Dwell time as a %

[Sean Connelly]

>From: Frank Mallory <frankm at erols.com>
>Subject: Re: Dwell time as a %

>Sean Connelly wrote:
>> 
>> Can someone help me... I am trying to work outthe ignition coil dwell time
>> expressed as a % for various engine combinations but I am getting confused.
>> 
>> I know the time for one engine rev (in ms), coil dwell time (in ms) and
>> number of cylinders (1, 2, 3 or 4) so how do I get dwell time ?
>> 
>> Is it
>> 
>>     Dwell(%) = (Dwell Time / (Time for 1 engine Rev / # Cylinders)) * 100
>> 
>> Sorry its such a trivial problem, but the easy ones are sometimes too
>> easy and you miss them completely.
>> 
>> Cheers
>> 
>> Sean Connelly.

>I think you have to divide by 2 (or use time for 2 engine revs) to
>account for the fact that in the Otto-cycle gas engine, the engine
>revolves twice for every revolution of the camshaft.

>To convert from percent to degrees dwell, multiply by:
>	90 for a 4-cyl. engine
>	60  "  " 6-cyl.    "
>	45  "  " 8-cyl.    ".

This might be the case for conventional ignition, but what happens for
a wasted spark system (distributor less) ? The ignition coil will charge
up twice in the one cycle. Should this affect the dwell measurement 
(degrees or percent) ?

I need to do this calculation on both types of system. I know expressing 
it as a time value would be much easier, bu they (customer) want it as
a percentage.....

Cheers

Sean.