Engine & Transmission · Exhaust & Cooling
LS3 Equal-Volume Long-Tube Header
GM LS3 (BMW E36 swap)
A NASCAR-style side-exit LS3 header, volume-balanced for a 5,300rpm powerband and sized with headroom for a future 235°-duration cam upgrade.
An optimal exhaust manifold has equal-length runners, but when there isn't enough room to route eight equal-length pipes, the next-best option is equal internal runner volume, achieved by varying pipe diameter instead of length. That's the approach used here.
The design targets a 5,300rpm powerband, resulting in 49mm-diameter runners at 820mm length, for a total runner volume of 1,540cm³ per side — sized with headroom for a future 235°-duration camshaft upgrade rather than only the engine's current spec.
The header uses a NASCAR-style side-exit layout with a stepped-diameter runner design. A bonus side effect of the stepped runners is that they amplify exhaust resonance, giving the car an exhaust note closer to an F1 engine than a typical V8.
Highlights
- Equal-volume runners (49mm × 820mm, 1,540cm³) tuned for a 5,300rpm powerband
- Sized with headroom for a future 235°-duration cam upgrade
- NASCAR-style side-exit, stepped-diameter runner design
- Stepped runners amplify resonance for a distinctive, F1-like exhaust note
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