Crawford Billet Power Blocks

[Luckrider]

Originally Posted by nelsmar

Just finished stock vs stock tuned. Installing on this hot ass engine...

130whp baseline. 145whp tuned. <3 me a heartbreaker dyno :P

That is true econocar numbers

[Pixie_Niner]

Looking forward to seeing the results

[nelsmar]

Tip: don't do this right after back to back dyno pulls. And don't misplace your magnet on a stick. Damn that burned. I could only imagine how dez would be on a rant at this very moment if he was here haha.

[governor]

Originally Posted by strat61caster

Every time a valve is opened or closed there is a sonic boom as the pressure differential is so great that the gases moving around break the sound barrier, there's a shockwave from this that can be used to aid (or hinder) in airflow not only to the single cylinder but to the system as a whole.

As an engineer with a very good understanding of hydraulics and fluid dynamics I feel the need to challenge the quoted statement.

Compressible fluid flow is a subject of which there is a good amount of information online. The one thing that you will find stated in almost every single resource is that without a very specifically designed nozzle mach speeds are not achievable and that in reality the maximum achievable speed in a piping assembly is going to be in the neighborhood of 0.7 mach. We use this bit of very well understood physics to design pressure relief piping in plants, however the fundamental physical limitation still exists and applies.

I find the notion that gas is breaking the sound barrier inside a vehicle a bit absurd. Disclaimer: I could be wrong, but in this case I highly doubt it. As a valve opens the mass flow rate through the effective orifice will be dependent on the upstream pressure, orifice characteristics of the valve, the downstream piping and the exit pressure. There's a very concise blurb about this and critical vs. subcritical pressure ratios and the effect of the piping on flows in Perry's handbook.

Now the speed at which a compression wave can move in the fluid is a different story. This will be close to the speed of sound in the compressible continuum I.E. Mach - 1.0. Once again however, nothing is -breaking- the sound barrier.

In terms of piston design and efficiency, pistons are used extensively to teach the topic of thermodynamics. The amount of available PV work (Pressure-Volume work) is well understood and good design for power will not necessarily be one that is efficient as an infinite amount of time would be required to pull out every last quantum of energy created by the increased pressure from combustion. So the piston and exhaust hydraulics could be designed in some way to balance a trade-off of efficiency and power-weight and of course cost.

-gov

[Sojhinn]

Originally Posted by governor

As an engineer with a very good understanding of hydraulics and fluid dynamics I feel the need to challenge the quoted statement.

Compressible fluid flow is a subject of which there is a good amount of information online. The one thing that you will find stated in almost every single resource is that without a very specifically designed nozzle mach speeds are not achievable and that in reality the maximum achievable speed in a piping assembly is going to be in the neighborhood of 0.7 mach. We use this bit of very well understood physics to design pressure relief piping in plants, however the fundamental physical limitation still exists and applies.

I find the notion that gas is breaking the sound barrier inside a vehicle a bit absurd. Disclaimer: I could be wrong, but in this case I highly doubt it. As a valve opens the mass flow rate through the effective orifice will be dependent on the upstream pressure, orifice characteristics of the valve, the downstream piping and the exit pressure. There's a very concise blurb about this and critical vs. subcritical pressure ratios and the effect of the piping on flows in Perry's handbook.

Now the speed at which a compression wave can move in the fluid is a different story. This will be close to the speed of sound in the compressible continuum I.E. Mach - 1.0. Once again however, nothing is -breaking- the sound barrier.

In terms of piston design and efficiency, pistons are used extensively to teach the topic of thermodynamics. The amount of available PV work (Pressure-Volume work) is well understood and good design for power will not necessarily be one that is efficient as an infinite amount of time would be required to pull out every last quantum of energy created by the increased pressure from combustion. So the piston and exhaust hydraulics could be designed in some way to balance a trade-off of efficiency and power-weight and of course cost.

-gov

As a physics teacher I really appreciate this explanation.

[Boofneenee]

Originally Posted by Sojhinn

As a physics teacher I really appreciate this explanation.

As a doctor I have no clue what your talking about

[Boofneenee]

Originally Posted by governor View Post
As an engineer with a very good understanding of hydraulics and fluid dynamics I feel the need to challenge the quoted statement.

Compressible fluid flow is a subject of which there is a good amount of information online. The one thing that you will find stated in almost every single resource is that without a very specifically designed nozzle mach speeds are not achievable and that in reality the maximum achievable speed in a piping assembly is going to be in the neighborhood of 0.7 mach. We use this bit of very well understood physics to design pressure relief piping in plants, however the fundamental physical limitation still exists and applies.

I find the notion that gas is breaking the sound barrier inside a vehicle a bit absurd. Disclaimer: I could be wrong, but in this case I highly doubt it. As a valve opens the mass flow rate through the effective orifice will be dependent on the upstream pressure, orifice characteristics of the valve, the downstream piping and the exit pressure. There's a very concise blurb about this and critical vs. subcritical pressure ratios and the effect of the piping on flows in Perry's handbook.

Now the speed at which a compression wave can move in the fluid is a different story. This will be close to the speed of sound in the compressible continuum I.E. Mach - 1.0. Once again however, nothing is -breaking- the sound barrier.

In terms of piston design and efficiency, pistons are used extensively to teach the topic of thermodynamics. The amount of available PV work (Pressure-Volume work) is well understood and good design for power will not necessarily be one that is efficient as an infinite amount of time would be required to pull out every last quantum of energy created by the increased pressure from combustion. So the piston and exhaust hydraulics could be designed in some way to balance a trade-off of efficiency and power-weight and of course cost.

-gov

Originally Posted by Sojhinn

As a physics teacher I really appreciate this explanation.

As a doctor I have no clue what your talking about

[Sojhinn]

Originally Posted by Boofneenee

Originally Posted by governor View Post
As an engineer with a very good understanding of hydraulics and fluid dynamics I feel the need to challenge the quoted statement.

Compressible fluid flow is a subject of which there is a good amount of information online. The one thing that you will find stated in almost every single resource is that without a very specifically designed nozzle mach speeds are not achievable and that in reality the maximum achievable speed in a piping assembly is going to be in the neighborhood of 0.7 mach. We use this bit of very well understood physics to design pressure relief piping in plants, however the fundamental physical limitation still exists and applies.

I find the notion that gas is breaking the sound barrier inside a vehicle a bit absurd. Disclaimer: I could be wrong, but in this case I highly doubt it. As a valve opens the mass flow rate through the effective orifice will be dependent on the upstream pressure, orifice characteristics of the valve, the downstream piping and the exit pressure. There's a very concise blurb about this and critical vs. subcritical pressure ratios and the effect of the piping on flows in Perry's handbook.

Now the speed at which a compression wave can move in the fluid is a different story. This will be close to the speed of sound in the compressible continuum I.E. Mach - 1.0. Once again however, nothing is -breaking- the sound barrier.

In terms of piston design and efficiency, pistons are used extensively to teach the topic of thermodynamics. The amount of available PV work (Pressure-Volume work) is well understood and good design for power will not necessarily be one that is efficient as an infinite amount of time would be required to pull out every last quantum of energy created by the increased pressure from combustion. So the piston and exhaust hydraulics could be designed in some way to balance a trade-off of efficiency and power-weight and of course cost.

-gov


As a doctor I have no clue what your talking about

I don't want to side track this thread but you had to take the mcat.

[Dimman]

Originally Posted by governor

As an engineer with a very good understanding of hydraulics and fluid dynamics I feel the need to challenge the quoted statement.

Compressible fluid flow is a subject of which there is a good amount of information online. The one thing that you will find stated in almost every single resource is that without a very specifically designed nozzle mach speeds are not achievable and that in reality the maximum achievable speed in a piping assembly is going to be in the neighborhood of 0.7 mach. We use this bit of very well understood physics to design pressure relief piping in plants, however the fundamental physical limitation still exists and applies.

I find the notion that gas is breaking the sound barrier inside a vehicle a bit absurd. Disclaimer: I could be wrong, but in this case I highly doubt it. As a valve opens the mass flow rate through the effective orifice will be dependent on the upstream pressure, orifice characteristics of the valve, the downstream piping and the exit pressure. There's a very concise blurb about this and critical vs. subcritical pressure ratios and the effect of the piping on flows in Perry's handbook.

Now the speed at which a compression wave can move in the fluid is a different story. This will be close to the speed of sound in the compressible continuum I.E. Mach - 1.0. Once again however, nothing is -breaking- the sound barrier.

In terms of piston design and efficiency, pistons are used extensively to teach the topic of thermodynamics. The amount of available PV work (Pressure-Volume work) is well understood and good design for power will not necessarily be one that is efficient as an infinite amount of time would be required to pull out every last quantum of energy created by the increased pressure from combustion. So the piston and exhaust hydraulics could be designed in some way to balance a trade-off of efficiency and power-weight and of course cost.

-gov

I'm not 100% certain on the gas itself (there is often talk of sonic choking if velocity gets to high) leaving breaking breaks the sound barrier, but there is a wave produced that travels at the local speed of sound. The wave is what is used to increase gas speed and flow by modifying the pressure differential across the valves. It's timing, sign and effective strength are affected by the tubing cross section, distance traveled, gas density etc... which is what part of header and intake tuning is about. You want a high pressure positive wave at the intake as it opens and a low pressure negative wave at the exhaust when it opens.

This is why you sometimes see headers "shift" power up or down the rpm range, with a bump at high rpm. The higher rpm bump is typically from flow improvement, whereas the shift is from acoustic changes.

[FrsDuke]

Originally Posted by Dimman

I'm not 100% certain on the gas itself (there is often talk of sonic choking if velocity gets to high) leaving breaking breaks the sound barrier, but there is a wave produced that travels at the local speed of sound. The wave is what is used to increase gas speed and flow by modifying the pressure differential across the valves. It's timing, sign and effective strength are affected by the tubing cross section, distance traveled, gas density etc... which is what part of header and intake tuning is about. You want a high pressure positive wave at the intake as it opens and a low pressure negative wave at the exhaust when it opens.

This is why you sometimes see headers "shift" power up or down the rpm range, with a bump at high rpm. The higher rpm bump is typically from flow improvement, whereas the shift is from acoustic changes.

Did you fall asleep during lecture? He said the compression wave can move at mach1.0 but no material breaks the sound barrier. His post was just to clear up the guy claiming sonic booms from flow velocity at the valves. I'm not making a claim about the validity of your statement only that it is not a correction of gov's.

[FrsDuke]

Originally Posted by Sojhinn

I don't want to side track this thread but you had to take the mcat.

Good thing "your" vs "you're" wasn't a major part of the mcat.

[Sojhinn]

Originally Posted by FrsDuke

Good thing "your" vs "you're" wasn't a major part of the mcat.

That's why I'm a physics teacher and not an English teacher. We get our point across and that's good enough.

[FrsDuke]

Originally Posted by Sojhinn

That's why I'm a physics teacher and not an English teacher. We get our point across and that's good enough.

Not you

Originally Posted by Boofneenee

As a doctor I have no clue what your talking about

I was making fun of this

[AdrianG]

Originally Posted by Sojhinn

We get our point across and that's good enough.

"Good enough": The standard Teacher mentality. :P