[Supras] richness under boost

[berniek at technicaldevelop.com]

The reading has been confirmed using both a Marquete and Sun A/F thermal
conductivity ratio meter carried in the car with a tube run to the
exhaust.  (Yeah, I do get weird looks, like I'm trying to commit suicide
in a contrived way).  Both types of devices indicate between 9.0 and 9.5:1
A/F ratio.  Both thermal conductivity meters are sensitive to extremes in
gas velocity, so standard practice is to pinch the hose just before
getting off the gas, and then read the meter.  The problem with a
wideband, as I'm told, is that you cannot leave it in place all of the
time due to temperature considerations.

Bernie
>
> Bernie, please do not tell us you are using this gadget to determine
> a/f ratio.
>
> http://www.3barracing.com/product_3.htm
>
> You NEED a proper wideband sensor for tuning.
>
> BTW, stock pistons have made 500rwhp reliably daily driven for years.
>
> On Mon, Nov 05, 2007 at 10:51:56AM -0500, Walker, Brian (Rich. Dist)
> wrote:
>>
>> Bernie, those spikes in boost seem a bit odd to me. I have a wideband
>> that measures press. and has peak storage. My peak boost is always ~14.5
>> (within ~.2 psi depending on ambient temps, ball & spring controller)
>> This is also the pressure I normally see under WOT (by autometer gauge
>> and real time Wideband display. To me spikes of 2-3 psi seem off. Have
>> you checked to make sure there is no play in the WG arm? Maybe that
>> variance is normal for other folks but my peak boost has been pretty
>> rock solid. (peak A/F on the other hand does tend to vary a little,
>> normally 9.6:1 -10.3:1 depending on weather)
>> Brian W
>>
>> Date: Sat, 03 Nov 2007 18:59:37 -0500
>> From: "berniek at technicaldevelop.com" <berniek at technicaldevelop.com>
>> Subject: [Supras] richness under boost
>> To: "Supras at supras.com" <Supras at supras.com>
>> Message-ID: <472D0B69.9090809 at technicaldevelop.com>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> Today, I temporarily wired up a Dawes A/F indicator, and found that as
>> expected, the engine runs richer under boost than needed for best power.
>> There are ways I will be considering to lower combustion temperatures,
>> such as water injection (already have the RV water pump).
>> But for now, the Dawes readout always has the blue LED lit under boost,
>> I guess the way Toyota intended it (about 9:1 A/F ratio).  The car feels
>> good, so I'd rather be safe than sorry, but can use any number of means
>> to get the A/F up to about 11:1 under boost.  I'm particularly concerned
>> about safety since I'm running the stock pistions at 15 PSI, with one
>> second long spikes up to 17-18 PSI.  Has 550cc, Lex, 3" exhaust, 57 trim
>> turbo, Walbro and the usual mods which go along with these parts.
>>
>>
>> As always, any information would be appreciated.
>>
>>
>> Berniek
>>
>>
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>