[JETmn]

Originally Posted by Rob_BMW_PNW

I havent seen enough evidence that it does this with stock turbo, could be wrong

Not all psi is equal when you upgrade to the PS2 or even PS1

The psi (pressure) is the same, but the temperature is lower on the bigger turbo so their is more oxygen in the same volume. That is where you get the extra power at the same psi for the ps2 vs stock or ps1.

[Rob_BMW_PNW]

Originally Posted by JETmn

The psi (pressure) is the same, but the temperature is lower on the bigger turbo so their is more oxygen in the same volume. That is where you get the extra power at the same psi for the ps2 vs stock or ps1.

Not all PSI is created equal...

The wheel and inlets/outlets are larger, how is it 'the same'?

How is temperature lower on a bigger turbo?

[Cory S]

Originally Posted by JETmn

The psi (pressure) is the same, but the temperature is lower on the bigger turbo so their is more oxygen in the same volume. That is where you get the extra power at the same psi for the ps2 vs stock or ps1.

Actually, when people say you are getting more power from the same PSI, it's because they seem to forget that the same PSI peak is being up in the higher RPM range, where the engine consumes more air and is more efficient also. Yes, the charge will be a little cooler, but that's what the intercoolers are for also.

So a stock N54/55 at 17psi at 4600rpm may be very close in output, but the larger compressor keeps holding pressure higher in the RPM range after that. That's where the output peak is increased.

[Jeff@TopGearSolutions]

Originally Posted by Rob_BMW_PNW

Pointless to get the GFB if you are on a stock turbo, such a pain to put it in since you have to remove your water pump and tstat.

I kindly disagree, we have had many customers on stock turbos purchase it and found out their stock DV was leaking. It increased their boost response, lowered WGDC, ETC

Obviously on a brand new car it might no do much but as that stock DV becomes weak, it definitely helps restore power. I can say that with a straight face all day.

[JETmn]

Originally Posted by Cory S

Actually, when people say you are getting more power from the same PSI, it's because they seem to forget that the same PSI peak is being up in the higher RPM range, where the engine consumes more air and is more efficient also. Yes, the charge will be a little cooler, but that's what the intercoolers are for also.

So a stock N54/55 at 17psi at 4600rpm may be very close in output, but the larger compressor keeps holding pressure higher in the RPM range after that. That's where the output peak is increased.

No, that isn't the only reason it can happen. If you ran same boost curve on both turbos, the ps2 would still make more power. It can happen because of being able to hold boost higher, but if you take a smaller turbo that is getting to the edge of its efficiency rating (like the N55 stocker or ps1) and compare it to the PS2, you will get a much lower outlet temp. Yes the intercooler lowers the temp, but it isn't near 100% efficient and you will end up with lower AIT with the larger turbo. This is also a huge benefit of meth/water/nitrous injection.

Originally Posted by Rob_BMW_PNW

Not all PSI is created equal...

The wheel and inlets/outlets are larger, how is it 'the same'?

How is temperature lower on a bigger turbo?

That is not correct at all, pressure is pressure. It is just a reading, so yes all PSI are equal. Now, that is not all of the equation that we are interested in. The equation is PV=nRT. R is a constant and N is the amount of the substance, so we can take them out for comparison purposes, so PV=T. What we have left is pressure * volume = temp. We know the volume inside the turbo tract is constant, so we can take out volume too. That means if we lower the temp, the pressure will also lower. So the same amount of oxygen is available for combustion at a lower pressure if we lower the temperature. A 20*F drop in IAT's will be an increase of 4% in power at the same boost level.

[DOCTOR.Y]

Originally Posted by Jeff@TopGearSolutions

I kindly disagree, we have had many customers on stock turbos purchase it and found out their stock DV was leaking. It increased their boost response, lowered WGDC, ETC

Obviously on a brand new car it might no do much but as that stock DV becomes weak, it definitely helps restore power. I can say that with a straight face all day.

How do we know if DV is leaking? Anyway to diagnose it?

[Rob_BMW_PNW]

Originally Posted by JETmn

No, that isn't the only reason it can happen. If you ran same boost curve on both turbos, the ps2 would still make more power. It can happen because of being able to hold boost higher, but if you take a smaller turbo that is getting to the edge of its efficiency rating (like the N55 stocker or ps1) and compare it to the PS2, you will get a much lower outlet temp. Yes the intercooler lowers the temp, but it isn't near 100% efficient and you will end up with lower AIT with the larger turbo. This is also a huge benefit of meth/water/nitrous injection.



That is not correct at all, pressure is pressure. It is just a reading, so yes all PSI are equal. Now, that is not all of the equation that we are interested in. The equation is PV=nRT. R is a constant and N is the amount of the substance, so we can take them out for comparison purposes, so PV=T. What we have left is pressure * volume = temp. We know the volume inside the turbo tract is constant, so we can take out volume too. That means if we lower the temp, the pressure will also lower. So the same amount of oxygen is available for combustion at a lower pressure if we lower the temperature. A 20*F drop in IAT's will be an increase of 4% in power at the same boost level.

I was referring to psi in making power
19 psi in a stock turbo, is not the same as 19 psi in a PS2 car

[Jeff@TopGearSolutions]

Originally Posted by Eric_Y

How do we know if DV is leaking? Anyway to diagnose it?

By the time you get to it and get it out (2-3 hrs) you mine as well spend the $130~ just to replace it. It's such an inexpensive upgrade worth every penny once installed.

To answer your question, IDK how to test it but I imagine a pressure test of some sort would be the answer.