Uprated Camshaft 3L

[projectrover]

Well this weekend the new cam is going in. Newman cams re-profiled new cam and it should give about 10-12 hp 1000-4000 rpm. With the same smooth driveability. Report to follow!

[Roy of the Rovers]

Look forward to it...

[djm16]

If you are after more HP, did you also match the exhaust ports in the block to the holes in the exhaust manifold, and enlarge the holes in the exhaust gasket to match them too?

I read somewhere, probably the Subaru WRX forum that the most significant mod in terms of HP per hour expended is to round off the sharp contours of the exhaust valves. YMMV

[enigmas]

This sort of discussion can get very esoteric very quickly, and I certainly don't want to deflect from projectrovers new camshaft exuberance. There's lots of debate regarding the porting of manifolds in relation to what is flowing either into or out of an engine. Carburettored wet flow systems generally favour smooth contours for inlet tracts but not mirror finishes...slight turbulance with a rougher wall finish breaks up any puddling in the fuel air stream improving atomization of the petrol air mix. Opening up the inlet tracts too much reduces velocity and can drop torque on a carburettored car but works a treat on an LPG fueled car as the 'gas' takes up a greater volume than does petrol within an inlet manifold. Slightly mismatching the inlet port sizes to the cyl head (fractionally smaller than the cyl head port openings) can reduce reversion (backflow)...ever wonder why the throats of carburettors on well used cars are black. And this is with a standard camshaft! You can actually see reversion on a car/motorbike with a performance cam. Even fitting an oversized exhaust system can drop performance by reducing the exhaust gas velocity exiting a motor. So if you've fitted a 4" exhaust pipe on the back of your car...I'd say you're in the wrong car club!