Aerochargers are better than a twin screw!! hahaha ;-)

[Jeff Meager]

You cannot get something for nothing in any situation.  Take a turbo. This
means exhaust backpressure.  If exhaust BP wasn't a bad thing, you wouldn't
put a big cam onto an Normally aspirated car would you?  Right, so a big cam
for peak power is best to get all the crap out....
Now we put on a turbo and reduce to buggery the overlap etc.  The turbo
makes up for the lack of power due to the cam, but now you have a large
amount of residual exhaust in the cylinder due to high BP before the
turbo....
SEE, it wasn't FREE!  You've cost yourself a clean burn by putting the turbo
on.....

Yes, on nearly every factory turbo setup, that will make usable boost at
2500rpm, you will by peak power have twice the backpressure vs
boost....measured it, seen it....

LJ

-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
Behalf Of Programmer
Sent: Monday, 15 October 2001 11:36 PM
To: diy_efi at diy-efi.org
Subject: Re: Aerochargers are better than a twin screw!! hahaha ;-)


Since I said it, I meant a turbo requires no parasitic draw from the engine
to operate it==free HP.

Twice the exhaust BP than boost pressure ? So you're saying your exhaust has
30 PSI backpressure ?

Lyndon.

----- Original Message -----
From: "Jeff Meager" <jmeager at bigpond.com>
To: <diy_efi at diy-efi.org>
Sent: Monday, October 15, 2001 3:37 AM
Subject: RE: Aerochargers are better than a twin screw!! hahaha ;-)


> And what about the losses that a turbo causes due to the horendous
> backpressures.....  you're not going to tell me turbo's are free
horsepower
> are you???  The T88 on the 2.2L nissan engine I worked on that's putting
out
> 732hp at the wheels doesn't suffer the backpressure fate, but it also is
not
> making any real boost until 5500rpm.....
>
> But a turbo that is on boost at 15psi, has on average, twice the exhaust
> backpressure, than boost pressure....
>
> LJ
>
> -----Original Message-----
> From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
> Behalf Of Jess Gypin
> Sent: Saturday, 20 October 2001 9:52 AM
> To: diy_efi at diy-efi.org
> Subject: Re: Aerochargers are better than a twin screw!! hahaha ;-)
>
>
> And suck 10-15 hp from the engine in parasitic loss to drive the blower.
>
> Jess
> ----- Original Message -----
> From: "Stephen Andersen" <SAndersen at advan-tek.com>
> To: <diy_efi at diy-efi.org>
> Sent: Sunday, October 14, 2001 18:31 PM
> Subject: RE: Aerochargers are better than a twin screw!! hahaha ;-)
>
>
> > The boost curve for the Positive Displacement SC
> > on aerocharger's web site is about as far from a
> > "fact" as you can get.  When sized and "geared"
> > properly for a give displacement engine, a PD
> > supercharger will provide within about 10-15% of
> > peak boost given WOT at somewhere just off idle.
> >
> > The twin screw compressors have extremely high
> > volumetric efficiencies and don't need to be spinning
> > very fast to generate boost.
> >
> > Aerocharger's site indicates that the boost curve
> > is linear and starts at or near zero.  Way off base...
> >
> > Steve
> >
> > Stephen M. Andersen, P.E.                              (302) 326-6405
> > Technical Director                                    FAX  (302)
326-6401
> > AdvanTek International, LLC                     Cell   (302) 547-9842
> > 56 Read's Way                               andersen at Advan-Tek.com
> > New Castle, DE 19720
> >
> >
> > > -----Original Message-----
> > > From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
> > > Behalf Of Greg Hermann
> > > Sent: Sunday, October 14, 2001 8:36 PM
> > > To: diy_efi at diy-efi.org
> > > Subject: Re: Aerochargers are better than a twin screw!! hahaha ;-)
> > >
> > >
> > > At 7:15 PM 10/13/01, Nicholas Parker wrote:
> > > > What a load of crap at http://www.aerocharger.com/tech1.htm
> > > >My little ol' 1600cc  MR2 with its cruddy 'two-lobe' Rootes
> > > SC makes 10psi
> > > >at 3000revs when max is only around 11.5 (by drive
> > > ratio...),  even the
> > > >turbo boost curve is not very fair to turbo-heads!!  Who
> > > ever drew those
> > > >graphs has probably got holes drilled through his SC lobes
> > > and in hs turbo
> > > >compressor housing!!
> > > >Nick.
> > >
> > > Whatever makes you happy. Don't let facts confuse you!
> > >
> > > Greg
> > >
> > >
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> > >
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