Curious about HP possibilities

alancordeiro at alancordeiro at
Thu Jan 3 17:28:21 PST 2008


The dielectric breakdown voltage of air at STP (atmosphere) is around 
If air is compressed, the breakdown voltage goes up in proportion to the 
of the pressure increase.

If an engine is running high boost to begin with, along with a 9:1 
compression ratio,
the breakdown voltage for a 2 mm gap could run into the 30+ kV region, and 
path of least resistance could be the seemingly large 1 cm gap in the 
atmospheric pressure
air in the internals of the distributor cap, especially if the gap is made 
smaller by spark advance
or retard (whichever case reduces the gap to the next closest pin in the 
( Note that since only one cylinder at TDC is being fired, the adjacent cyl 
is close
to atmosphere...and the small spark plug gap barely adds to the overall 
total air gap.)

Hope this helps,


----- Original Message ----- 
From: "Brett Dikeman" <brett at>
To: "Richard Harris" <rnharris at>
Cc: <s-car-list at>; <200q20v at>
Sent: Wednesday, January 02, 2008 11:24 PM
Subject: Re: Curious about HP possibilities

> On Jan 2, 2008, at 1:15 PM, Richard Harris wrote:
>>  according to most of people I've corresponded with, the distributor
>> ignition on the 3B limits
>> my possibilities.
> That's a ~630HP engine, and it's got a distributor.  Draw your own
> conclusions.
> I couldn't find a clear picture showing where the wires go on the 20v
> IMSA cars, or for the S1 rally cars...
> Nobody has ever explained to my satisfaction how this cross-firing
> situation is possible.  There's 72 degrees on the distributor between
> cylinders, timing is done by the ECU off a hall sensor, and
> electricity always takes the path of least resistance...
> Brett
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> 200q20v mailing list 

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