Tuning with GET

[TysonLin at mail.igs.com.tw]

Sorry, another questions.

Base on TURBO gasoline spark ignition engine, is it true that:
EGT raised when timing advanced under boost ?
And the temperature difference between  combustion chamber and exhaust pipe
would be enlarged while timing more advanced ?

These two questions really confused me.

Tyson.
-----Original Message-----
From: Carl Summers [mailto:InTech at writeme.com]
Sent: Thursday, March 08, 2001 12:10 PM
To: diy_efi at diy-efi.org
Subject: RE: Tuning with GET


Hi list,   been real busy so I haven't followed this thread.  I have tuned
quite a few twin turbo setups and EGT is pretty unreliable and extremely
slow.  One TT 540 I did was 1639hp at 6000 rpm.  Timing has a dramatic
affect on EGT.  This engine stabilized around 1430F EGT but when timing was
too low...EGT's were all over the place.  Individual cylinder tuning had
some effect but was not the cure all for the EGT variances.  Individual
cylinder ignition timing would be really good for us but we don't have the
control to do coil on plug yet.  I just finished a TT 572BBC that was 1145hp
at 6000 on 92 octane.  Took quite a bit of work but EGT's are stable in the
high 1300's and loaded it on the dyno till we started overheating the dyno
tanks(about 10 minutes) without a trickle of knock.  Most applications I
work on are more of a severe environment than drag racing as this is a
marine environment.  Climbing EGT's will cause ultimate exhaust valve
failure even with inconel valves.  We have done quite a bit of cam timing
changes to help reduce EGT and still maintain a decent spool up time.  What
cu in and environment is the 1600hp you are doing??? ttyl
-Carl Summers

-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
Behalf Of Bob Wooten
Sent: Wednesday, March 07, 2001 7:26 PM
To: diy_efi at diy-efi.org
Subject: RE: Tuning with GET


what are you running that is making 1600 hp?  is there a web site that shows
this beast?(off list if you don't want to continue the subject on list).

thanks,
BW

-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
Behalf Of Steve.Flanagan at VerizonWireless.com
Sent: Wednesday, March 07, 2001 9:09 AM
To: diy_efi at diy-efi.org
Subject: RE: Tuning with EGT


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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