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2013 CTS-V Coupe 6MT Silver/Black
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Discussion Starter · #1 ·
So I live in New England. The Boston area to be a little more precise. I'm on the fence about whether or not to invest in an expansion tank, and if so which one. I don't track my car. It's my daily. But I like to get on it occasionally, and tracking it eventually is not out of the question. For cooling I already have the Track Attack and am about to install the Varimax pump. Aside for it just being a good idea for our cars anyways, my cooling mods were motivated by how quickly our cars heat soak ESPECIALLY in stop and go traffic. So because of that, my cooling mods are just as priority as my go fast parts. And much like with any other rabbits hole I research my way down, there's way too much conflicting opinionated information online. Some say more fluid volume is a must, others say adding more volume only helps temporarily then you have way more fluid that takes way longer to cool down and recover. Again, my needs are more daily driving based. I don't need to ice anything. I just wanna keep it cooler and not heat soak AS BAD in stop n go traffic. So help me out guys. Do I need to do an expansion tank? Or am I good with just the T/A and Varimax. And side note, I was totally sold on the awesome Piersburg pump. Then I got a fantastic deal on the proven Varimax, so I couldn't turn the savings down for a slightly better pump at double the cost.
 

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In my opinion, adding capacity is like changing to a 160 degree tstat. You'll be running the same temps a few minutes later.

I'm in New Mexico and our summer Temps hover around 100 for 3 months and I've never considered adding a reservoir. I have the T/A and CW100 pump and Temps stay in line for my style of driving.
 
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I have a 2.5 gal Vadder exp tank (plus CW pump) and my recovery time is way better compared to what it was with stock "T".
One can make the same argument about a larger intercooler on turbo cars, yet it works just fine.
Also, 160 T stat works fine below that magic 88 degree ambient temperature.

This is all my personal opinion.
 

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With just a pump, you are circulating the same minute amount of coolant as before, just faster.
Logically, if you have a larger overflow tank that gets constant cool outside air flow through the fog light, you are bound to have cooler coolant temperature when it reaches the "brick".
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Add the tank, remove the hard lines and route tank>pump>HX>brick>tank


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I got the tank from dedicated motorsports that sits above the ecm. I'm pretty happy with it. Here in Utah it hits 97-100 through the summer and it definitely helped. I'm running 3/4 lines everywhere with a pierberg pump and it works great.
 

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I found the opposite, stock t much easier to bleed
 

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In my opinion, adding capacity is like changing to a 160 degree tstat. You'll be running the same temps a few minutes later.

I'm in New Mexico and our summer Temps hover around 100 for 3 months and I've never considered adding a reservoir. I have the T/A and CW100 pump and Temps stay in line for my style of driving.
True, adding capacity is a lot like a lower T-stat in that the IAT2s take longer to heat up. They also take slightly longer to cool down.

Unlike the engine coolant temp, however, it will repeat over and over after you make a pull then let off, make a pull and coast, etc. A longer "heat up time" during a pull is obviously beneficial as timing is pulled increasingly over IAT2 of 140* F


The problem with a stronger pump is cavitation- I can't run a programmed Stewart EMP without an underhood reservoir because it will literally start foaming out the pressure relief. The expansion tank is just that - a place for the water and air to slow, separate and then cycle again.

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i think i was getting cavitation until i swapped the stock hard lines out

i just think by the time you do tank and lines if you arent going to ice the car for the quarter mile all you are doing is moving the goal post a little further along for street driving
 

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i think i was getting cavitation until i swapped the stock hard lines out

i just think by the time you do tank and lines if you arent going to ice the car for the quarter mile all you are doing is moving the goal post a little further along for street driving
I agree with this. I can't say I saw a YUGE increase with the reprogrammed Stewart over some of the other stronger pumps now being offered (they came out after I swapped), but it was a big step up from the Varimax.

For a daily driver with bolt-ons... sure, it's much less black and white for a variety of reasons.
 

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my 1st V ran about the same IAT's and recovered about the same as my current one on the street so thats all I can base my personal data on.
that one had the stock pump, stock hard lines, and a fluidyne HX.
it was on ethanol most of the time, my current one isnt on ethanol but does have methanol injection also has an expansion tank, CWA pump and track attack which is twice as large as the fluidyne

granted I dont have real scientific data to back all that up I know random84 did some real data logging but again- if we are talking about the street all that matters is what what I feel and see on the aeroforce
 

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Discussion Starter · #15 ·
I agree with this. I can't say I saw a YUGE increase with the reprogrammed Stewart over some of the other stronger pumps now being offered (they came out after I swapped), but it was a big step up from the Varimax.

For a daily driver with bolt-ons... sure, it's much less black and white for a variety of reasons.
I was actually hoping you would jump in on this Random because If anyone goes all in on proven data and setup comparisons it's you my friend. So considering mine is mostly for street use. I already have the Track Attack in. And I'm most likely putting the Varimax in this weekend. Do you see any benefit in me investing in maybe the DMS Expansion Tank? Did I waste my money on the Varimax rather than waiting and spending double on the CWA100? Or do you think just my T/A and Varimax will suit my needs?
 

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I was actually hoping you would jump in on this Random because If anyone goes all in on proven data and setup comparisons it's you my friend. So considering mine is mostly for street use. I already have the Track Attack in. And I'm most likely putting the Varimax in this weekend. Do you see any benefit in me investing in maybe the DMS Expansion Tank? Did I waste my money on the Varimax rather than waiting and spending double on the CWA100? Or do you think just my T/A and Varimax will suit my needs?
I think you'll be fine for a daily. I'd run distilled water in the summer and swap to 50-50 dexicool in the winter.

The cw100 is better, but you'd be splitting hairs. In your position, I'd be happy with it.

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