plugs

[Seth Allen]

On Wed, 11 Jun 1997, Todd King wrote:

> Date: Wed, 11 Jun 97 09:10:00 PDT
> From: Todd King <Todd_King at ccm.co.intel.com>
> To: DIY_EFI at coulomb.eng.ohio-state.edu
> Subject: Re: plugs
> 
>   <<<
>   > The purpose of the plug is to ignite the fuel.  In some circumstances,
>   >
>   > different materials are more or less prone to oxidation in heated
>   > environments, so yes, in theory, different plugs might make a
>   > difference.
>   >  Also, plugs come in temperature ranges, different gap settings,
>   > different
>   > insulator materials.  I've honestly never figured out technically the
>   > reasons why, but if someone on the list can explain why a plug is not
>   > a
>   > plug, I'm all ears :)
>   >
>   The spark energy influences the power (by increasing the burn rate) more
>   than the spark plug itself, and this is related to the stored coil
>   energy and not necessarily the plug specification.
>   >>>
>   
>   I just received some new SAE books last night; two of the papers in the 
>   combustion book detail results of plug indexing, style (shape, number of 
>   electrodes, etc) and gap experiments. All three plug aspects did indeed show 
>   differences though the authors generally declined to make recommendations on 
>   which way is "best". Interesting that as Andrew points out the spark energy 
>   comes from what's stored in the coil, not really varying with the gap as is 
>   sometimes implied. Point of diminishing returns is reached from widening the 
>   gap when the spark begins finding alternate routes across the ceramic and 
>   ignition efficiency drops. Indexing was interesting too; seems that getting 
>   the ground electrode out of the "slipstream" of the small flame kernel showed 
>   improvement in ignition. However the slipstream (mixture flow) direction 
>   appears to vary with rpm, etc so nailing down a "correct" orientation is 
>   difficult at best. However both results appear to imply that the ignition 
>   process favors having hard parts out of the way of the initial flame kernel.
>   Pretty good reading; it would help to be an ME though...
>   
>   Todd_King at ccm.co.intel.com
>   
> 


Todd, I would be interested in the titles of those SAE publications, 
could you post them when you get the chance?

Thanks,

Seth Allen

PS-  Anyone know where I can get a good air to air intercooler for cheap?