Cylinder Head Flow numbers

[shelbydoug]

For those of you interested in subjects like this check out this web site.

http://users.erols.com/srweiss/tablehdc.htm

The Tunnel Port 302 cylinder heads did receive much negative press back in 68 but they really aren't the main culprit in the Ford racing failures that year.

For one thing there is no way that they flowed numbers that Ford had published. In fact they were around 250 on the intakes.

The iron Boss 302's stock were actually a little better out of the box BUT if you follow some of the magazine articles on the race prep for the B2 heads, they were getting epoxied down quite a bit to make the rpm usefulness scale.

It may just be that the C head was more adaptable to race prep then the TP was.

The only head of interest to me that Weiss has not tested is the GT40 iron head from what I can see. Even the Gurney head is on the list of testing.

All in all this is an interesting read and should answer many questions as well as probably shocking you as to how bad stock heads were out of the box then especially
considering what today's aftermarket heads do.

[pbf777]

     Do note:  "These numbers have come from various magazines, web sites, manufactures catalogs, and "

                      "We have tried to verify the accuracy of these numbers but use at your own risk!"

     As copy pasted from their site.   

     Scott.

[crossboss]

CFM 'Flow' is one thing, actual port velocity is another. Big port cylinder heads on the street were turds performance wise. Boss 429s, Boss 302s, Hemis, etc. were usually trounced by 'lesser' engines. CJs, 440+6, 455 Stage 1s, and 442s, etc. My Boss 302 T/A engine made huge gains by reducing the lower 1/3 of the intake ports with Devcon. Now, that said those big port engines really shined on the NASCAR and high RPM tracks. Did the Tunnel Port get a bad rep? Yes. The fact is when Ford assembled the engines, the failures began...

[pbf777]

CFM 'Flow' is one thing, actual port velocity is another.

     But, also note that "velocity" is a resultant effect of restricting and requires energy to be instilled.   

     Scott.

[98SVT - was 06GT]

Did the Tunnel Port get a bad rep? Yes. The fact is when Ford assembled the engines, the failures began...

They would have won LeMans in 1965 if they hadn't ordered CS to install Ford built engines. People at Ford operate in fear. They are very territorial. If CS engines were better they feared losing their job since they weren't the best.
Recent antics with their ranking of salaried employees has gotten them sued. They basically said their salaried employees were lazy and not doing a good job. What it boiled down to was they were going home after 40 hours and not giving Ford an extra 10-20 hours a week of unpaid work.

[pbf777]

       When one is handed a "salaried" employee job, your not being paid for the hours, rather for getting the job done;  if your not up to it, demonstrate some responsibility, and maybe a little class, and step back down to an hourly job.   

       Scott.

[98SVT - was 06GT]

       When one is handed a "salaried" employee job, your not being paid for the hours, rather for getting the job done;  if your not up to it, demonstrate some responsibility, and maybe a little class, and step back down to an hourly job.   

That's called piece work.

[pbf777]

That's called piece work.

     Yep, my previous posts' description also can be applied to "piece work" in say ..........a job shop environment, though it's often referenced to as being "contract work"; and it works very much the same as for the salaried office professional in the sense that your given a job to do, for a set payment sum, no matter how long it takes you to finish it!   

     Scott.

[crossboss]

CFM 'Flow' is one thing, actual port velocity is another.

     But, also note that "velocity" is a resultant effect of restricting and requires energy to be instilled.   

     Scott.

Not for Scott, as he knows this...
No, not really. Velocity makes power by increasing the flow (speeding it up). Remember, its not all about volume, its about efficient volume. Think of it like a fan. Turn the fan on...it just blows all over the place. Now, place a tube in front of it, and viola, it makes more velocity/speed!

[98SVT - was 06GT]

..... salaried office professional in the sense that your given a job to do, for a set payment sum, no matter how long it takes you finish it! 

I sure wouldn't work for a place that handed me an 60-80 hour job and expected it for 40 hours of pay. Of course when you're spending tax dollars it all changes. My dad was an aerospace engineer. There was X amount of dollars per project. He said when they ran out of money on one project they just accounted for their time on another project that still had money in the kitty. Now you know why there are $600 toilet seats and $400 hammers.

[98SVT - was 06GT]

.... Velocity makes power by increasing the flow (speeding it up).

Higher velocity air also has the effect of cramming more air into the cylinder. Carb reversion shows what happens when when high speed air suddenly hits a shut valve.  https://www.youtube.com/watch?v=Vw1ihxlCIzI

[crossboss]

.... Velocity makes power by increasing the flow (speeding it up).

Higher velocity air also has the effect of cramming more air into the cylinder. Carb reversion shows what happens when when high speed air suddenly hits a shut valve.  https://www.youtube.com/watch?v=Vw1ihxlCIzI

Well...not a really good example. Those Weber DCOE's are on an IR 4 banger. In his case its most likely a cause of too much PSI/gas into the carbs. Reversion as what you referred to in 'most' cases caused by a camshafts overlap/duration/rocker arms/poor vacuum, lack of cylinder fill/intake restrictions, and a very restrictive exhaust. Remember, lets keep this apples to apples here and taking about port size and velocity.

[98SVT - was 06GT]

Well...not a really good example. Those Weber DCOE's are on an IR 4 banger. In his case its most likely a cause of too much PSI/gas into the carbs. Reversion as what you referred to in 'most' cases caused by a camshafts overlap/duration/rocker arms/poor vacuum, lack of cylinder fill/intake restrictions, and a very restrictive exhaust. Remember, lets keep this apples to apples here and taking about port size and velocity.

The example is what you see with IR systems - Weber/SU/FI w/constant flow. Every engine suffers the same effect but you normally don't see it because it's absorbed within the intake manifold below the carb. It happens when you have a column of air/fuel heading at high speed into the cylinder. All of a sudden the door is slammed shut and that air/fuel bounces back. In a multi port intake it just heads for another open door. With an IR intake it has nowhere to go but back out into the atmosphere.

[gt350shelb]

  great link now i can be up all night  .........doug

[crossboss]

Well...not a really good example. Those Weber DCOE's are on an IR 4 banger. In his case its most likely a cause of too much PSI/gas into the carbs. Reversion as what you referred to in 'most' cases caused by a camshafts overlap/duration/rocker arms/poor vacuum, lack of cylinder fill/intake restrictions, and a very restrictive exhaust. Remember, lets keep this apples to apples here and taking about port size and velocity.

The example is what you see with IR systems - Weber/SU/FI w/constant flow. Every engine suffers the same effect but you normally don't see it because it's absorbed within the intake manifold below the carb. It happens when you have a column of air/fuel heading at high speed into the cylinder. All of a sudden the door is slammed shut and that air/fuel bounces back. In a multi port intake it just heads for another open door. With an IR intake it has nowhere to go but back out into the atmosphere.

So...what your saying is every IR carb's set up spits up? Not hardly.