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Alkydigger Technical :Common Supercharger Questions & Answers
You should torque the supercharger to 10-12 ft/lbs. lubricated for most applications. Some Intercoolers that use long steel studs may require more torque for a proper seal, normally 25 ft/lbs.
Be sure to use a new set of studs if you question whether yours are stretched: https://www.alkydigger.net/proddetail.php?prod=TBS-2590
Q. What type of oil should I run in my supercharger?
A. You should run a High Quality 80w/90 gear oil with a GL-5 rating with Zinc. Synthetic oil or Synthetic blends are OK to use. We do sell oil with Zinc, the part number is #4110.
How Much oil ? With a sight glass, fill it up until you see it. Without a sight glass, you can remove the snout bolt at 7 O Clock and fill it up until it runs out of that bolt hole.
6-71 and 8-71 usually take approx. 16 oz 10-71 14-71 sometimes take about 20 oz.
We sell a Synthetic supercharger oil on our site . https://www.alkydigger.net/proddetail.php?prod=ADBLOWEROIL
Q. How tight should I run my blower belt?
A. The blower belt adjustment should be done with the motor cold, and have 3/4″ deflection in or out on the long side of the belt. This should give you 1 1/2″ total deflection. Once the motor is warm this will decrease to roughly 1/4″ deflection in or out, or a total deflection of 1/2″. Over tightening the belt can cause severe damage to the blower and/or crankshaft.
Q. What makes the blower “surge”?
A. This is caused by a rich/lean cycle at idle. As the motor leans out the RPM’s increase and richen up the motor, when the motor richens the RPM’s decrease and the motor leans out again. This continual cycle is known as “blower surge”. With proper tuning, some of this surging should be able to be eliminated
With a mechanical injection , it is usually that the butterflies are closed too much or the barrel valve is too rich or both. See our injection notes for butterfly gap and leak down procedure and % .
We sell a nice leakdown tester for this purpose. https://www.alkydigger.net/proddetail.php?prod=LeakdownAD
Q. Do I need to use a balancer or a blower hub? Single key way or double?
A. Technically, you NEVER need a balancer on a blown engine. The belt under a load is a great eliminator of harmonics. We have blower, steel hubs, double key way for most engines . https://www.alkydigger.net/products.php?cat=141
If you insist on using a balancer, be sure to get a good steel , double keyed one, not a cast iron one.
When you get to about 10% under drive with a 6-71 , you should highly consider double keyway - We sell Pin Kits so you don't have to remove the crankshaft to pin the balancer for a blower
At 1-1 you should double key for sure
At 10% over with a 6-71 , you are ok with a double keyway, but with a 8-71 you should consider two things : A Crankshaft support, and/or a Big Block Snout on your crank.
At anything higher than 15% over with a 6-71 and 10% over with a 8-71 all small blocks should be equipped with a crankshaft support.
At 20% over with a 8-71 , 10-71 14-71... all Big Blocks should consider a Crankshaft support.
* Why ? - From the minute a blower begins to turn, it pulls the crankshaft up against the top main bearing- the more the boost or speed , the worse it gets. On a small block, you can snap the snout off the crank, on a big block, you will eventually beat the top main bearing out of the block-
More speed.... more of a problem.
The Crankshaft support acts like a 6th main bearing out in front of #1 main bearing, causing the crankshaft to be supported as if it is in a cradle.
We sell crank supports for Big Block and Small block Chevies, and we are about to introduce our LS Chevy support soon.
Be sure to use a new set of studs if you question whether yours are stretched: https://www.alkydigger.net/proddetail.php?prod=TBS-2590
Q. What type of oil should I run in my supercharger?
A. You should run a High Quality 80w/90 gear oil with a GL-5 rating with Zinc. Synthetic oil or Synthetic blends are OK to use. We do sell oil with Zinc, the part number is #4110.
How Much oil ? With a sight glass, fill it up until you see it. Without a sight glass, you can remove the snout bolt at 7 O Clock and fill it up until it runs out of that bolt hole.
6-71 and 8-71 usually take approx. 16 oz 10-71 14-71 sometimes take about 20 oz.
We sell a Synthetic supercharger oil on our site . https://www.alkydigger.net/proddetail.php?prod=ADBLOWEROIL
Q. How tight should I run my blower belt?
A. The blower belt adjustment should be done with the motor cold, and have 3/4″ deflection in or out on the long side of the belt. This should give you 1 1/2″ total deflection. Once the motor is warm this will decrease to roughly 1/4″ deflection in or out, or a total deflection of 1/2″. Over tightening the belt can cause severe damage to the blower and/or crankshaft.
Q. What makes the blower “surge”?
A. This is caused by a rich/lean cycle at idle. As the motor leans out the RPM’s increase and richen up the motor, when the motor richens the RPM’s decrease and the motor leans out again. This continual cycle is known as “blower surge”. With proper tuning, some of this surging should be able to be eliminated
With a mechanical injection , it is usually that the butterflies are closed too much or the barrel valve is too rich or both. See our injection notes for butterfly gap and leak down procedure and % .
We sell a nice leakdown tester for this purpose. https://www.alkydigger.net/proddetail.php?prod=LeakdownAD
Q. Do I need to use a balancer or a blower hub? Single key way or double?
A. Technically, you NEVER need a balancer on a blown engine. The belt under a load is a great eliminator of harmonics. We have blower, steel hubs, double key way for most engines . https://www.alkydigger.net/products.php?cat=141
If you insist on using a balancer, be sure to get a good steel , double keyed one, not a cast iron one.
When you get to about 10% under drive with a 6-71 , you should highly consider double keyway - We sell Pin Kits so you don't have to remove the crankshaft to pin the balancer for a blower
At 1-1 you should double key for sure
At 10% over with a 6-71 , you are ok with a double keyway, but with a 8-71 you should consider two things : A Crankshaft support, and/or a Big Block Snout on your crank.
At anything higher than 15% over with a 6-71 and 10% over with a 8-71 all small blocks should be equipped with a crankshaft support.
At 20% over with a 8-71 , 10-71 14-71... all Big Blocks should consider a Crankshaft support.
* Why ? - From the minute a blower begins to turn, it pulls the crankshaft up against the top main bearing- the more the boost or speed , the worse it gets. On a small block, you can snap the snout off the crank, on a big block, you will eventually beat the top main bearing out of the block-
More speed.... more of a problem.
The Crankshaft support acts like a 6th main bearing out in front of #1 main bearing, causing the crankshaft to be supported as if it is in a cradle.
We sell crank supports for Big Block and Small block Chevies, and we are about to introduce our LS Chevy support soon.