Forums/Z31P/z31-performance-upgrade-forums engine-mechanical-aa/OWO head cross section pics
Imported from Z31Performance.com Forums{{#if:Doug| — original post by Doug}}{{#if:2014-01-22 06:53:14|, posted 2014-01-22 06:53:14}}{{#if:25| · 25 post{{#ifeq:25|1||s}}}}{{#if:/Z31performance_archive/forum/z31-performance-upgrade-forums/engine-mechanical-aa/23236-owo-head-cross-section-pics.html|
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Doug: (2014-01-22 06:53:14)
Sectioned a scrap OWO head to get a better idea what the ports look like. Pics:
Intake
Exhaust
Exhaust short side zoom
G-E: (2014-01-22 17:58:42)
Velly nice, cut through the guide too [archived image: smile.png]
BLOZ UP: (2014-01-22 19:49:24)
This is nice, I've been meaning to start grinding on my VG33 heads.
jaqattack02: (2014-01-23 01:17:27)
Need to do some similar cuts on a set of earlier heads so we can compare.
Doug: (2014-01-23 03:33:52)
I don't have any earlier V52, 21V or 85E heads to section. If someone wants to send me one, I can do it.
jaqattack02: (2014-01-23 03:49:19)
That would be cool, would be even better if someone could get the sections on a scanner.
michaelp: (2014-01-23 04:29:52)
Pictures aren't loading over here. hmmm
stufferton: (2014-01-26 20:17:11)
Now, I've never ported heads before, but from what I understand the idea is to smooth flow as much as possible. That hard edge on the near side of the intake, and especially on the exhaust side, is it safe to smooth that whole transition out? Is there a reason why it should or shouldn't be touched?
G-E: (2014-01-27 00:25:55)
Yea, a lot of what you're trying to do is the same as using mandrel bent exhaust piping, you don't want the gases to expand and contract at each bend, everytime you expand the cross sectional area, from the area before it, the gases lose velocity…
For porting heads, there's another aspect to think about, and that is direction; you also want to shape the ports to turn the air to the ideal angle relative to the valve opening before arriving at the valve (intake side), which is why you see the near side hump
Doug: (2014-01-27 05:04:58)
Mr. 510 has an interesting post on the nissan pathfinders forum about VG cylinder heads:
Axel kain: (2014-01-27 18:15:31)
open up the top side of the exhaust ports, and youve got a real winner!
youngfg: (2014-01-28 00:20:53)
How timely, I just flow tested some heads.
I tested both heads on a SF600 bench, with a 3.3 sized cylinder bore at 28" of water.
R-21v results
Intake, average of all three ports.
lift, flow
.1, 57.33
.2, 108.33
.3, 144.66
.4, 160.66
.5, 163.66
.6, 167.33
Exhaust, Just one port
lift, flow
.1,43
.2,86
.3,97
.4,99
.5,100
OWO results
Intake, one port
lift, flow
.1,58
.2,112
.3,140
.4,164
.5,178
.6,176
Exhaust, one port
lift, flow
.1,39
.2,89
.3,112
.4,114
.5,115
.6,115
BLOZ UP: (2014-01-28 17:16:37)
Did you perchance flow at 0.05" increments?
BLOZ UP: (2014-01-28 17:18:25)
Made spreadsheet: https://docs.google.com/spreadsheet/ccc?key=0ArzU_jZP3kl4dGNySVdFVXBnTkJGWkFacGNQbGxOb 2c&usp=sharing
youngfg: (2014-01-28 19:05:25)
I now have access to a SF600 flow bench so I will be flowing several different heads.
I will start flowing every .050, and stop at .450, no use in going any higher, there really aren't any cams with that high lift to worry much over .450.
We did a back cut on a set of stock valves and re-flowed both heads, the difference was negligible.
I also flowed both heads with some minor porting, cleaned up the SSR, unshrouding, ect., they only picked up flow above .400" lift, so it really wouldn't help much in the real world.
I working now on testing with the +1mm Ferra valves. We have to get the right tooling to open up the throat, and do a good valve job. They normally work with engines that have 2.5" valves so they don't have any small tooling.
I also plan on testing with a 30deg. seat angle. The 30deg. seat is supposed to help with low lift flow, and with these engines that's all we have.
michaelp: (2014-01-28 19:19:54)
Quite interesting, as a22770 dudes flow tests as well as Jasons on redz31 show huge gains everywhere when ported and unshrouded.
Also, what were the actual lifts you tested the above VG heads at? Is the 1-6 just the test number or the actual lift?
I'd flow atleast to .5" as some VG cams do have *almost* .500" lift.
BLOZ UP: (2014-01-28 21:27:30)
If you can and are feeling generous, can you flow at 10" as well? I want to see if there's any big differences at low air speeds between the heads as well.
88sinZ: (2014-02-01 05:39:08)
bernoulli's principle
WTMP: (2014-02-02 02:59:48)
Or if you are feeling very adventurous, flow test at 48" of h2o and see if it will correlate with what it flowed at 28". Hint, it wont unless you fix the velocity profile in the port.
BLOZ UP: (2014-02-19 14:37:26)
bernoulli's principle
Yes, but with high air speeds air can just "give up" going around the SSR, resulting a different trend of gains. At low air speed, you can find that some porting work that seemed to give little benefit at high air speed really benefits at low speeds.
Stealth300zx: (2014-02-21 06:19:45)
This is a V52 head from an early '87 model (11/86). MAY or MAY NOT have been the original engine. The cylinder in particular is #5
Maybe we can compile these pics into a sticky head thread.
[archived image: DSCN3106_zpsd8647d3f.jpg]
[archived image: DSCN3110_zpsfb236ad8.jpg]
MAJOR difference in the intake port. No so much the exhaust
slammedfc: (2014-02-21 17:13:28)
Holy exhaust restriction.
88sinZ: (2014-02-23 06:44:40)
ITT: minds being blown by 20yrs of machining progress [archived image: confused.png]
88sinZ: (2014-02-23 06:46:02)
Yes, but with high air speeds air can just "give up" going around the SSR, resulting a different trend of gains. At low air speed, you can find that some porting work that seemed to give little benefit at high air speed really benefits at low speeds.
any material to elaborate on this? Just curious
BLOZ UP: (2014-02-23 17:08:31)
According to Vizard: "Air is heavy". At different velocities the air mass behaves a lot differently. An engine doesn't pump air in the same way that a flow bench does, there's a pulsing to it. Whenever the valve is closed air slows to a stop, then it speeds back up again when it opens. At peak velocity, most of the air entering the chamber is going through the end opposite of the SSR. At low speeds and lift, air is more uniformly going around the valve into the chamber.
So, testing on a flow bench at a low speed and a high speed will better indicate how your port work benefits on a running engine.