RE: O2 Sensors

["Lewis, Gerald" <gerald.lewis@domain.elided>]

I find this a distinction without a difference, as far as the street driver
is concerned.
As far a street driver is concerned, who cares about WOT.  Even racers do
not spend all, or even most, their time at WOT.  By your explanation once
you get off of WOT the advantage is gone.  BTW, I do not like to take
"facts" without some independent confirmation.  There is alot of amateur
info (including mine) that is worth exactly what you pay for it.  

Jerry in Houston

> ----------
> From: 	owner-alfa-digest@domain.elided
> Reply To: 	alfa@domain.elided
> Sent: 	Sunday, June 6, 1999 10:06 PM
> To: 	alfa-digest@domain.elided
> Subject: 	alfa-digest V7 #786
> 
> 
> BUT--that sensor on the Ferrari is a WIDE BAND O2 sensor. They do NOT tune
> to the stoich a/f ratio on FI engines--because that is not the a/f ratio
> which gives the maximum output. Some of the Aurora based Indy car engine
> are now running a wide band O2 sensor on EACH cylinder--and by eliminating
> the variation from cylinder to cylinder, they are are able to get best
> power at an a/f ratio somewhat closer to stoich (but still on the rich
> side) than they otherwise could.
> 
> A regular O2 sensor (such as what is provided on the newer Alfas) acts
> pretty much like a switch at stoich a/f ratio. Tells you whether the
> engine
> is above or below the stoich a/f ratio, and not much else.
> 
> And--by the way--these sensors switch at the stoich a/f ratio for whatever
> fuel you happen to be feeding the motor: It you are burning a fuel whose
> stoich ratio happens to be 13:1 rather than 14.7:1, then the 13:1 stoich
> a/f ratio is where the sensor will switch when you run that fuel.
> 
> A wide band O2 sensor (working together with its control box) gives a
> voltage output which varies, almost, but not quite, in a linear manner,
> from 0 to 5 volts, as an engine's a/f ratio varies from 10 : 1 to 30 : 1.
> The best, most responsive wide band A/F sensors/controls are made by
> NTK/NGK. A wide band control box/sensor/wiring harness from NTK costs
> about
> $1100 (USD).
> 
> You may find this rather incredible--BUT--a PROPERLY tuned set of Webers
> or
> Del'Orto's will give BETTER (lower, more efficient) bsfc at wide open
> throttle than all but the VERY most sophisticated design efi systems!
> 
> And I am not aware of ANY efi systems designed for street use which have
> reached the level of sophistication necessary to match the level of WOT
> bsfc that good, individual runner type carbs will give!
> 
> Not as much total power from the carbs as from efi, because the carbs need
> the air flow restriction of their chokes to function,  but more work
> output
> from the engine per unit of fuel burned at WOT with the good carbys, and
> by
> a statistically significant amount (5 to 10%).
> 
> There are lots of complex technical and thermodynamic reasons for this
> being true, but it IS a fact!
> 
> For the same group of reasons--it IS possible to obtain better throttle
> response from properly tuned GOOD carbs than can be had from any normal
> efi.
> 
> Regards, Greg
> 
> 
> 

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End of alfa-digest V7 #787
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