SRT Hellcat Forum banner
  • Hey Everyone! Vote for the Site Favourite HOTM winner for the year of 2022 HERE!

Blower bearings

1629 Views 10 Replies 6 Participants Last post by  Himmelkat
Hello all,

If i do a 2.85 do I need to port the blower? I been hearing a lot of stories about bearing failures after pulleys. BTW I have a 2020 Charger HC. Thx!
1 - 4 of 11 Posts
Why would anyone NOT go with a clutched pulley?
Also, go with ceramic hybrid bearings if you are going to change them anyway. Better all around bearings.
  • Like
Reactions: 2
The bearings they specifically use to replace the all-steel bearing in the blower aftermarket?
Please elucidate and elaborate.
Ceramic Hybrid bearings are good on the front rotors but I haven’t had good luck with them in snouts, especially the one right behind the pulley. On pulleys, I wouldn’t run anything but a clutched pulley. The rotors are not keyed to the gears that keep them in time with one another. The lighter slower one coupled to the input shaft its gear is a shrink fit on the rotor shaft and clamped in place by a bolt, just like the damper is to the crank, the if you don’t pin it you’ll spin it one. The heavier faster one is held in time only by a tiny collar and clamp load by a left hand thread bolt, that is how timing is set between the rotors. A solid non clutched pulley puts a ton of stress on that clamp timing method. John Bond pins that on his full race prepped blowers. Unless that is done running a non clutched pulley and spinning the blower to the moon is just asking for rotor clash and a ruined blower. My .02
What I gather from that is that right behind the pulley is the largest combination of loads, and steel, being tougher and less brittle, survives better as a bearing ball material there.
The rear bearing is being relieved a proportionally lower level of stress, and it is at the part of the blower where there is more downward thrust due to the rotors working against the air mass overtop of them.

So I would guess the least-stressed bearing would be the front non-pulley one, and the most-stressed the front pulley bearing.

However, the rear bearings are oil bath bearings, not sealed with some grease. There is quite a difference, as in, it is better, between an oil bath and a sealed bearing. Big rig trailers use oil bath bearings.
  • Like
Reactions: 1
With leverage, the front-most bearing that is at the front of the blower shaft, near where it attaches to the pulley, is the most loaded in the vertical axis, and the one in the front of the rotor beside it would be the least-loaded, in the vertical axis, of the front two bearings. The two rears would be a different load, as the front of the lobes "pulls" forward as the lobes force air backwards, and the rear of the lobes "pulls" downward due to their forcing air upwards.

So the most vertical load from air movement would be at the rear of the rotors, the most vertical load due to belt tension would be at the front of the pulley rotor, and some axial load would be exerted as the rotors pull air backwards, so the bearings all receive different load profiles and aggregates, and it varies based on boost and RPM. also, they are not turning the same speed, as the pulley rotor goes 3/5 the speed with its five lobes as does the non-pulley rotor with its three lobes.

Also, the gears provide some lateral load as the gears repel each other, as gears tend to do, but that is not significantly negative-due-to-leverage transferred to the front bearings, because they are so far, in relation to their centerline versus the distance from gears to rear bearing centerline, from the gears.

To sum up:
Vertical loads: front bearing due to pulley and rear bearings due to thrusting air upwards, also against pressure. No appreciable vertical load on front non-pulley bearing.
Axial loads; absorbed entirely by the rear bearings
Lateral loads: from air trying to push rotors apart, all four bearings will experience this, and also lateral load from gear mesh in the rear primarily on the rear bearings, as the gears try to repel each other due to tooth shape needed for most effective gear mesh/energy transmission.
See less See more
  • Like
Reactions: 1
1 - 4 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.