Quote:
Originally Posted by gmsii
i don't know what the 'clever wording' you a referring to is, but perhaps i can shed some light on this topic to the best of my abilities. i will keep it a conceptual high level overview.
lets start with a few facts:
1) the rotrex c30-94 charger used on the BRZ kit can support an impeller speed of 100,000 rpm. this is made possible because the rotrex employs planetary friction drive system that does not use internal gears
2) other centrifugal chargers used on the BRZ have a max rpm of about 50,000 rpm
3) potential airflow is proportional to the speed of the compressor wheel
4)pressure rise is proportional to the square of the speed.
what do the facts above translate to?
the rotrex can use a smaller compressor section to move the same amount of air and create the same boost pressures compare to other centrifugal compressors; in other words in order to function on the same efficiency, airflow, and boost range as the rotrex, other chargers would need to use larger compressor sections. also, the rotrex has a clear advantage when it comes to operating NVH as well as thermal management (the absence of internal gears allow it to run faster, quieter, and cooler)
how the centrifugal chargers from various manufacturers perform on the car is really dependent on the kit developer; what charger sizing they used and what rpm they decided to spin the charger at.
without dynoing the vortech, we cannot comment on the characteristics of its power delivery. the easiest way would be if someone with a vortech kit (or any other kit for that matter) came down here for a dyno session. anyone local to the socal area who would like to dyno their vortech or innovate supercharged BRZ/FRS on our dyno is welcome to contact us and schedule a free dyno session. we are just as curious as you are to see how different kits stack up on the same dyno.
i know everyone is throwing around this 280+whp dyno number, but enthusiasts need to realize that every dyno reads different. it is important to provide the stock baseline dyno numbers as a point of reference. our baseline dyno was only 151whp...certain competitors have baseline dynos in the 160's, 170's, and even 180's...do some simple math if you want a better number to compare.
also note that our dyno is a Rototest dyno. it is the only chassis dyno recognized by OE car manufacturers as being accurate and repeatable enough for OE development purposes. it tends to read quite a bit lower than some of the magic number dynos in the industry.
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What does any of that have to do with a Rotrex based system generating more low end torque than the other centrifugals that are available, which is the claim that I was addressing?
Back when I had my S2000, I paid a lot of attention to the Kraftwerks vs Vortech discussions on the forums. There was a WHOLE DAMN LOT of talk about the Rotrex's planetary drive mechanism and how that would result in boost coming on faster and claims that more RPM means more air and blah blah blah.
A T25 turbo spins a whole lot faster than a T04E at full tilt too. Which one makes more power?
RPM isn't everything.
There are perks and there are drawbacks to either design, but the boost curve and resulting torque curves are going to look damn near identical. Just like they did on the S2000.
But the Vortech is capable of moving more air.