Exhaust Manifold

Even on only a slightly tuned Natural Aspirated (NA) engine, the exhaust system is a key to high performance. Morgan 4/4, with the Kent engine, is standard using a banana manifold 4:1 and a one silencer system.

The 4:1 manifold should be best for top power, but if you go for torque at lower/mid RPM, a 4:2:1 manifold is better. It is also important with a low back pressure silencer system. The Ford Kent engine is very sensitive to back pressure.

I started out with the 4:1 standard manifold and a 2” pipe and a standard silencer.

A dyno power curve indicated that the manifold was not good enough.

How to have a better manifold made?

It’s not cheap. I decide to design and make it myself. Though, first I have to get a stainless steel welding machine (TIG) and learn to weld. I bought one and started to practice. Not so easy… Anyway, after a month I got started with ‘the test piece of work’.

It was not easy to work in the car, so I build a wooden model of the engine room and mounted an old cylinder head on the top.

As this was my first welding project, it probably took 100+ hours all together. Well, well the results wasn’t too bad.

A dyno run showed an improvement of 10-12 HP. ‘Worth the job’.

2:1 Collector Tricks

Reduce the area of each entry to approx 80% in the 2:1 collector. This will prevent most of a reflected wave from exhaust pipe to get back into the engine.