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Anyone have any good data on cyl head porting for the io320?

Turbo69bird

Well Known Member
I?m just looking into possibilities of more HP from porting the cyl heads.

Engine is just a big air pump, but there doesn?t seem to be the info out there as compared to automotive engines.
 
I flow benched some Lyc 540 heads many years ago and they were quite poor compared to most decent automotive stuff. The intake flowed around 136 SCFM at .400 valve lift at 10 inches H20 with a 2.2 inch valve. Considering that it's trying to fill a 90 cubic inch cylinder, that not so good.

I'm sure some gains could be made in the valve guide area at least.

Lycon probably knows all the tricks that work...
 
http://www.lycon.com/tech-docs.html
Click on the cylinder porting article.

Ed Holyoke

I flow benched some Lyc 540 heads many years ago and they were quite poor compared to most decent automotive stuff. The intake flowed around 136 SCFM at .400 valve lift at 10 inches H20 with a 2.2 inch valve. Considering that it's trying to fill a 90 cubic inch cylinder, that not so good.

I'm sure some gains could be made in the valve guide area at least.

Lycon probably knows all the tricks that work...
 
Lycon

Lycon can do this on their 5-axis CNC machine. When I had my O-360 cylinders done 8 years ago (sheesh! Time flies!) when I toured their facility they said they were no longer even flow bench testing the cylinders after they came off the CNC machine since they were always the same. I don't know what flow numbers they got at what lift. I do know they leave the surface fairly rough looking from the ball end mill that they use because the surface roughness actually helped flow and fuel atomization.
 
No need to flow bench heads once you know what profile you want and the CNC can duplicate identically over and over.
 
Wilson manifolds found years ago that wet flow (carberated) engines liked a rougher floor to keep fuel in suspension through turbulence. I was hoping some guys were doing home porting and had ideas as to how to increase flow at low lift numbers.

We have relatively low RPM engines so the way the cylinders are ported has to optimize these characteristics. I?m sure lycon has it down, and I don?t know the cost but maybe it?s worth it. On my cars I?ve always done my own porting after doing a ton of research. however. I haven?t been able to locate much for research materials probably because on certified airplanes people arent porting their own heads.

Anyway figured with all the DIY going on here surely some people are porting and getting more HP from the ole lycoming I?d rather move more air through the engine than up the compression or spin it higher (my prop is a limiting factor for RPM) and risk higher temps and detonation.
 
I hear that. I don't seem to have either, maybe 'cos I spend all of each on the airplane.
Back in ought 12, LyCon was charging $250/cylinder for the CNC porting job.

Ed Holyoke

Thank you for the lycon info I?m going to read through it.

Some people have more money than time and some have more time than money, unfortunately I fall into the latter group 🤔.
 
I hear that. I don't seem to have either, maybe 'cos I spend all of each on the airplane.
Back in ought 12, LyCon was charging $250/cylinder for the CNC porting job.

Ed Holyoke

That's pretty reasonable in the scheme of things.
 
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