I'm very interested in seeing your pictures. Can you add them when you get to a pic? Thanks. I can't ever upload pics from my phone either.
Probably no where near as many who misunderstand/misconstrue words in snide attempts to discredit what's being said. Perhaps this will help: http://www.sciencedirect.com/science/article/pii/S0307904X09002741 As I said before, it won't be completely necessary for the OP's purposes, but it does make a difference, depending on the time spent improving the efficacy and its intended application. I thought we could simply add some comments to help the OP and move on in a more linear direction of assistance, but for some, this is not enough. Foreseeing a(nother) potential thread derail, this information should stand well on its own, and withstand any attempts to further discredit the validity of suggestions offered up without further intervention on my behalf. Gary
Snide not intended! This time I was disregarding any science and suggesting something from the perspective of those that "charge extra" for special services, hoping the sarcasm of that came through. After re-reading it, I can see how it looks. Oops. My personal preference for hand porting (which doesn't have to be followed) is to leave burr and stone finish strategically in certain places, chambers as is except for major defect, and after any shaping in the exhaust port, continue with the same finish more for cosmetic reasons. I haven't read any above links but some go to great lengths to roughen or dimple certain areas and applications, even using the CNC to do it.
Bowl only. Ports don't need any material removed. Don't port match, waste of time and may hurt the flow. Just eliminate any of the head area that over laps the intake port.
Thanks. So my goal here is to make the area as tubular as possible while not disturbing the strength of the valve guide and keeping with the over-all shape of the port/bowl. I want to make it as easy for the air go around and over the valve guide as possible, right? Here's my progress so far: Before After Am I trying to achieve this?:
Thanks. My plan is to smoothen the port walls, there are some pretty rough areas. The intake ports were matches to my previous intake, I am not touching that area again.
Yes that would be good as far as I do. Not going all out just improved flow without spending a lot of time on it. Try to stay off the valve seat. But clean up area up to valve seat
It's not recommended to smooth intake port walls when fuel vapor is also carried along. Most head porters will also suggest to leave them no smoother than a stone or carbide would leave. So...if you want to...
There's a LOT of time added for what might be negligible returns for such a mild build. The shape is far more important. The articles can bring you far. Looks good so far :TU:
Porting- Use strip sand paper to do the floors of the ports. Run your finger from just under valve seat area around the sharp turn into the port. you must feel a really smooth and even radius. Flowbench really drops if least bit uneven. Valves- once converted to stage one valves and ported, you no longer can go back and install steel exhaust seats.
Up to a point. Intake side you want the texture there with a wet flow, since the fuel has more mass than the air and wants to separate from the air (around curves) and collect on the opposite side of the turn. The texture helps create a shear point prior to the surface, as well as increased surface area (on a very small scale) to help with fuel evaporation for any that does separate. Exhaust side is the only place where some recommend polishing, but there are diminished returns on this (particularly for perfectionists and high-end race applications) vs time spent. To get it 'el perfecto' you certainly will spend some time doing this. My preference is to have it smoother than the intake side, not necessarily 'buffed and waxed' to a mirror finish... This will increase the laminar flow closer to the exit side of the head (not necessarily closer to the valve, where it enters the runner), and is more important on the wide end of the turn (upper portion of the exhaust runner), which helps some on the air speed (velocity). I'm not sure if the science has been measured yet on the effects for Buick engines, but it is recorded elsewhere that turbulence also encourages heat transfer into the surrounding material due to friction and extra time spent in the vicinity...which means you should be able to put more heat into your headers and away from your engine (keeping it cooler), and works great with header coatings for additional scavenging. It could be debated on how much polishing affects the velocity of air flow (I believe it does, and is worth the extra effort (even on mild/stock engines) but you all expected that right?), but moreso that it improves laminar flow and reduces turbulence, getting the exhaust and heat out of the engine as fast as possible. Incoming comments on 'it won't matter' or 'it's all just theory', but that's ok. I'm saying it anyway. Funny how some people will nitpick nickels and dimes elsewhere on the engine, but want to skimp out on improving airflow quality on exhaust. o No: Removing hot spots is always a good idea for the combustion chamber, and so polishing the rough texture/sharp spots out of the combustion chamber does indeed help with this...however, for this particular engine's compression ratio, I don't believe there'll be problems with detonation. I would do it if it were me though, just because. Gary
