I just want to know what you are using to get your ports soo clean man. Great job and definity a inspiration to myself.

 

Check out this article on airflow from Paul Yaw. You may have already seen it. I'll copy and paste one particular sentence though.



"3. Cutting a large radius on the roof of an exhaust port. (12A, or 13B) A generous radius is helpful if the exhaust port is close to stock size, but if it has been widened considerably, a large radius will absolutely kill the flow. This is one of the most sensitive areas of any of the ports in a rotary engine, and you can lose 10% to 15% flow in a hurry. The difference between a .050" radius, and a .070" radius can easily cost you 25 cfm."



http://www.yawpower.com/Flow%20Testing.html

 

Hi Fred, long time no talk buddy



B

 

B.D.C, great port work looks stunning, but have two questions? Why did you not carry the 2mm radius around the exhaust ports and also how come you have not rounded the closing line on the inlet ports as per Itos comments and Lynes comments! it is great to have this site as it is far more informative than any site here in australia they are to secretive here! keep up the great work and information sharing!

 

Very nice ports. Mine are about the same size but not nearly as shiny. Good job.

 

B, nice work as usual

i hope we can see that in old europe soon as well

 

Hey DAT, I didn't round the closing edge of the intake port because I didn't extend the width of the port outlet any. These secondary intake ports were left skinnier on purpose; they have future use as bridgeports. I didn't take any of the iron out towards the inner o-ring land for the purpose of having a thicker bridge for a bridgeport later. Hence, I found no need to round out the closing edge if the side seal is not exposed to the open hole of the port outlet.



B

 

Looks great as always B.



Keep up the good work buddy!!!

 

I still "think" every port flows better with a sligt curv on the exit. The air along the port wall is laminar(wants to stay connected to the wall) a slight curv helps it spread out into the chamber better and sling shots the air above it better than a 90 deg turn that just creates vortecies arround its perimiter.



Velocity stacks use the same principal.



Thats what me and DAT are getting at. With or without a BP, with or witout comprimising the side seal, its an added edge over those who dont do it.



You can screw this up though as paul yaw wrote about. Think of the inside air (not the laminar air) like tubing behind a boat. When you make a quick(radius) yet not abrupt(90) turn the tube is going much faster than the boat. If you make a 90 degree turn the boat nearly stops and the tube does the same shortly after. The oppisite happens with a large radius. Not engough sling shot and the air moves slower.



The radus essentailly supercharges the air and it can keep doing so becuse the laminar air has enough velocity becuse of the radius to get out of the way and keep pulling in more air and accelertating it.



Thats how it was explained to me by a guy in Southern MN that has engines he built running in NASCAR.



Like I said though, great work!

 

B, could you please post a pic or a link of the abrasives your using to get that finish consistantly through the port.



I know you posted it onece before but I lost all my links and cant find **** anymore.



Thanks



GregW