(No negativity intended) Use a better tool and see if you go back to the old one. Better yet, test the accuracy of a program by dialing in a proven simulation and then make subtle adjustments to the specs (without changing cfm) in an attempt to manipulate information to skew the results. Then use known calculation methods as a way to cross check specific points. I still use the easy sims to study the torque curve shape somewhat, after nailing down specifics that "I prefer" using the tools at my disposal. Part of my preference is due to the fact that I'm not getting paid for the time involved, only the end result. It forces you to limit which projects you take on and how much time you put into things. Everything still has it's place, and tools are all subject to their mastery. I didn't mean my comments elsewhere to have a negative affect... enough to remove a thread. The new head thread was exciting, I was attempting to persuade the use of different tools to compliment. Gary, you have my apologies.
Talking with two great head porters Chris Skaling and Chad Speier. Both have two different ways of porting. Yes, one can definitely out do the other. Its called experience and knowledge. Chad posted a simple comparison of two different heads ( small block chevy aftermarket heads) one AFR 245cc and one Profiler 245cc. The AFR has awesome flow numbers but the Profiler shines way more. Then he proceeded to show a wetflow of the AFR. After looking where the vortises are at and moving around you can build a much better cylinder head. Here is a name many don't know in here but I haven't seen anyone do what he has done. On a BBB TA heads? 430+ cfm and varify with wetflow. Needless to say, his car hauls axx. 8.90's in a 3380 pound Skylark. Jeff Strube. Oh, your on the right path if thinking of using port intruders. Remind you know, there is two different types of port intruders. Choose wisely.
Yep, stick a fork in'er, cuz she's done! lol To the text in bold, I've talked about this elsewhere before, but never really got much response. Not sure if it was overlooked, misunderstood, or people just didn't know what to say about it/how to respond? Either way, it's nice to see I'm on the right track. Reaffirmation is important to me when I want to make damn sure I'm doing something right, or just wasting my (and others) time, which I do not want to do...which brings me to the next post I'm about to make:
Your apology is greatly appreciated and I would accept it, but it's not necessary. You (and others) help keep me on track and steer me in the right direction. If anything, I'm the one who needs to thank you and everyone else for all the help you give, not only for me, but for anyone who has the desire to learn. I had said in the beginning of that thread (on the first page somewhere I think) that I was doing it for entertainment, and that I may or may not be wasting my time on it. I deleted it because I didn't want to steer anyone down the wrong path or get the wrong ideas. I knew the program was flawed and even said this before, that it doesn't take everything into consideration, but there were some posts I made in there that were kinda silly or useless (as are probably 80% of all my posts lol). I'm still learning here too. I think we all do or at least could, no matter how much we already know. A humble demeanor is a great door opener.
Some of the links I've posted from the Wallace site get into sonic choke, along with CSA and velocity.
And because head porting is a very in depth, time consuming and skillful trade I find it best to hire a professional vs. hoping for the best without the tools or experience to verify the results and balance each port to the others. This is another reason I am excited to see the alum heads come out because Scotty brown is going to develop a CNC porting program so that people can just order a set of heads all ready to go fully ported. I'm sure my custom hand ported versions will make more power however for the average guy the CNC ported heads will be a better option. Less $, less time, and repeatable not a guess at what you will get but a known level of porting.
Speaking For myself , I can not wait for the day when aftermarket heads are sold on the factors of port area and the max HP they can make at a given rpm ,per a given cylinder displacement and there average port velocity without a word about air flow levels!
Very good thread guys. I've been following this and have picked up a lot of information I hadn't considered before. First, I've done very little porting work so there's no way I'd want anybody here to think I'm making suggestions or giving advice. My perspective on the whole thing is almost entirely based on the flow of water, which is something I'm very familiar with. But water is not compressible so it is also very different. I'm pretty good at identifying areas of rapid flow, boundaries, eddies and transitions. And I have a pretty fair idea of what obstructions will do to the flow, and how it should behave going around bends. Air, being so much lighter than water will act a bit differently but from what I've seen it's primarily going to be a change in the width of things like transition zones and boundary layers, those being much thinner with air. I am intrigued by the descriptions of an excessive velocity over the SSR. How far are those velocities below the supersonic level? It sounds like the general opinion is that this noise is the result of turbulence, flow separation, or the creation of a large eddy (i.e. "waterfall") below the valve seat? What is so curious to me is the existence of a relatively sharp cutoff where this phenomenon occurs. After all, it's not like hardly any of the intake charge is capable of following the inside of the chamber into the void, more like a garden hose nozzle set on wide dispersion spraying into a mason jar. So why the sharp cutoff? Seems like instead it should be a more gradual increase in noise level. The other thing I find interesting is the pulsating flow of the intake and exhaust. There sure is a lot going on there. Jim
I don't want to get to far off the OP of the sbb head but as far as noise goes I have had a few heads get noisy above .500 lift and start laying back the ssr and it gets smooth and quite and cfm goes up. Also I have read a few articles that say towards the end of the lift you want a little turbulence for tumble. It's all very interesting stuff. Also might be head specific also
Sure would be nice if someone with a flow bench could fab up a clear plastic model of the intake & exhaust runners then test the flow with some colored water mist to visually see what is really happening with this start / stop pulsation going on.
Interesting public service...sure would be nice if there was a fund set up for this. I think there are some wet flow vids on Youtube, I recall seeing a Kaase one posted in a forum where he sticks his finger into a T ram's runner.
The more you want to do with a head, the more time and expertise it will require. If one were to use the existing design and simply do some cleanup/smoothing along with some bowl work, I don't think the runner flow would be off too far from the original, and so would make the hair-splitting differences between each runners less important vs a complete redesign of the runner characteristics. This type of port work is repeatable, since you already have the template for your work (the existing runner shape), as opposed to reshaping everything, having to know how thick the metal is and where, etc. This is moot with mild porting. For us stocker/mild guys, this is enough. For more serious and financially intense builds, relying on a professional would be advised.
Port velocity would change depending on lift of the valve, and at the periods of time before and after the start/stop cycle of flow. Logically, this would indicate that a head that seems to have 'too much' velocity with a steady stream of flow being pushed through it at full lift would be drastically different at lower lifts and prior to starting and stopping. I would think this would be dependent on the individual engine's combination of parts, which included the cam's timing events that matched the ideal 'sweet spots' to the head flow at any given point. This is where it would get very complicated, and would require a lot of experience and knowledge, not just on building engines, but with engineering and science.
You can put together a flowbench for $1500 or so in materials that will negate the commonly recognized industry standard. Le$$ if you are resourceful or have specific purposes. It's extremely difficult to make $$ for porting time alone though, and that's only one reason why it's tough to find easily shared information. There are forums where this info is shared, and others are willing to help. At least one member here has done this and eclipsed some of the best known experts on a specific platform.
Good point Gary if not removing a lot of material but just smoothing and contouring then no need for all the flow testing and balancing... Vizard has something information in his books regarding his home made flow testing which was actually using vacuum cleaners to measure the restriction of the head instead of the actual flow. Very cool and worth reading up on.
I don't believe I've seen more than CFM #'s shared here, and that's what we are talking about specifically. The cfm #'s alone are such a vague way of determining potential that head manufacturers have long abandoned them to focus on what really makes top ends work. Chris is very generous to do so and I would think it's appropriate, being that he specializes in Buicks and members can benefit from his info.
Flow starting and stopping is irrelevant if we look at some math; 3,000 RPM is revolutions per minute, take that and divide by 60 gives revolutions per second which is 50! Divide 50 by 8 and we get 6.25/2 because a cylinder only fires every 2 revolutions = 3.125 times a cylinder will fire per second! The nano-second that flow would supposedly stop and start would be very hard to prove let alone try to measure inside an engine. Flow that may stop and start on a flow bench doesn't equate into what the flow is doing in an engine, although a good reference tool to gain performance, not a simulation to what's going on inside an engine. Anyways, this thread evolved into something WAY more than what my intentions were, LOL, proving very interesting so carry on. As to the original intent of the thread, Steve, I wanted to try to make it out this weekend but the weather isn't looking that good, maybe Sunday if the roads get cleared? Was trying to make it on a weekend but seeing how this is the last non-holiday weekend of the year I may have to go during the week if the roads aren't cleared up by tomorrow to get them to you this year? If you even want them that soon? Derek
Derek, No big rush. I need to start Christmas shopping soon so won't do anything with them til next year. Thanks
