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 Post Posted: Tue Sep 25, 2012 9:13 pm 
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Joined: Tue Apr 01, 2008 10:56 pm
Posts: 110
Location: Kilgore Tx [North East Tx]
I like that sound, the slow, smooth, even quiet sound of a warmed up carb equipped engine idling on methanol.

While the same engine setup on gas is much louder and much choppier.

So what are the characteristics of methanol that allow the low smooth idle?

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 Post Posted: Tue Sep 25, 2012 9:53 pm 
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Joined: Sat Feb 07, 2009 4:12 pm
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Location: Adelaide Australia
The methanol absorbs the exhaust reversion heat more and that stops the reversion from reaching the plenum. Well some of it anyway. Reversion is why hot cam engines run rough.


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 Post Posted: Tue Sep 25, 2012 10:06 pm 
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Joined: Tue Apr 01, 2008 10:56 pm
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Location: Kilgore Tx [North East Tx]
or, is it not so much the fuel but simply that at low idle we are allowing less air in the engine. Thus, slow, quiet, idle.

Could it be that the methanol part of the sound my be that the fuel allows less idle air. And as you suggest, the ERG effect of a big cam would be less with less air flow through the engine at low speed.

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 Post Posted: Tue Sep 25, 2012 10:26 pm 
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Location: Adelaide Australia
I dont quite follow you but if you close the butterfly or do something that results in less air flow through the engine the exhaust reversion gets greater not less. The exhaust port is an un-throttled intake port, especially at idle.
People constantly talk about the fuel volume of methanol taking up space in the port etc and all the different effects that has. Work out the amount of fuel needed per cycle and you realize its still insignificant.
The sound of exhaust has some merit to tuning. If the amplitude of the wave varies a lot then the cylinders are also varying in their burn rate. The exhaust is the left over energy from the burn, dull sounding exhaust is usually indicative of slow burns or excessively rich conditions. The ideal exhaust is sharp cracking supersonic wave.


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 Post Posted: Wed Sep 26, 2012 6:40 am 
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Location: N.J.
There is also a sound difference with E85 and unlike alky it don't make your eyes water...

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