Author Topic: C6AE-R  (Read 8335 times)

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cjshaker

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Re: C6AE-R
« Reply #15 on: December 11, 2017, 02:12:44 PM »
99% of the work is done the second that valve cracks off the seat. The rest is just time to let the "event" take place. We like to think we know what's happening in the ex port, but we really don't. Flow bench is all but meaningless when it comes to ex ports other than for cam design and selling heads.

I was sorta amazed at the slow motion video on YouTube of the Briggs & Stratton engine with the plexiglass head. Of course it has practically zero in common with any car engine, but you can still see how almost instantaneously the exhaust exits the chamber. And like you said, the rest of the event is just time to get that last little bit out to not contaminate the incoming mixture. Still, getting that last little bit out makes a big difference in the next combustion cycle. And despite some of the tests showing how little of a difference headers make in power production, there's plenty of data showing the effects of a well designed system in a drag application. Not so much on most street applications though.
Doug Smith


'69 R-code Mach 1, 427 MR, 2x4, Jerico, 4.30 Locker
'70 F-350 390
'55 Ford Customline 2dr
'37 Ford Coupe

scott foxwell

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Re: C6AE-R
« Reply #16 on: January 08, 2018, 09:11:19 PM »
bump for chilly460

chilly460

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Re: C6AE-R
« Reply #17 on: January 09, 2018, 10:18:53 AM »
Thanks, definitely helps me to see what I'm aiming for with the bowl blending.

scott foxwell

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Re: C6AE-R
« Reply #18 on: January 09, 2018, 10:48:54 AM »
Thanks, definitely helps me to see what I'm aiming for with the bowl blending.
No problem. Let me know if you'd like better pics.

cammerfe

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Re: C6AE-R
« Reply #19 on: January 09, 2018, 02:28:00 PM »
I just have to say this .With the new trick flow head and Jays over the top head prototype getting so much press .We all shouldn't forget how well the old iron can actually perform .Those flow numbers are as good as or possibly better than out of the box edelbrocks .Very respectable .The chevy boys just don't know how well those old ford heads actually work .Good job Scott I didn't want your post to get lost! Doug 8)
Thanks Doug. We'll see how they do on my 390.
My thought on ex ports; the air WILL go out that hole. The most critical part of the ex port is the valve job and throat. After that it's just a hole. 99% of the work is done the second that valve cracks off the seat. The rest is just time to let the "event" take place. We like to think we know what's happening in the ex port, but we really don't. Flow bench is all but meaningless when it comes to ex ports other than for cam design and selling heads.

Just as an experiment, bolt plates over the exhaust ports with a quarter-inch hole in them.  ;)  ANYTHING that interferes with the gas flow out of the chamber is a power-robber. Cylinder pressure is certainly helping the gas get out, but a free path is of great assistance!

KS

scott foxwell

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Re: C6AE-R
« Reply #20 on: January 09, 2018, 04:26:08 PM »
I just have to say this .With the new trick flow head and Jays over the top head prototype getting so much press .We all shouldn't forget how well the old iron can actually perform .Those flow numbers are as good as or possibly better than out of the box edelbrocks .Very respectable .The chevy boys just don't know how well those old ford heads actually work .Good job Scott I didn't want your post to get lost! Doug 8)
Thanks Doug. We'll see how they do on my 390.
My thought on ex ports; the air WILL go out that hole. The most critical part of the ex port is the valve job and throat. After that it's just a hole. 99% of the work is done the second that valve cracks off the seat. The rest is just time to let the "event" take place. We like to think we know what's happening in the ex port, but we really don't. Flow bench is all but meaningless when it comes to ex ports other than for cam design and selling heads.

Just as an experiment, bolt plates over the exhaust ports with a quarter-inch hole in them.  ;)  ANYTHING that interferes with the gas flow out of the chamber is a power-robber. Cylinder pressure is certainly helping the gas get out, but a free path is of great assistance!

KS
Not true. Velocity through the valve job and throat are important, just like the intake port. A certain amount of restriction is preferred/needed/desired. Your example of the 1/4" hole is ignoring the fact that the valve job and throat are the most critical part. You either didn't understand what I was saying or you took it way too literal.