[Tom Vaught]

Originally Posted by Stan Weiss

I have seen those flow tests numbers a number of times and they along with the depression they were tested at do not add up. If we use 12" water for McCarthy's numbers and convert then to 28" water I get.

.1 111.51
.2 198.58
.3 226.07
.4 236.77
.5 245.93
.6 248.99

If we use 15" water for McCarthy's numbers and convert then to 28" water I get.

.1 99.74
.2 177.61
.3 202.21
.4 211.77
.5 219.97
.6 222.70

Stan

Pete, Bless his heart for trying to do a good thing gave the reader a comparison between a bunch of heads all flowed at one depression (12' H2O) and nothing more.

He used a Laminar Air Flow Device and did not publish ANY of the information that you would need to make corrections at any other data point.


"Calibration Curve Table
Meriam performs an air calibration of the LFE using a master flowmeter that is traceable to the National Standards and Technology (NIST). The calibration data is standardized to an equivalent dry gas flow rate at 70ºF (21.1ºC) and 29.92 inches Hg absolute (101.3 k
Pa abs.). (The customer may request another standard condition such as OºC.) It is then possible to determine the actual or standard volumetric flow rate at your flowing conditions. Each LFE has at least one calibration curve or table. The standard curve/table is for dry air flow rate in units of cubic feet per minute (CFM) versus the differential Pressure (DP) in inches of water referenced to 4ºC produced by the LFE. You may request a curve/table for a different gas and/or for different flow rate units. Each curve/ table is generated using a quadratic (second order) equation.

B x DP + C x DP² = Flow
The calibration constants B and C are printed on each curve/table."

Actual Volumetric Flow Rate
The LFE determines the actual volumetric flow rate.
To obtain the actual volumetric flow rate, the differential pressure across the LFE and the inlet temperature to the LFE is measured. Using the calibration curve/table associated
with the particular LFE; a flow rate value is obtained by either
1) reading the value from the curve/table or:
2) using the formula, B x DP + C x DP² = Flow
Each curve has unique constants B and C.
Multiply this flow rate value by the ratio:

(viscosity of the flowing gas at 70 degrees F in micropoise
divided by:
viscosity of the flowing gas at flowing temperature in degrees F in micropoise)

The product is the actual volumetric flow rate. (The curve/table lists the type of gas used to generate the curve/table).

To help calculate the viscosity of air at flowing temperature, a viscosity equation based on temperature is included in this instruction manual (see Table A/32 422). The equation is from “tables of Thermodynamic
and transport Properties of Air, Argon, Carbon Dioxide, Oxygen, and Steam.” All other gas viscosity equations are obtained from "Physical and Thermodynamic Properties of Pure Chemicals" Table A/31986 lists the values of μstd / μf for air from 50/159ºF at 1º intervals when the standard temperature is 70°F.

Pete's Air was not Dry Air so he would also need to provide the correction for the Humidity at the time of testing the parts.

*Note: If you are flowing wet air, a humidity correction factor for viscosity must be used. The difference between wet/air viscosity (μwet and dry/air viscosity (μdry) increases with temperature and humidity, at 80ºF and 80% relative humidity, the ratio of μwet / μdry is .997.

The rest of the basic info can be read here:

http://www.meriam.com/assets/lfe_manual.pdf

Basically Stan, You are trying to solve a problem, knowing one small part of the problem and have no knowledge of the values used in the equations that provided the data.

Pete read some numbers off of a Inclined Scale (calibrated by Merrium for that specific flow device) and now you are trying to make comparisons with other equipment/data.

You need to do more research on how the data is generated BEFORE you make any posts comparing data, imo.

Tom Vaught

ps I helped Tom Wilhite years ago get his Laminar Flow Bench dialed in, when he also was having issues getting the numbers to line up. Call him and ask him sometime.

[gtofreek]

Well I worked on my heads some more today. Opened the port up some more. It does better, but still not quite there. It still turns over a little at .450" but is getting better. This time when it turns over at .450" lift, it drops to the 250 range. It was high 250's @ .425". I tried the flow balls that we made, and found that with careful placement of it in the port, the flow increased to 267 @ .450". Need to focus next on that area beyond there. Tried an LS Chevy valve that had a 12° back, but it was down a good 1%, give or take, at every lift point, compared to the Hemi valves 10° back, which equates to 1.5-3 cfm depending on lift point.

CC'ed the intake runner. It was a tiny 168 cc's. This is still using a Fel-Pro #1223 intake gasket opening size.

Reshaped the combustion chamber some more[but forgot to take a picture], because I wasn't happy with the first attempt. CC'ed it. It was 70 CC's. 71 cc's will put me right at 11:1 compression.











It's funny, looking at these pics, I can see areas I need to work on. A different point of view can make a difference.

[gtofreek]

I had been looking at cams a while back, and the VooDoo solid roller that is 255/263 @ .050" was really grabbing my attention. It is ground on a 110° LSA off the shelf, so I was going back and forth on a 110 or having them grind it on a 112° LSA. I want this thing to have a pretty broad power band. I want to run it to 7500-8000 RPM's, and still make power there.
Well, Monday we dynoed an engine we built with this same exact cam profile. It is a 439" SB Ford though. This has a 4.125 bore, with a 4.100" stroke[my engine will be 4.181 x 3.75"]. It has a set of Edelbrock Voctor JR. heads, that I mildly ported to 292/200 @ .600". We left the cam ground on a 110° LSA. It will be in a street/strip[mostly strip] 69 Mustang. This engine is also 13:1, mine will only be 11:1.
Here is the dyno numbers for it. The sheet was printed out with a dot matrix printer from the cave man days, with ink just as old! The sheet is so faint it's hard to read on a scanned image, so I will just copy it down here. It was pulled from 4800-7715 RPM. It was ran on VP112 racing fuel.

RPM_____TQ_____HP_____BSFC
4795___599.7___547.6____.409
4900___603.8___563.4____.40
5000___606.4___577.3____.39
5100___612.9___595.1____.39
5200___607.3___601.4____.38
5300___613.2___618.9____.38
5400___609.6___626.8____.37
5500___606.9___635.6____.37
5600___612.0___652.6____.36
5700___605.1___656.8____.37
5800___600.1___662.8____.37
5900___599.5___673.4____.37
6000___591.5___675.8____.37
6100___580.7___674.5____.38
6200___580.0___684.6____.38
6300___575.4___690.3____.39
6400___570.8___695.6____.39
6500___566.7___701.4____.39
6600___560.8___704.7____.40
6700___553.9___706.6____.41
6800___550.5___712.8____.41
6900___541.8___711.8____.42
7000___535.1___713.1____.43
7100___533.6___721.4____.43
7200___519.3___711.8____.45
7300___512.8___712.8____.45
7400___506.2___713.2____.46
7500___490.7___700.8____.469
7600___486.1___703.5____.47
7715___478.6___703.0____.47

Average from 5000 - 7000 RPM__584.8___665.3_____.387

This demonstrates the broad power band of these Voodoo cams, even ground on a tight 110° LSA! It made 600 Ft. lbs. of torque from 4800-5900 rpm's, didn't drop below 500 ft. lbs. until 7500 rpm's, and made over 700 HP from 6500- 7800 rpm's. That's pretty broad, especially for a long stroke engine similar to our Pontiac's, if you ask me.

I would have liked to see what this thing would have done down around 3000-3500 rpm[Lunati claims power band from 3000-7500]. After seeing this, I might just have to reconsider changing the LSA to 112°. Jeff and I will evaluate different lobes that Harold has designed to come up with something that will meet my expectations I'm sure. I still have a lot more head work to do[if I can keep my car from leaking water, spent last weekend fixing one water leak under the intake, only to develop another at the radiator], then we can decide on an exact cam.

Even though this engine is not a Pontiac, it is very similar in regards to bore,stroke, and head design/flow to our Pontiac's so a Pontiac built similarly, should net similar results.

[steve25]

Paul I can tell by your last posted pictures of the Intake runner as viewed from the flange that for the flow level you are at when sheer/ flow seperation takes place that you do not have enough floor width in regards to the approach area over the short turn.

You need to make the port shape trapizoidal from just before the short turn and over it in regards to the floor path being wider than the roof path.
I can not see it from the photo, but the meeting point of the push Rod wall and the short turn wall down most of the short turn needs to as Squared off as you can get it, much more so than it see in the picture of the same meeting point on the common wall and floor in your photo.

Numbers wise whatever you have for a throat diameter the roof path should only 94% of that for starters and you want the crown of the short turn to be at least 98% of the vakve bowl throat size.

The bigger a throat size you use naturally the more you will stand a chance of going thru the port wall on the common wall side just after the head bolt in the valve bowl side.
Do a measurement a fine out where the halfway point is in terms of the height of the short turn , the bottom half of that ( valve bowl side) controls the low lift flow numbers and velocity,
the upper side controls the velocity of the high lift numbers and its this area you may still need to lay back more once you widen up the floor width to get back in control of the velocity!
Your work looks great by the way!!

[Cliff R]

When you get out past about 240 or so @ .050" you need to start bringing the LSA in or the engine will simply extend the potential power range of the engine beyond the capabilities of the parts. That statement doesn't always hold true, the exceptions have been some of the 4.5" and longer stroke engines we've been associated with, seems the wider the LSA the better they like it.

Anyhow, relative small cams on tight LSA's are, and have been, the WORST choices for the long stroke Pontiac engines that I've seen to date with this sort of thing. I can't say TURD loud enough here.

For a 400 build at 11 to 1 compression, in the rpm range it's expected to run in here based on what I've read AND being manual transmission, I would NOT use a wide LSA cam in it. The 11 to 1 compression will offset the tight LSA enough where it will not be a total "dog" at low rpms. Of course the lobe profiles chosen are also a player in this deal, and with roller cams you can use shorter seat timing and still get the job done, so pulling the lobes together with less seat timing is really offset anyhow, at least if you were comparing it to a flat cam with more seat timing on a wider LSA, if you can follow that logic.

This is why when we back to back tested the Crower 60919 (113LSA) cam against a custom HR grind, we chose the HR cam as close as possible, but pulled it down on a 112LSA as it had shorter seat timing, but nearly identical .050" numbers.

We've built several 428 engines with KRE heads on them, and cam them very close to the 455 builds we do, but pull the cams down to 110-111LSA instead of 112-114. The 428's with their 4" strokes respond very well to this, and make very similar numbers on the dyno as the larger 455 engines, and still make peak HP at nearly the same rpm.

Here's two examples:

468, 10.48 to 1 CR, unported KRE's, 230/242/112 HR cam (.361" lobes). 494hp/567tq.
434cid, 10.6 to 1 CR, unported KRE's, 236/242/110 HR cam (.361" lobes, 497hp/540tq.

The 468 make peak HP at 5400rpms, the 434 @ 5600rpm's. Peak torque for the 468 was 3900 and 4200 for the 434.

We've done several others with the same heads and all have been very close to those power numbers, even when we used the larger 236 intake lobe in the 455 builds......Cliff

[gtofreek]

Steve, when I downloaded these pics, I was looking at them and saw what you are talking about, and a couple other things I want to change next time I start grinding on it. Thanks for the advise. This is my first set of iron heads that I went this far on porting. The other iron head port jobs I have done were just cleaning up and straightening the port that was there. Never got into making the port much bigger. I figure I need to get this port up to 180 CC's or so, to be where I need them.

[gtofreek]

Worked on the port some more. I made a set of flow balls to probe the port with. Flow balls are different size steel balls that we welded on a piece of wire to hold them with. I made 4 different sizes from 3/16" to 1/2". The idea is to probe the port with them to see what areas of the port are active and which are not. Or where bad spots are. If you place the ball in a certain area, and the manometer reading drops, then you are gaining flow, and there is a problem downstream from the ball. When you have a really good port, the flow ball will hurt flow wherever you place it. That is what I'm looking for. My initial probings found two areas where the flow increased. These areas surprised me. One is in the bottom radius of the port, against the divider wall, adjacent to the pushrod bulge. With a 3/8" ball placed here, the manometer drop 2". That was a gain of about 16 CFM or so. The other spot was on the roof, in the radius along the divider wall also, just above the short turn. Here the manometer dropped about 1". Everywhere else I placed a ball, even the smallest 3/16" ball, the flow dropped quite a bit.

With the flow ball placed in the lower radius, adjacent to the pushrod bulge, I registered about 267 CFM @ .450" lift. Without the flow ball, it flowed 251 @ .450". So I worked the short turn radius, along the divider wall, to widen and flatten it. Then I re-flowed it. Now the flow ball when placed in the lower corner, only drops the manometer about .3-.4". Now the port flows 265 @ .450" without the ball in place. When placing the ball in the upper radius, it no longer helps the flow like before. Now it only hurts the flow anywhere else I put a ball. This is what I'm looking for. A little more work, and I should be there. I'm still only around 170 CC's on the port volume. Now to get the cc volume up to slow the air speed down some. It's well over 400 feet per second at this point. Since I am going to install bronze thick wall valve guides, I'm going to grind the guide leader ramp the rest of the way out to see what happens there.

This is the first max effort iron head I have ported. Done many other d-ports, but they were all within the constraints of the stock port size. They would flow around 250-255 cfm.

Here's a pic of where I worked it the most. Looking at the pic, I can see I need to flatten the short turn a little more.

[68azbird]

Wow that's some good work in those ports. I think when you start hitting over 280 cfm you need to switch the flow balls to these.
IDPTTFMF

[gtofreek]

Worked on the head some more today. I ground the guide leader out, and now it is at 176 CC's. I also re-did the valve job with a different cutter that accents this flat floor chamber a little better. Here is the new flow numbers.

_Lift_____CFM

.100"____71
.150"____105.4
.200"____146
.250"____185
.300"____219.8
.350"____247.1
.400"____265.5
.450"____273.8
.500"____282.5 with use of a flowball, carefully placed in top divider radius, just above the short turn. It still turns over around .475" lift.

[gtofreek]

Here's what it did with the Victor intake bolted on, un-ported.

.100"_____70.3
.150"_____105.1
.200"_____147
.250"_____181.2
.300"_____207.9
.350"_____230.5
.400"_____247.7
.450"_____258.4
.475"_____261.4

Turned over at .480" lift.

[GOAT WHORE]

Paul, what's the love lift on that Voodoo cam you plan on running and are you going with 1.65's or bigger?
Is there a chance the Portland would pick up again at higher lift even though it turned over at .480?

[gtofreek]

I kept flowing it to .700" and it started gaining again but never made it back to where it was before turning over. I may just have to take a deep, close look at Harold's lobes to see what he has in the .475" lift range. I know he has some lift rule lobes out there that are in the .450" lift range. I was planning on 1.65's, but it all depends on these heads.

[gtofreek]

That Voodoo was .600" with a 1.5 rocker. Harold has a lot of lobes though, that aren't on anyone's website, so I will see what we can find.

[gtofreek]

Here is a pic of what the port looks like now at 176 cc's.

[72LuxuryLeMansLa.]

Originally Posted by gtofreek

Here is a pic of what the port looks like now at 176 cc's.

Paul,

Not to argue but that only looks like 174.3cc to me......

[gtofreek]

Maybe I need to re-calibrate my eyes!

[gtofreek]

Originally Posted by 72LuxuryLeMansLa.

Paul,

Not to argue but that only looks like 174.3cc to me......

Well, you're more correct than you think! It was actually 173 cc's, I mis-read the buret!

[gtofreek]

Worked on the roof, and the short turn some more. Poked a hole in the roof between the rocker stud boss, and the spring pad. Hit no water anywhere. Almost got the turn over out of it. Now when it turns over it only drops from 265-260, then starts climbing again. Makes it to 279 @ .800". A little more work and I think I'll have it. This thing flows 247 @ .350"!

Port volume is 175 cc's. I posted 176 cc's before I did this extra work, but realized I mis-read the new buret. It is in 1 cc increments, where our old one was 2 cc increments. It was actually 173 cc's before.

[72LuxuryLeMansLa.]

Originally Posted by gtofreek

Well, you're more correct than you think! It was actually 173 cc's, I mis-read the buret!

......

[GOAT WHORE]

Forget the buret, just send Karl a picture for assessment!