TPI Questions

[Gary Derian]

-----Original Message-----
From: Gary Derian <gderian at cybergate.net>
To: diy_efi at coulomb.eng.ohio-state.edu <diy_efi at coulomb.eng.ohio-state.edu>
Date: Tuesday, August 12, 1997 3:54 PM
Subject: Re: TPI Questions



>When nitrogen and oxygen (air) are combined at high temperatures nitrigen
>oxides are formed.  Nitrogen oxides are an ingredient which leads to the
>formation of ground level ozone.  EGR adds exhaust, an inert gas, to the
>intake.  This dilutes the air/fuel mixture and lowers the combustion
>temperature which reduces the formation of NOx.  Lower combustion
>temperature also makes an engine less prone to detonation.  The less NOx
>created in the engine, the less is emitted out the exhaust, even with 3-way
>catalysts.  Most but not all engines have EGR.
>
>In the bad old days of the 70's, engines ran with EGR and retarded spark.
>This led to a great loss of economy.  Modern engine controls can advance
the
>spark during heavy EGR use.  The EGR permits lots of advance without
>detonation.  This gets back most all of the economy.  When EGR is removed,
>the part throttle advance must be cut back to "normal" levels otherwise
>detonation will occur.
>
>At full throttle, EGR is not used so spark advance and power are already at
>proper levels.
>
>Gary Derian <gderian at cybergate.net>
>
>-----Original Message-----
>From: Clare Snyder <clsnyde at ibm.net>
>To: diy_efi at coulomb.eng.ohio-state.edu <diy_efi at coulomb.eng.ohio-state.edu>
>Date: Tuesday, August 12, 1997 2:58 PM
>Subject: Re: TPI Questions
>
>
>
>>>
>>>I was under the impression that EGR was to clean up emissions by
>>>recirculating exhaust gas. I read that a performance mod was to
>>>disable the EGR valve with big cams.
>>>
>>>gchan at compserv.senecac.on.ca
>>>>
>>
>>Big cams blead off effective compression at low speeds, where the ping is
>>usually the problem. A big cam can negate the requirement for EGR . Ping
at
>>full throttle is not affected by EGR as it is shut down in that mode
>>
>>My opinion, only, for what it is worth
>>
>
>