Can it be done, and if so, how do you do it? Thinking of running a 16v battery on my car for better starts, how does this work with an alternator? Do I need a 16v alternator?

Yes you would need a 16V alternator, so you need to make sure your lights and accessories can run at 18V or so while the car is running.

I would be more concerned with why your car may not start well on a 12V system.

Remember you can't buy a 16V battery anywhere for the most part, so if you have a problem on the road your stuck. I work for a battery distributorship and we occasionally get the call of a panicked racer looking for a 16V battery ASAP. 16V is special race car crap, that is not a battery used in any other industry that I am aware of. The panicked racer usually doesn't like the option of running 2 65lb 8 volt golf cart batteries run in series lol.

Point well taken.

That is why I do not understand why the old relay setup with two 12v batteries that sent 24v to the starter and 12v to the rest of the car is not more popular. My 605 can be a beast to turn over, and not a lot of room for a high torque starter.

Just a few minutes ago on Facebook there was a Rocky Mountain Race week participant looking for a 16v alternator on the road. That is a tough one to find, hopefully another racer has one for him.

Trust me having used a 16 volt battery years ago when I was out of town I always worried about it going bad. My 12 volt did exactly that this year and my buddy ran me into town to Advance Auto to buy another 12 volt battery. With that said my friend that does run a 16 volt battery had his alternator switched to 16 volt at a local alternator shop.

All I have ever ran is 16 volt. Voltage is power period. I would never switch back to a 12 volt system. With many of the modern electronics being used 12 volts is antiquated to keep up with them. Fuel pumps/fans/nos/ignition boxes/coils/switches list goes on.

I had my car completely rewired by a professional 4 years ago. Might be the best investment I have ever made in a car.
Guy who did the work told me with all new wiring and good grounds, properly sized battery cable to the back, etc, etc, etc.. I would be pleased.
Other than for a while popping alternator belts off which several times killed the battery( problem solved by new alternator bracketry), I haven’t had a charger within 100 yards of the car. Starts like it’s 16 volts, run fan and water pump between rounds, zero issues.
Most all the stuff mentioned above, hi amp electric fans, electric water pumps, fuel pumps, msd boxes, etc, have been around since the ice age. Mine is 12.5 compression.
To me, having had issues pre getting rewired, I would look at wiring first. If it’s golden, the chance of any issues with a 12 volt system are remote, in my opinion. 16 volt can well be a band aid masking a deeper issue( poor wiring)

I have done this on my Turbo Buick. GM alternators are easy to modify for 16 volt systems. It will actually need to charge at about 19.5 volts(about 2.45 volts per cell). The major benefits are hotter ignition, and more importantly electric fuel pump output goes up dramatically. On a high HP fuel injected car its far more beneficial since fuel pump output at high pressures are hard to achieve under high boosted applications. I used a Rock racing battery that had a 3rd 12v lug for some stuff I didn't want on the 16 volt side.

AG

Google: "what is a transformer?"

16V systems are great, until your battery or alternator craps out and you're in a pinch. I would not consider a 16V system for a car I was planning on taking on drag week.

I did back to back tests in my Daytona years ago and saw zero performance gain. And my cars start fine on 12 volts so why bother. I may stick a charger on my duster once a month.

That is exactly right. I have ran 16 volts on all my stuff for 30 years and would never go back to 12 volts. If your a nitrous guy or blown/EFI it is leaps and bounds better then 12 volts. Voltage is power. On a pure stock deal with some mods ok 12 volts but do a test on the draw down of voltage and you will be surprised.

I take it you have a battery in the trunk? Are you looking for better starting when the engine has heated up and the starter gets a little heat-soaked? Are you running a single 12V battery?

I almost went 16V (on the street) many advised against it. I wired it up for 12V and just run one small lightweight Braille Racing battery. It does just fine running my dual electric fans and giant Aeromotive 3000 fuel pump, Racepak etc on the street.

in my experience over the 55+ years playing with this stuff, most electrical issues crop up with poor grounds, undersize cable/wire gauge, poor connections caused by bad crimps or dirty terminals, and old internally corroded wire ["green death"].
just my personal experience. your mileage will vary.