Can anyone help me design which is best flow ?? material ?? price ??

Supertech ?? Ferrea or Rev ??? which is good or bad ???

thank you

 

I have used Ferrea since day one and neer had a valve, spring or retainer failure, problem or issue of any kind

 

This time i mean only vavle itself. Has anyone ever got them on flowbench ??

 

what is the benefit of upgrading valves if you don't go larger. I understand springs and retainers will et you run higher rpm.

 

The stem is typically undercut, reducing the area it occupies in the port, allowing more airflow. Usually the intake valve is also backcut, in other words another angle is cut in addition to the main 45, which allows for smoother airflow into the port.

 

Many times a narrower stem will lose flow over a larger one. The few times it will not hurt is if you have very close port and valve angles.. which very few engines have. Read on trailing wakes and fluidic switching.

If anything the reduced stem is there to save weight, but there are many good people who believe that if the stem is reduced there and can take it, that it should have that cross section all the way up, and not just at that location.

It is counter intuitive and the opposite of what many magazines and catalogs print, but that is the way it is. Up till fairly recently (last decade), even some very high level companies did not know about this.

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Oversize valves only help if you increase seat, and/or venturi or port size. Even then it may not improve flow. A lazy company can very well increase valve size, let the valve seat at an area pretty far in from its OD and you would gain nothing except increased mileage before valve starts sinking and really hurting flow. But that's not what you go oversize for. A good company would match all factors up for maximum power.

 

^so what do you suggest?

should people go for the 1mm oversized?

 

Shaun, do you have any recomended articles or papers on this directly pertaining to airflow in a port? I'm not saying this in a doubting manner, it's just that it's harder to find information related directly to engines on this subject, most of it is just unapplied fluid dynamics. Thanks.

 

no one never put them on flowbench ???

 

Hi ND, sorry I have none that deal specifically with these vortices downstream of the valvestem in a port. I do have however, many other papers that deal with other port parameters and testing, but it sounds like you only wanted the former.

I find it strange that you would think that fluid mechanics is not applicable, or is only applicable in some special way, to an intake port. Airspeed, stem diameter, air properties, are all known within a narrow range. Calculate Reynolds number for a small and large stem and see how the large stem moves flow further away from unstable inefficient flow.

Run a test on a good flowbench and it will show the flow difference too.

I have heard the same thing repeated by engine airflow engineers for DaimlerChrysler and Chevrolet, as well as by the person whose ports are currently run on the ALMS CTS-Vs.

So we have current theory, current experiment, current authority, and current race application, all in line with each other. Good enough for me. I have neither heard of, nor seen, any counter theory or application from an authority, but if there is one I would be happy to take a closer look and evolve my current experience and understanding.


Best regards

 

If two companies make a valve that has the similar dimensions, angles, and stem to head radius, there will be no difference in flow.

Because valve characteristic variation is small compared to the large difference that all other port work makes, valve to valve flow comparisons are very difficult to make unless carried out as a controlled test. What is easier compared is valve mass, strength, longevity.