Supercharger

The new MPS/G 250 record is 131mph (210 km/hr) which rules me out as I cannot get tyres rated that fast (assuming that I could get the scoot going that fast). Time to change class to "B" for blown. I did have a IHI RHB31 Turbo Charger Rotrex a lot

Using info from Supercharged! Design, Testing and Installation of Supercharger Systems Rotrex Technical Datasheet C8 Range.pdf Rotrex Technical Datasheet C15 Range.pdf Rotrex Technical Handbook.pdf

These are calculations in progress - I started looking at the C8 but the C15 might be better...

Rotrex C8/15 Vs ProCharger A-1

Summary from just looking at specs online - the A-1 looks cheaper and probably(?) less efficient but may be easier to fit and would have less stress on the engine. The A-1 however is twice the size of the C8, which might make the C8 better as weight can be distributed (e.g. oil reseviors etc).

Stats

ProCharger winning but unsure if we are comparing apples with apples...
Comparison of Specs
Rotrex C8-8 Rotrex C15-20 Procharger A-1 (range of models?*)
MSRP AUS$1,750 (if bought from the UK) AUS$2,030 (if bought from the UK) US$1,599 (AUS$1,530)
Base HP Range (Naturally Aspirated)
25-100
Max Supercharged HP 41-75hp 68-163hp 150hp
Max Flow (cfm) 450 cfm
Max Boost (psi) 15 psi
Max Set-up Ratio 12.52:1 12.67:1 4.1:1
Volute Diameter 7”
Outlet Diameter 2”
Oil Capacity (oz) 2.5
Max Impeller RPM 240,000 rpm 180,000 rpm 75,000 rpm
Inlet Diameter 3”
Self-Contained Yes
Reverse Rotation Available Yes
Weight 1.4 Kg 2.9 Kg 5.6Kg (estimated)
* ProCharger provide less info than Rotrex - I suspect that A-1 is a group of superchargers like the "C8". Rotrex provide info for each model (e.g. C8-6, C8-8, etc) but it looks like ProCharger just give info in a range and pick the best value.

Size

Rotrex is much

rotrex_procharger_size_comparision.jpg
Using a 1/1 model we see that the Rotrex is the only choice based on size.

Extras

ProCharger requires:
  • intercooler

Rotrex requires:

  • intercooler (probably a better one as it would generate more heat)
  • oil pipelines and configuration (some of it supplied)

Calculations

conversions.png

From Rotrex Info

C8-8 looks the best choice based on Rotrex Technical Handbook.pdf

Flow Rate

The rule of thumb for flow is:

rotrex_flow_calc.png

So for 50Hp we need: 0.042 kg/s

Pressure Ratio

The rule of thumb for pressure ratio is:

rotrex_pressure_ratio_calc.png

So for 50Hp from 40Hp we need: 1.44

From Bell Book

Comparing Bell to Rotrex

Flow Rate

Bell states for a 4 stroke:

Airflow rate = (cid x rpm x 0.5 x Ev)/ 1,728

So for a metric two stroke:

1 cubic centimetre = 0.0610237441 cubic inches

Pressure Ratio

The compressor map below shows that the C8-8 will give this at 160K-200K rpm (~13K-~17K input rpm) - though I need to understand pressure maps more (off to do some reading).

rotrex_c8-8_compressor_map.png

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Paul McIntosh,
Mar 24, 2015, 11:47 PM
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Paul McIntosh,
Mar 24, 2015, 11:46 PM
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Paul McIntosh,
Mar 24, 2015, 11:46 PM
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Paul McIntosh,
Mar 24, 2015, 11:46 PM
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Paul McIntosh,
Mar 24, 2015, 11:46 PM
ą
Paul McIntosh,
Mar 24, 2015, 11:46 PM
Ċ
Paul McIntosh,
Mar 24, 2015, 11:47 PM
Ċ
Paul McIntosh,
Mar 24, 2015, 11:47 PM
Ċ
Paul McIntosh,
Mar 24, 2015, 11:47 PM
Ċ
Paul McIntosh,
Mar 24, 2015, 11:48 PM
Ċ
Paul McIntosh,
Mar 24, 2015, 11:48 PM
ą
Paul McIntosh,
Mar 24, 2015, 11:48 PM
ą
Paul McIntosh,
Mar 24, 2015, 11:48 PM
ą
Paul McIntosh,
Mar 24, 2015, 11:48 PM
ą
Paul McIntosh,
Mar 24, 2015, 11:49 PM
ą
Paul McIntosh,
Mar 24, 2015, 11:49 PM
ą
Paul McIntosh,
Mar 24, 2015, 11:49 PM
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