Liam in Montreal

is 20psi in a k03 car as fast as 20psi in a k04 car? assume sustained boost

BigDog

constant, all that matters is the relationship of pressure and temperature to determine the real thing you want to measure, the concentration of O2 molecules. I would bet, however, that at 20psi the KO3 is so far out of its comfort zone that it's increasing temps significantly more than a KO4 (for which 20psi is also a lot of air), thus the KO4 should be able to produce more torque with the extra, cooler air. This would be especially true on a track where repeated runs caused temps to become more critical.

Lazyg

I'm going to argue that point. ;-)

Wouldn't the mass of air movement be greater with a larger turbo? Much like the difference between a bike tire and a car tire, pounds per square inch are relatively close but the amount of air that is required to obtain the same pressure is much greater.

My two cents.


Kind Regards

BoostLad

Assuming sustained boost is the major point that separates the K03 from the K04. The K03 just cant sustain that boost level as high up in the rev range as the K04 can. That fact alone (assuming equal boost, equal 02 flow, equal temps, most of which may not be true) will make the K04 faster thru the quarter mile.

WYSIWYG

no, because you can't get the same output from k03/k04 with same amount of exhaust gases

[ej257]

K03 still has smaller components. It would have to work a good bit harder than a K04 to get the same power. And by working that much harder I would think you would be at the very limitations of a K03.

My basis was that it feels almost as fast as a K04 (I don't recall how much psi the k04 kits were making, one was over a year ago, and the other was last month)

BigDog

are related). If you pressurize the manifold it's pressurized, regardless. Now, the larger turbo does move more air, but that's irrelevant here. The ability to move more air more efficiently simply means that the big turbo can charge the air to a greater psi rating. However, if the psi is the same (20 in the example) then it doesn't matter. There is still a question of how long it will take to build up the 20psi of boost with each turbo. The small turbo takes less time to reach max. rpm but the larger turbo moves more air, thus reaching 20psi of pressure in a fewer number of total rpms.

Toaster29

the turbo has hit a wall. Yes, it can deliver 20psi or more, but the amount of air being pumped over, say 15psi, decreases sharply. Once you are out of the efficiency range of the compressor, you've turned the turbo into a charge heater, not charge compressor. Given the same volume of air, simply heating it up more will raise the PSI.

There comes a point where a turbo just adds more heat than added flow. This "extra-heated" charge starts to slightly detonate where the cooler charge didn't. This causes the ECU to pull timing enough to begin to LOSE power over lower boost settings. Such is the case w/ the WRX, its faster at 16 psi than at 18.