Rotrex'd NB1

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11-11-2022, 02:06 AM

#21

rascal

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Join Date: May 2009

Location: SE Melbourne, Australia

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Quote:

Originally Posted by BimmerSchnitzel

Thanks for the info! Few more questions if I may:
-How far away is your restrictor from the inlet of the rotrex?
-What pulley setup are you using? Are you still 145/105 to hit those numbers?
-What do you mean properly radiused? Like something that has a gradual reduction from 75mm to 43mm opposed to just a plate with a 43mm hole in it?
-What negatives do you foresee if you went with a small SC pulley for getting more power in the low-mid range and shrinking down the size of the restrictor hole to make your HP cap? Can the restrictor be too small?

Thanks again!

My restrictor is about 3 inches away from rotrex intake.
Below is not my car but approx position indicated by arrow

Yes, 145/105 to get those numbers. Though is 11:1 pistons (on stock head) and e85.

Correct. A tapering reduction would make a nicer flow, whereas I am sure I am getting turbulence due to the square edges of the hole in the restrictor.
Kinda like below would work better. Depends if you could be bothered with the effort. I couldnt. Made my power cap so didnt need to fiddle with it.

Spinning the blower harder to just then choke it down further didnt seem sensible to me, and would probably heat up the air more.
The smaller you make the restrictor hole, then the lower in the rev range it starts to affect power anyway, so kind of counter intuitive.

If you wanted to spin it faster to make better low end, then I'd be more inclined to plumb in a blow off style valve to dump the excess top end air, so at least you arent choking the rotrex as much. (or at all)