W2 head porting observations help needed!

PRH said:

That seems like a situation where the risk/reward ratio is pretty unfavorable.
Personally, I’d set a pretty easily attainable goal, especially since at this point it doesn’t appear that you’ll be able to use your numbers to gauge where you really are .......compared to the potential of the head(you don’t know what a “300cfm” w2 flows on your bench).
You’ve picked them up 15% already.

Use some scrap J head or something for the learning tool, and save the W2’s until you have a better handle on how your numbers translate to the rest of the world.

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Yeah, I totally agree, I think the gain I've made so far is a step in the right direction, and a good stopping point....the other, newer W2s are mine, and I know the are a bit better as cast, I think I'll spend my efforts on them, after I get a handle on the bench calibration. Its within 4 CFM of the calibration plate that came with it, but I dont think the vaccum source is enough to keep up at the higher flow points.

What is the flow rate of the test plate?

You’d really like to have a test plate that’s somewhat close to the heads you’re testing.

I had to swap the inclined manometer on my bench at one point, and the replacent wasn’t dimensionally identical to the original, so I had to make adjustments to the orifice rates.
I bought 5 plates so I could test more than one point in the test ranges I use the most.

I’d say for SB Mopar Heads, if I were to only get two it would be like a 200 and 300.

Does/can the FP software display the actual test pressure?
If so, what is it at say .500 lift on that reworked w2?

I'll check the test pressure when I get back out to the shop...thanks for the help guys!

Test pressure was showing 4.8 @ .550 lift

replicaracer43 said:

Yeah, I totally agree, I think the gain I've made so far is a step in the right direction, and a good stopping point....the other, newer W2s are mine, and I know the are a bit better as cast, I think I'll spend my efforts on them, after I get a handle on the bench calibration. Its within 4 CFM of the calibration plate that came with it, but I dont think the vaccum source is enough to keep up at the higher flow points.

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If your vacuum source isn't strong enough then you won't be able to maintain 28" of depression past a certain flow rate. Check what they flow at 20" h20 and convert to 28" . Play around with it.

W2's flow 234-235 cfm out of the box on my bench and a SF-600 local to me. They don't flow near what MP claims without work. The bowl shape is great, the port size is enough for most applications . The shortside is tricky. You can get great low lift and high lift flow numbers if you get it just right. .020-.030" too much in the wrong place and a poor flowing port at all lifts will result. J.Rob

replicaracer43 said:

Test pressure was showing 4.8 @ .550 lift

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That’s interesting. It’s higher than I would have expected by a fair amount for only having one vaucuum motor.
Imo, putting aside the actual numbers, if you’re able to pull over 3” at the higher lifts, I’d say the trends seen from the porting are going to be valid......... unless it’s a head that does something odd as the test pressure goes up(which some do, some don’t).

The old Mullen’s tests were done at only 3”.

It’ll be interesting to see how/if the numbers change with a higher hp vacuum source.

I’d def get some PTS plates before going too much further.

My understanding of how the shop vac type flow bench works is, there is no “flow control” to regulate the test pressure.
The flow bench is running at max pressure at all times.
As the valve in the head is opened, there is less restriction to flow and as a result, the test pressure drops.
The computer in “the box” is measuring the air flow through the flow element, and monitoring the test pressure, and calculates/corrects that flow, at that pressure(whatever it is), to what it would theoretically be at 28”(or you can select 10”).

When I had my SF-110, I would test the “big” heads(like a big BBC head or a B1) at 5” or 6” at high lifts.
Those benches have 4 motors, but only use 2 at a time(2 intake/2 exhaust).

So, for heads that were too big to be able to pull 10” of vacuum at the higher lifts, rather than use a lower test pressure for the whole test, I’d test at 10” until I got to a lift point where I couldn’t pull 10” any more, then I’d drop to 8”...... until I couldn’t pull that anymore, then drop to 7”, then to 6”, etc.
At that point I was basically doing manually what your “box” does automatically.

So, after examining things a bit more, I did find a issue with the bench, there is a flange right at the bottom of the head adapter plate, with quite a pronounced lip, I think that is skewing the actual numbers, especially as air volume goes up. I will address that soon, and do some more testing. Again, thank all you guys for you help and suggestions, its MUCH appreciated!

Now, ACTUAL flow numbers aside, I have noticed quite a few interesting differences in this set of early W2s, and the later set that are mine. The early set has that rounded short turn shape, where the later ones are flatter, the early ones have a big square guide boss, later ones are much smaller, the early ones have a hump in the exhaust port roof, later ones do not, and interestingly, there is almost NO pushrod hole bulge, or headbolt bulge in the early ones, but quite noticeable on the later ones.

W2 heads are a very nice head and take about 1/3 the work as an Edelbrock head to hit 300cfm. I kinda soured on them when mine cracked. I the sold off two and a half set of rockers and the W2 Victor intake I ported. Years later I bought a set of W2 race heads with Norris rockers and an intake from a friend and sold it all off making a small profit. Should have probably kept them.