Cooling System
LS engines make a lot of heat in a tight bay. Plan radiator capacity, fan strategy, and oil cooling early — especially on BK1 cars with less front clearance.
Before You Start — Clearance
- BK1: Prefer Corvette-spacing front accessory drive for maximum room between the engine and radiator fans. F-body (middle) spacing can work but is tighter.
- BK2: Roughly 1.5" more front clearance than BK1 — more forgiving.
Radiator
A 3.8 upgraded radiator with a proper fan shroud is strongly recommended. Jason Riddle builds these for the community — reach out on Facebook if you need one.
Fans & Relays
Factory radiator fan wires (at the harness):
- Red / Orange — High side (black/red on the fan side)
- Green — Low side (black/white on the fan side)
- Black — Ground
Factory fan wires at the bulkhead — orange/red (high) and green (low). Many builders pull these toward the battery for clean relay power.
Many builders cut into the harness at the firewall, pull the thick red/green wires toward the battery, and feed new solid-state or conventional relays. Holley fan #1 (gray/yellow) and fan #2 (gray/red) typically go to pin 85 as triggered ground on traditional relays.
Example of Holley fan controllers mounted near the battery.