Windsor Super Victor – plenums, port forms & finishes Vs flow

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David Vizard
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Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by David Vizard » Sat Jul 22, 2017 7:00 pm

I am not sure who started the ball rolling here – maybe Chad or Larry but the subject of surface finish sure pull in a sizable response. I did not contribute anything at the time because I was in the depths of a head and intake porting rush. Now the bulk of that is done here is my ten cents worth on the subject on porting intake, the flow bench techniques, runner forms and surface finishes that I currently favour.
First lets deal with the preferred methods for flowing a 1 x 4 single plane intake.

There are many ways of putting the air through the induction system but the method I use is about the simplest as far as a bench installation is concerned. The flow test setup starts by placing a carb up-side-down into the five inch hole that is usual for most commercial flow benches. This is clamped in place so when the bench starts blowing air through the system it does not take off.

Next, if one is to be used, the spacer is positioned and finally the intake placed on to and the assembly bolted together.

With the butterflies wired in the open position we are ready to start masking of all the ports that are not going to be flow tested at this moment. This is how 99.99% of manifolds are flow tested. In fact when I did the intake manifold for Buick's factory shot at the land speed record for under 4 litre V6 production sedans this is how I did the intake. I suppose the results were OK as it out-powered Smokey’s intake and the car did beat the existing record by quite a big margin but was it the best? Who knows?

A few years later Roger ‘Dr. Air’ Helgesen came into my life and taught me a bunch more about 1 x 4 SP intakes than I already knew.

And here is how that came about. I had been friends with Roger for a couple of years and at one drag race event I bumped into a couple of his customers. Both were running Victor Jnr’s on their SB Fords (289 & 302). Both had originally used ported and matched versions of this popular intake but when they installed Rogers modified version of the Victor Jnr. their cars dumped a bunch off the ET (I am trying hard to remember here but I think it was in the region of 2.5 – 3 tenths for both cars) and the trap speed went up by about 3 MPH.

About a year or so later I am building a flat tappet, iron headed magazine project 5.0 and am just about a week from having it dyno ready. Roger spots the build and asks if he can test his intake against mine. This engine was not intended to be a max effort deal but more of a ‘build it at home with your Sears tools’ type of project. My Victor Jnr was port matched and the casting roughly cleaned up with 60 grit emery rolls. In short it was nothing you could not do in your shed with an electric drill. Only a couple of hours went into it. Stock shapes but with casting flash mostly removed. And for what it is worth these intakes work well in this almost out-of-the-box form.
I pull the intake from the test engine and Roger passes me the replacement. I am almost horrified. There is not a sign of any emery work within the intake. All surfaces were finished with course tooth carbide leaving a scalloped surface. Still the test went ahead because of the results those two guys at the strip had reported. After about 30 minutes of timing and mixture tests the results seen at the strip repeated on the dyno. 453 hp before and 474 after.

OK - what gives here RH?

Here is the inside story on this.

First the flow testing method. There is always 2 ports drawing at the same time with a SP V8 intake. When the piston is 90 degrees down the bore on the intake stroke a second cylinder is in the overlap period where the exhaust is pulling hard on the chamber and on through into the intake runner. This means that to simulate how the air is moving in the plenum you need to not only have the port under test open but also the following port to draw a certain amount open so as to simulate what is actually happening in reality. A figure of about 20% of the area of the port at the manifold face for the second cylinder seems to get the job done.

Let’s consider 351 Windsor’s cylinders 6&5 because that is what I am currently working on. When 6 is pretty much on a max draw cylinder 5 opens up and sends a pretty fierce pressure wave up to the plenum and this partially robs cylinder 6 of it’s full draw.

The lead-in to most runners is in the form of a radius but when adjoining cylinders are in a robbing mode it is better to have a sharp divider biased as in the sketch below. The first cylinder to draw has a large radius leading into it. This big radius takes it’s curve from the adjoining cylinder which should have no radius on it – i.e. a sharp edge. Because both cylinders are drawing jointly for a substantial period the sharp edge helps flow on both cylinders and has some measure toward reducing inter cylinder robbing. If the manifold is flowed just one cylinder at a time the flow tests will not reveal the effect of this sharp edge move on adjacent drawing cylinders thus compromising it’s performance.

OK that’s it for today. Will discuss surface finishes and what the bench showed in terms of CFM in the next day or so. (does that carbide finish actually help flow?)

DV
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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by Walter R. Malik » Sat Jul 22, 2017 7:29 pm

David Vizard wrote:
Here is the inside story on this.


Let’s consider 351 Windsor’s cylinders 6&5 because that is what I am currently working on. When 6 is pretty much on a max draw cylinder 5 opens up and sends a pretty fierce pressure wave up to the plenum and this partially robs cylinder 6 of it’s full draw.

The lead-in to most runners is in the form of a radius but when adjoining cylinders are in a robbing mode it is better to have a sharp divider biased as in the sketch below. The first cylinder to draw has a large radius leading into it. This big radius takes it’s curve from the adjoining cylinder which should have no radius on it – i.e. a sharp edge. Because both cylinders are drawing jointly for a substantial period the sharp edge helps flow on both cylinders and has some measure toward reducing inter cylinder robbing. If the manifold is flowed just one cylinder at a time the flow tests will not reveal the effect of this sharp edge move on adjacent drawing cylinders thus compromising it’s performance.

OK that’s it for today. Will discuss surface finishes and what the bench showed in terms of CFM in the next day or so. (does that carbide finish actually help flow?)

DV
Your text and drawing about which side of the divider should be radiused or sharp edged seem to contradict with each other here, as with a Ford 351 Windsor, number 6 cylinder intake port is already first drawing air when the number 5 cylinder runner begins.

Which is correct & not correct... the drawing or the text ...?
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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by David Vizard » Sat Jul 22, 2017 7:53 pm

Your text and drawing about which side of the divider should be radiused or sharp edged seem to contradict with each other here, as with a Ford 351 Windsor, number 6 cylinder intake port is already first drawing air when the number 5 cylinder runner begins.

Which is correct & not correct... the drawing or the text ...?
Walter


Walter, I have drawn the mirror image. Text is right.

Thanks for spotting it so quick.
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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by MadBill » Sat Jul 22, 2017 8:38 pm

So with a 1-5-4-2-6-3-7-8 FO then, the sharp edge goes on runner # 8?
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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by gvx » Sat Jul 22, 2017 8:57 pm

Lets see if i can ask this question correctly. The answer to this question can potentially huge but here goes, at what RPM, horsepower level, airflow potential ratio from cylinder head intake port to intake manifold runner, or maybe it can be quantified in depression scale of measurement. At what level can porting a single plane intake for a V banked engine start to show an effectivly benificial improvment over not porting. In other words when do you start to see a value in return of investment.
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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by swampbuggy » Sat Jul 22, 2017 10:27 pm

GVX------GREATquestion-----i'm hoping for some answers ? .

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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by mag2555 » Sun Jul 23, 2017 6:49 am

Great info David and thanks much for sharing as always!!
Your description of how you flow test a Intake set up leads me to ask this question that has been on my little wee mind for a good long time.
If as has been determined and written about the the descending piston on a running motor can only make a void ( not a Vacuum ) that air flow then rushes in to fill under atmospheric pressure , then in testing Intake ports of any cylinder head should we not only be applying 14.7 psi of air pressure at the Head flange and measure total air flow that way, not by sucking in thru the ports as we do now?

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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by Walter R. Malik » Sun Jul 23, 2017 11:49 am

mag2555 wrote: If as has been determined and written about the the descending piston on a running motor can only make a void ( not a Vacuum ) that air flow then rushes in to fill under atmospheric pressure , then in testing Intake ports of any cylinder head should we not only be applying 14.7 psi of air pressure at the Head flange and measure total air flow that way, not by sucking in thru the ports as we do now?
Air flow testing a port is about pressure DIFFERENTIAL and to get about 14 pounds different from entry to exit would require a bench to pull about 200 inches of water depression.

Not a whole lot of air flow benches can get near there unless the cfm is very low; if at all.

I used to run one but, it had a Roots type air transfer unit about 4 feet long and a foot high powered by a 125 horsepower electric motor. I certainly don't know of many air flow testing units like that.
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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by MasterUMC » Sun Jul 23, 2017 2:13 pm

Am I mistaken or if the firing order is:

1-3-7-2-6-5-4-8 the only adjacent divider(s) that would be affected by this theory and would benefit from the sharp edge.. would be 6 & 5 then 4 & 8?

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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by BigBro74 » Sun Jul 23, 2017 2:18 pm

mag2555 wrote:Great info David and thanks much for sharing as always!!
Your description of how you flow test a Intake set up leads me to ask this question that has been on my little wee mind for a good long time.
If as has been determined and written about the the descending piston on a running motor can only make a void ( not a Vacuum ) that air flow then rushes in to fill under atmospheric pressure , then in testing Intake ports of any cylinder head should we not only be applying 14.7 psi of air pressure at the Head flange and measure total air flow that way, not by sucking in thru the ports as we do now?
:D

I like this reasoning and have thought about it quite a bit, it lets you approach things from a different way!(which can be good sometimes)

- as post above (walter) great point) , but also think about that piston around TDC and the exhaust energy leaving the scene too!(overlap)

This conversation will be interesting to me!

Jason

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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by Walter R. Malik » Sun Jul 23, 2017 4:27 pm

MasterUMC wrote:Am I mistaken or if the firing order is:

1-3-7-2-6-5-4-8 the only adjacent divider(s) that would be affected by this theory and would benefit from the sharp edge.. would be 6 & 5 then 4 & 8?
YEP ...
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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by Curtis Mc » Mon Jul 24, 2017 9:43 am

I am also interested in how the 4-8 is handled as well. I see the 6-5 teaser and am following along, but the 4-8 are on opposite banks and there really isn't the same type of common divider like the 4-8 where you can "easily" bias a radius.

Thanks DV, good stuff so far.

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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by David Vizard » Mon Jul 24, 2017 11:56 am

MadBill wrote:So with a 1-5-4-2-6-3-7-8 FO then, the sharp edge goes on runner # 8?
Windsor 351 F/O 13726548
sharp edge on 5 & 8

Curtis - you just have to do the best you can on 4 &8.

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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by GARY C » Mon Jul 24, 2017 12:22 pm

Would this be addressed the same way on SBC? Sharp edge on 7, radius on 5?

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Re: Windsor Super Victor – plenums, port forms & finishes Vs flow

Post by stokerboats » Mon Jul 24, 2017 12:40 pm

Roger's sharp edge or "knife edge" as I've seen it referenced has certainly drawn controversy. I'm using one of his intakes (Dart) on my BBC with good results.

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