preservation 2/3 Vinegar...1/3 Water...Is it safe?

The peppers should be slit to allow the vinegar solution to get into contact with all surfaces.  2:1 ratio is OK for safety. 
 
here's an extension service site-
  http://www.ext.colostate.edu/pubs/foodnut/09314.html

Thanks, salsalady, for recommending the Colorado extension site.  They really are awesome.
 
I have used their recipe that calls for 6 cups of vinegar to 2 cups of water, or 3 to 1.

Roguejim said:

If I boil 2 parts vinegar with 1 part water, and pour it into sterilized jars filled with raw peppers, is it shelf safe? Do the peppers need to be sliced open?

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To clarify, if they are not heat processed the shelf should be in the refrigerator.
 
That level of acidity will prevent the growth of Clostridium botulinum but it may not prevent other means of spoilage.   Generations of people before us have preserved just as you describe (and many still do), but current thinking dictates you should heat process if you don't refrigerate.

https://youtu.be/kzw1_2b-I7A

cone9 said:

 
Generations of people before us have preserved just as you describe (and many still do), but current thinking dictates you should heat process if you don't refrigerate.

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Part of the problem with the "my granny did it this way for 40 years and never got sick" mindset is-
 
For things like tomatoes, the produce has changed over the years.  Newer Hybrid varieties of tomatoes have been bred to have lower acidity than the older heirloom varieties. 
 
The older tomato varieties that had higher acidity could safely be processed with a boiling water bath.  The newer hybrid tomatoes have less natural acidity so most extention services recommend doing a full on pressure can or adding some acidity to the tomatoes (lemon juice, citric acid, vinegar a small amount of something..).
 
 
My mom told a story of Grandma cooking quarts of green beans in a large kettle for (6 hours or something??? )  Safe processing is a combination of acidity-time-heat.  A quart of green beans (which has no acidity in it naturally) could be "theoretically" safely processes in a boiling water bath by boiling the quart jar of green beens for about 6 hours.    And then it has to be considered....what would the texture quality of said green beens be after being boiled for 6 hours? 
 
back-in-the-day...it may have been the only preservation means available on the homestead. 
 
 
Using vinegar and doing a "pickle" is another method of preservation.  The link to BB81's post is a great cold pack pickle recipe that should be kept refrigerated.  Cold Packed pickled products keep their Krunch better than anything  Hot Packed but storage space for cold packed things can be an issue.  Other pickling recipes using acids (vinegars) and BWB are more like a typical cucumber pickle recipe. 
 
 
Then there is the whole fermentation realm....
 
And also the OP of pressure canning...
 
 
They are all acceptable and usable preservation methods.  Each requires different equipment, and level of efforts. 

Nice job Salsalady very concise answers!! And when I doubt pressure canning is the safest way to go!! better a few extra dollars spent on the right equipment!! Than getting a friend family member or a customer!! sick!