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RE: EGT with Supplier Questions

To: "MARK J WEATHERS" <markjwea@email.msn.com>, <fot@autox.team.net>
Subject: RE: EGT with Supplier Questions
From: "Bill Bartlett" <billbartlett@homerebuilders.com>
Date: Sat, 1 Feb 2003 23:16:39 -0500
Hi Mark,
I can tell you what I run in my MGA and Lotus super 7.
I have found that a good lean goal is 12.5. that is 1250 deg Farenhieght. I try 
to keep 13 as a top end goal as I use alluminum pistons and 14 as the max. 
Beyond that the pistons risk getting fried and will pitt and actualy melt 
leaving holes in the pistons. As you can imagine the holes do not help the 
compresion ratio. The thing to remember is that temperature, humidity and air 
pressue all efect the fuel air ratio and therfore the exhaust temperature. I 
can tell you that I was running the 7 at 13 spot on all summer and then went to 
VIR for the fall finaly with SVRA. I love the track and SVRA is a great group 
so I really like the event. However when the mist comes off the track at 8:00 
in the morning and it is about 46deg (as it was last fall); when I take the 7 
out for her morning dance on the tarmac I practicaly get cross eyed from 
watching the egt's at the end of the straights since they will bang right up to 
14.0. However after the engine suffiently warms up the air thins into the carbs 
and the EGT;s fall back to about 13.5, if not I have to stay off the juice (or 
stop and re-jet the carbs) . The only place to take the readings by the way is 
at the end of the strainghts as the sensors foul at the low revs and lower 
loads, and you are seeking the max temps anyway.
I have also been told by some respected engine builders that teh EGT are not 
teribly accurate and that one should trust more on the color of the plugs, the 
briliance of the exhaust note etc.. but the engineer in me simply cannot resist 
the imediacy of the EGT readinings.
BIll B
 
PS: I have a question about suppliers: I am rebuilding a GT6+, I ned to buy 
just about every moving part. I am currently sorting out the suspension. Who 
has the best parts. I have heard taht some of the British parts supliers are 
actualy remanufacturig parts in ASIA and they are inferior. Sice the suspension 
parts are important to ones health I want to buy the best  and do not car to 
save $25 to take the risk another front upright might fail. The suppliers I am 
curently considering are

1.      Victoria British
2.      Spit Bits
3.      Dave Bean Engineering (Lotus)

I have included Dave Bean since many of the Lotuses used GT6 parts. Does anyone 
have any feedback on who has the best parts?

Thanks 

Bill B

 

-----Original Message----- 
From: MARK J WEATHERS [mailto:markjwea@email.msn.com] 
Sent: Sat 2/1/2003 8:53 PM 
To: fot@autox.team.net 
Cc: 
Subject: EGT



        Amigos. 

        Greetings from sunny Phoenix where it is over 80 degrees today. 
Speaking of 
        temperature, on my last rebuild I installed temperature sensors in each 
branch 
        of my header close to the head for purposes of collecting data on EGT. 
With 
        this accomplished, I realized I have no idea how to optimize mixture 
based on 
        EGT. I have heard higher is better but certainly a lean running engine 
is 
        going to produce a pretty hot exhaust stream. Can anybody point me in 
the 
        right direction? I had an O2 sensor and mixture gage hooked up to the 
        collector but I never got any readings that made sense relative to plug 
        appearance. I think it may have been too cool that far down the exhaust 
to 
        work. 

        Thanks 
        TR6 Mark 

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