In fluid dynamics the difference between push and pull is irrelevant the flow is just a result in the pressure differential between the runner and the intake manifold. You can call 30psi in the intake manifold and 25psi in the runner (random numbers) 5psi of pressure pushing the air through or -5 psi pulling the air through it's irrelevant.

The angle of the picture is somewhat deceiving in reality the tops of the stacks are well below the halfway point of the plenum. There's a reason every race car in a major series has velocity stacks like that.



They aren't "necessary" but neither is a turbo...

 

That is not true at all Momentum, you obviously don’t understand fluid dynamics very well. According to your theory a car at -10 psi manifold pressure and one a +10 psi pressure should make the same horse power. After all, the pressure differential is the same. Both cars have a 10 psi pressure differential. However we all know that the car running +10 psi will make vastly more hp. I think you might want to do some research on something called air density. Any time you pull air you create a negative pressure differential ahead of the pull source, plain and simple, there is no way around this. And a negative pressure differential lowers air density which in turn lowers hp. Anytime you push air you develop a positive pressure differential, which increases density and hp. So yes air does care if it is pulled or pushed through the manifold, it makes all the difference in the world. In fact it is essentially the difference between forced induction and natural aspiration.

 

he wasn't comparing pressure ratio, you are talking about forcing air into a fixed space..which is the only way you can create a positive differential, he is talking about flow in general... he wasn't talking about making power, of course the car will make more power with more air...

 

I've got a question!


Why did you copy my intake manifold?

 

I'd say Momentum has a very good understanding of fluid dynamics.

I'm not trying to be a smart ass, but you should read his post a little more carefully. If it doesn't make sense, do a little research.

 

I was wondering when you would step in here!

 

I did read his post, if you don’t see the problem with his statement you also obviously lack a grasp on the fundamentals of fluid dynamics. His statement was “In fluid dynamics the difference between push and pull is irrelevant the flow is just a result in the pressure differential between the runner and the intake manifold.” Which is completely incorrect. There is a huge difference between push and pull when it comes to compressible flow dynamics.

 

Again, what he said is completely correct.

He isn't making a comment about the density of the gas, just pointing out the facts about what makes a gas flow in an intake manifold. And that is a result of a pressure differential.

 

That's what I was getting at......

As for a copy or not... all that really matters is who can bring it to market at a place people can afford. I have not been able to find any good compairison data for the hypertune manifold, nor would it be easy and affordabe to get one from hypertune.

Great you made it first, show me that it works and make it so I can get one when I want one for a good price.

 

Lets use your example. Car A has "-10psi manifold pressure" so the pressure at the inlet of the velocity stack is actually 4.7psi. The pressure in the cylinder even at idle would likely be just under that (lets say 4psi) so the pressure differential in this case is .7psi resulting in just enough flow for idle.

Now Car B has "+10psi manifold pressure" so the pressure at the inlet of the velocity stack is actually 24.7psi. Lets say were looking at the portion of the intake stroke where the valve has just opened for simplicity, the pressure in the cylinder is likely just above atmospheric (or just below if it's very efficient) so lets assume 14.7psi. Car B has a pressure differential of ~10psi.

"negative pressure" is actually not something that exists, most of the time when referencing pressure we use "gauge pressure" to make things easier to look at. In reality you cannot have below 0psi.

For volume flow rate (and velocity stack design) the difference in pressure is all that matters, you want to create the lowest possible pressure drop in the system. The volume flow rate will be virtually the same if Car A has 10psi over 0psi as Car B with 20psi over 10psi. However Car B will make more power because there is an increase in mass flow rate.

It's true that a velocity stack becomes less important in a forced induction car because the resulting difference in pressure loss has less effect on the total mass flow rate but it doesn't mean they don't work better than bottom mounted stacks.