AFM measurement/backpressure (was Turbo speed sensor)

[Espen Hilde]

Hi!
Thanks Clay great sum up.
Yes the turbo engine needs special care ,when using EFI, learned that the
hard way....Have tryed blow trou with Webers and Dellortos and the
drivability was wery good. I read a test of Lotus turbo car that where
using 
dubble dellortos and the journalist stated it was the best turbo engine he
had driven, offcurse we have to compare this with the crude ways of early 
oem turbo charging.
One carb in each runner has an advantage over efi , it measures and
delivers induvidual amount of fuel.Carbs has one problem the mixture leans
out when the density of the air increases.This can be counteracted 
by fattening the fuel curve at the point where the boost sets in .
Maybe the best of both worlds?
Block the idle and low output channels in the carb and use efi for light 
cruising and closed loop with wery small injectors witch goes over to carb 
for high output , the carb can deliver as much fuel as the engine can use.
Combined with a advanced ignition control.  
Remember how fun it was in the old days when you could just change a
jet.......:-) But the mechanical  ignition is for the past .
Espen
 
> Compared to what Mechanical, FI, Carbbies?.
> Sweeping statements are often wrong.
> AFM are probably the least accurate of the air flow sensors, or at least
the
> most restrictive.
> In the archives at the GN Ttype there are statements from actual dyno
> testing where even a MAF sensor cost 30HP.
> An SU and electonic ignition control (far a small engine) would be hard
to
> beat when set up right.  Webers come close to IR, and a blow thru IR vs
> Weber would be within tenths of a percentage, I'd wager.
> VE, and HP well there is alot for who's doing the tuning.  Just really
about
> dry walls vs wet, and reelated issues.
>   Now drivibility, tunability, reliability, emissions are all other
matters.
> But, to claim EFI is that "secret to HP + VE" or especially good for
turbos,
> is kinda stretching a point, IMHO.
>   I notice noone has mentioned cross over so far.  And that opens the
doors
> for all kinds of things.
> Grumpy
> 
> 
> > Espen Hilde wrote:
> > > What I tryed to say was that the AFM cant give info for the retard of
> > > ignition advance that the backpressure is indicating.
> > > AFM is not fast enough for a high rpm engine with big turbo, the
engine
> can
> > > dubble the hp in 250rpm change.
> > > In a oem application ...no problem.
> > <good discussion snipped>
> > Your points serve to illustrate a less-than-well-known (?) fact that
> > sophisticated engine management contributes  more efficiency and HP to
a
> turbo
> > motor, than to a NA motor.
> > - Clay (not that it isn't worthwhile on an NA motor...)
> >
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