Anyone else a little excited for the HKS Turbo kit?

[Yoshoobaroo]

Originally Posted by Grady

6psi is 6psi no matter what turbo you put on it.

Nope.

[mrg666]

Originally Posted by Yoshoobaroo

Nope.

It is better if explained. Let me try. To define flow in a given pipe, we need two parameters, pressure and flow rate. Pressure is the force applied at unit area. There is flow rate which is mass of air flowing per unit area per unit time. Equal pressure does not mean equal flow rate. Two different compressors can have the same pressure at different flow rates. It simply means that the compressor with the larger flow rate can pump more air per unit time assuming the pipe cross-section areas (diameters) are the same for both.

Another example: We can push a small amount of air from a nozzle at high er pressure without changing the flow rate. To have larger flow rate of air at the same pressure, we need a larger cross-section pipe and a larger compressor.

[Irace86.2.0]

Originally Posted by Grady

Yes but the resistance is the engine. After the turbo.

The turbo is before and after. The exhaust has to go through it, as well as, the intake.

[Grady]

Originally Posted by Irace86.2.0

The turbo is before and after. The exhaust has to go through it, as well as, the intake.

If the turbo is the restriction then you will start to loose boost. Now we are back to, it does not matter how effecent your exhaust flow is you will not make 360 at 6psi.

[gtengr]

6 psi from a large turbo doesn't equal more power than 6 psi from a small turbo if IATs are the same and the amount of horsepower consumed by the turbo is the same. Differences only come about when the small turbo is undersized or there are differences in efficiency. Differences in efficiency mean different IATs and a different amount of power consumed by the turbo.

[Irace86.2.0]

Originally Posted by Grady

If the turbo is the restriction then you will start to loose boost. Now we are back to, it does not matter how effecent your exhaust flow is you will not make 360 at 6psi.

A turbo is always a restriction.

[Irace86.2.0]

Originally Posted by gtengr

6 psi from a large turbo doesn't equal more power than 6 psi from a small turbo if IATs are the same and the amount of horsepower consumed by the turbo is the same. Differences only come about when the small turbo is undersized or there are differences in efficiency. Differences in efficiency mean different IATs and a different amount of power consumed by the turbo.

Your ifs illustrate the inherent differences between different sized turbos that make the claim that ‘6psi equals 6psi no matter what’ is factually incorrect.

[Yoshoobaroo]

Originally Posted by mrg666

It is better if explained. Let me try. To define flow in a given pipe, we need two parameters, pressure and flow rate. Pressure is the force applied at unit area. There is flow rate which is mass of air flowing per unit area per unit time. Equal pressure does not mean equal flow rate. Two different compressors can have the same pressure at different flow rates. It simply means that the compressor with the larger flow rate can pump more air per unit time assuming the pipe cross-section areas (diameters) are the same for both.



Another example: We can push a small amount of air from a nozzle at high er pressure without changing the flow rate. To have larger flow rate of air at the same pressure, we need a larger cross-section pipe and a larger compressor.

Fair enough, I already gave the short version earlier, doesn't matter if people won't listen though.

Either way, good concise explanation!

[gtengr]

Originally Posted by mrg666

It is better if explained. Let me try. To define flow in a given pipe, we need two parameters, pressure and flow rate. Pressure is the force applied at unit area. There is flow rate which is mass of air flowing per unit area per unit time. Equal pressure does not mean equal flow rate. Two different compressors can have the same pressure at different flow rates. It simply means that the compressor with the larger flow rate can pump more air per unit time assuming the pipe cross-section areas (diameters) are the same for both.

That analogy doesn't really work because the flow rate is dictated by the volume of air the engine can consume at X psi/Y IAT/Z turbo efficiency. You're forcing the case by assuming the larger turbo is more efficient, and that's a strawman because if the larger turbo makes more power at the same psi, then you screwed up in selecting the smaller turbo. There is no small or large turbo. It's either the right turbo, the right turbo for the budget, or the wrong turbo.

Originally Posted by mrg666

Another example: We can push a small amount of air from a nozzle at high er pressure without changing the flow rate.
To have larger flow rate of air at the same pressure, we need a larger cross-section pipe and a larger compressor.

Not without changing the temperature of the air. Can't change the cross section on a turbo kit, and again you only need to change compressors if the current one is no longer fit for the job.

[Grady]

Originally Posted by Irace86.2.0

Your ifs illustrate the inherent differences between different sized turbos that make the claim that ‘6psi equals 6psi no matter what’ is factually incorrect.

Ok I will give you “factually incorrect” The effecentcy of the turbine will change numbers a little.

The issue is everyone is comparing numbers without any true baselines. Different dyno, different atmospheric conditions, different tuners, non calibrated MAP readings. Company’s that fudge numbers for sales. If you were able to test all the turbo kits on same dyno, same tuner, same atmospheric conditions, same engine you would see the ones that are able to make more HP are the ones that have lower IAT’s

[Irace86.2.0]

Originally Posted by Grady

Ok I will give you “factually incorrect” The effecentcy of the turbine will change numbers a little.

The issue is everyone is comparing numbers without any true baselines. Different dyno, different atmospheric conditions, different tuners, non calibrated MAP readings. Company’s that fudge numbers for sales. If you were able to test all the turbo kits on same dyno, same tuner, same atmospheric conditions, same engine you would see the ones that are able to make more HP are the ones that have lower IAT’s

My comment earlier was directed at this:

6psi is 6psi no matter what turbo you put on it

...which was an odd thing to say when you followed it with this:

The more effecent turbos and intercoolers keep the IAT down. That is how they make more HP.

My point was that 6psi is not always 6psi (it shouldn't be said as an absolute, even a relative absolute). Efficiency in turbo design could be one way, but the easy example I gave was comparing different sized turbos, which don't make the same amount of power at the same psi.

Like it has been mentioned, a larger turbo achieves lower IATs, which means there is greater density for a given psi than a smaller turbo (same boost, more air which equals more power). Also, lower IATs means a tuner can be more aggressive or less conservative with the tuning; they can alter timing, etc. Lastly, the larger turbos are less exhaust restrictive, so they will act as less of a bottle neck for flow. This can mean there is less back pressure, which can result in better cylinder filling. Remember that boost is measured in the manifold--not the cylinder. Flow characteristics in and out of the cylinder will also influence power.

[gtengr]

Originally Posted by Irace86.2.0

Like it has been mentioned, a larger turbo achieves lower IATs

No it doesn't, not necessarily.

Originally Posted by Irace86.2.0

Lastly, the larger turbos are less exhaust restrictive, so they will act as less of a bottle neck for flow.

Depends. Less restrictive exhaust flow can be canceled out by a compressor efficiency drop. Again, as I explained in an earlier post, thinking about this in terms of large and small turbo is a misleading oversimplification. The analysis is more nuanced than that.

[weederr33]

Still waiting to see more people field this kit....

[Irace86.2.0]

Originally Posted by gtengr

No it doesn't, not necessarily.



Depends. Less restrictive exhaust flow can be canceled out by a compressor efficiency drop. Again, as I explained in an earlier post, thinking about this in terms of large and small turbo is a misleading oversimplification. The analysis is more nuanced than that.

Again, forgive me if I am not being clear or spelling out the implication enough.

The quote “6psi is always 6psi”, as if to say there will be equal power at 6psi always, is what I was addressing with an example. My example wasn’t an absolute or an always statement. In fact, it would be odd of me to try to use an absolute to refute an absolute. Don’t you agree?

My point is that it can’t be said that a certain psi will always deliver equal power with the sole variable being turbos. That’s it. To what extent this turbo kit will deliver more power at the same psi as another kit wasn’t really what I was addressing. I simply wanted to eliminate the absolute that was stated.