[Supras] spark retard and fuel management devices

[berniek at technicaldevelop.com]

Jim:

    First, I'm going to double space paragraphs with Mozilla 
Thunderbird.  The damn program is better than Outlook, but it compresses 
text when sent.

    MSD makes a 4 channel unit which will work with the MkIII wasted 
spark system (one channel not used).  Trouble is that it retards by a 
settable fixed amount, triggered by application of 12V to it from a 
pressure switch, etc.

    Good to understand the ECU learns from the knock sensors.  At 15 PSI 
boost, the retard should be about 7 degrees more than the most retard at 
stock boost.  The ECU will interpret 15 PSIG boost as about 7 PSIG boost 
due to the larger size of the Lex AFM (based on absolute pressure 
calculation). 


    I'll take another look into the Apexi and Maft stuff you mention, 
but those seem like an awful lot of work to reduce the 9:1 A/F at high 
boost to something like 11.5:1, or leaner with water injection.  Time is 
precious with work and other commitments that take up about 70 hours per 
week. 

    Thanks.

       Bernie

Jim Jobe wrote:
> MSD unit will not work due to the multiplex ignition signal,
> that is unless you want to run three of them.
>
> The ECU has some learning capabilities around ignition related
> knocking.
>
> Suggest the Apexi Super AFC to lean it out.  If you can swing
> it by NJ emissions, the Maft or Maft-Pro units are excellent.
> E-manage might be another solution for you since I believe it
> can use the stock (or lexus) afm.
>
> On Tue, Sep 11, 2007 at 09:27:36AM -0400, berniek at technicaldevelop.com wrote:
>   
>> Wade:
>>
>> Yes, I did read your last mail, and will strongly consider a bigger
>> turbo-back system, but NJ is a pain in the butt with exhaust emissions.  I
>> wonder if a large downpipe and large single cat would do the job.  Anyone
>> know?
>>
>> Thanks for the info on the MSD retarder.  I'll look into it.  But from
>> what you say, it seems essentially unnecessary.  Does the ECU "learn" a
>> new retard curve?  Different gas qualities found around the world would
>> seem to indicate this.
>>
>> What type of Piggyback is most popular for taking out top end richness in
>> the Lex-550 setup?  Any ideas for the most popular downpipe and big cat? 
>> I already have an 80 mm cat-back HKS systemI also have a 57 trim turbo.
>>
>> Any and all help and thoughts would be appreciated.  Thanks.
>>
>>      BernieK
>>
>> Wade Tobin Wrote:
>> -------------------
>> Message: 7
>> Date: Tue, 11 Sep 2007 01:59:50 -0700 (PDT)
>> From: Wade Tobin <wwt3198 at yahoo.com>
>> Subject: Re: [Supras] Spark retard and top end fuel redux
>> To: supras at supras.com
>> Message-ID: <908299.23720.qm at web52502.mail.re2.yahoo.com>
>> Content-Type: text/plain; charset=iso-8859-1
>>
>> That's some interesting reading but perhaps you're going into this a bit
>> deeper than
>> necessary.:)  There's dozens and dozens of 7m's running around w/ Lexus
>> AFMs, 550s,
>> piggybacks and no problems.  Been using a Lexus AFM/550s since 02 on the
>> same engine
>> which came from a junkyard (140k miles).  The car has made 420rwhp on the
>> dyno 50
>> passes on the track both 1/8 mile and 1/4 mile.  About 20 of those passes
>> were over
>> 17psi.  Best time was a 12.4 @ 117.
>>
>>   Don't know if you got my last email Bernie, but running the stock CT26
>> elbow, DP
>> and both cats is an area I'd far more concerned with than Lexus AFM tech. 
>> Surely,
>> a choked up exhaust will cause higher EGTs and detonation, Lexus AFM or not.
>> Also, a big intercooler is also a good idea.  The stock MK3 exhaust and
>> intercooler = garbage.
>>
>>   Your absolutely correct about the ECU not retarding the timing w/ the
>> Lexus.  MSD
>> sells a boost timing retarder box for your needs.  I don't run one.
>>
>>   -wt
>>
>>
>>
>> _______________________________________________
>> Supras mailing list
>> Supras at supras.com
>> http://supras.com/mailman/listinfo/supras_supras.com
>>     
>
>
>
>