Heat Exchanger or TCU Tune - Next Mod?

[AerotusX]

Hello guys, I have an itch for my next mod and would like to hear your suggestions. As the weather is heating up in SoCal, I'm think of adding the APR CPS to fight against heat soak. I'm also wanting to do the APR TCU tune to smooth out gear shifts and increase the redline for harder pulls on top end. This is my DD and I drive pretty hard regularly. Both cost about a grand and I can only do one of them. Which one would you suggest and why? My goal is best bang for the bucks performance gain overall. My current mods are in my sig. Thanks in advance!

[Rodizzle]

Hello guys, I have an itch for my next mod and would like to hear your suggestions. As the weather is heating up in SoCal, I'm think of adding the APR CPS to fight against heat soak. I'm also wanting to do the APR TCU tune to smooth out gear shifts and increase the redline for harder pulls on top end. This is my DD and I drive pretty hard regularly. Both cost about a grand and I can only do one of them. Which one would you suggest and why? My goal is best bang for the bucks performance gain overall. My current mods are in my sig. Thanks in advance!

Since your running apr stage 2 already I would do the heat exchanger , TCU is great investment but u would just get throttle happy and eventually heat soak sooner :p .


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[theweebabyseamus]

Hello guys, I have an itch for my next mod and would like to hear your suggestions. As the weather is heating up in SoCal, I'm think of adding the APR CPS to fight against heat soak. I'm also wanting to do the APR TCU tune to smooth out gear shifts and increase the redline for harder pulls on top end. This is my DD and I drive pretty hard regularly. Both cost about a grand and I can only do one of them. Which one would you suggest and why? My goal is best bang for the bucks performance gain overall. My current mods are in my sig. Thanks in advance!

Split the difference. TCU tune and then divorce the factory heat exchanger and run straight water/WW and do the coolant pump mod. It would help IAT's modestly (but an improvement for sure) and cost about $50. Then do the heat exchanger when you find a cheap one, namely not an APR CPS.

[brs2c]

Heat Exchanger-the cooler the better on all our setups...you may what to consider some better options, outside of APR if you ever want to step your game up to a DP and/UC and want to maximize power on hot days.

[cspcrx]

HE, I did it before doing any tune and saw a benefit. Must have on these cars.

[B18b1ex]

Hello guys, I have an itch for my next mod and would like to hear your suggestions. As the weather is heating up in SoCal, I'm think of adding the APR CPS to fight against heat soak. I'm also wanting to do the APR TCU tune to smooth out gear shifts and increase the redline for harder pulls on top end. This is my DD and I drive pretty hard regularly. Both cost about a grand and I can only do one of them. Which one would you suggest and why? My goal is best bang for the bucks performance gain overall. My current mods are in my sig. Thanks in advance!

Get the Merc, and the TCU after.


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[AerotusX]

Thanks guys, seems HE has the majority vote. The Merc is only $400, is there anything else I need? The Merc volume is massive compared to others, is it just as efficient as APR or better? Seems like a no brainer at this price, unless I'm missing something.

[Fresh.S4]

ooh! a local with the same color/ new body style!! have pics of what that woodgrain looks like?

[B18b1ex]

Thanks guys, seems HE has the majority vote. The Merc is only $400, is there anything else I need? The Merc volume is massive compared to others, is it just as efficient as APR or better? Seems like a no brainer at this price, unless I'm missing something.

I think the price difference is because Merc realizes its just a radiator and has not added the Audi tax. It’s a quad pass, and good quality. I have run one for almost a year here in SOFL, i’m not dual pulley but I know the car runs better now than it did with stock HE in our constant heat!


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[AerotusX]

ooh! a local with the same color/ new body style!! have pics of what that woodgrain looks like?

Here you go.

http://drive.google.com/uc?id=0B7_Yx-MhBTKoekxCUGN4LS1yWDQ
http://drive.google.com/uc?id=0B7_Yx-MhBTKobUZOYlR4RXQ5U0U

[Bartlett]

Thanks guys, seems HE has the majority vote. The Merc is only $400, is there anything else I need? The Merc volume is massive compared to others, is it just as efficient as APR or better? Seems like a no brainer at this price, unless I'm missing something.

The issue with the Merc is the diminished flow rate due to its quad-pass design. The solution is, in order of least to most effective is: stock pump mod, booster pump, CWA-100 pump.

[4Rings3Liters]

I personally never got into the TCU tune hype if drag racing is your thing. I went 11.7 on a stage 2 single pulley tune with no TCU tune and from what Ive seen is better than a lot of DP cars with TCU tune.

[blackfunk]

I personally never got into the TCU tune hype if drag racing is your thing. I went 11.7 on a stage 2 single pulley tune with no TCU tune and from what Ive seen is better than a lot of DP cars with TCU tune.Strangely that's one of my biggest fears, getting a TCU tune and hating it. As it stands I love the way my stock programming shifts. I supposed if you were chasing every tenth after eking every ounce of performance from your car it would matter but for me currently I prefer smoothing shifting stop and go driving than all out shift times.

Guess we're in 100% agreement here.

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[B18b1ex]

The issue with the Merc is the diminished flow rate due to its quad-pass design. The solution is, in order of least to most effective is: stock pump mod, booster pump, CWA-100 pump.

Is this an assumption or has someone actually measured a decrease? Could the passages on the Merc be large enough so that in comparison with stock the flow has not changed much? I did not do the pump mod and the Merc has been helpful.


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[theweebabyseamus]

Strangely that's one of my biggest fears, getting a TCU tune and hating it. As it stands I love the way my stock programming shifts. I supposed if you were chasing every tenth after eking every ounce of performance from your car it would matter but for me currently I prefer smoothing shifting stop and go driving than all out shift times.

Guess we're in 100% agreement here.

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Increased clamping force from the TCU tune is something I would definitely consider a big benefit, especially on a stage 2 car. Also, if I had a B8.5 the increased rpm would help on power.

[sbw]

I’d personally think that you’d be happy with both, but the HXE is IMO a necessity...especially if you see real heat where you live. Heat’s the enemy and overall, should you decide to track/no track, stage 2/DP, you’ll probably get more consistent and better performance out of a HXE. I run the AMS HXE but seeing some of the kits people are putting together is awesome and it gives you a ton of options also. This is great for you and allows you flexibility in terms of what you want to spend.


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[Bartlett]

Is this an assumption or has someone actually measured a decrease? Could the passages on the Merc be large enough so that in comparison with stock the flow has not changed much? I did not do the pump mod and the Merc has been helpful.


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The disadvantage of multiple passes is the difference in pressure between the inlet and the outlet. This is called flow maldistribution. Thus, it's a bottleneck for flow throughout the system. But, how much does this affect it? I have no clue. It could actually be negligible. Disclaimer: I'm not an engineer.

[AerotusX]

Hmm, okay. So upgrading the pump is recommended with Merc quad-pass? Has anyone ran Merc with stock pump vs upgrade pump and noticed the difference? I want to do it right the first time around to set and forget, so my assumption is Merc + CWA-100 is > than APR CPS. I don't plan on DP/UC since I don't want to deal with the CAT burning up (I need my CAT in CA). I don't drag race, but hope to take it around the track once a year.

[Bartlett]

Hmm, okay. So upgrading the pump is recommended with Merc quad-pass? Has anyone ran Merc with stock pump vs upgrade pump and noticed the difference? I want to do it right the first time around to set and forget, so my assumption is Merc + CWA-100 is > than APR CPS. I don't plan on DP/UC since I don't want to deal with the CAT burning up (I need my CAT in CA). I don't drag race, but hope to take it around the track once a year.

I don't know enough to say that you need to upgrade the pump, but I believe that it's going to be beneficial in the case of the Merc. One thing to note is that you don't want the fluid moving too fast. I could see a case made to not upgrade the pump when running a single-pass or maybe even dual-pass exchanger. But, maybe a case can also be made for the Merc.

The Merc has a smaller surface area, but seems to have a greater volume than the APR CPS. But, it's also quad-pass, so it could actually have greater cooling capabilities than the CPS, which is a dual-pass unit.

For what it's worth, my money at the moment is on the Forge Cooler, as it has the largest surface area of any B8 exchanger, and I believe the largest volume aside from the Merc. It will also enable me to divorce my loops and run 95% water and 5% water wetter in the SC loop. I will likely add a PLM reservoir, and potentially the CWA-100. IMO, this will be the best performance setup one can have aside from a killerchiller. The AMS is often touted as the best, but the Varimax pump isn't better than the CWA-100 and the AMS cooler is smaller than the Forge.