Homemade Zinfandel, addition of vodka?

I am making Zinfandel with juice from California. We have been making it for several years, just does not have the firepower I recall from years ago when my great uncles were making it. I am in day 4 of 7 of letting the juice breathe in the plastic 6 gal. with the yeast, prior to transferring to glass carboy. I wanted to try jacking up the alcohol a little more this year without imparting too much flavor. Has anyone added vodka to the juice, and if so how much and at which stage of racking?
Thanks

Add some red juice grape concentrate to the must before fermentation to boost the sugar level which will result in higher alcohol in your finished wine. Don't add vodka, it will not improve the wine in my opinion