A few questions about roots/twin screw SCs. Do they have compressor maps akin to those on centri/turbos? Pressure ratio on y, airflow on x, and efficiency islands but just different shapes? And do they have a calculation for drag on the crank power when running?

Edit:
Google, Dim, google...

http://www.eaton.com/ecm/groups/publ.../ct_127897.gif

Now need to convert m^3/hour into something familiar...

m^3/hour divided by 60 is good for calculating the power requirement though :D
But the true power requirement would be after you subtract the work done on the piston by the compressed air during intake stroke, and that gets a bit annoying since the pumping loss is hard to find.

+
16.67l/min X inlet flow?

1m3 = 1000L for reference...

That was a long read,

I hope that in coming months more members of this board will come to realize what DI is all about, that 12.5:1 and a turbo get along great, that S/C's are heat pumps and not suitable for cars with a wide RPM range.

The fellow up top (this page) talking to DW injectors please PM me so I can personally tell you why to stop trying development with them, I have pictures that will make you cry

I Pre-Ordered a BRZ because I'm already making DI pumps and Working on Upgrade injectors for several other models, this will be my new pet...

Looking forward to see where we can take this car without sacrificing the DD aspect...I ruined too many S13's with too much power...so I'm gonna try balancing this one...for a while

care to explain this statement? have you kept abreast of the latest supercharger tech? and is a turbo supposed to be "suitable for cars with a wide RPM range"?

Good to hear -- tell us more. Get this thing to a reliable DD with 250+ whp and people will be lining up for your kit.

for example using the TVS 1320 (since it is the smallest available currently)
http://www.eaton.com/ecm/groups/publ.../ct_127898.gif

If you are shooting for 6 psi (~.4bar or 1.4 pressure ratio)
(1m^3 = 1000L, volume is per hour)

2L X 7400rpm X 60 (minutes in hour) X 1.4 = 1,243,200 or 1,243.2M^/hr

If you look at what that gets us, it gets us running on the lower side of good efficiency and still spinning those poor bearings into the high side of their range, (diagonal lines are Rotor RPM) and this Super charger is still too big for this application really, and it's 15" long and needs to be intercooled some how.

This is, to the best of my knowledge, the best super charger line up on the market currently. I don't want to talk about the vortec style or procharger what ever you want to call the half-turbo-parasitic-loss-lumps, those were designed because they are easier to install than turbos (for driveway tuning) and didn't have the same limitations for effective power band,


Turbo's overcome their RPM limitations by having Wastegates to alleviate extra exhaust flow that would exceed the turbo's safe RPM limits. they also allow tuning of the manifold pressure based on loud pedal position relative to the floor.

TURBO LAG...anyone who complains of turbo lag needs to go drive something with a new, properly sized, turbo. and the High compression and DI are only going to make the turbo spool faster. My track car (hpde time attack) is an S13 with a 9.0:1 SR20det and a Forced Performance gt2868 (billet 68mm wheel on a garrett GT28 Hotside/CHRA) it made 230 lb ft at 2700 RPM, and before i got the TiAl Vband housing and external wastegate it would hit boost cut at 6000 (well shy of redline) putting 341hp down on 19psi (boost cut value)

That is my idea of a perfectly drivable, MONSTER. I envision using the same turbo on this motor in this calendar year....shhh it's a secret...

^ Twin screws (Lysholm) still have better efficiency than the TVS Eatons, and approach the 'half-turbo' centris.

Plus is the R900 no longer available or not available yet or just temporarily out of stock? It would be a better example, given the sizing, rather than using an over-sized one.

That's kind of like saying turbos suck, if only the GT45's were available to turbo old Civics....

I looked at the graph for that S/C aswell it is closer to a good fit but you are turning it pretty hard and still well below the peak efficiency of the unit, it is listed on their site as not yet available.