4G93p Porting Progress

Question and answer direct with GC. Competition engines and 'live' projects only. Good photos to illustrate your post are expected.
Guy Croft
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Re: 4G93p Porting Progress

Post by Guy Croft » February 12th, 2011, 5:18 pm

Looks like the diligent application of some good engineering principles, Iain, well done indeed! A marvellous no-nonsense thread, this one.

Hope the cam does 'the business'.

G

PersonaGrata
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Joined: October 8th, 2009, 7:42 pm

Re: 4G93p Porting Progress

Post by PersonaGrata » February 18th, 2011, 7:45 pm

Much appreciated Guy thanks

If you don't mind I've got some more pictures that are worth posting for this job....

Shaved guides on the scrap head. The big plus point of shaved guides for me is that the machining of the ports is much easier and can be performed with the guides in place. Good for low cost development.
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Combustion Chamber - completely unworked. Smoothing the recess pockets make no difference what so ever to the flow figures and reduce compression ratio. Therefore its completely pointless on this head.
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Typical inlet port on the head that was actually bolted to the engine. Valve guides re-profiled versus shaved. This is the best in terms of flow for the guide but hard work and manual, and it makes it much harder to machine the ports through the SSR.
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Guy Croft
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Joined: June 18th, 2006, 10:31 am
Location: Lincoln, UK
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Re: 4G93p Porting Progress

Post by Guy Croft » February 19th, 2011, 10:11 am

Irrespective of valve-in flow and behaviour around the valve during inlet and ex event - don't overlook the influence of cc shape on burn. I take the view that any intrusion (particularly a sharp edge) into the flame front is going to reduce efficiency; I would definitely trade CR in favour of that (that is my exp anyway) and get on and do some nice blending there.

GC

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