Custom Coolant Expansion Tank

There is a discussion thread regarding the first group purchase of a custom coolant expansion tank for the SL-C here. Below are some pictures of the first generation tank.

I have modeled the tank in SolidWorks and I'm talking with Chuck from Superior Radiator about making them (he makes the beautiful radiators that come with the kit). At this point he's waiting for me to finalize the design.

The second generation tank will have the following improvements.

  • It has been suggested that it is preferable to move the engine steam and radiator bleed connections from the bottom of the tank to the top so that the air bubbles and steam don't need to percolate through the liquid. In my first design I moved them to the top of the right side of the tank. However, after looking at pictures of completed cars it would appear difficult to service those connections. My current thought is to leave them on the bottom of the tank, but have optional aluminum tubes welded inside of the tank.
  • Two female bungs have been added to the front face to support an optional level indicator tube. One option is to use two right-angle, single-push fittings with a clear tube (see pictures and part numbers below). The challenge is that the temperature rating isn't as high as I'd like. 
  • The mounting flange has been replaced by four aluminum spacers that are welded to the side of the tank. These provide space to reduce heat transfer into the cockpit. These will be optional. I haven't decided how much space they should provide from the bulkhead nor the best place to locate them. Four 1/4-28 stainless bolts mount into self-locking nut plates that are attached to the back of the bulkhead by rivets. This enables the tank to be removed without having access to the back side of the panel, which is extremely useful if you're using the tub.
  • The metal will be upgraded from 0.093" 5052 aluminum to at least 0.100"; that's what the Canton Racing tanks use. I will discuss with Chuck.
  • The 5/8" and 3/4" hose barbs will be replaced with -8 AN female weld bungs. This will enable the builder to determine which hose goes where and to choose barbs or AN fittings. We can also consider using NPT female weld bungs -- I'm not sure which would be less expensive.
  • Several owners of the gen-1 tanks indicated that the rear aluminum bulged, so some sort of stiffener might be added to the interior. I will discuss with Chuck.

3-D Renderings

The following are some SolidWorks renderings of the tank. Note that the four weld bungs on the bottom aren't shown.

The following parts are welded to the tank (part numbers should link to product specification page):

Qty.Part NumberDescriptionUnit Price
1 CTR-80-092 Canton Weld-On Billet Aluminum Fill Neck $22.00
4 EAR-996702ERL 1/4" NPT Female Aluminum Fitting Weld-In Bung $4.40
2 800-8113 -8 AN Female Weld-In Bung $9.7
4 92510A459 Aluminum Spacer, 1/2" OD, 2-1/2" Length, for 1/4" Screw Size $5.47

Suggested parts to be purchased by builder:

Qty.Part NumberDescriptionUnit Price
1 WPM34U 3/4" Barb Fitting; -8 AN Thread with O-Ring $18.79
1 WPM58U 5/8" Barb Fitting; -8 AN Thread with O-Ring $18.79
2 SUM-G3118  1/4" NPT Hose Barb $5.97 
4 92949A554 1/4"-28 x 3" Stainless Steel Button-Head Socket Cap Screw  
4   1/4" Stainless Steel Washer  
4 MS21059-4 1/4"-28 Floating Nut Plate with Self-Locking Thread $1.29

Level Indicator Tube Examples

The pictures below show three examples of push connectors being used to construct level indicator tubes.

Review of the Radium expansion tank. 

Parts for optional fluid level view: 

Qty.Part NumberDescriptionUnit Price
2  5523K36 Push-to-Connect Tube Fitting Swivel Elbow for 1/4" Tube OD x 1/4 NPT Male Pipe $7.05 
    Clear Tube  

BLK75125 Billet Specialties Radiator Cap (16 psi) $31.70

209004-BL -4 AN Fitting, 90 Degree, Hose to Female Hose End, Socketless, Aluminum, Black Anodized, Each

Another fluid level connector (here)