A buddy nearby has been modding a 1992 Metro, and occasionally I work with him on his or my car, or both. That's what we did yesterday, and the result is this brake booster mod, which for him was practice for his own car and for me was an excuse to become more familiar with my braking system and upgrade the car's abilities. The mod works well and seems to have doubled or tripled my braking capacity when the engine is off. It is mostly a safety mod, though it does allow longer EOC in long downhill zones because of the longer span of safe braking I have without restarting the engine, so it might benefit over all mpg averages. Might.
Supplies: 14" section of 4" diameter PVC pipe, two PVC endcaps, PVC glue, copper strap "tape," 3' or 4' vacuum hose, a "T" splitter for vacuum hoses, and a hose fitting for vacuum canister, 4 new hose clamps.
Tools: drill, wrenches, pliers, snips, screwdrivers.
Pic 1: the vacuum line in its bracket. The check valve is located between the two ends of the bracket, so cut into line for the "T" on the right:
Pic 2: some of the supplies:
Pic 3: the assembled and glued 14" x 4" diameter canister:
Pic 4: threading the top of the canister for the hose line nib (drilling already done):
Pic 5: Engine bay, showing installed canister top on left beside battery and the "T" in the master cylinder vacuum line on right near the firewall:
Pic 6: closeup of canister with hose attached and secured in place using existing screw holes for copper strap (bottom of canister wedged into a frame section below battery):
Pic 7: closeup of the "T" in the vacuum hose beside the master cylinder:
Driving home yesterday, during EOC I experienced at least two or three times the reserve braking boost over the OEM setup.