I set my voltage based upon what the scanmaster states so is this volts at ecu or is it measured somewhere else? Reason I ask is that I've never seen a scanmaster show much more than high 13s for volts when hot using a factory style alt and that drops to low 13s with ac and high beams on. Using the powermaster I've never seen less than 14.5 and it's always 14.8 or higher when racing. Not as high as the vb but with over 200 passes on this alt and 40k street miles, I'd say it's getting the job done. Maybe it won't be enough when I start making more power, but I'll probably just go overkill on the pump setup before I try to extend the capabilities of my current pump. I can't help but think that the vb would play havoc with an alky tune. Especially a dual nozzle setup. Can it be done? Sure. But for my streetcar, I simply prefer the voltage to be constant and address the fuel issues, if they even arise, with other methods. To each their own, but clearly there is more than one way to skin a cat.
Volt booster or not?
- Thread starter baby6
- Start date
Are you seeing these numbers on the Scanmaster?
I know. That is a nice feature. Back in the early 70s and earlier,cars had external regulators and you could adjust them. It was a sad day when they changed to internal regulators because your voltage wasn't adjutable any more.
XXQUICK6XX
Well-Known Member
- Joined
- May 24, 2001
I run Caspers on both mine.
- Joined
- Feb 18, 2006
I think it's been proven. The fast guys are running some type of volt boosters.
TurboBuRick said:
A lot of the fast guys are old school too. There are always new ways of doing things. How many people thought 109 blocks would regularly be in the 8s? I'm not a fast guy but again, there is always more than one way to skin a cat. I'm not saying my solution is better but it is another solution.
Then your battery might be seeing 15.8. Can you put a volt meter on the battery while the car is running to see what voltage the generator is putting out? Yes,the Scanmaster number is always lower than the generator.
getdowngranny
Mr. Fix It
- Joined
- Jan 8, 2006
I think this is one of those cases where the 2 sides are arguing the same point. There is more than one way to skin a cat. The way i see it, as long as the proper voltage is making it to the pump to provide the desired fuel pressure that is all that matters. I really dont think it matters which way you go about it as long as your fuel pressure is happy. In my case all i have is a hotwire and big gauge wires everywhere and my fuel pressure is happy at WOT. When the time comes to upgrade, ill go with the volt booster only because im cheap. we4Mateo I agree with you, im sure you are accomplishing the same thing the volt booster does.
- Joined
- Feb 18, 2006
Good point! I would check it.
To get the ecm to read closer to actual alternator output/battery voltage, take all aftermarket accessories off the factory fuse panel. A separate panel can be added for that stuff.
Is this something I would want to do? If the system is happy, I'm inclined to leave it alone. Ignition module and fuel pump are hotwired and if they are happy with 15.8 system volts, then I'm still inclined to leave everything alone. My volt meter is at work so I won't get it checked until I take it to work again, but I'll post it when I do.
I also have quite a few extra grounds all around the car, so I'd think the difference isn't all that much, but we'll see I guess.
- Joined
- Feb 18, 2006
Like mentioned I would check voltage at the battery. When you set it according to the scanmaster chances are your going to have more at the battery. Above 14.8 your overcharging.
Make sure you have the voltage at the battery under control then see what the ecm reports. From there you can make the call whether take load off the fuse panel or not.
RL
11.20n1320
Active Member
- Joined
- Oct 16, 2001
When voltage is high amps is low,when voltage is low amps are high,some food for thought. Amps is the force of current.
No,the problem is the poor factory wiring. By the time the voltage gets to the ECM it is much lower than the output voltage of the generator. One of the areas where you might find a voltage drop is the ignition switch. The only way to tell is to read voltage before and after the switch. The other problem with our cars (as it relates to voltage) is the aluminum wire that GM used. It's a very poor conductor.The way to make sure that the computer sees more voltage is to get rid of the resistance in the wiring. This is what we are doing when we hotwire the ignition and fuel pump. As TurboBuRick mentioned,you don't want to overcharge the battery it will be detrimental to it. 14.5 volts is something that a factory charging system might put out. You won't typically see voltages any higher than this because the battery won't like it for sustained periods of time.
The other thing that happens to a battery that is constantly overcharged is that the electrolyte will boil out of the cells. When a battery is fully charged the electrolyte is in the water you see when you take the tops off and look into the cells. When a battery is fully discharged,the electrolyte moves into the plates. It's the electrolytes (sulfuric acid) that keeps the water in the battery from freezing in the winter. When you see a battery that is frozen,you know that it was first discharged before the temperature dropped below freezing. I tell you this to show you how important it is to not overcharge the battery. I,as I say,the acid is in the water when the battery is fully charged,overcharging and boiling the acid out of the battery requires the replacement of the electrolyte. Re-filling with water doesn't replace the lost acid.The more times you refill with water,the more you dilute the mixture and more and more the performance of the battery suffers and the less tolerant to cold temperatures the battery is. Again it is critically important to not overcharge the battery.
In conclusion,I like to keep the generator output at 14.5 volts. This will be the same voltage that a hotwired pump will see. Buying a volt booster is not something a cheap person does. It's something a wise/informed person does. It gives you the extra voltage you need only when you need it. It's a wonderful plus that it happens to be inexpensive. Again, nothing takes the place of a volt booster.
To answer an earlier question of yours about weather or not it's just as important to have a lot of voltage at an idle as it is at WOT,the answer is no. As the combustion chamber pressure rises,it becomes more and more difficult for the spark to jump the gap of the spark plug. This is why we gap our plugs tighter when we run a lot of boost. The only other thing that we can do to help the spark jump the gap is to create more spark energy. If we supply more voltage to the primary side of an ignition coil,it developes more voltage on the secondary or output side.
When you are able to read voltage at the battery with a volt meter,set it to 14.5-14.8 volts. No higher.
Why? Short of shortening the life of a battery, what ill effects does the extra voltage cause to the system itself if sustained? I still don't know where mine is but it's been like this on the car for 40k miles now and I never had coil packs and modules last as long as I have since upgrading my alt and setting it up the way it is currently. I have a TR-6 now and it seems happy too. 30psi with a lean cruise friendly .040 gap and no issues at boost. The last stock module and coil pack are now my backup but they both had 30k miles and over 100 passes on them.
I'm starting to come around to the vb, but can it be hooked up ONLY to the fuel pump so the alky pump doesn't get the voltage spike?
TIA.
we4Mateo said:
There is such an animal called a kenne bell boost-a-pump. The last one i saw was on a mustang site. It only boosts voltage to the fuel pump. I think msd makes one too. I don't remember pricing, but i do remember thinking the msd unit was expensive. Google search should pull it up pretty quick.
Whenever I troubleshoot wiring, I will always use a voltmeter set on zero-to-two volts DC. With this, you run the engine, and put your probes between the battery negative and engine block. Look for voltage; this means losses. Also, check between the engine block and the firewall. Then again between the battery negative and the firewall.
Follow this same procedure to check between the battery positive and the coil positive feed, wastegate positive feed, injector feed and mass airflow feed (and any pink/black wire under the hood - voltage drops at these points are an indication of bad wires or terminals in connectors and possibly high resistance in the ignition switch). Also, check for voltage loss between the battery positive feed and the starter stud, and alternator stud. That's an easy way to find a bad battery cable, BTW. Any more than half a volt and you can isolate the problem that you're guaranteed to have. I've found bad ignition switches and bad connections at the C100 bulkhead as a result of this testing.
A voltmeter is your best friend in finding voltage drops.
Follow this same procedure to check between the battery positive and the coil positive feed, wastegate positive feed, injector feed and mass airflow feed (and any pink/black wire under the hood - voltage drops at these points are an indication of bad wires or terminals in connectors and possibly high resistance in the ignition switch). Also, check for voltage loss between the battery positive feed and the starter stud, and alternator stud. That's an easy way to find a bad battery cable, BTW. Any more than half a volt and you can isolate the problem that you're guaranteed to have. I've found bad ignition switches and bad connections at the C100 bulkhead as a result of this testing.
A voltmeter is your best friend in finding voltage drops.
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