For those of you that have looked into the secondary ports, to see the path that the air has to follow to get into the engine, doesn't it seem like it could be better? The air has to almost do a 90 degree turn as it passes the bulge in the port where the ecentric shaft oil cooling area thingy is (somebody has to know what I'm talking about). I'm rebuilding a friend's engine right now, and when I go to port it, I was thinking about building up the port to smooth out that area. So that the air would more fluidly flow into the front of the chamer that is opening, instead of running into the air coming from the primary ports. In Bruce Turentine's rebuild video, he did something similar to the 5th and 6th ports on a 6 port. I wonder what is more important, the path in which the air travels, or the sheer volume of a port.
I remember reading somewhere that the biggest improvents to be had from porting, were not actually gotten from the shape of the port on the face of the housing, but rather the shape of the inside of the port, and where the air is directed. Looking into the secondaries, the air goes in from the LIM, makes an almost 90 degree turn to run almost directly into the air from the primary port. With a little bit of time and effort, the ports could be contoured to not make the air turn so abruptly, and face the inside of the opening chamber, rather than the other port.
I probably won't do that to the engine I'm currently porting, but maybe when it's time to do mine i will.
Any suggestions are welcome, even if you're just calling me a dumb bastard.
--Danny

 

In my world (which granted, has two suns and purple sky) the path of least resistance beats the size of the port anytime.

To look at it from the other end, everyone
ALWAYS thinks that bigger exhaust pipes are better, which is not usually true. Horsepower is what counts. Straight pipes rule.

I've always felt that porting is kind of like black magic. It has awesome effects on flow if well done.

Your friend owes you to take the time and thought to do his engine like this!
It will be awesome.

 

I wouldn't be afraid to try the method Bruce T. uses as it probably works well. He seems very straight-forward in his video and I've talked to him over the phone before. He has been building rotaries for some time and I believe he is fairly popular in the rotary aviation community. He uses the "moldable metal" that comes in a tube; basically creates a "ramp" of sorts to smooth out the flow of the air so the air won't be ramming up against wall and then make a 90 degree turn as was stated previously. Cheers.

Kyle

 

you dumb bastard!

just kidding... just had to take the opportunity.

 

I'm going to call some of the experts pretty soon, and see what they think of this idea.
Doe no one else have an opinion on this?

 

I would expect that smoothing the flow would be well worth the effort, but I have no experience to back that up. What we need is a race builder who's tried several methods, and tested them on a flow bench of some sort.

BTW- I may be dropping the turbo idea from my airplane engine, which will mean that I'll have to do some work on the new turbo engine that I have. Porting will be a big part of that, so take good notes

 

as far as fluid dynamics are concerned the gas/air mixture will fill that area and form a ramp like you are talking about and then the rest of the incoming mixture will use that ramp. so the mixture is not really making a 90 degree turn. try to picture this using tiny *****. the first ***** in would fill the hole and remain there because the rest of the incoming ***** would keep pushing on them. if forms its own contoured ramp. what is a important about the port is how early it opens and how late it closes without to much overlap depending on your application.

 

I realize the importance of port timing, but I think a lot of people underestimate the importance of the angle at which the air enters the port. Some monster J-ports are bigger in volume than a peripheral port, but since the j-ports angle the air towards the other port (to some extent) and the p-port angles the air directly toward the opening chamber, the p-port gives much better power gains.

 

Ok, but this would restrict (choke) the size of the inlet, if you fill in one side and enlarge the other, you would have better flow without restricting the inlet size.

 

I just talked to Bruce Turentine, he said that the turbulence the 90 degree turn in the secondary ports creates helps with gas mileage. He also recomended going in from the manifold side of the exhaust port, and match the port to the liner. He said that it wouldn't change the timing, but just smooth the exhaust flow better. I'm going to make a few more calls.

 

funny, i also had these thougts about the angle a few days ago. just wanted to add my dumb comment intresting thread

 

[/B]trust me, i know owe him. danny has been a tremendous help to me.
Yoouuu can do it!
but wait, NOOO! THEIR ALL GONNA LAUGH AT YOU!

-brad

 

Thanks Brad. And yes, they're all gonna laugh at you.

 

They'll be laughing at his lumpy idle, but crying when they see his tail lights. Zoom, zoom. Match port and polish as much of the intake manifold as you can, it's worth up to 6% increase, and that's serious.