All You CHT Gauge Drivers Report Here

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asiab3
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Re: All You CHT Gauge Drivers Report Here

Post by asiab3 » Tue Oct 02, 2018 10:06 pm

Latest post of the previous page:

Has anybody who stays in one state for a while noticed a rise or fall in head temps due to fuel formulation? I just realized my DD CHT ADD may just be... that..

Robbie
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Amskeptic
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Re: All You CHT Gauge Drivers Report Here

Post by Amskeptic » Wed Oct 03, 2018 10:00 am

asiab3 wrote:
Tue Oct 02, 2018 10:06 pm
Has anybody who stays in one state for a while noticed a rise or fall in head temps due to fuel formulation? I just realized my DD CHT ADD may just be... that..

Robbie

I do not believe I am able to discern fuel formulation as a CHT variable.
It is a great mystery to me why ambient temperatures seem not to have as great an effect on CHTs as I might have surmised.

I have done delta-T analyses in my head that suggest that a drop in ambient temperatures from 115* to 43* should improve heat transfer off the heads by a nice ridiculous amount, but when you add to the equation that the engine is a big huge heat sink that has stored up a big pile of excited atoms, the cooling air that only briefly passes by the hot heads is limited in its absorption of heat. That means that 43* air can only absorb "X" calories of heat barely different than 115* air that briefly passes by. Does this make sense?
Colin
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asiab3
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Re: All You CHT Gauge Drivers Report Here

Post by asiab3 » Wed Oct 03, 2018 2:43 pm

It makes sense!

I think back to my remote control car racing years and years ago, when changing ambient temperatures would screw with our fuel mixtures enough to warrant leaning out the engine when hot (thinner air = less O2 content) and richening the mixture when cold (more O2 content in cooler/denser air) for optimal performance without smearing pistons on the cylinder walls. My, those 1.2/1.5cc two-cycle engines were remarkably similar to our Volkswagens...

366* tops last night, floored from New Hampshire to Manhattan.
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Re: All You CHT Gauge Drivers Report Here

Post by SlowLane » Wed Oct 03, 2018 3:45 pm

Just want to be clear that I have no special insight into gasoline formulations or how they may or may not affect cylinder combusiton temperatures. I was just throwing that out as an example of a variable which one might normally not consider when deciphering CHT behavior.

Although I could certainly see how the winter gas could be formulated to run hotter in parts of the country where winter actually occurs. I should think that it would help with improving engine warmup times.

Or maybe I'm just blowing gas and simply adding to the conjecture, myth and poorly understood science that drives our internet entertainment.
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