car off. Removed the check bolt from the Transmission again. And started to add more fluid until it overflowed from the check bolt hole.

That way I knew for sure not only did the hoses and cooler have fluid in them. But the Transmission itself was at the full level as well.

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[ClintFK7]

Sounds like a good method.

 

[AlexSt84]

First of all awesome guide, Respect!

I am an owner of Sport Plus FK7, the one that comes with a stock CVT cooler, but the place it's located and because we have Honda Sensing Radar in front of it, so can't do holes in the Bumper/Mesh Insert to give it more air. I am thinking of upgrading the cooler and putting it behind the grille, the catch is that I have an Engine oil cooler from Maperfromance installed, so I guess, I need to do some measurements to fit it in. Why upgrade it, recently I brought this car to full stage2 and the temperature of the CVT is hitting 200F easily.

 

[ThatWhiteFK7]

First of all awesome guide, Respect!

I am an owner of Sport Plus FK7, the one that comes with a stock CVT cooler, but the place it's located and because we have Honda Sensing Radar in front of it, so can't do holes in the Bumper/Mesh Insert to give it more air. I am thinking of upgrading the cooler and putting it behind the grille, the catch is that I have an Engine oil cooler from Maperfromance installed, so I guess, I need to do some measurements to fit it in. Why upgrade it, recently I brought this car to full stage2 and the temperature of the CVT is hitting 200F easily.

I still hit like 219F° on my CVT during a very spirited 2 hour backroads cruise in our most intense parts of the drive. But that is about 20-25F° less than what I was seeing before the CVT Cooler. I may need a bigger core than the ETL CVT Cooler Kit provides.

 

[Smellycat]

Isn’t there an efficient temperature range for the cvt to grab and operate
Wouldn’t it being too cool, make it slip more? Or am i wrong lol

 

[ThatWhiteFK7]

Isn’t there an efficient temperature range for the cvt to grab and operate
Wouldn’t it being too cool, make it slip more? Or am i wrong lol

Best temperature range is around 170-200F°. Which is what you see all the time usually just driving normal. I wouldn't beat on a CVT trans that's not even atleast at 140°F first. Obviously you wanna let it warm up. But no CVT cooler will keep the CVT so cold it can't reach operating Temps. Even if you eliminate the CVT warmer aspect and just go with a cooler only after warming up to operating Temps the CVT isn't gonna get cooled down so much by any cooler that it causes slip. But the goal is to keep CVT Temps below 220F°. If you do some research and look up how Transmissions are affected by high Temps. It's something like every 20°F over 220°F starts to exponentially wear out seals in the trans and burn up interior clutches in the Transmission and etc.

 

[CVT4NYC]

I wanted to share my method of what I think is a necessary upgrade for anyone looking to do prolonged spirited driving with a CVT. I upgraded the entire cooling system on my FK7 but the real DIY part revolves around the CVT cooler as I ended up building my own kit.

I experienced CVT slip at 17K miles due to hot fluid temps with nothing more than a PRL intercooler, Ktuner stage1 (18 psi) base tune for 87 octane, and a K&N drop in air filter. Just before this happened I had noticed my coolant temps had climbed up to 219 after several hard pulls at the end of a 40 mile commute on a 91 degree day. Once the coolant temps came down, I made another pull and instead of holding at 6K rpm, the engine bounced off the rev limiter. In hindsight the engine oil and transmission fluid had not been able to shed the stored heat in the same way the engine coolant had, so I have no way to know how hot they had gotten from earlier. I eased the car home without further issue. After thoroughly changing the CVT fluid, the transmission held torque just fine, so for now it appears no damage was done.

Given I don't want to baby the car everytime it's hot outside, I looked into engine oil coolers and CVT cooler options. While there are multiple oil cooler options for 10th gens as the turbo tends to heat the oil under serious driving, there really wasn't much out there for the CVT likely because the 6MT gets all of the love.

I found that PRL had discontinued their CVT kit before it ever even took off. I found a few custom jobs on random Facebook pages, but nothing for sale as a kit until I came across the ETL kit available on Two Step Performance. There wasn't a lot of information in the product description and I only found 1 writeup with a picture of the mounted location on the forum but I decided to pull the trigger as it was my only option for a complete kit.

I ended up ordering the kit, but I did not think the cooler would get enough airflow behind the bumper where ETL intended to mount it similar to where the Spanish or Turkey factory CVT Civics have them. I also couldn't use that location because I needed to start running a PRL Cobra cold air intake in that location because my previous 27Won airbox had to be removed once I added the PRL intercooler as it would not clear the charge pipe and even my stock air box had never fully cleared the charge pipe causing the two to work together but always rub each other.

I decided to mount the trans cooler behind the grille, which also narrowed which oil cooler kits I could use. MAPerformance makes a beautiful engine oil cooler kit but I knew it took up too much of the factory grille to also run a trans cooler. That's when I noticed that the Sirimoto Oil Cooler kit from PRO Car Studio appeared to take up exactly half of the radiator, leaving the other half open for an identical sized cooler. That's when I found that Derale made a 19 row stacked plate transmission cooler with AN-6 fittings for 3/8 hose barbs that was the same size as the 19 row engine oil cooler. This was not only the right size, but had identical mounting tabs, and can shed more heat than a tube and fin style cooler. I picked up some Evil Energy 90 degree AN-6 to 3/8 barb fittings to make routing the lines from the cooler a bit easier.

I also knew I needed to get more airflow through the grille than the factory solid bar grille would allow, so I picked up a Pro Car Studio open mesh grille.

I did not like how easily the factory engine coolant temps would spike from 185-195 during normal driving and now I was going to be blocking the entire surface area of the radiator with 2 coolers in front of the AC condenser so I decided to upgrade the radiator. I reached out to Unity Performance and picked up a Koyorad 2 row aluminum radiator. I also decided to run the 3 piece silicone radiator hose kit from MAPerformance.

Lastly adding these coolers would give me a way to mount temperature sensors for these two fluids that Honda didn't bother to monitor from the factory, so I picked up a pair of glowshift gauges.

Once I mounted the engine oil cooler, it was apparent that I could use longer bolts on the inner mounting brackets to mount the transmission cooler as the bolt patterns are the same. I used some aluminum spacers from McMaster Carr to overlap the mounting tabs and I made two brackets from a sheet of stainless for the outer mounts of the trans cooler. The upper bracket is a basic L bolted to a threaded hole in the radiator support that Honda left unused. For the lower bracket, I just made an exact replica of Sirimoto's outer bracket.

I also purchased a thermal bypass valve, but have not installed this yet. I still needed to know which line was hot for installing my temperature sensor as I wanted my gauge to read the temp from the hot side. I installed the trans cooler and used an infrared thermometer to see which line was hotter and which line was cooler. The bottom line from the ETL adapter block was hotter which tells me it is going to the cooler and the top line is lower temp so it was the return after the cooler. A few cheap aluminum hose spacers and some Earle's Vaporguard clamps help to protect the 3/8 rubber lines.

I will watch my temps without the bypass and as we head into winter I will decide if I want to install it. I was going to use the bypass valve Derale makes but after test fitting it in every possible location, it's just too big for how tight everything else is on these cars. I ended up getting a TruCool by Long and it is much smaller, lighter, and therefore doesn't need a bracket. Again, I may not install it unless I see my temps are staying too cold in winter.

When all was said and done, the ETL adapter block is the only part I used from the whole CVT cooler kit, but I'm happy with the end result. I do wish ETL had made their adapter block with a tab to hold the trans filter further in like the OEM warmer block has. I tested how far back the filter would be allowed to pop out when flush with the cooler adapter block and it did not appear to be able to travel beyond the full seat of the o-ring but I always like to see aftermarket parts retain factory fitment when possible.

The two coolers completely disappear behind the grille.

I mentioned above that the PRL Cobra CAI was a necessity for me due to space issues with my PRL intercooler charge pipe. For this reason I can't attest to how much room the ETL adapter block would have behind the factory airbox as it does push the factory CVT warmer forward about an inch. I did have to bend the lower coolant line coming out of the warmer back a little to give more clearance to the back of the charge pipe. Given the necessary CAI, I went with a race MAF and adjusted my tune accordingly. I also cut the back out of the dummy slot on the driver side fake vent so some cool air can make it's way to the air filter. The hole is above the Lane Watch Sensor so it remains protected. I also added a shield to the front of the air filter so no direct road spray rain can hit the filter.

I plan to keep enjoying this CVT and the +3 psi base tune certainly won't kill the transmission provided I can keep the fluid cool enough to do it's job...mission accomplished.

How much fluid did you end up adding?

 

[ClintFK7]

How much fluid did you end up adding?

Post #30 on page 2 has some specifics about additional fluid capacity. If running the ETL cooler you would add 9 ounces. If running the large stacked plate cooler you would add 18 ounces.

 

[CivilizedSavage23]

Great info here! Thanks for your time sharing your wisdom. Looking into this just to provide some more security when driving the CVT in a “spirited” fashion. lol. This answered so many questions. I’ll post pics when I finish up my DIY. Thanks again! B

 

[AlexSt84]

@CivilizedSavage23 Are you sure that an upgrade to an OEM fan isn't required? it's kind of blocked now with three lines of coolers. I tried to find if any vendor did a dual shroud for our radiator, and found only one vendor which sells with radiator and not separately. I guess it depends on where you live, in a hotregion, a such upgrade would be relevant.

https://www.yonaka.com/product_p/ymar-civ1615.htm

 

[ThatWhiteFK7]

@CivilizedSavage23 Are you sure that an upgrade to an OEM fan isn't required? it's kind of blocked now with three lines of coolers. I tried to find if any vendor did a dual shroud for our radiator, and found only one vendor which sells with radiator and not separately. I guess it depends on where you live, in a hotregion, a such upgrade would be relevant.

https://www.yonaka.com/product_p/ymar-civ1615.htm

Honestly a better flowing aftermarket grill would eliminate most any problems that adding coolers infront of the radiator would create. I just upgraded mine and both my coolant and trans Temps are even happier with the extra air flow.

 

[ClintFK7]

@CivilizedSavage23 Are you sure that an upgrade to an OEM fan isn't required? it's kind of blocked now with three lines of coolers. I tried to find if any vendor did a dual shroud for our radiator, and found only one vendor which sells with radiator and not separately. I guess it depends on where you live, in a hotregion, a such upgrade would be relevant.

https://www.yonaka.com/product_p/ymar-civ1615.htm

I have ran custom shrouds and dual Spal fans on other vehicle platforms, but when the OEM fan on this civic turns on, the coolant temps drop very quickly which tells me the fan moves sufficient airflow across the radiator which is the most rearward layer. (I have watched the coolant temps go from 204F to 174F in about 6-8 seconds). I think the aftermarket open mesh grille is important to give the OEM fan more area to pull through.

When running the air conditioner, the fan is generally running intermittently regardless of coolant temps so I rarely see anything above 183F with the Koyorad radiator.
If not running the AC, the fan doesn't turn on until something like 204F, but I have to be sitting still on a very hot day for several minutes for it to even try to climb that high.

K-Tuner allows you to adjust the temps that trigger when the fan comes on if you want it to kick in at a lower temp, but again if you are running the AC system those settings are fairly irrelevant unless you somehow build enough heat to need the higher fan speeds to kick in.

 

[AlexSt84]

@ClintFK7 I do have a mesh grill, i just thought that putting oil engine and transmision coolers, will reduce the airflow to radiator and engine bay itself.

 

[Type-JZ]

Nice job. Pretty slick! Was thinking of adding something like this to my fk8. I track often and the trans fluid don’t seem to last. We have a similar oem cooler setup. Ac delco synchromesh with FM only lasts about 3 track days for me before I feel the trans oil break down and get very notchy. Similar with redline. Redline lasts longer tho. Maybe 5-6 track days. Curious to see if this would help the longevity of the fluid.

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