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Tuning the Exhaust Manifold of a TU-Series Engine

The standard cast iron exhaust manifold on the TU series engine is OK as it is. I have seen must worse cast manifolds... Offcourse you can mount some 4-2-1 extractors, to get some extra horsepower and torque, but this is not really needed... The preformance gain by porting the cast manifold is not measured, but should be noticeble on the TU3 and TU5 series, the 1360cc and 1587cc, engines.

All the Peugeot and Citroen TU-series engines share the same exhaust manifold! This makes you wonder if the portsize is enough for a 1.6 engine...

TU3 exhaust manifold As you can clearly see, there is a small obstruction on top of the exhaust port. This wil create a lot of turbulence... (exhaust manifold is upside-down)
TU3 Exhaust manifold port closeup

Here is a closeup of the exhaustport at the manifold. The diameter of the first 3mm of the port are 31mm, probably for port matching. The smaller diameter you see is 29mm. On the top you can see carbon deposits; there are no high gas speeds in that area (this manifold was mounted on a tu3 engine).

TU3 port flowing Work in progress.
In the middle of the cast manifold there is an "wall". Not sure why they did that. The centre section is prone to crack.
TU3 exhaust manifold tuned and flowed Port is ready, nicely round, a bit concentric and pretty smooth. This will prevent carbon buildup and remain high gas speeds!


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