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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Don,

Great info on stock CDI!



I am wondering why the stock components can not be tuned to get close to an ideal for max acceleration from idle through full boost to red line?

This is not a chalange, just a hope to learn. I know adding a programable function to the stock components or a full upgrade would be much better.


It seems we should be able to get pretty close by playing with the mechanical advance curve & total. We also have control over the total amound boost-retard the pot gives as that can be adjusted. Further, we can use or kill the Vac-Ratard function.


Thus, if a single plug 930 needed say -20 at WOT on full boost that is of coursde easy.

Are you saying we can benifit from running more than say about -32 between idle and full boost (apx 3000rpm) at WOT off the line?

I know cruse advance will be less than ideal but seems we should be able to get close on the at temp WOT range.


I love this stuff so any help you can give would be appricated.

Thx in advance.


Quote:
Originally Posted by DonE View Post
If you wanted to spend the money on quality crank fire CDI ignition, you could get some great torque numbers with CIS. Despite some of its limitations, CIS is a great platform even 30 years later.

You really can't do too much to the stock ignition system and that's a big problem when tuning for peak torque and HP. Leave it stock unless you get a quality system. And although Richard Clewett is tops in the Porsche world, the wasted spark system that Electromotive builds is nowhere as good as the stock CDI - even though you can set a timing curve. Given the choice, I would always opt for the stock CDI system over a wasted spark because of spark energy and the quality of Electromotive.

And yes, my 36 degrees is up to about 3000 rpm. At WOT, its closer to 18 degrees.
Old 04-26-2010, 07:32 PM
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