To Renovate or Not To Renovate

[Leeling Chew]

New landlord here. I recently purchased a fourplex in Killeen, TX. Asking price was $350K, but after negotiation, it went down to $333K. Down payment $87K. Each 2/1 unit is close to 800 sq ft. The neighborhood has about 30 other fourplexes, and is a safe neighborhood. My For Rent sign drew many inquiries from people with under 600 credit scores, and a few are section 8. The rent comps nearby range from $700 - $985.

Unit A has an existing tenant, and I increased the rent to $830 with only newly painted wall and vinyl floor.

I spent $16K renovated unit C to STR standard except without changing the existing appliances, and is currently renting for $950. Contractor worked fast, and he only took two weeks to finish.

Unit B will be vacant starting in Nov, and I am needing help in deciding if I should renovate or not, and if I do, how much renovation to do?

Unit D will be vacant starting in mid-Nov, and original plan is to renovate it to STR standard and to do STR for an experiment.

The pictures in unit C came out stunning and I listed it for $1000 just to see if there's any takers. Many people inquired on Zillow but none panned out after one week. 

It takes $16K to renovate each unit to STR standard (rent $950-$1000), but around $11K to paint and have new vinyl floor (rent $830-$900). How do I go about determining if I should put $16K or $11 into unit B?

I did some calculation below (assuming all four units have the same renovation). (Did I even do it right?) Should I do another calculation with partial renovation and compare the cash on cash return with the return of the full renovation?

Down payment	87,000
renovation	$16,000 x 4 = $64,000
Total Cash down	87000+64000=151000
PITI	$2,284
Monthly Projected Rent	$950 x 4 = $3800
Positive cashflow	3800-2284-120=1396
Cash on cash return	1396x12/151000 = 11.1%