Last time we wrenched on Project Scarlett we installed a sweet fuel system. But, anyone who’s been deep into an engine swap will realize fuel isn’t the only plumbing involved in putting a hotter motor under the hood. In addition to giving it something to drink, you’ve got to cool the beast, which necessitates a more robust cooling system. In the case of LS engine this also includes making provision for the steam lines that cross from one cylinder bank to the other.
In our case, we used a heavy-duty aluminum radiator from DeWitts that came equipped with a pair of SPAL electric fans, as well as a fitting for the steam line from the front of the engine. Although the radiator was designed for LS swaps, unfortunately ours had to go back home a couple of times to get the inlets and outlets oriented to clear the control arms, a frustration that unfortunately fit with the “everything has to be done three times” rule Tray and I discovered early on.
Since we were changing to a different kind of radiator, we bolted it in place in a new big-block core support provided by Corvette Central, along with the upper clamps and rubber cushions that hold it firmly in place. We also purchased the foam seals needed to keep air flowing through the radiator instead of between the radiator and core support. Since there was no way factory radiator hoses were going to fit, Tray bent a piece of thin metal rod to the size and shape we needed, and we adjourned to the local O’Reilly. When he was asked by the counter guy what car it was going in Tray simply said “It doesn’t exist,” since an LS-powered C3 wasn’t going to show up in the computer. He was kind enough to let us peruse their hose selection in the back until we found 1.50-inch ID hoses that were close enough to work.
Another thing we realized wouldn’t be a stock item was the radiator overflow bottle. Required for track work, and just a general good idea, an overflow bottle (aka “puke tank,”) gives the radiator some place for the overflow to go when the coolant expands beyond the radiator’s capacity. Preferably, it should also let the coolant flow back into the radiator when it cools. Unfortunately, we couldn’t readily locate an aftermarket one that would fit in our limited space confines and opted not to modify a stock one, so we made one from aluminum. Once it was done and mounted in place properly, we pulled it off to have it polished.
As a separate system that needed to be plumbed, we also had a hydroboost system donated by Hydratech. The factory power brake booster that operates off engine vacuum can be troublesome in applications like ours where a hotter cam may not make the vacuum required to keep everything working. The Hydratech system solves this by using fluid shunted off the power steering pump to provide the power assist for the brakes. Known for giving a firm pedal feel, we expect it to make the Wilwood brake system, with its six-piston front and four- piston rear calipers, feel even better than it already does.
1. Not only will our 600-plus-hp LS benefit from the added cooling capacity of the aluminum DeWitts radiator with its dual SPAL electric fans, the DeWitts unit also has the proper fitting for an LS steam line. As it turned out, due to the limited clearance, we had to remove the fans to get the radiator in place, then locate and mount the fans.
2. Here’s the top of our DeWitts radiator showing the fittings for the upper radiator hose, overflow, and LS steam line, which is the small nipple with the black cap. This is the modified radiator since ours had to go back to have the upper and lower hose outlets relocated. In their original orientation we had clearance issues with the control arms.
3. We seated our radiator in a new core support provided by Corvette Central, which is shown here (front) compared with the factory one we pulled out. While there are several different configurations for the core support, we used a big-block support to pair with the new radiator. Shipping these is a challenge since UPS bent ours twice.
4. While the lower mounting brackets are on the bottom of the radiator core support, the upper ones comes separately, and were provided by Corvette Central. Both the upper and lower will need the rubber cushions that lock into place in the brackets, and you’ll also need the foam seals that go between the radiator and core support.
5. Another example of why it’s a good idea to take a hard look at your cooling system: the parts, such as this mounting screw tend to rust. We replaced all the hardware with new stainless fasteners.
6. The front of the engine compartment with the factory core support removed. The core support is held in place through the three diagonal holes, as well as two bolts at the bottom. Access to the diagonal holes may be difficult: we had to trim a little fiberglass inside the fenderwell to get to the top passenger-side bolt.
7. Since this isn’t a factory installation, we couldn’t just buy radiator hoses by make-and-model. Instead, we used pieces of wire bent to match the general shape of hose we needed and then compared that to hoses in stock at the local O’Reilly. Word to the wise; write down your part numbers.
8. Somehow our motor made it here without a steam line, so we had to install one, which required removing the throttle body as well as the bracket for the fuel pressure regulator that mounts to the throttle body screws. The steam line, which is partially covered with the black hose, connects the two steam vents on the front corners of the motor, and has a nipple for a hose that connects to the radiator.
9. The final upper hose configuration, with the upper radiator hose and the steam line. The left side of the steam line goes to the block where it attaches to a nipple on the crossover, and the right side loops under the upper radiator hose and seats on the radiator beneath the radiator hose. After ensuring the aluminum on top of the radiator was thick enough, we clamped the steam line to it using self-tapping screws.
10. We have machine tools, and aren’t afraid to use them. When we realized we’d have to make an overflow bottle, we cut open an old aluminum A/C drier to use as a starting point. While I turned a bung for the bottom of the bottle on the lathe, Tray drew the bottle’s lid in a CAD/CAM program so he could cut it in the CNC mill.
11. The components for the overflow bottle, ready to be welded up: The A/C drier that we cut to make the bottle itself, the CNC-machined lid, and the bung for the bottom. The elbow will be mounted in the bottom, and the air vent threads into the top.
12. Once the bottle was complete, we bent and welded on a mount, then bolted it in place on the fenderwell and clocked the lower 90-degree fitting in the proper direction to meet the overflow hose from the radiator filler neck. The bottle will come out for polishing before final installation.
13. As we covered in an earlier installment, we had to relocate the heater hose fittings from their ordinary position on the water pump so they would clear the front suspension (the original holes are shown here plugged beneath the current hose location). With this done, to seat the hoses to the block we just slipped them on the nipple and tightened the hose clamps.
14. We’ll cover the full installation of the Vintage Air A/C in a later installment, but for the time being we’ll note that the firewall end of the heater hoses had to be seated on their respective fittings on the new heater core.
15. The lower heater hose needed to have a valve installed, so we measured the length of the valve, cut a section that long out of the hose, and seated and clamped the hose. The valve had a molded arrow indicating flow direction, and a contrary label on it that read “disregard molded arrow,” which I did.
16. With the lower heater hose cut for the inline valve, we oriented it downwards to provide the cleanest appearance possible: This photo is taken from outside the passenger-side fender vent.
17. Here’s the Hydroboost system provided by Hydratech. A replacement for the factory power brake booster, which is operated by engine vacuum, the Hydroboost operates the power brakes using pressure from the power steering pump.
18. The Hydroboost comes with both braided steel and rubber hose and loose fittings, a mix of -AN and NPT, and you’ll need to cut and assemble them for your specific application. These are the lines from the bottom of the Hydroboost that go forward to the power steering pump and valve.
19. At the pump, the rubber return hose goes back into the power steering reservoir, while one braided steel line goes from the bottom of the pump to the Hydroboost, and another from the Hydroboost to the valve. The braided lines are held in place with the billet hose clamps, always a nice touch.
20. Improvise, adapt, and overcome. For our application, we needed to weld up a fitting combining the factory part and a provided AN adaptor so we could connect up the hoses properly.
21. The finished cooling system, complete with hoses and recirculating overflow bottle. The radiator itself is hidden behind the Vintage Air condenser. Since the condenser brackets are held in place by the same bolts that hold the upper radiator brackets, it had to go in at the same time.