Dual exhaust is generally a negative on 4-cyl cars. With proper
manifold tubing arrangements the exhaust pulses sorta help each other
along.
Unfortunately our Spridgets only have three exhaust ports, the two
middle cylinders exhausting out the same "siamesed" port. That's why
you hear of "LCB" (long center branch) headers. The longer center
tube tries to compensate for the lack of a fourth port.
Four-into-one (or 3->1 for us) headers work best at very high rpm.
For street/autocross/etc a tri-y (4->2->1) is better because it helps
low-mid rpm torque more. (Carroll Shelby used them on his GT-350s.)
ANYway; my opinion is to stick with a good single exhaust on Spridgets.
Ed in NC
(There used to be a Saab Sonnett around here with dual sidepipes.
Kinda neat lookin'! (They had a V4 4-cyl instead of an inline 4.))
|