capn

Hey all

i work at a rebuild shop for alternators and starters and i was noticing how low our charging systems put out. i know we can make the FC alternators put out more, and i was thinkings if we could we could sell them on here is anyone interested? it may be a cheaper alternative to buying an FD one so lemme know

ilike2eatricers

Depends on price and how much of an improvement it is. Also would there be a core charge?

E6KT2

silverrotor has it covered. Sorry.

BlueSteel

what would the amperage be?

sunshine

iTrader: (3)

I would be interested.
-a

91mazdarx7

it all depends on the amps it would put out

capn

well as with our dinky little mitsubishi alternators you cant really boost them up. BUT, since they only use L, R terminals you can use my favorite little delco 10SI the amps on those things are towards the sky. as long as i can get it to mount correctly i can have amperage anywhere from 30amps to 240amps and i'll make it up tommorow and see what the price will be on the things. and if you can get me a core of what i need then no core charge just charge for parts. but if you dont hav eone then yes corw charge. and hopefully i can make it more affordable then the FD alternative.

PS whats the going price on those around here?

Enthu

iTrader: (1)

Silver rotor does already have it covered with the FD alts. The 240 amps is higher, but the FD alts he has test around 130, which is plenty for almost all apllications. For someone with a load of stereo equipment, you could help out with that.

bingoboy

i talked to an Alt rebuilding/fixing/rewrapping place locally and they told me there wasn't much they could do with the FC alt to get more juice out of it. although i don't know if he didn't want to help or actually couldn't. the guy seemed like kind of an ***.

91mazdarx7

i think the price is around 150 for the fd alt if you can get it so it puts out 240 amps i may be interested i am about to have alot of stereo equipment

RETed

First, more amperage means more noise.
Be careful those of you running big audio systems.

Second, I've been told the stock FC Mitsubishi alternator case cannot be rewound very easily.
Are we talking about a rewound stock unit or a retrofit larger case?

Third, I got a source that quoted me they can do rewinds for $130 for a 120 ampere unit.
Can you beat that price?

Are you talking about using the original spec shaft and case?
A lot of us run special double pulleys, and it would help tremondously to use the same size shaft.

I'd like to have the voltage level set at 14.5VDC.
Nothing more...nothing less.

Warranty?



-Ted

Kenteth

200 amp 3wire aftermarkets cost about $250... Thats twice the stock s5 output. Take the time and engineer the brackets, wiring, and belting for it, and you've got yourself a charging system capable of whatever you need, plus some.

BTW, a 200 alternator WILL chew about 2-3hp off the crank. Its about 70amps per hp in a 100% efficiancy state. I say 2-3hp, because theres no way a rotary crank is 100% efficient (duh).

WonkoTheSane

iTrader: (2)

Just to make sure you're aware of the competition: I just recieved my SilverRotor FD Alternator a few weeks ago (haven't had a chance to put it in). he says it should be good for at minimum 115 (most likely somewhere in the 130 range), came with a double pulley already, and it's a brand new FD alt, not a rebuilt or rewound anything. It cost me $185 shipped here to the states (SilverRotor lives in Canadia). I'm very happy with it

SonicRaT

iTrader: (6)

Used they're about $80-100

Aaron Cake

iTrader: (1)

It will only use this amount of power IF it is being asked to produce it's full 200A. At, say, 50A, it shouldn't take much more then the stock alternator.

capn

well yes the stock mits alternator on the FC cant be bumped up thats why we can just wire up a delco 10si instead they are much more interchangable and have many more amperages.

and on monday when and if i get some time i will make up a delco 10SI 200amp alternator that will bolt to a stock FC. so no rewounds for the mits alternator, just a better replacement and then probably sell to anyone that wants a beefed up FC alternative.

RETed

Is this a true saddle mount like the stock RX-7 alternators?
Or are these GM cases you're trying to retrofit onto the 13B?


-Ted

capn

they are true saddle type, they may need a spacer or something for proper fitment but that would be it, and the stock wiring harness would work too

Kenteth

But only if wired 3 wire config? One wire config would make it depenandant on rpm?

drago86

no, the alternator automatically adjusts its output to the load by changing the amount of power going to the field coils, no matter how many wires it has.

Kenteth

I thought one wire was depandant on the batter post voltage and rpm.

I throught the only time a 3rd voltage was used (opprotating circuit voltage) would be with a 3 wire that has input for the remote circuit voltage

drago86

?


alternators have voltage regulators. These keep the voltage comming out of the alternator at a set amount (usually ~14 volts) by varrying the amout of power sent to the field coils on the alternators rotor. When an electrical load is placed on the system the voltage starts to drop as the demand surpasses the amout of amps the alternator is currently producing, the voltage regulator see's this and lets more power to the field coils thus producing more amps to to satisfy the demand , thus bringing the voltage back up to spec making the voltage regulator happy.

The only difference between 3 wire and one wire alternators afaik is that the 3 wire remotly senses the voltage for the voltage regulator,.. like far down stream in the wire harness so you get a more accurate voltage with accessories like lights and such on,.. the one wire can only sense the voltage comming directly out of the alternator and thus doesnt do as good of a job at keeping the voltage constant in the entire system.


just wanted to add that in a one wire alternator the voltage regulator is also internally powered insted of externally.

Aaron Cake

iTrader: (1)

An alternator is a generator. The mechanical drag on it's shaft will be directly proportional to the amount of power that it is being asked to produce.

Copied and pasted from another page because I'm too lazy to explain it myself:

System Draw:

This is probably the single biggest determining factor. An alternator changes mechanical energy, i.e. horse power and torque, into electrical energy, watts (which is amps x volts). Your alternator only produces the amount of energy required by your vehicles electrical system.
So as you increase the load of your (turn on more electrical devices), you also increase the amount of HP to create the electrical energy to handle the increased load.
An example of this is: You have an alternator that is capable of 200amps of output at 14.7 volts, and a pulley ratio of 2 to 1. At 25 amps of out put this alternator will require 1.97hp to turn it. Using the same alternator with a 100amp load and it will require 7.89hp to turn it. Double the load to 200amps and you have to double the HP requirements as well, making it 15.77hp.

Pulley Ratio:

This the next biggest factor and the only variable that can be easily modified. Your alternator usually has a smaller pulley than your crank pulley. This allows the alternator to spin faster than the actual engine rpm. This is necessary because alternators have charge curves that usually start somewhere between 1200 and 1800 alternator rotor rpm. Then the faster you spin them the more amperage they produce.
Since the alternators pulley is smaller, the crank pulley has to work harder to turn it. This causes the hp requirement to turn the alternator to increase in direct proportion to the difference in the size of the pulleys.
To determine your pulley ratio simply divide your crank pulleys diameter by your alternators pulley diameter. Typically this will be around 3 to 1 in a stock application.
So if you have an alternator that requires 3hp to turn it at a 1 to 1 ratio, it still only requires 3hp. But if you change the pulley ratio to 2 to 1, it would then be using 6hp. Increase it again to 3 to 1, and the requirement becomes 9hp.
It is easy to see that keeping the pulley ratio as small as possible is very desirable from a hp savings point of view. But, and that is a big but, it is more important to make sure that you do not put to small of a ratio into your system. For if the alternator is not spinning fast enough at idle, it will not have enough watts (amps x volts) to carry your system load. When this happens your voltage drops and then your system does not work efficiently.
The bottom line of this happening is ignition spark starts to drop off in power, which reduces your motors HP. So the 2-3 HP you say by going too small with a pulley ratio is thrown way out the window when you cause your motor to lose 10-50+ HP from lack of spark. Also when you run everything at a lower than optimum voltage it cause extra heat in the device, extra heat causes damage and premature failure.To read more on pulley ratio’s please read the article “Pulley ratio” You can also read more on the subject of system voltage in the articl titled “System Voltage”

Alternator Efficiency:

As we mention earlier, alternators change mechanical energy into electrical energy. Surprisingly they are not very efficient at doing this. Each style of alternator is slightly different in its efficiency rating, typically varying from 45-55% efficiency. This means that for every watt of mechanical power you put into the alternator, you will only get between .45 and .55 watts of DC electricity out of it. The only exception to this rule is with the new Ecoair units, which are 73% efficient. We suggest reading the article “What Does 5% mean”.What Does 5% Mean
Where does the other 45 to 55% of the input power go? Glad you asked, it becomes watts of heat. That could actually be written as lots of heat. A typical alternator charging at 100amps output, is also producing close to 1500watts of heat. That is enough heat to heat a 10 x 12 room in the middle of winter.
The older style of alternators, i.e. 70’s thru the mid 80’s, are typically around 50% efficient. While the newer units with avalanche diodes and such are slightly better at 55%.
What does this really mean? An example would be comparing a 50% efficient alternator to a 55% efficient alternator. Both producing 100amps with a 2 to 1 pulley ratio. The 50% efficient alternator would require 7.89HP, while the 55% unit would require 7.17HP. Not really enough to justify the change in units on its own, but the other added advantages of the higher efficiency units do add up to make for a wise upgrade. The Ecoair unit in the same application would only require 5.33HP



Here is the actual formula:

1.) Amperage output x voltage output = watts output
i.e. 100amps output at 14.7 volts = 1470watts

2.) Watt output x efficiency = watts input required
for 50% divide by .5, for 55% divide by .55, for 73% divide by .73

3.) Watts input divided by 745.7 = HP requirement

4.) HP requirement x Pulley Ratio = Actual HP used in vehicle

http://www.svapowerproducts.com/html...lternator.html

Kenteth

meh, yeah.

drago86

the only thing I dis agree with is that an alternator is NOT a generator.