In other words, if you were in equally programmed cars, one with K16's and the other with K24's, would the k24 pull harder, or are they pushing equal volumes of air? It seems that a chipped k16 pushing 1.0-1.1 bar may be quicker than a chipped k24 pushing 1.1-1.2 when you factor in spool time.....just wondering.

 

Ah you opened up a can of worms. I won't even give me answer because I'll get raped by a few physics text books by a few members. I'll let them answer it.

 

A K16 at 1.5 Bar and Markski at 1.5 bar is the same pressure... the volumes(CFM's)of air at those pressures are night and day....

 

i THINK that the difference is that the k24 can pull in a higher volume in air therefore creating more power ???
i could be wrong though

 

I think a K16 may have to work the air more to generate 1 bar vs a K24. This would likely create more heat meaning the K24 at 1bar would be denser.

 

K24 is moving more air at the same pressure. I would say the k24 should be faster because it is making more power by pushing more volume. You are well past spool up at 1.0-1.1 bar.

 

It (a K24) can move more air up top (maintain a given boost level at higher RPM's because it can flow more), however at 1 bar at a given RPM each turbo is moving the same amount of air (if it were moving more, they would move more air the engine consumed and the pressure would go above 1 bar).

The bigger compressor on the K24 doesn't have to work as hard to produce 1 bar of compressed air as the K16 unit does at a given RPM...

 

Interesting replies...

 

The K24 compressor would be operating more efficiently at those boost levels, which means, the compressed air won't be as hot as the K16, thus producing more power. The compressor however would be slightly heavier (greater rotational mass), so the K24 would be slightly lazier than the K16, but when it gets spooling... bye bye

Same goes for a Super 60 or 16G compressor... more effiient than a K24, but greater rotational mass = slightly laggier, but will flow more top end HP and be more efficient at higher boost levels. It's all a trade off. More power = bit more "lag", or reduced boost response.

All comes down to what you want and what you use your car for. If it's fast street and stoplight -> stoplight racing, a smaller quicker spooling turbo would be the way to go. If it's top end HWY runs, drag racing / track events, then a bigger turbo would be a better choice.

 

I guess I was thinking that since the turbo is bigger, it would be more volume of air at the same pressure. No matter how you slice it, 1 bar is 1 bar no matter what turbo you are using I guess....

 

Basically.

No matter what turbo it is, 1bar is 1bar, its static, however the bigger turbo produces denser air opposed to the smaller turbo thats working significantly harder, denser air = more powah when I get the chance I'll elaborate more.

 

Put it this way, 1bar of air through a 1" ID tube hasn't got the same amount of volume as 1bar of air through a 2" ID tube. The 2" tube is flowing more air. More air = more power. The more efficient the compressor = the colder the air = the more power is developed

 

The little K16 has a hard time holding 1 bar throughout the range. They typically fall back to .9 by redline because the compressor is out of it's range and cannot hold that boost. It's only a little 25lb compressor, so is hard pressed to hit even 500hp at the crank.
The K24 has a 28-30lb compressor, so at the same boost pressure falls right in the heart of it's efficiency island, so if you have both compressors at 1 bar, the k16 at 45-50% efficiency and the k24 running at 75% efficiency, you'll be seeing about 300degF coming out of the k16 and only 160degF out of the K24... Huge difference there.
Then, the turbines are different sizes as well. To flow that much air, the k16 will produce more backpressure and require more boost to make the same power. So, it's also hampered by the turbine backpressure as well as the limited compressor. It shines in it's little island where it's effient, but that's only up to mid-high 400hp levels. Pushed beyond those levels, it gets pretty cranky.

 

Alright I finally have time before court to elaborate a little bit more.

Coincidentally Todd explained what I was going to.

Each turbo has its particular efficiency range, where ideally it produces the most dense air (CFM). Anything above that and the air is less dense because its hotter, colder denser, hotter less dense.

 

Great explanation Todd..thanks!