b3 exhaust

[bhearts]

hey guys. so im wanting to start on my uber fuel eco build within the month. but first im going to build a new header for the beast. can anyone source me a flange for a b3 motor. when i tear my head off im going to fill that off circle shape on the exhaust ports with aluminum. so instead of it looking like a circle with a square side. itll look like a circle. ive decided that way would be the easiest to port match. since everyone knows that port matching make for an effient flow path.

[Bert]

Measly B3? These are fire-breathing dragons compared to the mileage-master B1s that were OEM on European and Asian Festys.
You'll want a carb car for sure since EFIs are fixed, and the 5 speed. Acceleration can't be high on your list either.
If "Uber" is what your're looking for VW has had a 3 cyl Diesel out in the European market for 20 years.

[iceracerdude]

Take an exhaust gasket and send it to a "waterjet" cutter equipped machine shop. Tell them to make you the flange like the gasket but radius the tear drop portion of the holes.
There's a guy I can't think of his name right now (weir-tech or something like that), does this exact work reasonably.

Never have used this guy but maybe: http://www.davesport.com/cgi-bin/davesport/flanges.html

[blkfordsedan]

Not sure I would try to reshape the port. The floor of the port is flat for a reason. If you look at ports and compare to the swirl design of the combustion chamber, it will make sense why it's designed the way it is. At least, I would want some time on a flow bench to verify the benefit of any drastic changes.

[bhearts]

what do you mean. efis are fixed?

[zoom zoom]

If it was me, I'd leave the ports the shape they are. Just source an aspire exhaust manifold, they're steel and you can cut the runners off the flange. blkfordsedan means you shouldn't make a circle a triangle, or something like that, just make it flow better...and searching his threads will lead you in the right direction.

[Safety Guy]

Was Bert responding to another thread? I don't think it fits here.

Karl

[FB71]

since everyone knows that port matching make for an effient flow path.

why can't you port patch a teardrop port? I did. Not hard.

And agreed, the port is teardrop shaped for very specific reasons relating to gas scavenging. Also, on the exhaust side, you want a slight mis-match. You'll want the port to be just ever so slightly smaller than the runner, to reduce reversion. This will keep your VE up.