Just found out that Bosch is offering high output alternators, up to 200amp. I don't know if they are offering them for our cars yet though. They are new not reman and have lightweight aluminum pulleys and are straight bolt on with no bracketry
altercations. Tested up to 14,000 rpm, rx7doctor

 

This is a completely contradictory statement....how the Hell can they be "a straight bolt on" if they're not even offered for our cars yet?? How about we wait until some hard info is out there before posting??

 

wouldn't a 200 amp alternator rob the car of some serious power? I don't see a purpose for running that powerful of an amp unless you got a like a 10, 000 watt stereo

 

My thoughts exactly. I have an 85 amp alternator and it handles all my needs. Don't won't any more than what I need in the alternator catagory, thank-you-very-much.

Doc ? Where did you go to school ?

 

Well, since alts only put out what is needed, a 200 amp alt will not draw any more power from the engine as your stock alt does during normal operation. The only thing is that it would have more capacity. It would place a larger load on the engine only if and when it is needed.

I do think that 200 amp is overkill, though. I think an S5 (80 amp) or a 3rd gen alt (100 amp) is more than most of us will ever need. If you did draw enough current to max out a 200 amp alt, the power needed to turn the alt would be around 4.5 horsepower. I am sure this would cause major belt slippage with our single v-belts. I bet these alts would not come in a single v-belt configuration because of the belt slippage. They would most likely come as a serpentine or dual v-belt as a minimum. I remember reading that a 0.5" v-belt can support something like 100 amp alt and dual v-belts will get you in the 150 amp or so range. You really need a serpentine belt on these larger alts. I believe that a serpetine belt will support up to a 300 amp alt.

 

just use an s4 alternator.....

 

It's more power. You don't ever NEED a 200+hp ported motor so why would you ever 'waste' your money on one!! Jeeeez....

One upside to a stronger alternator is that your battery is damn well going to be charged up even after the shortest of trips.

 

Thats interesting i always thought an alternator required the same amount of force to turn rather than it being harder to turn on a hard load.

 

Nope, He's right. The more current you draw, the more resistence to turning at the alternator. A higher amp alt will not be much harder to turn with a low load on it.

 

Yea, basically what happens is the regulator determines if the alt needs to output more power or less. It then feeds back current through the coils in the alt which creates the magnetic field. The more current through the coils, the higher the magnetic fiels, the harder it is to turn the alt (but more power is output). Here is a pretty good link that explains how alternators work.

http://www.vtr.org/maintain/alternator-overview.html

I read that the RX-8 will cut the A/C compressor as well as the magnetic field to the alt for short periods under hard acceleration in order to free up that extra bit of power.

 

The reason i posted is for the guys that run heavy stereo amps, i am checking into the application for our vehicles. The info that i came across is stating that their are
no mods needed for mounting them for the applications that they will be supplying.
And they stated up to 200amps. The benefit for a alternator that can put out more
is that for people that do short hops in their vehicles where they are getting in and out and stopping then restarting or say for worn out starters that start to draw too much amperage. the stock rated alternator is only there to supply enough amps to maintain the system. if you start taking more out of the system than it's capable of putting in then the battery life is shortened. A alternator is not designed to charge the battery up from discharge but to maintain that system under normal loads. If the alternator has to constantly put out max load for too long of a period due to failing components then it willl also fail. Just like any upgraded product their are people who want and need them. Not everyone wants
a 500hp motor but thier are alot that do and want the product that will help them achieve that goal. I have no use for a 200amp alternator, but i did not post this for
myself, just info that some rx members may be interested in. rx7doctor

 

What year model does the s4 and s5 alt come from? I am somewhat electronically challenged but am determined to update my 79. the 55 amp just isnt taking care of business. I got some excellent infor from the faq, (excellent work mar3, thanks) but his example did not include info onhow to switch a 79 which is still running external regulator. can anyone help.

 

Seems kinda complex... Too many failure points. Why not just use a permanent magnet generator? DC already, so no rectifiers... No regulator... And one set of coils to worry about...

 

S4 and S5 refer to the years of the cars, not the type of alt.

SA=1979-1980=S1
FB=1981-1983=S2
FB=1984-1985=S3
FC=1986-1988=S4
FC=1989-1991=S5
FD=1993-1995=S6(I believe)

Jon

 

Ok. My mind is changed. Next alternator will be more than I need.

 

The flip side to 140+ amp alternators is that one often finds that their charging amperes at idle to 1500 rpm is often LESS than the stock alternator...before anyone asks more questions not involving this new Bosch alternator...


The "Economical" Alternator Upgrade Thread...and by economical, I mean $50....

 

Any idea of how much this new bosch alternator is going to cost? It might be a cool thing to have if it doesn't make my motor struggle more then it has too.

 

A bit off topic, but....


My high school Physics teacher would smack anyone who actually used the word "amperage" SOOOO hard upside the head (well, not really, but he'd verbally slap you)...

The correct term is CURRENT...
And for the record, the "proper" term for Voltage is Potential Difference....

See? Who says I didn't learn anything in high school...

 

Well on that track, alot of people believe that when they have ample voltage/potential difference that their alternator is operating properly. When in fact
you can have ample voltage/potential difference and have low amperage/current
output. Current/amperage is what maintains your system. current/amperage is described as pressure. Now you got me started on correct nomenclature everytime
i post,lol.
rx7doctor

 

I was looking at a high output alt as well.

Reason: Eventually, when i get my project(dream) car done, its going to have, 400X4 amp, 400X2 amp, 500watt power inverter to a UPS running a PC and 7" flat panel touch screen.. ect... Have everything sound/video running though the PC. Granted i still think a 200 amp alt would be over kill, but an S5 alt has trouble keeping up.

 

My car stereo/PC goes in in march... I'm going a step further and the PC will be a complete stereo/CD/DVD/Navigation system...

 

I find it funny, I remove extra, non-essential parts from my car...

some of you put extra "****" in.

 

Get a 13B. They can tote more "****". Get it ported and then it will tote more "****" even faster.

 

That's what I did...

We have 2 '85 RX-7s.

One is an S which we're gonna strip down to be a racer.

The other is a GSL-SE which is my daily driver and I want to be a bit more of a cruiser... Still a good performer, but more comfortable and with a backseat for my daghter....

 

400x4 + 400x2 + 500x1 = 4500w

4500w / 13.8volts = 326 amps!

I assume you mean 100x4 and 200x2 and 500x1 which would require 94.2 amps of current to run at 13.8volts.

One of my GSL-SE's is a dBDrag competition car. I have a dual alternator setup with a stock 55 amp (dual belt pulley) alternator running the cars accessories. Also an additional Ohio Generator 210 amp alternator charges an isolated battery bank which provides power for the amplifiers. The alternator is mounted on custom brackets located where the A/C pump used to be, with a dual V-groove pulley.

It is very hard to find a dual foot alternator that will fit in the stock location, the selection is very limited.

When selecting a high output alternator look for an output vs rpm graph, you want an alternator that will put out as much output at idle as possible.

I suggest for those with stereo systems, or high current demanding accessories to upgrade the 'big three' connections, consisting of; alternator output to battery (+). Battery (-) to chassis ground. and Chassis ground to starter retaining bolt.
Upgrading these connections will reduce voltage drop and should provide less resistance for high current demands. Upgrading these connections may even prevent or stop light dimming!

P.S.
If you want an alternator with high low end output go with a CS-144

There is no such thing as overkill!