JHM C7 Heat Exchanger DIY (3.0T & 4.0T) - SOO EASY

[ericw.]

Figured I'd do a quick write up since this was so easy that a write up is really minimal effort and it might help someone gain the confidence to tackle this project themselves.

Disclaimer: I'm not a professional mechanic and I'm not responsible if you damage your car while following this DIY guide.

LOE: About 2 hours
Tools: Impact or drill with socket attachment, 8MM socket, T20, T25, T30, hose clamp tool or pliers, and ideally some hose clamps (links in the writeup)
+ It's always nice to have a helping hand when lining up and reinstalling your bumper.

1) Remove your bumper (not doing a writeup here because it’s been covered and is nearly identical for almost all Audi cars)


2) Note how tiny and wrecked your old heat exchanger is, then locate your coolant delivery and return lines and clamp them to minimize your loss and prevent any necessity to burp the entire coolant system.
Cheap coolant hose clamps, I’d buy 2 because it's nice to have 2 of each size: https://www.amazon.com/gp/product/B074338394/


3) Set out your coolant catch pan so we're not polluting the environment and remove your coolant hose clamps, then pull the hoses off. NOTE: Take note of which hose goes to the bottom and which goes to the top.
This is a great tool to have in your box if you don’t have one already: https://www.amazon.com/gp/product/B07NZLQ8SD
Also these hose picks are always nice to have if you ever encounter a stubborn hose: https://www.amazon.com/gp/product/B071JVYFD2/


4) There’s 1 T30 torx screw on the right side and a squeeze clip on the left side.
Remove the T30:



Squeeze the left side clip and pull the stock HX out:


5) Slide your new JHM heat exchanger (with bracket attached) in between the crash bar and A/C condenser/radiator. Line it up in the center and use an impact or drill with the JHM supplied self-tapping bolts and a 8MM socket. JHM's bracket rests right on top of your crash bar which makes this a breeze.


6) Install the barbed couplers in your stock coolant lines and put the hose clamps back in place. Trim JHM’s supplied coolant lines to your desired length and install.. NOTE: Make sure to reconnect the original bottom line to the bottom of the HX and the top to the top. For efficiency reasons, heat exchangers are directional.


7) Unscrew the top bleed valve of the heat exchanger and pour coolant (useful tip) in small amounts to allow air to escape after each pour.


8) Reinstall your bumper, reconnect all your sensors, and run the car to temp to make sure all the air is out. Top off coolant if necessary and enjoy!

[ericw.]

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[2by2handsofblue]

Nice. I assume this would work on the s5 too

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[kebabman]

Thanks for the write up!

Any before and after IAT logs you can share?

[charrigan]

Thank you for the brief write up! Based off how much easier this looks to install vs the merc racing I would rather pay a couple hundred more for the install time savings.

[ericw.]

Nice. I assume this would work on the s5 too

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It should, and from what I've heard there's a lot more space between crash bar and AC condenser so you should have no problems. This kit has already been installed on an S4 and A6 3.0 supercharged.

Thanks for the write up!

Any before and after IAT logs you can share?

I didn't log IAT because I was having some problems connecting to that sensor with the logging tools I had at my disposal but I did log stock coolant temps on 3 back to back 0-60 runs at 54 degree ambient temp on an overcast day. I didn't find it incredibly inefficient at stock to be honest, but I do plan to log "after" as soon as I can replicate the scenario. It's been raining since I installed so I haven't had a chance yet.

I observed the coolant temps would come back to normal between the time I could turn around and run 0-60 again.

Thank you for the brief write up! Based off how much easier this looks to install vs the merc racing I would rather pay a couple hundred more for the install time savings.

Another bonus for the $, JHM includes everything you need to install except the coolant. Install kit from Merc Racing will run you another $50 which slightly closes the price gap.

[Jake@JHM]

Right on! Glad you like it I'm sure this will help people with the install (if it wasn't already easy enough)!

[Jake@JHM]

Nice. I assume this would work on the s5 too

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Absolutely!

[Jake@JHM]

Thank you for the brief write up! Based off how much easier this looks to install vs the merc racing I would rather pay a couple hundred more for the install time savings.

Let me know if you have any questions!



https://jhmotorsports.com/heat-excha...3-0t-4-0t.html

[2by2handsofblue]

What's the difference between a dual pass vs quad pass?

I read that it wouldn't much a difference between a dual vs quad in cooling.

Wouldn't moving more coolant on a dual pass be more efficient vs going through a quad design and moving less coolant?

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[Jake@JHM]

What's the difference between a dual pass vs quad pass?

I read that it wouldn't much a difference between a dual vs quad in cooling.

Wouldn't moving more coolant on a dual pass be more efficient vs going through a quad design and moving less coolant?

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Dual vs Quad is how many times the coolant passes back through the HX. A Dual Pass is two times and Quad is 4 times. The more times the coolant can "pass" through the HX the more time it has to dissipate heat.

Your question cannot be answered correctly as there are too many variables missing. However, moving coolant faster you will want MORE passes (provided that the overall size of the HX is the same between the two), as the quicker the coolant is moving the less time it has to shed heat, so you will want it to spend more time in the HX.

We haven't tested the various coolant pumps yet that is a popular upgrade on these platforms, but there is a possibility that people are hurting their performance by moving the coolant too quickly through the HX.

This is a widely debated subject though, and what you need can vary depending on platform and cooling requirements. In motorsports, more passes are commonly used than less.

[2by2handsofblue]

Dual vs Quad is how many times the coolant passes back through the HX. A Dual Pass is two times and Quad is 4 times. The more times the coolant can "pass" through the HX the more time it has to dissipate heat.

Your question cannot be answered correctly as there are too many variables missing. However, moving coolant faster you will want MORE passes (provided that the overall size of the HX is the same between the two), as the quicker the coolant is moving the less time it has to shed heat, so you will want it to spend more time in the HX.

We haven't tested the various coolant pumps yet that is a popular upgrade on these platforms, but there is a possibility that people are hurting their performance by moving the coolant too quickly through the HX.

This is a widely debated subject though, and what you need can vary depending on platform and cooling requirements. In motorsports, more passes are commonly used than less.

Thanks.

It's on this forum. And there seems to be a debate whether is dual is efficient enough vs quad or I've read there is a tri pass as well.

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[flyfishing]

Do you all with HX notice that it takes longer for the coolant gauge to hit midway? Makes sense if it does b/c more cooling of coolant...

[2by2handsofblue]

Do you all with HX notice that it takes longer for the coolant gauge to hit midway? Makes sense if it does b/c more cooling of coolant...

I wouldn't know. I'm still on OEM. But I'm looking to purchase one 1 day. Maybe if there is a nice sale.

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[wootwoot]

Let me know if you have any questions!



https://jhmotorsports.com/heat-excha...3-0t-4-0t.html

What are the dimensions?

[Twkdcd595]

Interesting, I like that the inlet and outlet are on the driver side (US drivers).

I need to consider this when doing the upgraded pump.

ETA: Is the mounting hardware to hold the heat exchanger bracket to the crash bar stainless?

[Jake@JHM]

Interesting, I like that the inlet and outlet are on the driver side (US drivers).

I need to consider this when doing the upgraded pump.

ETA: Is the mounting hardware to hold the heat exchanger bracket to the crash bar stainless?

They are UCR Steel Very sturdy when mounted.

[Jake@JHM]

What are the dimensions?

W 22″ x H 17″ x D 2.5″

[BuickTypeR]

So what is the difference between JHM C7 Heat Exchanger and merc or others?

[Mark.in.tulsa]

Hypothetically speaking, if you put a larger heat exchanger like this on a stock 3.0, would it increase HP at all.
Now I get it after multiple runs or dyno pulls it would help. But on an initial 1/4 mile run or dyno pull would it help HP numbers at all?

[ericw.]

Hypothetically speaking, if you put a larger heat exchanger like this on a stock 3.0, would it increase HP at all.
Now I get it after multiple runs or dyno pulls it would help. But on an initial 1/4 mile run or dyno pull would it help HP numbers at all?

When you're doing pulls, the motor gets hot and computer responds by pulling timing (hp) to keep things safe. This will help keep things cooler for a little bit longer. It doesn't add horsepower but just helps you maintain your existing power for a bit longer.

[A6kycat]

Have the JHM heat exchanger going on at this moment with Unitronic Stage 3 dual pulley, cant wait to finally chime n on some of these posts....

[Jake@JHM]

Have the JHM heat exchanger going on at this moment with Unitronic Stage 3 dual pulley, cant wait to finally chime n on some of these posts....

Thanks for the order Make sure that the system is properly bled. Many leave air pockets in the system which significantly reduces performance. Bleed from the HX as well as both supercharger intercoolers

[A6kycat]

I will certainly ask when i pick it up, thank you! How is the ECU tune for the C7 A6 A7 coming along??? Anytime soon?

[Jake@JHM]

I will certainly ask when i pick it up, thank you! How is the ECU tune for the C7 A6 A7 coming along??? Anytime soon?

We are practically done with it. Just waiting on the cooler weather again to run an official number and any final touches. So far we have done 12.0@114 with stock pulleys. Would definitely be 11s in the wintertime and then if we go race gas we can likely get even further into the 11s on stage 1.

Then after that, we will be doing stage 2 and DP files.

[A6kycat]

We are practically done with it. Just waiting on the cooler weather again to run an official number and any final touches. So far we have done 12.0@114 with stock pulleys. Would definitely be 11s in the wintertime and then if we go race gas we can likely get even further into the 11s on stage 1.

Then after that, we will be doing stage 2 and DP files.

Picked up the car this morning with the dual pulley install with JHM heat exchanger and forge motorsports divorce coolant system. it was nice getting up to those speeds a little quicker, drove for 3 hours and the temps never made it up higher than half way up the gauge, where it has sat for most of the cars life. I was hesitant of going dual pulley for fear of over heating the car and any issues that come along with this but the system really worked well for me today! Hoping it stays that way!

[Ford Prefect]

Do you all with HX notice that it takes longer for the coolant gauge to hit midway? Makes sense if it does b/c more cooling of coolant...

This upgrade is for charge cooling, not engine cooling. Nothing changes on the engine coolant side which is what you’re referring too. They only share a reservoir, everything else is separate.


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[GodFatherMav03]

Is JHM one better then the APR one?

[ericw.]

Is JHM one better then the APR one?

We don't have data to back it up yet but APR is a 3 pass heat exchanger and JHM is a 4 pass heat exchanger.. In theory, and based on what we know in other applications, it should be better.

[GodFatherMav03]

We don't have data to back it up yet but APR is a 3 pass heat exchanger and JHM is a 4 pass heat exchanger.. In theory, and based on what we know in other applications, it should be better.

I figured it would be and for a better price too.

[dragrace8]

I recently purchased the JHMotorsports one in black. On Saturday July 18th, I made 10 runs at Bandimere. 6 of those runs were with the temp above 90 degrees. The other 4 the temp was between 82-89. After crunching the numbers, on runs where I had less than 45 minutes between pulls, the car was about 5 hundredths quicker than stock. On runs where I had an hour or more in between, the car was between 8 hundredths and a tenth and a half quicker. I forgot my laptop so I didn't record any IAT numbers, but based on the time slips and runs I've made before in similar conditions, there definitely was some improvement with the new heat exchanger. I've never ran the Merc or the APR so I can't compare, but I'm happy with my JHM purchase and would have no issue recommending it.

[Jake@JHM]

I recently purchased the JHMotorsports one in black. On Saturday July 18th, I made 10 runs at Bandimere. 6 of those runs were with the temp above 90 degrees. The other 4 the temp was between 82-89. After crunching the numbers, on runs where I had less than 45 minutes between pulls, the car was about 5 hundredths quicker than stock. On runs where I had an hour or more in between, the car was between 8 hundredths and a tenth and a half quicker. I forgot my laptop so I didn't record any IAT numbers, but based on the time slips and runs I've made before in similar conditions, there definitely was some improvement with the new heat exchanger. I've never ran the Merc or the APR so I can't compare, but I'm happy with my JHM purchase and would have no issue recommending it.

That's awesome, thanks for the feedback

[ArkAudiA7]

Thanks EricW for the write up! I followed this guide and installed the JHM hx this weekend. Acquired the tools in the links too. That saved a lot of time searching and is appreciated.
Test run went fine but that was only to get the temp up and check for leaks. I probably should log IAT since I'm APR stage I now and will have APR tage II with JHM 207mm pulley installed Nov 6.

Couple of differences on my A7 that I'll point out for future DIYers. My stock HX has a coolant hose on the drivers and passenger side. No big deal but it freaked me out at first.
JHM sends a strip of thin rubber foam that appears to be for sound deadening but had no idea where it is intended to install so it went in between the bumper and hx install bracket.
JHM does not send any install instructions in the box. Without knowing about this site and write-up, I probably would have been slightly irritated...or something like that.
I have a RS style grill and I had to trim just a small amount of plastic so it didn't hit the hx. Might have been avoided if I measured first.
Noticed during the test fit that there is enough space that one could install the JHM hx and kept the stock hx. Not sure if that's a good or bad idea but it looked like an option.

[Jake@JHM]

Thanks EricW for the write up! I followed this guide and installed the JHM hx this weekend. Acquired the tools in the links too. That saved a lot of time searching and is appreciated.
Test run went fine but that was only to get the temp up and check for leaks. I probably should log IAT since I'm APR stage I now and will have APR tage II with JHM 207mm pulley installed Nov 6.

Couple of differences on my A7 that I'll point out for future DIYers. My stock HX has a coolant hose on the drivers and passenger side. No big deal but it freaked me out at first.
JHM sends a strip of thin rubber foam that appears to be for sound deadening but had no idea where it is intended to install so it went in between the bumper and hx install bracket.
JHM does not send any install instructions in the box. Without knowing about this site and write-up, I probably would have been slightly irritated...or something like that.
I have a RS style grill and I had to trim just a small amount of plastic so it didn't hit the hx. Might have been avoided if I measured first.
Noticed during the test fit that there is enough space that one could install the JHM hx and kept the stock hx. Not sure if that's a good or bad idea but it looked like an option.

Thanks for the feedback! We have this write-up linked on our product page =]


The cushion clamp we include will mount onto the heat exchanger to core bracket to hold the hose coming from the passenger side behind the heat exchanger keeping it out of the way.

If you can fit both heat exchangers it definitely wouldn't hurt. We do this for other platforms that don't have the spacer for a large HX like this one.

When logging IATs make sure you keep as many conditions the same as what you are comparing against. For example, 3rd gear pull from 20mph to 90mph on a 75F day. Do your best to use the same section of road as well.


My car (C7 A6) the IATs stay around ~10 degrees above ambient with this HX with the recovery time being very rapid.

We are working on a large Supercharger Coolant Tank for the C7 A6/A7 that will improve IATs even further

[mwmaroney1]

Thanks for the feedback! We have this write-up linked on our product page =]


The cushion clamp we include will mount onto the heat exchanger to core bracket to hold the hose coming from the passenger side behind the heat exchanger keeping it out of the way.

If you can fit both heat exchangers it definitely wouldn't hurt. We do this for other platforms that don't have the spacer for a large HX like this one.

When logging IATs make sure you keep as many conditions the same as what you are comparing against. For example, 3rd gear pull from 20mph to 90mph on a 75F day. Do your best to use the same section of road as well.


My car (C7 A6) the IATs stay around ~10 degrees above ambient with this HX with the recovery time being very rapid.

We are working on a large Supercharger Coolant Tank for the C7 A6/A7 that will improve IATs even further

Any tips on the best way to bleed this system with a S6? Also it was a little more challenging installing this on my car with all the options equipped. Night vision, camera etc got in the way.

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[ericw.]

Any tips on the best way to bleed this system with a S6? Also it was a little more challenging installing this on my car with all the options equipped. Night vision, camera etc got in the way.

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I use this anytime I need to bleed coolant on an Audi.
https://www.amazon.com/gp/product/B07NM8ZRPM/

However you shouldn't need to bleed the system if you follow my writeup and clamp the coolant lines. Fill the HX coolant from the top of the HX, not the coolant overflow tank.

[Dasquade]

Is it me but that cooler doesn't look all too big (compaired to my wagner cooler witch covers the complete grill surface in height and width and is also ticker, it is also a triple pass).
Just saying...

[ericw.]

Is it me but that cooler doesn't look all too big (compaired to my wagner cooler witch covers the complete grill surface in height and width and is also ticker, it is also a triple pass).
Just saying...

This is quad-pass not triple pass.

I played with fitment to see if it could be mounted differently.. 1 inch higher will touch the intake scoop with the bumper on, 1 inch lower will be below the AC condenser which would make it the lowest object on the front of the car. Left/right and the HX will touch the AC condenser. I really doubt you could fit much more HX behind the crash bar without sacrificing. (edit: on the 4.0T anyway)

[mwmaroney1]

I use this anytime I need to bleed coolant on an Audi.
https://www.amazon.com/gp/product/B07NM8ZRPM/

However you shouldn't need to bleed the system if you follow my writeup and clamp the coolant lines. Fill the HX coolant from the top of the HX, not the coolant overflow tank.

Not sure there's any bubbles in there or not was just going to do it to make sure. So there's no traditional way to burp these I'm guessing? The lines are always pressurized right?

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[ericw.]

Not sure there's any bubbles in there or not was just going to do it to make sure. So there's no traditional way to burp these I'm guessing? The lines are always pressurized right?

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I read on the forums that someone was successful the traditional way, I just always use the tool.

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