CrossThreaded

Hello all,

I have done a bit of research and there seems to be a lot of people have asked this question, but there always seems to be mixed responses in regards to the minimum belt angle on your pulleys. While some people say that it's fine to use a 90 degree angle, some argue that it should be a minimum of 120 degrees wrap around to prevent slippage. This is an LS1 that's coming out of a Holden Commador and the idea was to delete the power steering pump since I will be going electric power steering on this build. There are even ICT billet mounts (https://www.ictbillet.com/ls1-altern...ls-billet.html) that create this exact angle that I would get if I delete the pump and use a shorter belt.

Here was the link where I found the cheap work around where all you need to do is replace the idler and use a shorter belt: The youtuber mentions that people are scared of running that angle on their belt, but he says that "he's seen high HP drift cars running this setup without any issues".

What would be the risks of running this setup, and what other options should I consider. I am open other options, and not hellbent on making this hack work for me, so if there are better solutions, please let me know. Also worth mentioning, this is going into a swapped 1971 Datsun 240z.

Thanks so much!

I've attached a photo of my engine just to help illustrate the modification. (AC compressor will also get deleted too but it's a separate belt).

conexion914

iTrader: (5)

I ran the same setup shown in the video for a long time in my track only car using the stock LS1 balancer and had no issues, but when I rebuilt a new engine with a 10% underdrive pulley I started having belt slip on the alternator and was losing voltage over 6k rpms.

I tried getting a bigger alternator pulley thinking it was an RPM problem and it kept happening, so I added a smooth idler between the crank and alternator to get more belt wrap on the alternator which worked, but the belt would hit the top bolt on the alternator and eventually shredded itself. I did buy some hex cap bolts that I didn't change out because I thought it was good enough, but it wasn't. I now have the ICT Billet Power Steering delete kit and have no issues; I also opted for a mechanical tensioner.

the_merv

iTrader: (88)

Bigger Alternator Pulley would make it spin slower. You would have wanted a smaller Pulley there, that's why it kept happening. Underdrive Crank Pulley spins everything slower already, hence the "under"drive.

conexion914

iTrader: (5)

Yeah, agreed. I wasn't sure how high I would end up turning it so I got the larger pulley to keep from over revving the alternator. The under drive balancer with a stock alternator pulley in the configuration from the YouTube video didn't work out for me with a stock tensioner, it tossed the belt on the dyno and would stop charging after about 6300rpm.