Quote:
Originally Posted by diss7
Before I get into some examples, I should point out that I am aware that my difficulty in completely understanding these systems probably revolves around my understanding of pressure and volume. FYI, my understanding of this is that pressure/volume are directly related. If one container is compressed to 1 Bar, it effectively contains twice the volume of air than it did at atmosphere. I realise that my understanding here maybe flawed, as I have seen discussions on similar turbo systems running the same PSI but one flowing more air than the other. This has never made sense to me.
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I'll clear this up since no one seems to have noticed it was a question, or bothered to answer it. The answer is simple and I'll try to make it easy to understand:
You have a 45mm turbo capable of pushing 15psi. That turbo will be moving, let's say, 300 cfm. You get tired of the 250 whp it gives you and want to step up. You then buy a 78mm turbo and set it at 15 psi. That turbo is pushing 800cfm since the intake path and the compressor housing is bigger, thus can take more air in and in the process will not drop as much pressure when the intake valves opens then the smaller one.
The difference between both at 15 psi is the larger turbo will create 15 psi in the same motor with less effort than the smaller one, creating less heat in the process. both turbos are pushing 15 psi, but since one is almost twice the size of the other, he is pushing a lot more air in than the other. Your engine will always take the same amount of air, but since the bigger turbo is able to fill your engine faster and with less heat, you get more hp.
If my understanding of it is flawed, by all means correct it, but this is what I learned talking to engine builders and ppl involved in turbo 4s and diesel engines.
I hope this helps.