L98 under drive pulleys
Thread Starter
Pro
Joined: Sep 2019
Posts: 716
Likes: 135
From: Buchanan, Michigan
L98 under drive pulleys
Hey guys, are any of you running a smaller crank pulley?
I recently picked up a 6" crank pulley, stock is 7" am I going to run into charging issues at idle if I don't change the alternator pulley too?
Hoping for some real world experience from the 85-91 L98 guys.
I recently picked up a 6" crank pulley, stock is 7" am I going to run into charging issues at idle if I don't change the alternator pulley too?
Hoping for some real world experience from the 85-91 L98 guys.
Pro
Joined: Mar 2006
Posts: 520
Likes: 143
From: Caribbean/Florida
Never had any issues but I bought the 3 pulley kit from March Pulleys Which keeps the alternator right where it needs to be, also upgraded to a high flow water pump and a bigger wattage Alternator... Maybe someone else with only the crank pulley change and clarify... Further, the stick shift cars allows more control over engine rpms at lower speed. Thus I would assume the Automatic cars would have a steady idle rpm that would be kind of low for proper charging, I believe the alternator puts out 100% at around 1,800 to 2,000 rpms... Hope this helps a bit...
Racer
Joined: Apr 2023
Posts: 274
Likes: 60
From: Texas
Anytime I have run them in the past, I had a slight undercharge with the included alt pulley. Specify you want a 1-7/8" or 1-3/4" and it should charge fine at idle. Went from a 6" to 4.5" (25% under) on a truck and cured it with the smaller alt pulley which just overdrives it at idle. Try to procure aluminum ones as they are lighter than steel, ASP out of Houston makes them that way still I think.
The LT1 CS144 alternator has more peak output and should have more *** at idle too. I plan to do this once I fix my braking issues.
Lastly, I am not sure the L98 revs high enough in near stock form to take advantage of them as I have been on the fence for them for this reason.
The LT1 CS144 alternator has more peak output and should have more *** at idle too. I plan to do this once I fix my braking issues.
Lastly, I am not sure the L98 revs high enough in near stock form to take advantage of them as I have been on the fence for them for this reason.
