With basic porting jobs the key is to removes as LITTLE as possible from the ports to maintain gas velocity and throttle response and to maintain the factory fundamental port shape and direction (unless its a shitbox to begin with which the VG30dett isnt). Basically, if it "looks" good and "feels" good to the fingers, the gasflow will tend to think similarly. Its really high end stuff with huge boost and insane rpm that will gain from the major detail and reshaping jobs and that is a total black art. You might go thru a lot of heads to arrive at the very best setup. There is nothing wrong with port matching using gaskets. Even if the gasket sizes vary, they can be easily trimmed later but the two port relationships wont change much unless grossly different thickness papers are used. Always avoid the tempation to "knife edge" port dividers. In subsonic gasflow, a bullnose is more efficient than a sharp edge. There is an effective radius but i cant remember it now. This is why sub sonic airplanes have round leading sedges on the flying surfaces and fuselage and supersonic planes have knife leading edges and sharp fuselage noses points. M8 youve done excellent work there. Id consider throating the seats slightly. This fools the head into believing it has much larger valves than it actually does but watch the seat to valve face contact area. It looks like you have spent a little long there with the mop around the valve throat area and ended up with the seats being somewhat smaller in diameter than the ports. Make sure the valves are in really good nick or new as any previous cutting of the valve faces will result in overly thin valve edges directly over the contact area with the seat face and possible failure due to heat or just plain fatigue. After throating, you will spend another fair bit of time blending in the throating job into the existing port shape!!! Doesnt need to extend far up into the port tho changing its fundamental shape. Itll be worth it tho! Id also consider blending in those plenum ports further up into the plenum to even out the shape and reduce any further turbulence. Youve gone this far you might as well clean it right up. Consider having the valves and seats cut with 3 angles (3 angle valve job) this will especially help with low lift flow at the beginning and moreso, at the end of the valve lift cycle. Itll cost you but the benefits are considerable and well worth the money. Some slight relieving around the combustion chambers and a home CC job and you will be grinning very wide indeed! Keep going M8, youve done a nice job so far. L8tr E
Hey, any more progress or end results? I read this all when it was first posted, and again just now because i'm having my heads looked at at the moment and trying to decide what to do. Started out as just a reco job, then thought why not go O/S valves, then snowballed from there and now i'm looking at cams, springs etc etc etc Still undecided, but your work has been very interesting reading and I would love an update Ben
No new updates sorry. My next step is to make a template of the ports so that I can replicate it evenly across all ports. Once I'm happy with it Ill get my second head flow tested to see what improvements were made. I have a few job on right now so it most likely wont be untill next year. I will update when I have more progress.
hows this project going along... am about to start a similar thing myself, if im game enough, so i thought some updates from here migth inspire me
Thread digggg!!:br: Because its a cool thread and it would be great for more advice and input added Joe
Sorry Joe, project kind of got abandoned. Got stuck into all this fiberglass business and haven't had any time to touch it. My zed has retired its race suit and I have no need to go any further with the second engine. :zlove:
