What not to do when porting!!!

Kinda expected this, I was really trying to open these things up WIDE! I guess I went too wide?

 

Just fill it with JB weld.. lol


At least you kinda saw this happening, still sucks either way.

 

Ive heard of TIG welding repairs being possible, still might try it, I know a pretty good welder. If not, I just use the head as a test mule for just how much you can take off before blowing through on both the intake and exhaust. Good info if nothing else.

 

He'd have to be if he could fix this, I've never done it, but I've heard horror stories of people welding alluminum.

 

hogging them out like that can actually hurt performance.

 

Exactly.. That is more less older school tech. You want to keep the most velocity you can. Opening them up huge could actually cause swirling, instead of getting it in,out..

 

Thanks for trying this! Now I won't haha

 

yup. From what I've heard making the port a D- shape yields the best performance. Kinda similar to the LT4 head.

 

I did that on one of my aluminum heads, Father in law welded it back up and made it back to the D shape and has had no problems, but he is a boilermaker and has been weldin for 30+ years

 

Agreed, but there was a method to my madness. My goal was to get a 3% decrease in volume on the intake from the manifold side to the valve. That 3% I have read is good for port velocity. Shape also plays a factor, but maintaining a similar shape, the 3-4% would have worled fine. I wasn't just hogging them out for the fun of it.

Keep in mind that this is the exhaust port. I believe that there is somewhat of a scavenging effect that can be attained from having a lot of empty volume in the exhaust runner for all that waste gas to fill, as is first stop on its way out. I was in the process of putting that to test when I found the limits of the runner!
Seeing as how I kinda saw this coming, my intent, if it happened, was to find the limits of the casting and post up the info for the board. Hopefully people can benefit from this.

Is there any info to support these claims? I'm not saying they are wrong, but if I didn't ask for supporting info and belived everything that I read on the internet, I'd have about 45 masters degrees right now!! Really though, I would love to see some flow #s, an airflow animation, something that supports this.