New Magnuson Supercharger belt tension Issue.

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raisinhell2

raisinhell2

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Aug 6, 2021
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Location
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For anyone with a New Magnuson kit , Wouldn't hurt the people with the old kits to check this as well. We had 2 defective belt tensioners back to back from Magnuson. The 6 rib blower belt should have a tension of about 180lbs per dayco . After burning the frt seal out of a brand new Blower due to belt slippage caused by a brand new defective weak tensioner . 1st 1 had 85 lbs 2nd had 110lbs I am waiting on a 3rd tensioner from them. Both rigs ran good But just didn't have higher boost, both clocked in around 3.5 lbs . I see 4 to 5 lbs on most of them . After 2 days on the phone and emails with Magnuson (who was very little help with these kind of specs) Dayco and Jon from Jon bond performance . I was able to get a little more info on the belt and its life which dayco recommends replacement at 30k miles. Jon was a major help with info on the tensioner and how to look at the blower pulley for signs of slippage. The symptoms I encountered . 1st was just not the power under load ( doing a bunch of these I have a good feel for how they should be ). This was a complete engine rebuild with a land tanks alt kit and their deep v belts which I have never used. During break in I was getting a Hot belt smell I wrote that off to new engine smells and the Land tanks belts(which it wasn't). Nothing felt hot to the touch. Before I was finshed with the 500 mile break in the frt seal of the blower was leaking . As with most of everyone else I never thought to check belt tension due to the kit being new and having a spring loaded adjuster. Jon gave me a short course on belt tension and the tensioners for these kits. He pointed me to a kircket style belt tensioner made by gates for around $20 and to buy the one for ribbed belts not v belts . He also told me about the different tensioners you can buy . The supercharger uses a heavy duty one. The ones found on amazon and the local auto parts store that are cheaper are not the HD ones. This could be a very costly Issue if your not under warrantty. I think I have found a HD tensioner for 1/2 the cost of the magnuson cost. I will update this thread with a part # when it gets here and I have confrimed proper tension. I will also post pics of the gates tool and the worn pulley next to a good one when I get back into the shop. Hope this saves someone from what my last week has been like .
 
landtank said:
I designed my own tensioner. I didn’t like the tensioner as it was’t sealed, the hokey way they mounted the idle pulley, the fact that pulley was plastic and the wrap spring for tension.

If you would like to try it I wouldn’t mind you letting me know what you think.
Click to expand...
We have definitely gone down the same road of thought on this one I have already done about the same thing. The HD tensioner I found is sealed and comes with a ribbed metal pulley which works perfectly to replace the Plastic one Magnuson supplies. I would hate to see yours then have you accuse me of macking your ideas again. I appreciate the offer though. Alt kit was nice well thought out.
 
I bought my SC second hand but I think it came with the @landtank tensioner. While it is super stiff and provide great tension, it is large and the belts rub on the bottom of it. I had to clearance the shell with a file but it still got polished from belt rub afterwards.
 
lumbee1 said:
I bought my SC second hand but I think it came with the @landtank tensioner. While it is super stiff and provide great tension, it is large and the belts rub on the bottom of it. I had to clearance the shell with a file but it still got polished from belt rub afterwards.
Click to expand...
I adjusted the position of the bracket for that rubbing. I wasn't aware of you having the problem. using an angle grinder with a flap disk can take off the metal pretty quick.
 
Update on tensionors. I'll start this mess with the fact magnuson has been unable/unwiling to provide me with a spec for the belt tension . This all started with 2 superchargers developing a snout seal leak for no reason ( I suspect belt slippage as the cause). 1 rebuilt and 1 unit brand new. Dayco says 180 lbs of tension on the 6 rib belt. Out of the 3 new kits I have been able to test average belt tension was 60 lbs .. I found the same Magnuson tensionor out of 3 of them I tested I got 60 to 65 lbs .. I found a HD tensionor The same one LandTank and we use out of 2 of those we tested we got 65/70 lbs. Landtank also sent me 1 of his Tensioner assembly's to test . I will say at this time it was a very high quality piece Well done Landtank. If you need to or want to replace the whole assembly this is the go to part. On the land tank part I used 1/2 inch shorter belt. Their different size pulleys ,tensioner and idler allowed that I got 80/ to 85lbs . And what I would call a very happy blower. I will be offering just the Hd. tensionor on our web site soon. I want to test 1 for a few months just to make sure it holds up. Here are some of the symptoms I had other than seeing a physical leak. 1st was choppy idle worse when cold. Once the blower warmed up idle settled to a degree. The lose belt allowed for it to slip on the blower pulley and caused what will call choppy air flow which cause the erratic idle. Performance and boost fluctuated Until the blower warmed up (blower drag) . I also saw boost vary by almost 1 lb during this warm up. Under the hood also smelled hot What I would cal the smell of a belt burning . For those who are going to offer trouble shooting ideas. The new blower was on a brand new engine with everything on that engine new. Other than MAP TPS and IAC which all tested perfect. The rebuilt on was on a older bottom end with new head and all parts brand new oem Toyota. Both are now idling perfect and holding consistant boost since new tesionors and belts. ..
 
There are 2 Things that Cause 90% of Belt Failures - Wrong Tension and Sheave Alignment off. Use a Ruler to Align.
Gates sells a Finger Tension Tool or OTC sells a Fancier Version with Dial.

If Tension is too high it will cause Premature Failure of Bearing.

I would go just enough Belt tension to keep it from Slipping on Sheave.
 
Land tank has the whole assembly.. I'll have just the HD tensioners Mid next week, Ill post here when they are in ..
 
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