I would like to see the video clip.
Have we been going about this all wrong? Discussion welcomed
- Thread starter Wesman07
- Start date
Are you able to figure out air flow demands at other parts of crank rotation. Say using a cam with a 220 duration at 0.50”?
The airflow calculations above show how much air would be rushing into the cylinder without a cylinder head in place at peak piston velocity.
You can calculate the piston velocity at different crank angles using Trigonometry.
He gets into the LS7 design around 12:20. The video is long, but it’s full of about 100 “Ah Ha!” Moments.
Thanks
There is good information concerning the short turn radius and how to use it.
Looks like bigger valves with close to a 90% throat size is in order.
Raise the port floor and roof.
Could you try raising the roof as high as possible and if you break into the water jacket just fill it in with clay or epoxy so you can get a flow reading?
Raise the port floor and roof.
Could you try raising the roof as high as possible and if you break into the water jacket just fill it in with clay or epoxy so you can get a flow reading?
I don’t think we could mimic the LS7 port design because of a lack of real estate to work with. Our ports are closer to the Windsor style that was shown a few minutes earlier.
Another thing to consider is the ports and valve is already plenty big for 300hp demands. It’s the throat that gets choked off as air speed increases.
By starting the short turn earlier, the throat will have less choked area. The head then becomes more efficient.
The problem you run into by increasing the throat and valve too much is you will run out of material to re work the short turn. So your stuck with a larger system of the same efficiency but with increased flow.
Another thing to consider is the ports and valve is already plenty big for 300hp demands. It’s the throat that gets choked off as air speed increases.
By starting the short turn earlier, the throat will have less choked area. The head then becomes more efficient.
The problem you run into by increasing the throat and valve too much is you will run out of material to re work the short turn. So your stuck with a larger system of the same efficiency but with increased flow.
That is something I plan on trying as step one of attempting a faster more efficient port.
The aluminum inline Chevy 6 cylinder race head I manufactured a few years back had the intake ports raised about 1-3/4" higher that the production cylinder head did. The exhaust ports were also raised quite a bit. It wouldn't have been difficult to have modified, or even made more patterns to produce a Ford 240/300 head from the Chevy patterns since the heads on these two engines are very close to the same length and bore spacing.
Did it have shared ports? Do you remember what it flowed? Or a picture?
No, it has 12 individual ports, hence the name 12 port head. It was originally designed by Frank Duggan in Australia in the mid-1960's as a replacement performance head for the Chevy 250/292 engines. He latter partnered with Kay Sissell in the US that owned Sissell Automotive. Several upgrades and versions were produced through the years. The patterns I purchased came from Joe Deppe, who tried to also partner with Sissell in the 1970's, but a disagreement between them left Sissell and Deppe with their own patterns for the cylinder head.
My heads routinely would flow in the 330 CFM range, with the best being just above 340 CFM. Mike Kirby, the owner of Sissell Automotive after Kay passed away, had a solid head that was CNC ported and flowed 400 CFM. I'll dig some pics up of the heads....
My heads routinely would flow in the 330 CFM range, with the best being just above 340 CFM. Mike Kirby, the owner of Sissell Automotive after Kay passed away, had a solid head that was CNC ported and flowed 400 CFM. I'll dig some pics up of the heads....
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Wow. That’s impressive. Im assuming these did not have cooling passages?
Yes and no, the were two versions available, one with water jackets and one that was solid. The water jacketed heads flowed 330 to 340 CFM. The solid version that Sissell Automotive produced reached 400 CFM. The cylinder heads as cast were capable of 300 CFM with just minor port cleanup and deburring...
There are several turbo'd 292's out there making over 1000 HP with these heads. Not bad for a head that was probably updated last in the early 1980's. Who knows what starting from scratch with 21st century technology and techniques could yield....
What would a head like that cost today?
Since so much advancement have been made in the CNC industry with the cost of doing business, and machines becoming cheaper and more affordable to the masses, a CNC water jacketed head has been done for close to 10 years now by at least one major racing cylinder head manufacturer. So, spending 10's of thousands of dollars to make casting patterns and going through the whole casting process has become almost extinct and no longer a cost effective way to make a cylinder head. Also, Brodix has made 2 piece intake manifolds for V8's for over 15 years now, so making a 2 piece intake for an inline using a CNC mill is very easy and takes away a great expense of having to create patterns and have one cast. Technology has finally caught up and replaced many of the century long methods of making parts.....