V1 Alternator pulley/belt question

[David]

Ok so was going thru everything snice I have half of the goblin apart. I checked my belt and its starting to shred and the tensioner pulley has a lip.

The original builder mentioned he had an issue with ZZP belt recommendation which was a 345 5 rib. It was to lose and he had to buy a belt from Autozone which was a 335 5 rib.

I have an ATI dampener and not sure what alternator I have. From the sticker on the alternator seems like its from a 2.4 that runs the 5 rib.

Wanted to see if anyone has changed the pulley on the alternator to a 6rib. So I can use a Gates 6rib RPM belt.

If possible getting a OAD pulley would be best I believe. I tried to cross reference some pulleys by using Gemini and it recommended Litens 920834A.

More Information for LITENS 920834A

As for the tensioner im assuming I need to replace the whole thing or is it possible just to change the pulley?

Sticker on Alternator

You can see the shiny grove on the tensioner

ZZP belt to long

 

[jirwin]

Its hard to recommend a belt because I've learned that different tensioners - OEM and aftermarket - actually required me to similarly use different length belts. I also have the ZZP Turbo LSJ belt setup with an underdrive ATI damper. My tensioner was rattling (still does tbh) so I tried a tensioner from AutoZone IIRC. The belt I was using was whatever ZZP included in the kit but it was way too lose. I ended up getting this Goodyear 33" (330) belt and it fits a lot nicer. https://www.amazon.com/gp/aw/d/B08SPLKHZ4
Just play around with the lengths and find one that fits. I just measured the length of the existing belt and tried half an inch tighter steps until I found a nice fit.

That being said, my tensioner pulley looks like that too. I wouldn't worry about it personally or the 6 rib conversion. Not really worth it IMO. You could do it if you want since that alternator doesn't have the fancy pulley on it like the stock LSJ alternator does though

 

[David]

Its hard to recommend a belt because I've learned that different tensioners - OEM and aftermarket - actually required me to similarly use different length belts. I also have the ZZP Turbo LSJ belt setup with an underdrive ATI damper. My tensioner was rattling (still does tbh) so I tried a tensioner from AutoZone IIRC. The belt I was using was whatever ZZP included in the kit but it was way too lose. I ended up getting this Goodyear 33" (330) belt and it fits a lot nicer. https://www.amazon.com/gp/aw/d/B08SPLKHZ4
Just play around with the lengths and find one that fits. I just measured the length of the existing belt and tried half an inch tighter steps until I found a nice fit.

That being said, my tensioner pulley looks like that too. I wouldn't worry about it personally or the 6 rib conversion. Not really worth it IMO. You could do it if you want since that alternator doesn't have the fancy pulley on it like the stock LSJ alternator does though

Yea im always over thinking and engineering everything. If its not to.much and it improves the belt system. I will want to see if i can upgrade the alternator pulley. Would be interested to see if anyone has done it.

 

[David]

So now I went down another rabbit hole which is over spinning the alternator. Here is some math to determine alternator RPM.

-Crank Pulley (ATI Super Damper): 6.78 inches (This is the "5% Overdrive" version common for the LSJ).

Alternator Pulley (Litens 920834A): 2.16 inches (55mm).Your Engine Redline: Let's assume 7,500 RPM for a Turbo LSJ build.

The Math:
Ratio: 6.78 ÷ 2.16 = 3.14
Alternator Speed: 3.14÷7,500 = 23,550 RPM

Alternator max speed is 18,000 RPM

So now at 7,500 RPM Engine speed im spinning the alternator 5,000 over. Is it a big deal? Not sure

To fix the RPM on the alternator I would need ro get a bigger pulley around 72mm or 2.8 in.

So the question is whats is better. Go with the OAD pulley and spin the alternator faster. Im assuming it will shorten lifespan.
Or get a solid bigger pulley and spin the alternator slower and worry about belt slapping?

Just figured I post this finding to have some opinion and solution for the guys that over think everything lol.

 

[jirwin]

ATI underdrive seems to make the most sense to me for ease of setup. It's what I'm running. Overdrive is a total waste on a turbo LSJ. Underdrive will get you more power in theory too. Be warned though, if your crank does not have an extended keyway for the ATI damper I would just leave it alone. It will be a nightmare to line up.

That being said I really miss the OAD or similar thats on the stock LSJ alternator. It made my belt buttery smooth in comparison to the current setup. If I could bolt one onto this alternator easily/cheapy I'd consider running it myself.

 

[David]

ATI underdrive seems to make the most sense to me for ease of setup. It's what I'm running. Overdrive is a total waste on a turbo LSJ. Underdrive will get you more power in theory too. Be warned though, if your crank does not have an extended keyway for the ATI damper I would just leave it alone. It will be a nightmare to line up.

That being said I really miss the OAD or similar thats on the stock LSJ alternator. It made my belt buttery smooth in comparison to the current setup. If I could bolt one onto this alternator easily/cheapy I'd consider running it myself.

Ok so I went back on the builder thread and found the picture of the part number he used for the ATi. So I redid the math and its alot better to the 18,000 RPM limit of the alternator.

The Rev Limit Math (Re-calculated for ATI 917288)With a 5.67" crank and a Litens 920834A 55mm (2.16") alternator pulley:

Ratio: 5.67 ÷2.16 = 2.625
Alternator RPM at 7,500 Engine RPM: 2.625 ÷7,500 = 19,687 RPM

So, Yes if possible to install the OAD pulley it will be the best route.

Might order the Litens 920834A and see how it lines up.

 

[Rttoys]

We had a thread here or maybe it was on another forum, that spinning the alt too fast was smoking bearings or something like that. Or over voltage because the regulator couldn’t keep up. I can’t remember. A larger alt pulley was the cure (or go back to stock crank, but what fun is that?).

 

[jirwin]

Did a bit of digging myself... I think you could use an alt off a ~2014 2.4L Equinox without issue if you just want 6 rib. Something like this: https://www.rockauto.com/en/moreinfo.php?pk=10942968

That being said, it would be cooler to have an OAD/OAP to quiet the belt.

 

[Ross]

jirwin, you made me look it up.
Overrunning Alternator Decoupler (OAD) and Overrunning Alternator Pulley (OAP) are specialized pulley systems designed to reduce noise, vibration, and harshness (NVH) in a vehicle's belt drive system.

 

[jirwin]

jirwin, you made me look it up.
Overrunning Alternator Decoupler (OAD) and Overrunning Alternator Pulley (OAP) are specialized pulley systems designed to reduce noise, vibration, and harshness (NVH) in a vehicle's belt drive system.

Yeah when I went from the ZZP SC 2.2/2.4 belt routing with a solid alternator pulley to the OEM LSJ routing with its OAD or OAP alternator it made a HUGE different in belt smoothness and tensioner rattle/movement. The video comparisons they have of them are really cool to see too:

 

[David]

Yeah when I went from the ZZP SC 2.2/2.4 belt routing with a solid alternator pulley to the OEM LSJ routing with its OAD or OAP alternator it made a HUGE different in belt smoothness and tensioner rattle/movement. The video comparisons they have of them are really cool to see too:

Yes sir thats the reason I want an OAD. I will give it a try and see what I find.

 

[David]

Ok so just realized something, the OAD requires a threaded shaft not a nut. So the pulley I ordered doesn't work. In order to get a OAD you need an alternator that has the correct threaded shaft.

 

[jirwin]

I did a little more poking around and we might be able to use something from the LTG. 2015 Cadillac ATS 2.0 LTG has one from the looks of it and it turns clockwise

More Information for GM GENUINE 13529304

 

[David]

I did a little more poking around and we might be able to use something from the LTG. 2015 Cadillac ATS 2.0 LTG has one from the looks of it and it turns clockwise

More Information for GM GENUINE 13529304

Wow that looks like a good find, I wonder if the mounting points are the same. Looks pretty dead on. I was going to stop by a local alternator rebuild shop and see if they had anything they recommend.

Was thinking if there was a way to change the direction of the OEM LSJ alternator. I believe the only thing that makes it counter clockwise is that the fan direction and the bolt threads. Bolt threads you can use red lock titr and it should stay.

 

[David]

I did a little more poking around and we might be able to use something from the LTG. 2015 Cadillac ATS 2.0 LTG has one from the looks of it and it turns clockwise

More Information for GM GENUINE 13529304

Was just comparing pictures of the tabs and they are not the same

 

[jirwin]

AFAIK the LTG (Cadillac ATS) and LHU (Buick Regal) both use this alt. The LHU looks like this:

Looks like you might be right. Looks like it has something else between it and block.

 

[Dale E]

Take the belt tensioner off the engine and look if the pulley is replaceable separately. The tensioner might be wearing out - dependent on mileage - so just replace the entire tensioner assembly. The tensioner pully is smooth so no rib should be on it??

Any alternator rebuild shop should be able to mount a normal 6 rib pully on your alternator. They may also have a different diameter alternator pully that would match your speed issue. I'm assuming the ATI balancer pulley is 6 rib???

Get your Goblin back together and drive it - you can change cosmetic and other things down the road.

 

[Ross]

Was thinking if there was a way to change the direction of the OEM LSJ alternator. I believe the only thing that makes it counter clockwise is that the fan direction and the bolt threads. Bolt threads you can use red lock titr and it should stay.

The LSJ has an OAP that runs counter clockwise too. You would need pulley that goes the other way. The stock OAP pulley is half the cost of an alternator... $80 when I bought one years ago.

 

[David]

The LSJ has an OAP that runs counter clockwise too. You would need pulley that goes the other way. The stock OAP pulley is half the cost of an alternator... $80 when I bought one years ago.

Yea I finding a clockwise OAP is the easy part. It finding an alternator that spins clockwise and except a OAP is the issue.

 

[David]

Take the belt tensioner off the engine and look if the pulley is replaceable separately. The tensioner might be wearing out - dependent on mileage - so just replace the entire tensioner assembly. The tensioner pully is smooth so no rib should be on it??

Any alternator rebuild shop should be able to mount a normal 6 rib pully on your alternator. They may also have a different diameter alternator pully that would match your speed issue. I'm assuming the ATI balancer pulley is 6 rib???

Get your Goblin back together and drive it - you can change cosmetic and other things down the road.

Yes in the process, but in the while im waiting for parts. My OCD drags me to just do research for future projects.