bear with me here. I have a number of issues that I believe are all related. I don’t have a lot of options here with my setup. There’s just not much support with the way things are set up. I’m just looking for any suggestions.

I have a 2004 Tacoma with the TRD Supercharger. When you make the conversion you’re converting the tiny 4rib alternator static tension belt to a dynamic tensioner. Per Magnuson you set the alternator to the middle of the bracket for “proper” tension.

That being said I’ve always had an issue with serious belt slip. It’s so bad I can hear it screaming inside the cab. As a side note I believe this is contributing to another issue I have where my timing advance takes a dump. I believe that the knock sensors are picking up this resonance as knock. This “seems” to be confirmed by tightening the belt and hearing less slip and better timing advance displayed on the OBD2 reader.

it’s odd that the belt slip only happens in the ~2500-3500 range and tapers off. Once the belt screeching noise goes away power comes on and timing jumps back to what it should be. Hitting the gas hard enough for a downshift at cruise seems to also prevent this from happening. I think the higher and sudden RPMs tightens the belt up and the tensioner takes the slack up.

It’s important to note that I’ve never heard any bit of knock when this happens. I’m quite familiar with knock on these engines. They’re prone to knock in particular circumstances. Ive since been able to fix this for the most part. Just to get it out of the way there’s no way for me to look at the computer to see the knock count or anything like that. These ECUs are locked down old tech.

For whatever reason I don’t think Magnusons recommend tension is anywhere near sufficient. The belt is so loose it won’t even register on a crikt tension gauge. I can twist the belt with ease almost 360 degrees.

Ive since moved from a 2.34 to a 2.1 griptec pulley, moved the alternator all the way in, and I’m using a 61” belt as opposed to a 62” belt. This seems to work fairly well, for a while. Then I think the gator back belt I’m using stretches too much and it’s back to screaming. Again, tightening it up seems to keep it from slipping so bad and my timing numbers shitting themselves.

Nobody seems to be able to help on this. The general consensus is that a dynamic tensioner should take care of everything. And speaking with Magnuson they were no help with how much tension should read on a belt gauge.

Now to make things eve more complicated I only have a few belt choices, PK gates, PK Bando, PK Goodyear and Continental gator back. Ive stuck with the gator back for one reason. Because I have a slight crank pulley misalignment. it always chirps in the morning. There’s nothing I can do about this. I just happened to get one of the few factory cranks where the pulley bolt hole was drilled slightly crooked and it clamps the crank pulley more on one side than The other. Other than some vibrations it hasn’t been much of an issue running it hard supercharged for 60k miles. With 170k on the clock. However, It’s possible the chirping get from gates it more related to slipping and glazing. I’m not sure.


I just want some recommendations for how tight a belt should be without damaging the bearings in the supercharger. While I have been able to somewhat remedy this by tightening the belt I’ve been very modest in how much I add. I don’t want to over tension things.

All the other information isn’t really that important at the moment but I thought I’d get everything out there so there’s no unknowns. I’m hoping that if I can figure a way to properly tension with a new belt, keep that tension even after stretch that it will help solve those other issues.

 

With a new belt it does well. The belt just barely goes over the supercharger pulley.

But once it stretches it slips any time you’re in mid RPM boost. And it’s evident that it stretched because it’s much easier to fit on the pulley.

#ad

 

The GripTec is very conservative as opposed to carbonite. It’s like a sanded surface as opposed to bed liner. Only way to test that theory is to buy another pulley and try it out for a while. But I really think it’s a inadequate belt tension/rib section/wrap issue. Since I’ve got as much wrap as possible in without modification I’m looking at tension. I can still adjust the alternator for more. I just don’t want to go beyond what the bearings are supposed to handle.

The crank pulley thing isn’t an option. There’s no real aftermarket support for these engines which is a real shame.

 

it’s a completely insufficient 4rib belt. They don’t make a 4 rib near long enough for my application in the RPM.

I could use a 8 rib and cut it in half. Ive done that before with a new razor blade in a vice and careful attention. But then I’m risking ruining a pretty expensive belt if I screw up or it doesn’t cut like other belts.

 

There’s not. Theres just no real aftermarket support for this application. But Im actually diligently working on a solution. It’s going to be a 8 rib x 6 rib for the accessories.

not only do I love engineering things like this and I want to fix this for my own enjoyment I hope to be able to come up with a kit to sell and start a little part time business. I doubt I’ll get a lot of orders but the idea is to fill a void in the market and work on something I enjoy.