B2 Motorsports - Jeff Lipton 487 FE Build

[blykins]

Your heads and Anthony's heads came in yesterday from Pond. Unfinished seats. As soon as the valve job is done and they're milled, I'll post pics and flow numbers.

[lippy]

Originally Posted by blykins

Your heads and Anthony's heads came in yesterday from Pond. Unfinished seats. As soon as the valve job is done and they're milled, I'll post pics and flow numbers.

Sweet. How does the porting look? I hope to see some big flow numbers.

[blykins]

They are CNC ported and they look great. The exhaust ports have a different design than the edelbrocks, but they supposedly perform better too.

Flow numbers are a big part of it, but they don't tell about velocity, which is extremely important too. These will do just fine though.

[lippy]

Originally Posted by blykins

Flow numbers are a big part of it, but they don't tell about velocity, which is extremely important too. These will do just fine though.

If flow is volume per unit of time, and velocity is distance per unit of time, then velocity is flow divided by area. Since the area of a port is constant, I would think flow and velocity should be proportional, aside from variation of flow across the area. Is this incorrect?

[blykins]

Port area isnt constant....

But think of it this way: air and fuel has momentum. It takes time to get it moving. Guys that port their stuff at home have a tendency to hog the ports out as big as they can, thinking a big port makes more power. In reality, a smaller port that flows the same as a big port will most likely perform better because the velocity of the charge will be higher and you can shove more in with respect to time.

Perfect scenario is a port that flows a lot, but is efficient enough to have high velocity as well.

[Chilibit]

I was with you right up until the last phrase:

"and you can shove more in with respect to time."

Does this not violate the "flows the same" premise?

I agree with the 'perfect scenario.'

Originally Posted by blykins

Port area isnt constant....

But think of it this way: air and fuel has momentum. It takes time to get it moving. Guys that port their stuff at home have a tendency to hog the ports out as big as they can, thinking a big port makes more power. In reality, a smaller port that flows the same as a big port will most likely perform better because the velocity of the charge will be higher and you can shove more in with respect to time.

Perfect scenario is a port that flows a lot, but is efficient enough to have high velocity as well.

[blykins]

I'm not the best at explaining things...

Let me try it this way...

You can have an excellent flowing head that performs like doo-doo. You can have a poorer flowing head (read lower numbers) with excellent velocity that performs awesomely.

The reason is because the application varies from case to case and since we're speaking of street engines here that require great throttle response and operate at "sane" rpm levels, you want a head that has higher velocity so that it's easier to make an amount of air/fuel move.