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BLACKCAT
10-16-2008, 07:35 AM
Can someone please post some pictures of a quality ported 7M head & what sort of airflow increase is possible?
92nsx
10-16-2008, 07:40 AM
Sorry right now I dont have access to photobucket right now. But I have pics of mine posted in my thread. post #6 or 7 IIRC http://www.supramania.com/forums/showthread.php?t=74301
BLACKCAT
10-16-2008, 07:19 PM
Excellent, thank you very much.:icon_bigg
BLACKCAT
10-18-2008, 06:43 AM
Have a look at the intake port picture.
Any reasons why knife edging that horrid divider would not be a good idea?
Supraholics
10-18-2008, 09:20 AM
Knife edging it will actually create turbulence. You want it to be round.
Doward
10-18-2008, 04:41 PM
Think of a teardrop falling ;)
Tun_x
10-18-2008, 04:54 PM
here is mine.. with flow #'s
http://www.supramania.com/forums/showthread.php?t=79866
IJ.
10-18-2008, 05:06 PM
Think of a teardrop falling ;)

Something every 7M owner should be well aquainted with :D
Tun_x
10-18-2008, 05:09 PM
Something every 7M owner should be well aquainted with :D

Its the truth
IJ.
10-18-2008, 05:17 PM
Its the truth

^ See Jason knows his stuff :D
amichie
10-19-2008, 04:49 AM
Think of a teardrop falling ;)

That is a myth.
Doward
10-19-2008, 10:45 AM
That is a myth.

Negative.

http://www.wonderquest.com/beer-streamline-size.htm

Unless your airflow is supersonic? ;)
Tun_x
10-19-2008, 11:10 AM
That is a myth.

not according to the flow bench....
Doward
10-19-2008, 11:16 AM
not according to the flow bench....

Or CFD ;)
Flateric
10-19-2008, 11:35 AM
Sort of an "untechnical" question about a technical subject, but.....

What is the actual speed of the air going through our intake system under boost? Say 14psi, or 24 psi? Meaning through the IC and all of it's piping etc?

I honestly don't even have the slightest clue is why I ask. 100 Km? 500 Km? Anyone have an idea?
amichie
10-19-2008, 11:48 PM
Rain drops are spherical. The tear drop shape that is familiar to most is just an artistic impression that we have all come to know.

Shot towers make sperical lead shot by dropping little balls of molten lead that forms into spherical balls.
IJ.
10-20-2008, 12:01 AM
Sort of an "untechnical" question about a technical subject, but.....

What is the actual speed of the air going through our intake system under boost? Say 14psi, or 24 psi? Meaning through the IC and all of it's piping etc?

I honestly don't even have the slightest clue is why I ask. 100 Km? 500 Km? Anyone have an idea?

"Critical" is around 304 Mph/ 0.40 mach and this will change based on pipe diameter/cfm.

2" = 585 cfm max = 304 mph = 0.40 mach

2.25" = 740 cfm max = 304 mph = 0.40 mach

2.5" = 913 cfm max = 304 mph = 0.40 mach

2.75 = 1100 cfm max = 303 mph = 0.40 mach

3" = 1300 cfm max= 301 mph = 0.39 mach
Flateric
10-20-2008, 09:09 AM
Holy crap thats way faster than I would have ever guessed! Thanks man!

So I was told that smoothing out and polishing the runners on a 7m was actually determental to performance because the pebbly texture was actually better for the supersonic air passing by it. This is obviously false.

I was told this by someone after they saw the litterally 2 weeks of polishing and port matching I had gone through and it's my belief he didn't want to endure the same dirty effort it was.

I personally felt it gave me a little better bottom end, better sounds and just felt "quicker", but didn't know if this was just wishfull thinking on my part after having been down two weeks. I'm not talking earth shatteringly better, but you know, it just felt like a positive change.

Certainly not a negative result by any means anyways.
IJ.
10-20-2008, 05:22 PM
You need to work out the actual CFM your Turbo is making at your maximum output then choose a size that keeps it below the .4 mach critical speed.

In the past I did all the calcs and came up with 2.5" as being the ideal for my combination at the time, I changed IC's and as it came with 3" In/Out I made new pipes to suit and to give me some more overhead.

I was fully expecting to experience more Lag either perceived or real and was surprised to find it spooled earlier so "theory" doesn't always play out in the real world!

Having said that Modern BB Turbo's have forced me to reexamine EVERYTHING I thought I knew :)

As for polishing the insides that's going to promote sticky laminar flow inside the plenum so a pebbly surface is better (think of a golf ball, dimples make them fly further)