t-von

iTrader: (8)

Ok I need some input. I'm in the process of rebuilding my 12A. I decided to experiment on the old unusable housings. I didn't have a template or anything just free hand. I just tried to enlarge and retain the stock oval opening. The upper inside of the port is tapered upward. Basically just seeing if I could port at all. All opinions welcome!

88IntegraLS

Craftsmanship looks pretty good to me.

Exhaust porting is a black art. Paul Yaw uses a special rotary engine modeled flow bench to test his exhaust ports. It's amazing how the port shape and chamfer radii enhance or disrupt the flow.

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

I really want a flow bench now!

t-von

iTrader: (8)

Thx for the complement! That site is where I learned about keeping the 2mm bevel around the port.

RandomHero

iTrader: (2)

Thats pretty clean, but you could prolly go farther up.

t-von

iTrader: (8)

Well with this design, I'm trying to keep the engine somewhat emissions compliant. I may try something differant on the other housing.