Kraftwerks Rotrex Supercharger Discussion

[ATL BRZ]

Originally Posted by Adeets

I found it on google images under "BRZ vortech flow graph" but I'm on my phone so can't link it, I did notice max rpm on the rotrex 94 was 100k, but looked like they did data up to 250k

Found it

I have no idea what I'm doing actually reading the maps and comparing the two, but here they are next to each other.

Rotrex C30-94 on the left, Vortech V-3 H67B on the right.

[King Tut]

The key to reading them is to know the air flow which runs along the X axis, but calculating that is really guess work, but there are formulas. The Garrett website has a turbo size calculator that attempts to guess it.

[Adeets]

Originally Posted by ATL BRZ

Found it

I have no idea what I'm doing actually reading the maps and comparing the two, but here they are next to each other.

Rotrex C30-94 on the left, Vortech V-3 H67B on the right.

Found a website on how to calculate it I'm gonna plug in the variables as standards, like engine temp at 250, ambient temp at 75, and the block at 122cuin, I'll write umm all up and post, prolly gonna need u to edit the pics and put the lines where the should be,also basing them both of of 9psi achieved, well do a check at 2500 5000 and 7400 rpm.

[gmsii]

Originally Posted by Sellout

That has always been the assumption. Clever wording from Rotrex coupled with internet forum jockeys piecing together assumptions from what they read resulted in people thinking that a Rotrex unit would have a better boost curve than every other centrifugal supercharger on the planet, which would give you better low end torque.

It's never been proven, to my knowledge.

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.

[gmsii]

Originally Posted by ATL BRZ

Found it

I have no idea what I'm doing actually reading the maps and comparing the two, but here they are next to each other.

Rotrex C30-94 on the left, Vortech V-3 H67B on the right.

checked out your link....that does not look like the compressor map for the c30-94
you can find it at rotrex.com under the technical section

[Adeets]

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.

2 things, new vortech oilfeed upgrade spins to 65,000 but were talking base kits.
And impeller size has everything to do with cfm. Smaller impeller size, the faster u have to spin it achieve the same results...

Oh and you could always just dyno the kit on a dynojet like everyone else... Not to mention it says your Dynos were completed with a header and full exhaust. So shouldn't you post the header+full exhaust + tune vs your kit? Not doing so would be misleading.

Either way I'll get those equations posted.

[Adeets]

Originally Posted by elopez

^^^

hum, 65k vs 100k. which has more potential...

please dont post in this discussion again.

[Adeets]

since were both running 9PSI and with 125 degree inlet temp we use 28.6 Lbs/air per sec. with a compression of 1.88

(for rotrex map 28.6LBs/min = .216 k/g per second.)

[Adeets]

So the vortech is spinning around 44k in its 70% efficiency band, where as the rotrex is spinning around 75,000 in its 75% efficiency band...

[DJCarbine]

Originally Posted by Adeets

So the vortech is spinning around 44k in its 70% efficiency band, where as the rotrex is spinning around 75,000 in its 75% efficiency band...

I started to work out the conversion factors and gave up after a headache.
I wonder what the relative amounts of air supplied are...

[Adeets]

Originally Posted by DJCarbine

I started to work out the conversion factors and gave up after a headache.
I wonder what the relative amounts of air supplied are...

its the same since the PSI is the same, 28.602 Lbs/min. on our motors 28.602 Lbs/min = 9psi. Its the efficiency that maters, since the rotrex is working in its 75% efficiency zone it will have 5% lower temps exiting the compressor compared to the vortech.

[Sellout]

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.

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.

[gmsii]

Originally Posted by Sellout

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 flowing more air.

read what i wrote...i think your point was addressed...im not disagreeing

[Sellout]

Originally Posted by gmsii

checked out your link....that does not look like the compressor map for the c30-94
you can find it at rotrex.com under the technical section

Correct. that's definitely the wrong map.

The correct map is here: http://www.rotrex.com/media/7df7470f...30%20Range_pdf