My alternator was DOA so I figured I would upgrade it while replacing it and I found a rebuilt 140A one on eBay for $85 with no core charge so I gave it a shot. The Roadfly DIY article does not mention one thing that would've probably been a deal killer for me had I known about it up front: airbox interference. I'm not sure how they didn't run into this (MAF conversion, maybe?) but this was a head scratcher for me. I decided to cut the airbox for now which provides great cooling for the alternator but also gives me a sweet Warm Air Intake :oops: I'll either build a plate to seal this off or change the intake entirely. Without cutting the box I was able to sandwich it between the hood and the alternator but the boot alignment sucked and this just seems like a bad idea so out came the sawzall. 
Otherwise, it was fairly straightforward. As mentioned in that article you need a longer lower bolt (I used a 5/16" 5" long bolt) which is almost identical in diameter to the original M8 bolt. What's not mentioned in that article is that the lower forward mounting ear does not protrude as much as the original 90A alternator so you need to space the alternator rearward to maintain belt alignment. I found 3 washers to be a close approximation of the difference.
Look at the lower right part of each alternator below to see the difference in mounting nub height:
To keep junk out of the cooling snout I used a piece of nylon window screen held on with a 40-60mm clamp:
I added an extra ground wire between the lower rear mounting ear and the frame since the mount grounding is somewhat iffy with this upgrade. It's just a generic (16" 6 AWG, I think) ground wire from WalMart.
Lower mounting bolt with 3-stack of washers (nut not installed yet). There wasn't enough room to insert the bolt from the front like the original but it works fine with the nut up front:
The wiring is easy. All I did was cut back the plastic sheath and put heat shrink tubing over my crumbling insulation on the power wire. The field terminal is slightly bigger so I had to cut the ring terminal on the field (D+) wire and open it slightly. Referencing the picture below, I made this cut slightly CCW from the wire crimp so that when I tightened the nut it didn't push the terminal open. Crude but works fine.
Stupid airbox mod:
Forced induction alternator:
For those on a diet, this alternator is 15 lb 13 oz while the 90A is 13 lb 3 oz, both with pulleys. I didn't take the new alternator apart so I'm not sure if the rotor is any heavier so there may or may not be more mass to accelerate. Has anybody compared the two? The stator, case, and rectifiers are probably where most of this increase is found but there very well could be a performance hit with this upgrade if the rotor is heavier. The Warm Air Intake is my bigger concern :down:
Otherwise, it was fairly straightforward. As mentioned in that article you need a longer lower bolt (I used a 5/16" 5" long bolt) which is almost identical in diameter to the original M8 bolt. What's not mentioned in that article is that the lower forward mounting ear does not protrude as much as the original 90A alternator so you need to space the alternator rearward to maintain belt alignment. I found 3 washers to be a close approximation of the difference.
Look at the lower right part of each alternator below to see the difference in mounting nub height:
To keep junk out of the cooling snout I used a piece of nylon window screen held on with a 40-60mm clamp:
I added an extra ground wire between the lower rear mounting ear and the frame since the mount grounding is somewhat iffy with this upgrade. It's just a generic (16" 6 AWG, I think) ground wire from WalMart.
Lower mounting bolt with 3-stack of washers (nut not installed yet). There wasn't enough room to insert the bolt from the front like the original but it works fine with the nut up front:
The wiring is easy. All I did was cut back the plastic sheath and put heat shrink tubing over my crumbling insulation on the power wire. The field terminal is slightly bigger so I had to cut the ring terminal on the field (D+) wire and open it slightly. Referencing the picture below, I made this cut slightly CCW from the wire crimp so that when I tightened the nut it didn't push the terminal open. Crude but works fine.
Stupid airbox mod:
Forced induction alternator:
For those on a diet, this alternator is 15 lb 13 oz while the 90A is 13 lb 3 oz, both with pulleys. I didn't take the new alternator apart so I'm not sure if the rotor is any heavier so there may or may not be more mass to accelerate. Has anybody compared the two? The stator, case, and rectifiers are probably where most of this increase is found but there very well could be a performance hit with this upgrade if the rotor is heavier. The Warm Air Intake is my bigger concern :down:
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