Hi Tim, it's a bit of a myth that acetic acid is more sour than lactic acid. Both produce sour flavor, but lactic acid is always more prevalent in sourdough, so it's really about increasing overall acid production when you're striving for that vinegar flavor. Part 3 of this series offers even more precise directions if you're goal is sour:

For bread with stronger sour flavor, the preferment should be: 

• Looser (100% to 125% hydration), rather than stiff (see “a cautionary note,” below)
• Ripened at a higher temperature (75°F to 82°F)  
• Fed a larger meal; rather than 1:1:1 (starter:water:flour), the feeding ratio should be more like 1:4:4 or similar
• Added to the dough when it’s a little bit past its peak (more ripe)

And the dough should be: 

• Made with at least 10% to 15% whole grain flour, preferably rye or wheat 
• Warm (79°F to 83°F): after kneading, and during bulk fermentation 
• Refrigerated at some point after its warm bulk fermentation 

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