We recently put our ChumpCar Alfa 116 on a chassis dyno
and learned lots of neat stuff. Like, we were at 13:1
and thought it was good.
We adjusted the fuel injection to 12.5 and picked up a few
horsepower until the ratio started to slowly lean out to
13.1: at 5k rpm. This told us we had a fuel delivery
problem of some sort that we had not been aware of. Also told
us there was some more hp on the table.
Our dyno operator was very helpful and knowledgeable.
Money and time VERY well spent.
art de armond
-----Original Message-----
From: Barr, Scott
Sent: Thursday, May 23, 2013 1:15 PM
To: 'Tony Drews' ; Bill Tobin
Cc: fot
Subject: Re: [Fot] EGT's again... the averages
Tony wrote: << a bit richer than stoichiometric, ie 13:1. >>
And I said "...wait, what?". 13:1? I have always heard that gasoline
fuel
stoich point was 14.7. A little research says Tony's right as usual. I've
been reading my A/F meter at 14.5 or so and thinking that was a good thing.
Time to turn the adjusting nuts out a few flats and take a look at the
plugs...
-----Original Message-----
From: fot-bounces@autox.team.net [mailto:fot-bounces@autox.team.net] On
Behalf
Of Tony Drews
Sent: Thursday, May 23, 2013 10:58 AM
To: Bill Tobin
Cc: fot
Subject: Re: [Fot] EGT's again... the averages
I made best power when the car ran slightly "rich", a bit richer than
stoichiometric ie 13:1. I ended up with best power closer to 12.5:1. So,
some
of the high EGT is due to fuel still burning when the exhaust port opens.
The A/F meter was at the dyno, I don't have one in my car. The leaded gas
kills the A/F pickup. I bought a new one for the dyno session and we killed
it by the end of the testing.
Tony Drews
At 10:38 AM 5/23/2013, Bill Tobin wrote:
>Tony, what kind of A/F ratio setup do you use? And what ratio do you
>shoot for?
>Thanks, Bill
>----- Original Message ----- From: "Tony Drews" <tony@tonydrews.com>
>To: <toodamnfunky@comcast.net>; "Scott Janzen" <sjanzen@me.com>
>Cc: "fot" <fot@autox.team.net>
>Sent: Thursday, May 23, 2013 10:30 AM
>Subject: Re: [Fot] EGT's again... the averages
>
>
>>By the way, my carb jetting was determined on an engine Dyno, and
>>included the use of an air/fuel ratio gauge. So, I just noted the
>>EGT's produced at that time as "baseline".
>>
>>Tony Drews
>>
>>At 09:19 AM 5/23/2013, toodamnfunky@comcast.net wrote:
>>>Thanks guys for the input.
>>>
>>>We see probes mounted anywhere from 1.75 " to 6" from the flange
>>>
>>>and EGT's from 1300 to 1400. So it's an average of 3.9" from the
>>>flange and 1362F for EGT's.
>>>
>>>Very helpful,
>>>
>>>Jim G.
>>>
>>>
>>>
>>>----- Original Message -----
>>>
>>>
>>>From: "Scott Janzen" <sjanzen@me.com>
>>>To: "fot" <fot@autox.team.net>
>>>Sent: Thursday, May 23, 2013 6:42:37 AM
>>>Subject: Re: [Fot] EGT's again
>>>
>>>2" from the head. B 1300 degrees on the GT6 at 7000 RPM, 32 degrees
>>>advance.
>>>Tailpipe is tan/grey, leaded 110, forged Venolia pistons, 12:1
>>>compression I suspect I could lean it out a bit - need some dyne time
>>>with the webers to determine.
>>_______________________________________________
>>fot@autox.team.net
>>
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