Tuning with EGT

[Steve.Flanagan at VerizonWireless.com]

I use 8 EGTs to aid in tuning a 1600 HP Turbo setup. We see temps from 1700
F to
1900 F.  Lets say we do not like to see anything over 1900 but we have seen
it.

Typical range I would say for blown applications is 1600 - 1800 F.

As far as tuning, its aids in individual cylinder tuning, but there is no
absolute
value that you can tune for.  Its more or less used as a reference from the
last 
pass.  Its also great to see if you have a problem with any one cylinder.
We use
116 octane.  Combined with wide band 02 provides a great basis to tune from.

steve

-----Original Message-----
From: Larry Heath [mailto:lgheath at earthlink.net]
Sent: Monday, March 05, 2001 3:24 PM
To: diy_efi at diy-efi.org
Subject: Re: Tuning with EGT


Most guys that drag race use EGT to tune. Most of us look for a max of about
1200 to 1250 degrees F as the car crosses the finish line, i.e. max load max
rpm. This is of course using fuels with very high octane ratings, generally
no less than 105 octane and as much as 118, that are generally not prone to
detonation even under extreme conditions. I lot of guys use the EGT's in
tuning alcohol fueled engines, as the typical signs use to tune gas fired
engines are generally not present, the alcohol fuel being very clean burning
and has such a wide range of flammability. Most guys seem to use the same
basic temp range as a max, although I have seen references to EGT's much
lower than the 1200 to 1250 range as being ideal for max power.

Thermocouples (K type) are generally fairly slow as far as response time
goes, at least for the typical thermocouples used in this application. The
faster the response rate of the couple the shorter the average life of the
unit is.  I have seen bare wire thermocouples with standard response times
of as little as .004 sec, but these would not last any significant amount of
time, in an exhaust gas environment. About the minimum wire size that would
be usable as a EGT is .015" and this has about a .8 sec response time going
from 100 to 800 degrees in 60 ft/sec gas.

Along these same lines I have a question; does any have any info about
tuning alcohol fueled engines using an O2 sensor or other similar sensor to
allow A/F ratios to be determined on a much faster basis than the typical
EGT thermocouple sensors.

Later Larry

----- Original Message -----
From: "Grant Crockett" <idratherbedriving at yahoo.com>
To: <diy_efi at diy-efi.org>
Sent: Monday, March 05, 2001 11:41 AM
Subject: Tuning with EGT


> Has anybody done air-fuel mixture tuning with exhaust
> gas temp rather than O2 sensor?  I have read that the
> thermocouple has a much quicker reaction time to high
> heat/lean fuel conditions than an O2 sensor.
>
> If so, what are you getting for temperature readings?
> I am wondering what temps (deg F) would equate to
> optimum performance, without detonation.
>
> end
> --------------------------------------------------------------------------
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