16 Volt Setup

[turbodragster]

i feel a 16 v setup works extremmly well in race applications. but i do understand things will have a tendancy to burn out quicker ( lights, possibly fan motors , etc....) . just be aware that there might be issues that you need to adress . as far as racing 16 v i can make three or four pass before i even notice the cars starter slowing. i still charge between rounds. so my advice is with a race car, i think 16 volts is a must but with a street car its all up to you. both sytems have there pluses and minuses. just got to decide whats best for you and what your trying to do.

[DonWG]

Does amperage go up or down when switching from a 12V system to 16V?

Do the lights get brighter or dimmer with 16V? Is more or less heat generated from a light bulb on 16V? If the answer is brighter and more heat, then you're telling me that particular electrical circuit is creating more heat due to higher amperage flow. A light bulb circuit is a very simple and basic electrical circuit. You have power (battery), wires, switch and load (the light bulb). Every electrical circuit has a load. The load is in the form of resistance to electron flow. Amperage, which is actually electron flow through a circuit, creates heat. The higher the flow, the higher the heat. That's why circuits that are expected to flow high amps are a larger wire. A high voltage wire can actually be small if the load resistance is high causing a low amperage draw through the circuit.

[DonWG]

I'm not trying to talk anyone out of running 16V. My concern is that so many people don't understand the possible problems with doing so. As turbodragster wrote, there are pros and cons to both systems. Be aware.

I, for one, can't afford to send my ECM back to the manufacturer to have them tell me it's fried due to too much voltage. So far my ignition has been adequate and as long as my battery is in tip, top shape, I have no starting problem. Although I'm sure it could be so much better on 16V.

[Bent6]

The only difference between a 12v and 16v battery is the number of cells. A 12v uses 6 cells vs 8 cells in a 16v. A fully charged cell is around 2.1v - x 6 = 12.6v for a fully charged 12v battery and x 8 = 16.8v for a fully charged 16v battery. Somewhere around 1.8 volts per cell is considered fully discharged so you can see that a fully discharged 16v battery will still put out 14.4v - still more than a fully charged 12v. There is a limit to this as amperage draw, etc comes into play but you get the idea.

The reason an alternator putting out 16volt is considered bad on a 12v battery is that the plates will become corroded and it will also cause excess gassing which causes the cells to loose electrolytes. In simple terms, the battery will wear out prematurely or possibly explode. AGM type batteries require higher currents to fully charge and are more tolerable to higher charging alternators.

It is recommended to upgrade all wiring to a minimum of 16ga when making the switch. I don't see any reason to run a 16v system on a street car unless you are into car audio. I would never go back to a 12v system on my race car. FWIW

[ijames]

Don, you and Bent6 are both right. If you keep the resistance constant and increase the voltage you will increase the current flow (amps) and increase the power dissipated (watts). If a component is not rated for the higher voltage and power dissipation it may self-destruct. That's the situation if you put a 16 V battery into a car with a 12 V system. If you keep the power (watts) constant and increase the voltage then the amps will decrease, which lets you use smaller wires and increases efficiency. To do that you have to completely redesign whatever you are powering so that it has higher internal resistance so at the higher voltage the amps will be less and the power the same - that's what is done in motors and appliances that run on 220 V instead of 110 V, and if you just plug a 110 V appliance into a 220 V outlet you are virtually guaranteed to see smoke. On a car, just as we can push the hp of a stock block up some because it was engineered with a safety margin of strength, car electronics are also engineered with a safety margin on the input voltage. They have to be because alternators and batteries are notorious for voltage spikes and noise. What that margin really is only the manufacturer can say, but the empirical evidence is that the ecms and radios can take 16-19 V. Don't at least some of the aftermarket ecm manufacturers even advertise the input voltage range (I think FAST does but I'm too lazy to go look)? Light bulbs are close to constant resistance and so at the higher voltage will draw more current, dissipate more watts, burn brighter, and burn out sooner. That 12 V alternator putting out 16 V and described as overcharging is only overcharging because it is connected to a 12 V battery. It would be undercharging if connected to a 16 V battery :-). Lead acid batteries need about 2.3-2.35 V per cell to reach full charge, which is why alternators for 12 V batteries put out 6 x 2.3=13.8 V (in the old days; several years ago they changed the internal battery chemistry slightly and now the target is more like 14.2 V), and an alternator for a 16 V battery would put out 18.6-18.8 V.

[DonWG]

Thank you for coming to the rescue ijames. The last two posts by ijames and Bent6 are factually correct. Very well put by both. I was becoming afraid I was the only one that understood electricity.

Understand the risk involved when switching to 16V.

[BlownV6]

Donnie, Stick with transmissions!! Electric still isnt your thing!! MIke

[DonWG]

Originally Posted by BlownV6

Donnie, Stick with transmissions!! Electric still isnt your thing!! MIke

Yeah, I have to admit I didn't explain it as well as ijames, but I hope you now 'see the light' after ijames' explanation. The key to understanding is resistance, resistance, resistance. Read his post again.

The loads (resistance values) in an automotive 12V system are constant. The resistance values don't change, but very little because of heat buildup or with temperature sending units, potentiometers (TPS), etc. Pick a solenoid and measure the resistance value (ohms). Even simpler, take a long length of 16 gauge wire and measure the resistance with a simple volt/ohm meter. Now take the equations I posted earlier and plug in your resistance and voltage values. You will see the amperage value increase with more voltage. Mike, please just do it. Transmissions have electrical switches, solenoids and force motors. There are probably more electrical problems than mechanical with transmissions these days. I have to deal with electrical issues with cars on a daily basis. I don't teach the subject, but I do understand it. And anyone considering changing the voltage rating of their auto should too.

Another thing to ponder. If the fuel map has been tuned with 12V and you switch to 16V and the electronic injectors see this 16V, you may have to play with the voltage compensation value of your ECM to get your fueling back on track or adjust your fuel map. Fuel injectors will deliver slightly different volumes at different voltages (quicker turn on times). If your ECM is built in such a manner that it will supply a flat 12V to your injectors no matter what the main circuit voltage, then you don't have to worry about that. I haven't heard of a system that does that though.

[Bent6]

If you switch from a 12v system to a 16v system you WILL have to adjust your VE tables and sometimes the spark map as well. The 16v system will increase the fuel pump speed, increase injector response and give a hotter spark. Some folks increase plug gap to compensate for the spark. Again, IMO the 16v setup is THE way to go with a race only car.

[DonWG]

Thanks for confirming that Bent6. Be careful about increasing plug gap. In a high boost, high cylinder pressure, along with a hotter secondary current situation, the larger spark plug gap would raise your ignition secondary circuit kv level to a point that 1) wears on the secondary circuit components (mainly wires), 2) causes voltage leaking and crossfiring (again, the wires). 40kv is a good upper limit in most cases.

[turbopaul]

I guess nobody read my post I repeat, you do not get anything more out of the stock ignition except for being able to rev higher before the ignition starts to fall off. The stock ignition is current limited to 6.5 amps. No amount of higher voltage is gonna change that 6.5 amps. The output transistor is in a current feedback loop which is why you can't get more than 6.5 amps. The higher voltage allows for quicker charge, hence the higher rpm before ignition dropoff.

[DonWG]

Originally Posted by turbopaul

I guess nobody read my post I repeat, you do not get anything more out of the stock ignition except for being able to rev higher before the ignition starts to fall off. The stock ignition is current limited to 6.5 amps. No amount of higher voltage is gonna change that 6.5 amps. The output transistor is in a current feedback loop which is why you can't get more than 6.5 amps. The higher voltage allows for quicker charge, hence the higher rpm before ignition dropoff.

Is that true for aftermarket ignition systems too?

[turbopaul]

Most aftermarket ignitions are cd ignitions. I only have experience with an MSD 7 and that was many many years ago, and I don't remember if it has output regulation. If you go by the specs provided by MSD, it implies output regulation.
I'm sure most people are still running the stock ignition system, and whether you run a volt booster or change to a 16 volt system, the stock system will not give you more output with higher voltage....only more heat and higher rpm capability.

Without going over each and every response again, the main point about higher voltage has been missed. When you raise voltage in a DC circuit, current increases, but the good news, or bad news, is the power. Power = E squared/ r. It's that squared term that can be a killer to the load. It's the power, not the current that makes magic smoke. I've only touched on this subject a little bit, so maybe we should have a discussion about every system on the car and exactly what happens?? The other power killer is Power = I squared R.
This has to do with AC power transmission lines and why really high voltage is better than low voltage and why you have less current with higher voltage. And please don't mix AC circuits with DC circuits. There are some similarities between the two and also some dissimilarities.

HTH

[DonWG]

Dang AC. Forgot about that. Good thing I don't work on houses.

I was wondering about the MSD units. We've all witnessed the reliability issues with MSD boxes. I personally don't use one, but I see other racers at the track dealing with them. Does going to 16V with an MSD box make it more of a problem?

[turbopaul]

You have to ask MSD or look at the spec. I wouldn't think that 16 volts would be a problem, but you never know.

[Bent6]

No problems with MSDs and 16v. I just made the switch to an MSD 7AL2 and distributor from the stock DIS system. I do know the 7AL2 makes a stronger spark with 16v.

[John Wilde]

Originally Posted by Bent6

No problems with MSDs and 16v. I just made the switch to an MSD 7AL2 and distributor from the stock DIS system. I do know the 7AL2 makes a stronger spark with 16v.

Will, that is great news.
Good luck this week!

[Bent6]

Originally Posted by John Wilde

Will, that is great news.
Good luck this week!

Thanks John. Hoping the switch to the 7AL2 with distributor will solve many of my past gremlins along with a little extra HP to boot. New heads + XFI + good ignition should = FAST car......at least that's what I hope. PLUS it has a 16v electrical system!

[DonWG]

I'm seeing this more and more. Why are people having to switch to a distributor? Are most of the same people using the XFI system?