Porting Inlet manifold
Discussion
[quote=Briefträger] 1)I have got the inlet manifold off my Chimaera, is it worth getting it ported/polished to get a bit more power? 2) if so could I do it myself at home?[/quote]
1) Unfortunately the real limitations to breathing on the RV8 are related to the cylinder head port shape and size and valve sizes. The later injection manifolds are better flowing than the original stock carb ones and improving this element of the engine is only going to bring power gains if the rest is already optimised . Assuming the heads are basically stock items, as is the case on most TVR RV8s other than (IIRC) the 500 and some of the 4.3s and HCs - allegedly, then it is unlikely spending time and effort on the manifold will result in any noticable benefit unless this is part of a integrated package of improvements. Incidentally polishing the inlet tracts can be a mixed blessing; vis a vis, with a carb set up very smooth shiny walls will encourage fuel condensation (and so leaning-off the mixture) on the manifold walls especially when cool / cold, some texture to the walls will create a bit of turbulence in the surface layer of gas and promote good mixing and evaporation. However with injectors spraying fuel directly on the back of the valves, there may be some benefit to ultimate gas flow from the reduced drag in a polished manifold.
2) Yes, but only if you are experienced and competent with a suitable flexible drive / die grinder and appropriate burrs, or are prepared to junk a few manifolds whilst practising. Bear in mind that the valley gasket will determine the maximum dimensions of the manifold runners at the interface to the heads and if accurately used as a template will enable you to achieve the best possible match between the manifold and heads, which IS a point of potential improvement and can be achieved without spending ages profiling the rest of the inlet tract.
1) Unfortunately the real limitations to breathing on the RV8 are related to the cylinder head port shape and size and valve sizes. The later injection manifolds are better flowing than the original stock carb ones and improving this element of the engine is only going to bring power gains if the rest is already optimised . Assuming the heads are basically stock items, as is the case on most TVR RV8s other than (IIRC) the 500 and some of the 4.3s and HCs - allegedly, then it is unlikely spending time and effort on the manifold will result in any noticable benefit unless this is part of a integrated package of improvements. Incidentally polishing the inlet tracts can be a mixed blessing; vis a vis, with a carb set up very smooth shiny walls will encourage fuel condensation (and so leaning-off the mixture) on the manifold walls especially when cool / cold, some texture to the walls will create a bit of turbulence in the surface layer of gas and promote good mixing and evaporation. However with injectors spraying fuel directly on the back of the valves, there may be some benefit to ultimate gas flow from the reduced drag in a polished manifold.
2) Yes, but only if you are experienced and competent with a suitable flexible drive / die grinder and appropriate burrs, or are prepared to junk a few manifolds whilst practising. Bear in mind that the valley gasket will determine the maximum dimensions of the manifold runners at the interface to the heads and if accurately used as a template will enable you to achieve the best possible match between the manifold and heads, which IS a point of potential improvement and can be achieved without spending ages profiling the rest of the inlet tract.
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