You wanted it, you got it!
Part 1: I'm going to post a complete how-to installation thread with suggestions, pitfalls and all of the collective Forum wisdom compiled into one place. There are several great threads and references, but it's time to have a single depot for this popular - yet deceptively frustrating modification.
Part 2: I'm going to datalog a standard Stewart EMP vs a high output / "reprogrammed" Stewart EMP and see how much that extra RPM makes. Feel free to save all of the bickering for a different thread!
(Please be patient - I am finishing up the installation and photos today; pump comparison over the next few days)
Introduction
Basic premise: the key to low IAT2 temperatures in this platform is fluid capacity. In my previous tests, adding an under-hood fluid reservoir, such as the BMR, NorCal or others, I saw a significant IAT2 reduction during WOT pulls relative to baseline. When I then swapped out the Varimax for a standard Stewart EMP W29 pumps, I found further improvement - but not nearly to the degree as when I simply added more fluid volume to my setup. I also suspect this is partly why the "Track Attack" and other aftermarket heat exchangers do so well: they are much larger than the stock unit and thus add fluid volume (in addition to larger cooling surface area, fin design, etc).
In other words, the bulk of heat creation is the supercharger, and the primary means of expelling this heat is airflow over the heat exchanger. The intercooler fluid is just the vehicle for moving this heat energy from one place to another - and in any given system, the heat exchanger is limited by:
* how much heat energy can be transferred from air to water based on the fluid (dexcool vs straight water),
* airflow or vehicle speed and atmospheric conditions,
* the intercooler fluid velocity / circulation rate,
* and the cross-sectional area of the heat exchanger.
These are big picture assumptions on my part, so don't take me to task on tiny details. BUT, for the purposes of testing we will try to mitigate as many of those variables as possible and I will focus primarily on the differences in increased capacity (5x or more that of a stock system) and lastly the differences in fluid circulation.
Both of those referenced comparison tests above (reservoir tank and pump comparison) were done using 3/4" hose, deleting the factory metal "hard lines" from the intercooler system and using a ZL1 lid. I did my best to keep the dexcool ratios similar; and limit the little design tweaks that inevitably crop up, like hose length, routing, the number of fittings or sharp bends, etc.
Ergo, the mother of all capacity increases: a ~10 gallon trunk tank. Yay, Wagons!
Part 1:
Disclaimer: You are going to have a large water reservoir in the trunk of your car, with electrical connections / terminals and the very REAL risk of a leak at some point. Bear this in mind when running cables, fuses and securing unused connectors up and out of the way. You WILL need a "drain" for the trunk, as pumps, fittings and water filling will inevitably leave you with overflow that needs a way out.
Costs:
A tank made to my custom specs ($250)
A Stewart EMP pump ($450)
50 feet of 3/4" ID heater hose ($50)
10 feet of 1" ID heater hose ($20)
Assorted hose clamps ($10)
Assorted hose adapters ($30)
Assorted wiring connectors, etc ($10)
4-5 gallons of antifreeze ($100)
Approximate cost for the DIY project: $900+
Time for installation: 6-8 hours
General Concept:
* You don't need a huge tank. I went with approximately ~10 gallons, and it's probably twice as big as I really need; and water is heavy! Check below for suggestions on a better tank!
* You WILL use 3/4" ID hose for the bulk of the runs and in wheel wells. I've tried more than once to get 1" ID hose to work and it's just too big of a jump to fit without excessive kinking. Since the Stewart pumps use 1" outlets, you will need a few feet of 1" ID hose, and some adapters. These are uncommon, so you'll either need to source them online or buy a few from me (have have several extras!).
* Recommended Routing:
![Image]()
The benefit here is long contiguous runs of hose, that will NOT be exposed to road hazards or visible from behind, and only two fittings are needed (the 1-3/4" adapter and a 3/4" 90" elbow for the rear rocker cover transition). You also won't have a bunch of holes in your subframe from an Aldo install like TriTexan (haha!).
* Alternate Route:
![Image]()
The hoses run straight down from the trunk area using bulkhead fittings - the hoses have to be secured near exhaust or onto the frame rails as they travel up, and pass through the inside of the engine compartment right next to your headers / exhaust. This is arguably a more labor-intensive, and less efficient way to do the installation. Example here:
Here's an example of the tank design itself:
![Image]()
Starting off: MEASURE THREE TIMES, CUT ONCE! You don't want any unnecessary holes in your trunk.
Step 1: Visualize the layout of your tank, and where your hoses will run. Test fit often as you go. DO NOT CUT ANYTHING until you have your tank - and don't order your tank until you really think about what you're trying to do, and whether or not you will modify anything beyond my suggestions here (ie a nitrous bottle or other goodies nearby).
Here is the general layout: a custom tank, two hose connections and room for a pump. Although we have generous space in the spare tire well, each variant (Wagon, sedan, Coupe) will have slightly different dimensions, etc. Again, check below for suggestions on how to custom build your own tank for $250 or less.
![Image]()
Here, a hose is exiting the spare tire area over the passenger-side muffler, from the tank shown above:
![Image]()
![Image]()
Note: I've run the 3/4" hose over the gas fill to help support it - NO need for drilling hose clamps or mounts at any time.
Step 2: Time to cowboy-up! Using a metal hole saw of 1.25" diameter or up to 1.5", cut a hole in the rocker transition area as show. I suggest cleaning up with degreaser and applying a rustoleum product to limit future rust.
![Image]()
![Image]()
Note: this is the one area where you're likely going to kink the hose. It's very tight, but either leave plenty of slack or consider a 90* elbow fitting here to ensure full flow. You'll push the hose all they way to the front of the car before cutting or splicing, to make sure you have enough. MEASURE THREE TIMES, CUT ONCE, asshole!
Step 3:
Remove the front wheel liners by popping out the plastic retainers. Very easy, and there is plenty of room to run hose here, and I secured mine with zip ties using existing holes in the body panels.
![Image]()
![Image]()
Step 4: Decision Time!
IF you are a daily driver like me, and will not ice very often - run your hose through the front of the car to the passenger side fitting of the Track Attack. The Track Attack is non-directional, no need to cross back and forth. The idea here is your coolant will be cooled off by the heat exchanger and then go straight to the supercharger (then the return line to the back of the car).
IF you are primarily a drag racer, or you throw a bag of ice in the trunk every morning before work... then you will use the "alternate" route: run the hose up through the passenger side front quarter panel, near where the ECM and hood latch are. There you will see how you can easily reach the lower inlet of your ZL1 (then down to the heat exchanger)
![Image]()
I chose to use the first option, and that is what I'll outline here: The hose running to the front of the bumper / heat exchanger:
![Image]()
![Image]()
Step 5: I used the Dayco hose to tackle that tight area on the driver's side of the Track Attack, and ran that up to the ZL1 lid - it fit without any need for splicing additional hoses.
![Image]()
Step 6: Run your hose from the supercharger to the driver's fender, down to the rocker and back to the driver's rear wheel just as you did moving to the front of the car on the passenger side:
![Image]()
Step 7: Time to nut-up again, and drill another hole for for the hose to pass through the rear of the rocker cover:
![Image]()
Step 8: Up and over the wheel well - you'll have to lean on that liner cover to get it back in place with the hose there. Check your fit frequently - but again no need to drill or secure the hose.
Step 9: Drill another hole in your trunk on the driver's side, to get the return line in there and run it over the muffler. The muffler does not get hot enough to melt heater hose (I tried) - but I secured the hoses on both sides up against the frame by then using metal zip ties and running them through existing holes.
Note: If you don't have enough room with the wheel liners loosened or off, you can also easily drop the muffler: using silicone lubricant, pop off the three rubber hangers with a large screwdriver - no need to take the exhaust apart. I used more zip ties to wrap my heat shielding around the hoses for good measure:
![Image]()
Step 10: Secure your hoses to the tank and pump: You'll wind up with something like this:
![Image]()
Regarding the spare tire well: Remember that the spare tire area is thin metal, so any elevations (such as the hump for the spare tire attachment) can easily be hammered down for clearance - no need to cut them out. It is very easy to cut through this material and bend it to shape (see drain petcock photo below).
Step 11: Install the drain petcock. Thankfully, due to running the hoses in the rocker panels, this install is almost invisible from the exterior. The only visible portion will be the drain (for icing, etc), and the drain / thread size will depend on what you specify when ordering your tank. You may need a small extension so that the drain valve can be turned without interference.
Here's mine (1/2" NPT ball valve w/ a 1/2" extension for clearance):
![Image]()
So is it LOUD?
Actually, no - even with the unsealed area near the petcock, the Steward EMP is a very quiet pump. It sounds much like the fuel pump energizing: the radio has to be off, and you have to be expecting it to notice. I have not even secured the pump yet and there are no obvious noises or vibrations from the driver's seat (with the trunk cover open, no less). The short of it is, I can't tell it's even there under normal conditions.
[continued in next post]
Part 1: I'm going to post a complete how-to installation thread with suggestions, pitfalls and all of the collective Forum wisdom compiled into one place. There are several great threads and references, but it's time to have a single depot for this popular - yet deceptively frustrating modification.
Part 2: I'm going to datalog a standard Stewart EMP vs a high output / "reprogrammed" Stewart EMP and see how much that extra RPM makes. Feel free to save all of the bickering for a different thread!
(Please be patient - I am finishing up the installation and photos today; pump comparison over the next few days)
Introduction
Basic premise: the key to low IAT2 temperatures in this platform is fluid capacity. In my previous tests, adding an under-hood fluid reservoir, such as the BMR, NorCal or others, I saw a significant IAT2 reduction during WOT pulls relative to baseline. When I then swapped out the Varimax for a standard Stewart EMP W29 pumps, I found further improvement - but not nearly to the degree as when I simply added more fluid volume to my setup. I also suspect this is partly why the "Track Attack" and other aftermarket heat exchangers do so well: they are much larger than the stock unit and thus add fluid volume (in addition to larger cooling surface area, fin design, etc).
In other words, the bulk of heat creation is the supercharger, and the primary means of expelling this heat is airflow over the heat exchanger. The intercooler fluid is just the vehicle for moving this heat energy from one place to another - and in any given system, the heat exchanger is limited by:
* how much heat energy can be transferred from air to water based on the fluid (dexcool vs straight water),
* airflow or vehicle speed and atmospheric conditions,
* the intercooler fluid velocity / circulation rate,
* and the cross-sectional area of the heat exchanger.
These are big picture assumptions on my part, so don't take me to task on tiny details. BUT, for the purposes of testing we will try to mitigate as many of those variables as possible and I will focus primarily on the differences in increased capacity (5x or more that of a stock system) and lastly the differences in fluid circulation.
Both of those referenced comparison tests above (reservoir tank and pump comparison) were done using 3/4" hose, deleting the factory metal "hard lines" from the intercooler system and using a ZL1 lid. I did my best to keep the dexcool ratios similar; and limit the little design tweaks that inevitably crop up, like hose length, routing, the number of fittings or sharp bends, etc.
Ergo, the mother of all capacity increases: a ~10 gallon trunk tank. Yay, Wagons!
Part 1:
Disclaimer: You are going to have a large water reservoir in the trunk of your car, with electrical connections / terminals and the very REAL risk of a leak at some point. Bear this in mind when running cables, fuses and securing unused connectors up and out of the way. You WILL need a "drain" for the trunk, as pumps, fittings and water filling will inevitably leave you with overflow that needs a way out.
Costs:
A tank made to my custom specs ($250)
A Stewart EMP pump ($450)
50 feet of 3/4" ID heater hose ($50)
10 feet of 1" ID heater hose ($20)
Assorted hose clamps ($10)
Assorted hose adapters ($30)
Assorted wiring connectors, etc ($10)
4-5 gallons of antifreeze ($100)
Approximate cost for the DIY project: $900+
Time for installation: 6-8 hours
General Concept:
* You don't need a huge tank. I went with approximately ~10 gallons, and it's probably twice as big as I really need; and water is heavy! Check below for suggestions on a better tank!
* You WILL use 3/4" ID hose for the bulk of the runs and in wheel wells. I've tried more than once to get 1" ID hose to work and it's just too big of a jump to fit without excessive kinking. Since the Stewart pumps use 1" outlets, you will need a few feet of 1" ID hose, and some adapters. These are uncommon, so you'll either need to source them online or buy a few from me (have have several extras!).
* Recommended Routing:
The benefit here is long contiguous runs of hose, that will NOT be exposed to road hazards or visible from behind, and only two fittings are needed (the 1-3/4" adapter and a 3/4" 90" elbow for the rear rocker cover transition). You also won't have a bunch of holes in your subframe from an Aldo install like TriTexan (haha!).
* Alternate Route:
The hoses run straight down from the trunk area using bulkhead fittings - the hoses have to be secured near exhaust or onto the frame rails as they travel up, and pass through the inside of the engine compartment right next to your headers / exhaust. This is arguably a more labor-intensive, and less efficient way to do the installation. Example here:
Here's an example of the tank design itself:
Starting off: MEASURE THREE TIMES, CUT ONCE! You don't want any unnecessary holes in your trunk.
Step 1: Visualize the layout of your tank, and where your hoses will run. Test fit often as you go. DO NOT CUT ANYTHING until you have your tank - and don't order your tank until you really think about what you're trying to do, and whether or not you will modify anything beyond my suggestions here (ie a nitrous bottle or other goodies nearby).
Here is the general layout: a custom tank, two hose connections and room for a pump. Although we have generous space in the spare tire well, each variant (Wagon, sedan, Coupe) will have slightly different dimensions, etc. Again, check below for suggestions on how to custom build your own tank for $250 or less.
Here, a hose is exiting the spare tire area over the passenger-side muffler, from the tank shown above:
Note: I've run the 3/4" hose over the gas fill to help support it - NO need for drilling hose clamps or mounts at any time.
Step 2: Time to cowboy-up! Using a metal hole saw of 1.25" diameter or up to 1.5", cut a hole in the rocker transition area as show. I suggest cleaning up with degreaser and applying a rustoleum product to limit future rust.
Note: this is the one area where you're likely going to kink the hose. It's very tight, but either leave plenty of slack or consider a 90* elbow fitting here to ensure full flow. You'll push the hose all they way to the front of the car before cutting or splicing, to make sure you have enough. MEASURE THREE TIMES, CUT ONCE, asshole!
Step 3:
Remove the front wheel liners by popping out the plastic retainers. Very easy, and there is plenty of room to run hose here, and I secured mine with zip ties using existing holes in the body panels.
Step 4: Decision Time!
IF you are a daily driver like me, and will not ice very often - run your hose through the front of the car to the passenger side fitting of the Track Attack. The Track Attack is non-directional, no need to cross back and forth. The idea here is your coolant will be cooled off by the heat exchanger and then go straight to the supercharger (then the return line to the back of the car).
IF you are primarily a drag racer, or you throw a bag of ice in the trunk every morning before work... then you will use the "alternate" route: run the hose up through the passenger side front quarter panel, near where the ECM and hood latch are. There you will see how you can easily reach the lower inlet of your ZL1 (then down to the heat exchanger)
I chose to use the first option, and that is what I'll outline here: The hose running to the front of the bumper / heat exchanger:
Step 5: I used the Dayco hose to tackle that tight area on the driver's side of the Track Attack, and ran that up to the ZL1 lid - it fit without any need for splicing additional hoses.
Step 6: Run your hose from the supercharger to the driver's fender, down to the rocker and back to the driver's rear wheel just as you did moving to the front of the car on the passenger side:
Step 7: Time to nut-up again, and drill another hole for for the hose to pass through the rear of the rocker cover:
Step 8: Up and over the wheel well - you'll have to lean on that liner cover to get it back in place with the hose there. Check your fit frequently - but again no need to drill or secure the hose.
Step 9: Drill another hole in your trunk on the driver's side, to get the return line in there and run it over the muffler. The muffler does not get hot enough to melt heater hose (I tried) - but I secured the hoses on both sides up against the frame by then using metal zip ties and running them through existing holes.
Note: If you don't have enough room with the wheel liners loosened or off, you can also easily drop the muffler: using silicone lubricant, pop off the three rubber hangers with a large screwdriver - no need to take the exhaust apart. I used more zip ties to wrap my heat shielding around the hoses for good measure:
Step 10: Secure your hoses to the tank and pump: You'll wind up with something like this:
Regarding the spare tire well: Remember that the spare tire area is thin metal, so any elevations (such as the hump for the spare tire attachment) can easily be hammered down for clearance - no need to cut them out. It is very easy to cut through this material and bend it to shape (see drain petcock photo below).
Step 11: Install the drain petcock. Thankfully, due to running the hoses in the rocker panels, this install is almost invisible from the exterior. The only visible portion will be the drain (for icing, etc), and the drain / thread size will depend on what you specify when ordering your tank. You may need a small extension so that the drain valve can be turned without interference.
Here's mine (1/2" NPT ball valve w/ a 1/2" extension for clearance):
So is it LOUD?
Actually, no - even with the unsealed area near the petcock, the Steward EMP is a very quiet pump. It sounds much like the fuel pump energizing: the radio has to be off, and you have to be expecting it to notice. I have not even secured the pump yet and there are no obvious noises or vibrations from the driver's seat (with the trunk cover open, no less). The short of it is, I can't tell it's even there under normal conditions.
[continued in next post]
