Need help finding part number (pulley upgrade/serpentine belt sizes)

Hey folks,

I have a Pumaspeed aluminum pulley on the way, after talking with the Puma people I'm interested in getting a larger belt because the pulley is a bit larger diameter (MOAR POWR!!!!!) which means the belt will be stretched tighter. Puma says they have a bunch of folks who installed it that way and it's tight but fits no problem, but they did mention one installer chose to go with a slightly longer belt so it didn't stretch so tight. They couldn't give me part numbers but did say that the OEM one is 1555mm and the longer one is 1583mm which is about 1.1 inches longer.

I'm trying to track down which Ford belt they used for this....if anyone has access to the Ford part vault/info please let me know, from what I understand the OEM belt is P/N BM5Z-8620-B located here:

https://www.oemford.parts/oem-parts...vPWZpZXN0YSZ5PTIwMTUmdD1zdCZlPTEtNmwtbDQtZ2Fz

I could be wrong on that P/N someone correct me if I am.

I might keep the stock belt on there but I want to have a longer belt on hand during install in case I feel like I want to put it on if I feel it's too tight.

Any help would be super thanks a bunch.

slopoke who has created all of the Peron aux fuel kits threads has a longer belt part number listed in his install thread
I'm not sure if it's the size you are after but it is longer than OEM

Thanks man that is helpful. I saw where you mentioned the Gates K060615 belt linked below, is this the one you're referring to?
[MENTION=9564]slopoke[/MENTION] maybe you can help further it is appreciated.

https://www.amazon.com/Gates-K06061...&qid=1543974695&sr=8-1&keywords=GATES+K060615

that's the one!
I'm anxious to see what this pulley does
There were pics from one of the UK customers that installed it
The OEM pulley actually fits inside the new pulley which means it's an oversize or overdriven water pump pulley
The only benefit I can see coming from this is possibly cooler temps since overdriving the water pump will speed up the pump so maybe help with the overheating issues? Not sure
Weight difference for just 1 pulley will most likely not be a quantifiable difference unlike if it was a full set of billet pulleys.

It's probably the first of many pulleys, before long they'll have a whole set you can buy.

That's how it is in the Honda Acura world from my last build.

The smaller pulleys like the power steering one only gave like 10% of the gains, it was the larger pulleys that did 80-90% of the improvement. This is a larger one so it should help speed up revs a noticeable bit. At least that's how it was in the Acura world...

The Gates belt K060615 is the next size up from stock. I took a screenshot of the Gates belt chart, just in case you need to go bigger than the one listed. Just in case you are wondering how I got the part number for the next size, I just used my local autoparts store part fitment feature.

awesome !