Rotrex C38-92 Supercharger with 20b>?
 

Hi you all i found that not many people tried a supercharger setup on their rotary's.
I also found no kits avaidable for rotary engines as far my research showed me
Are there specific reasons for this?

I was wondering if someone could fill me in about any go's or no's about a supercharger system on a rotary.

and specific how a Rotrex C38-92 charger would perform on a streetported 20b

Please share your thoughts and info.

here some info about the charger:

http://i41.tinypic.com/rc25px.jpg
http://i39.tinypic.com/2enxges.jpg

C38
Max air flow 0.63 kg/s
Power range: 200-530kW (272-720hp)
90,000 rpm maximum impeller speed
1 : 7.50 gear ratio

The C38-91/92 units share the same basic C38 drive dimensions and feature a compressor housing only
8 mm longer (axial dimension) than that of the other members of the C38 family.
The C38-92 features a large 89mm inlet, while the C38-91 has the standard C38 size inlet.
The C38-91/92 units have a wide high efficiency island, guaranteeing forceful acceleration all throughout the rev range.


Thanks.

number one .. do some research into supercharger classes.. positive displacement types,, V non positive displacement types

adiabatic,, and mechanical efficiencies

once you get a head around that,, then you will find its all about sizing , and gearing
,, and very few positive displacement types can follow the same TQ curve and rev range as the rotary engine
so at one point it may rob too much drive power.. and others be undersped or oversped,, and just heating the air

when you look at non dispalcement types you may see that they offer few advantages over a turbo.. for more complexity,, and less reliability

especially when you consider the load of accell and decell on the step up gearing means they or the belt drive may have a short life on a rotary engine


how did i know this? i used to have a wray ( positive displacement , vane slat ) blower on a 13b in an rx2
it had gobs of TQ low down .... but restricted the engine revs , as the supercharger could not work at those flows and speeds without running over the top with heatsoak and internal expansion

changing the gearing from overspeed to underspeed can only do so much , and kills the low down fun

essentially there is a miss-match between the most efficient airflows and the relative RPMs between the blower and the engine ,, and only completely resizing the supercharger will fix this

What about twin charging? as in the delta s4 series setup non compounding.

using something along the lines of a whipple w140ax using an electric clutch and bypass valve so that its only used up till 3000-4000rpm before kicking out (preventing over reving the supercharger but maintaining the required boost at low rpm)and letting the larger turbo do the work there on.

I know that sequential turbo's solve this issue but they are limited to there max power, so if say you were chasing 700hp atw that's a bit of a no go.

Have you had any experience in this Bumpstart?

This obviously adds more cost and complexity but have there been any viable 20b setups like this?