Combustion chamber temps vs coolant temp
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,599
Likes: 24
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
Combustion chamber temps vs coolant temp
Are coolant temps a good indicator of combustion chamber temps? My coolant temp is generally in the neighborhood of high 170s / low 180s, but today my plugs indicated that combustion chamber temps were a bit high after a few WOT blasts. I saw a few brown / black specs on the porcelain of the plug. Not many at all (and no shiny diamond specs), but I am thinking of dropping one heat range below the stock heat range, which I am currently running.
What has been your experience?
What has been your experience?
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,599
Likes: 24
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
Hey Joe -
No - all engine. I didn't see any knock counts or knock retard in the data log, and the WB shows 12.9:1 at WOT. Power seemed all there. So I'm thinking instead of dropping the timing, I'll go down a heat range.
No - all engine. I didn't see any knock counts or knock retard in the data log, and the WB shows 12.9:1 at WOT. Power seemed all there. So I'm thinking instead of dropping the timing, I'll go down a heat range.
Racer
Joined: Dec 2006
Posts: 325
Likes: 2
From: Chattanooga TN
coolant temps are not a good indicator of actual combustion temps.
air/fuel ratio is... at 12.9:1, you are a bit on the lean side for WOT.
not dangerously so, but still a bit richer would certainly bring peak combustion temps down some.
no harm in trying a slightly colder plug though.
air/fuel ratio is... at 12.9:1, you are a bit on the lean side for WOT.
not dangerously so, but still a bit richer would certainly bring peak combustion temps down some.
no harm in trying a slightly colder plug though.
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,599
Likes: 24
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
coolant temps are not a good indicator of actual combustion temps.air/fuel ratio is... at 12.9:1, you are a bit on the lean side for WOT.
not dangerously so, but still a bit richer would certainly bring peak combustion temps down some.
no harm in trying a slightly colder plug though.
not dangerously so, but still a bit richer would certainly bring peak combustion temps down some.
no harm in trying a slightly colder plug though.
Instructor
Joined: May 2007
Posts: 175
Likes: 0
temperatures...
in fact, at 12.x f/a ratio you are WAY lean. Ideal is more on the order of 14.8-14.6 or so.
By combustion chamber temps do you mean the metal or the exhaust gases?
If you're talking gases you're up in the 1300 degree F range.
Jim
By combustion chamber temps do you mean the metal or the exhaust gases?
If you're talking gases you're up in the 1300 degree F range.
Jim
Thread Starter
Safety Car
Joined: Sep 2003
Posts: 3,599
Likes: 24
From: Orange County NY
St. Jude Donor '10-'11-'12-'13
I mean exhaust gas temps, in relation to coolant temps.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
One of the indicators of pre-ignition or detonation are speckles (we call them "fly-shi*) on the porcelain.
You can do a Google search and find some pics and more details on this condition.
Jake
You can do a Google search and find some pics and more details on this condition.
Jake
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