3.4L supercharger

80lb static sounds like way too much. I think mine is like 40lb with the alternator just to the right of center. I added some because I was slipping as well.

I think the automatics cause slip more depending on load, gear and O/D.

 

Your snout bearing is not the problem bearing, the snout bearing is actually the strongest of your supercharger bearings, your rotor pack bearings are usually the 1st that go out, not the snout.FYI.

In 600,000 plus miles driven all superchargered my supercharger has never failed from
a snout bearing. It’s always been the rotor pack or needle bearings that have failed.
Rebuilds have lasted as long as 150,000 to as short as 80,000 because a rotor pack seal leaked out the oil from the supercharger into the rotors,

 

Have you seen this tension gauge? Only $20 on Amazon
https://youtu.be/z11wfc-0-hY

 

This is the kind I have. You have to be slow and steady with it to get an accurate and repeatable result. But it seems to work fine.

 

Another problem with the high tension is that it increases heat in the supercharger. It's the little things that make the difference (if i increase the angle on the pulley from 170* to 220* then 2.3 times as much force can be exerted on the pulley without slipping.) I can use it to hopefully decrease needed tension or just make sure I do not slip.

No one has their old pulley I assume?

 

You can find just the idler pulleys on Amazon pretty cheap.

 

But I will have no good way to mount one so if i used an old one someone doesn't want, I could countersink the hole and mount the pulley knowing that it will be perfectly perpendicular to the sc

 

I thought the added idler pulley just bolted to the flat static tensioner bracket..
?

 

As @Shortman5 asked earlier in his photo, I'm trying to add a second idler to increase the angle that the belt contacts. If I can increase the angle by 30* (170 -> 220), I can exert 2.3 times as much force on the pulley without it slipping.

 

How much is it slipping already - @1997tacomav6 had a steel pulley made that didn't slip compared to the URD ones.

 

It's slipping enough to be noticeable, I believe I read somewhere highspeedlab stopped offering to make those.

Tensioner gauge is bought and on it's way to me.

 

Just so you know according to Gadget TRD got rid of the double pulley in favor for the single because it, surprisingly, reduced slip.

Texas Ace on 4Runner forums and Customtacos tried incorporating a second pulley and had to rebuild his supercharger. He claimed that it wore the nose cone bearing out.

Personally the Gates belts didn’t work to well for me. I’m using a GoodYear gatorback that works much better for me, the ribbed design by is meant to grip pulleys better. You’ll get a shiton more dust but it has reduced slip and noise.

I’ve read multiple articles that belt choice has a larger impact that some people are led to believe. Try another belt before you try to fab another bracket.

 

@TacoBike you not using the dynamic tensioner or you are and it's still slipping? Yeah increasing friction area also increases load perpendicular to the rotation. Possible the nose cone would wear due to that, but hard to say without replicating and testing.

 

I could not find a thread or such about Texas Ace doing so. Would you help me out and link it?
I thought Gadget got rid of the double pulley because the belt was coming off, not because it slipped?
If the tension gauge does not help, I may have to resort to a different belt or pulley.
Also I think I could fit the second idler on the same bracket, possibly even keep the same belt.

Static tensioner, with less tension on the belt, would it not reduce strain (load) on the bearings?

 

Well I’m probably mis-remembering some of this. You may be right on the TRD/URD double pulley thing.

I found the thread Texas Ace posted some pictures on. I could have sworn that he had premature wear but I may be wrong.

Either way keep us posted.

If I turn O/D off and WOT I will eventually loose hit a point where I loose speed fast and I can hear belt slip. I’m not sure why it happens. I just drive around it.

https://www.customtacos.com/threads...ger-with-differnt-sized-pulleys.150180/page-2

 

Maybe I misinterpreted / don’t understand completely but if you increase the contact area on the pulley with the same amount of tension on the belt, there will always be more perpendicular force to the rotation. If you’re increasing contact area while reducing tension on the belt you’ll have to calculate the resulting frictional force, but you’re not going to get more friction without adding perpendicular force to the rotation no matter what.

Any reason for not using the dynamic tensioner? You probably already mentioned that - I missed it.

 

I don't think I really have, but I don't believe there should be any reason to have a dynamic tensioner, if the belt needs it to not be flapping around, then it is slipping. I also don't like that it is on a spring and as the tensioner moves, the force it exerts changes. Maybe it is better, but on some cars (mustangs) a fix for slippage is going to a static tensioner. Also I just replaced the bearing and am a bit on the cheap side right now, after having to do my top end.

Also the reason being for my thought that the perpendicular force would decrease is because of the formulas that give the coefficient of friction around the pulley have it as e^θ where θ is in radians. So I would have the same perpendicular force either way, but I would have more margin where the belt would not slip. Or, by decreasing the tension, the load would decrease perpendicular to the pulley while staying within static friction.

Oh, that thread! That and the original TRD setup is why I'm looking into doing the extra idler. I believe he converted to turbo before he ever had any problems with the extra idler?

Edit: After finding multiple threads on this subject, dynamic is better (if spring is strong enough) but for my price range and low boost application, I'm hoping to make the static work.

 

If @1997tacomav6 was able to fix the slippage with the steel pulley it rules out the dynamic tensioner being the cause of the slippage. Not to say it wouldn't cause it altogether, in this case it seems safe to say that the material of the pulley matters more.

You need to keep in mind that normal force is related to contact area in this case.



If you keep the same tension then the more contact the belt has with the pulley, the more it increases the normal force.

 

I would not keep the tension the same though, because I would be able to run it lower because of the increased contact patch. Also would the normal force decrease after 180*? (force would follow a sin/2 curve as you increase degrees of wrap?)

(Also did edit to say dynamic tensioner isn't the problem, just the fact that I do not know how much force it exerts with different angles. Also would like to increase the wrap angle so I might get it but mount in in a different way.)

 

Unfortunately you're not gaining anything by doing that - friction will be directly related to the normal force. More contact area with less tension gives the same normal force as less contact area with more friction if you want to achieve the most friction.

And you can't go past 180*