J pipe is a joke

[trbotaln]

I recently got a 14b from someone and it came with a J pipe. The diameter of the J pipe is so small that I wonder how it will outflow my T25. Do you guys with 14b's feel a nice power gain when swithching to a bigger J pipe? I have seen pics of a 14b and a J pipe, and in person they look so much smaller than they do in the pics. How does this thing flow more than the T25? better design? WTF

 

[Thomas91169]

my jpipe is 2". it can be small like that cause the air is hot, thus less dense, coming from the turbo.

watch when you take off your downpipe next time. it is also very small, but just as above, hotter air is less dense so it can get away with being smaller.

 

[tstkl]

i just want to make sure you realise that less dense air means that it will have a greater volume.....because its density is lower,...but its still all the same gases, its just expanded...

 

[boosted95]

i just want to make sure you realise that less dense air means that it will have a greater volume.....because its density is lower,...but its still all the same gases, its just expanded...

you might want to think about that again. They both have the exact same volume, the less dense, cold air, just has less air molecules than the more dense, hot air, for a specific volume. Density is the amount of molecules for a given volume.

 

[tstkl]

so your saying if you heat up a balloon, it doesnt get bigger? and if you follow the equation: pressure x volume = number of gas molecules x boltzmann's constant x temperater

notice how if you increase the temperature, either the number of gas molecules has to decrease (impossible in our situation) or the volume or pressure increases, and if the pressure increases, the density will stay the same, but in most cases, because it is easier for the gas to do this, the gas increases in volume...thats why it is not always the case that you would want a bigger exaust, bigger exaust = more time gas is in exaust = more time to cool = denser air = heavier and requires more pressure to push because the volume of a given amount of gas has decreased to increase the density...

 

[tstkl]

you might want to think about that again. They both have the exact same volume, the less dense, cold air, just has less air molecules than the more dense, hot air, for a specific volume. Density is the amount of molecules for a given volume.

also after reading what you said again, i noticed you said the less dense cold air, and then said the more dense hot air,....even though hot air is less dense than cold air...which is why us tuners perfer cold air to enter our cylinders, more oxygen molecules per liter, or in our case, more oxygen molecules per 500 ml in our four cylinders...

 

[Attack Eagle]

Lets not turn this into a physics argument.

IS that jpipe the OEM one or a bigger aftermarket version?

I have seen the OEM ones and they are ridiculously tiny.

AS soon as the air leaves the compressor it is hot and thus less dense for the same volume. (say 1 cc) as the sooner the pipe begins to get bigger the sooner that hot gas can expand and begin to lose heat and velocity. And of course the less parasitic loss (psi drop) you will see between the compressor outlet and the TB.
At least that is my practical interpretation of the "rules".

 

[daren_p]

I would go with an aftermarket jpipe. RRE makes a nice one, starts at 1.5" and expands to 2.25" right away. As for the 14b looking like it won't flow as good as the t25, looks can be deceiving. The turbo might look physically smaller but internally its alot larger. The turbine housing volume is much larger as is the comp. & turbine wheels.

 

[trbotaln]

cool, I am going to use the stock J pipe for now. So it is worth upgrading or not?

 

[daveyfx]

Worth upgrading? That's your call as many people are making a lot of power on the stock J-pipe.