Ever since I installed a Proform 140amp alternator, I cannot put up my power windows without reving the engine. Do you know a better alternator that has better output at idle, or would you recommend I install a bigger pulley to spin the alternator faster to get more power at low rpm?

The new CVR billet aluminum alternators look nice (but only 200amp available), but I havent seen them sold anywhere yet.

thx

mike

Check with Proform to see what they suggest first. We had a similar problem and installed a slightly smaller pulley and it cured the problem. The smaller pulley will spin the alternator faster at idle and allow the alternator to put out more power at lower engine speeds. Hope this helps.

Ever since I installed a Proform 140amp alternator, I cannot put up my power windows without reving the engine. Do you know a better alternator that has better output at idle, or would you recommend I install a bigger pulley to spin the alternator faster to get more power at low rpm?

The new CVR billet aluminum alternators look nice (but only 200amp available), but I havent seen them sold anywhere yet.

thx

mike

Smaller pullies will speed up the alternator as mentioned above. A larger pulley on the alternator will have the effect od slowing down the rotational speed of the alternater.

"Only 200 Amp available" ?????? Emphasis here is on the work only. What are you trying to power with this thing? It is interesting that your list of "stuff" in the car makes no mention of the electrical appliances / pieces that are in this car. It might help to understand what on earth is in the car that would make you say "Only 200 AMPs available"! Honeslty 200 AMP is nearing the outer limits for most cars. I suggest that if you don't have a load equivalent to an entire city wired into the car something in the 130 AMP range should get the job done ...assuming that the wiring is done correctly and everything is working correctly.

Just the other day I was informed by some folks here that there is not even a need for my 130 / 140 AMP alternator. The question on that post was very closely related to your question. The focus of that discussion realted to the available power that can be pulled / supplied by the Alternator at low engine speeds or at idle. Some guys here suggested that running electric fans "off the battery" at fan start up (when amperage load is highest ) and the engine was at low speed or idle up worked "just fine" with alternators supplying less than 100 amps. It always seemed to me that you need an alternator that can supply a fairly HIGH amperage draw at low engine speeds. Sizing the alternator is done by looking at all the possible devices that can be calling on the alternator and building / wiring for the worse case. IMHO if this "worse case" is not planned for things like you are experiencing with your wndows can occur. Headlights dim, power seats don't work etc etc etc. I guessed after reading that post that the problem you are experiencing and the problem I was trying to avoid was just not an issue. Perhaps it is not such a trivail issue when enough devices are wired into a car. Hmmmmmm.

All that said your statement "Only 200 AMPS available" still does leave me saying one word. Yeeeeow!!!!!!!!!!!!!!!!!

Thanks FTG53.. I will looking into the smaller pulley, although I thought a bigger driven pulley would speed it up the way bigger tires increase MPH.

Oman.. you totally misread me. By 'only 200 amp", I mean the only one they have is too big and I heard that can fry old wiring in these old cars if there is too much draw. I prefer an amperage similar to the size I have now. I am running the size alternator recommended by Be Cool for the dual electric fans.

mike

Thanks FTG53.. I will looking into the smaller pulley, although I thought a bigger driven pulley would speed it up the way bigger tires increase MPH.

Oman.. you totally misread me. By 'only 200 amp", I mean the only one they have is too big and I heard that can fry old wiring in these old cars if there is too much draw. I prefer an amperage similar to the size I have now. I am running the size alternator recommended by Be Cool for the dual electric fans.

mike

Mike what size is your wire coming off of the alternator going to the main splice??

Tell us more about how it is wired, the alternator probably can put out enough juice, it just might not be able to get there, if all the wiring is still stock...Just a thought :)

Oman.. you totally misread me. By 'only 200 amp", I mean the only one they have is too big and I heard that can fry old wiring in these old cars if there is too much draw. I prefer an amperage similar to the size I have now. I am running the size alternator recommended by Be Cool for the dual electric fans.

mike

Ok I see. BW the issue of the wire size need to support the large alternatorsis not a big deal. Large that original guage wire from the alternator out to the "distribution" lug on the firewall is reall all that is required.

I am running whatever alternator came with an airconditioned 72 SBC Chevelle. As to electrical load I get 30 amps when my electric fan comes on. I have had no problems with my alt since fan was installed. I am assuming that I have one of GM's 63 amp alternators. Works fine with the origional external regulator.

Many thanks guys. It has the stock wiring from 1973. It is a Proform 1-wire alternator, However, I have it hooked up as a 3-wire. I assume you can also install this Proform alternator as a 3-wire? ..since it has the provisions for doing so, but doesnt mention in the instructions. Do I need to use a different alternator to hook up as a 3-wire? If not, then I am guessing it is a pulley issue.

Some people said that all 1 -wire alternators do not output below a certain rpm, but a tech guy at Powermaster told me that is not quite true. He said that a 1-wire alternator needs to rev above 1500-2500 rpm (depending on the brand) only once after the engine is started and it will output at all rpm, even idle. Once the engine is shut off and the alternator stops spinning, the process had to be repeated. This is not my problem because when I pull into the garage after a drive, I still need to rev the engine to put up my power windows. Therefore, I beleive I need a smaller alternator pulley since my crank pulley is pretty small due to the blower pulley set up. My current alternator pulley is 2.6" and I will try the smaller 2.1". MSD has a great graph showing the pulley: output relationship;

http://www.msdignition.com/1aps.htm

This new billet CVR alternator is quite something. Beautiful. I am having trouble finding a place that sells it, though. I found one unknown site selling it for $660! Nice.. but that is too pricey. It is one-wire but has a self exciting regulator that automatically cuts in so it will work at low rpms.

http://www.cvrproducts.com/powerhouse_billet.html

mike

Therefore, I beleive I need a smaller alternator pulley since my crank pulley is pretty small due to the blower pulley set up. My current alternator pulley is 2.6" and I will try the smaller 2.1". MSD has a great graph showing the pulley: output relationship;


What is the crank to alt pulley ratio? The output of high amp alternators can drop off substantially under 2400 rotor RPMs.

http://www.powermastermotorsports.com/power_pulleys.html