Ok so I have my 3G conversion complete. It came out quite nice. I used a 3G from a 94 Mustang 5.0. I have checked the forums about pulley size as well as did some research on-line. I thought that the 3G pulley would be too big at 2.375 inches (2 3/8), so I plugged some numbers into PA Performance's pulley RPM calculator and came up with the following.
3G Pulley
Crank Pulley size 6 inches divided by 2.375 inches = 2.52
Max Engine Speed (Redline) 5800 RPM
5800 RPM X 2.52 = 14616 Alt Shaft RPM at Max Engine RPM
Seems to be within limits set forth in this calculator.
Idle RPM I believe to be somewhere between 800 and 900 RPM in my Manual SSP Coupe.
Idle RPM (800) x Ratio (2.52) = 2016 Alt Shaft RPM at Idle
Idle RPM (900) x Ratio (2.52) = 2268 Alt Shaft RPM at Idle
So it seems to me that if this calculator and my figures are correct that the alt should be putting out the required volts at idle. I ran the same numbers with my stock alt pulley size (1 3/4 inches) and it seems that I would be blowing up the alt if I run to redline, somewhere close to 20000 alt shaft RPM at redline. The crank pulley that I measured was an extra I had lying around from an 89 5.0 automatic Mustang, so I would assume that I have the same size crank pulley on my 92 5.0 5 speed. This is the only reason that I could think of that these estimates would not be correct.
Just wondering if this seems correct to everyone. Maybe it will also help someone else out if they are trying to figure out why their alt is not charging enough at idle. The only thing I will have to change if this is correct is the belt length by about 1/2 inch.
Also I have a 150 AMP wafer style fuse (see photo link mine is 150 AMP) for the alt, do you think this is too high. I have the 4 gauge power and ground wires with everything soldered and heat shinked. I did not connect the stock power wires at all. I will get some pics attached to this to let everyone see as well. Thanks in advance.
3G Pulley
Crank Pulley size 6 inches divided by 2.375 inches = 2.52
Max Engine Speed (Redline) 5800 RPM
5800 RPM X 2.52 = 14616 Alt Shaft RPM at Max Engine RPM
Seems to be within limits set forth in this calculator.
Idle RPM I believe to be somewhere between 800 and 900 RPM in my Manual SSP Coupe.
Idle RPM (800) x Ratio (2.52) = 2016 Alt Shaft RPM at Idle
Idle RPM (900) x Ratio (2.52) = 2268 Alt Shaft RPM at Idle
So it seems to me that if this calculator and my figures are correct that the alt should be putting out the required volts at idle. I ran the same numbers with my stock alt pulley size (1 3/4 inches) and it seems that I would be blowing up the alt if I run to redline, somewhere close to 20000 alt shaft RPM at redline. The crank pulley that I measured was an extra I had lying around from an 89 5.0 automatic Mustang, so I would assume that I have the same size crank pulley on my 92 5.0 5 speed. This is the only reason that I could think of that these estimates would not be correct.
Just wondering if this seems correct to everyone. Maybe it will also help someone else out if they are trying to figure out why their alt is not charging enough at idle. The only thing I will have to change if this is correct is the belt length by about 1/2 inch.
Also I have a 150 AMP wafer style fuse (see photo link mine is 150 AMP) for the alt, do you think this is too high. I have the 4 gauge power and ground wires with everything soldered and heat shinked. I did not connect the stock power wires at all. I will get some pics attached to this to let everyone see as well. Thanks in advance.