Spinning The Right Way?

[mbdblue]

So I read on here one day that theres a right way and a wrong way for the alternator to spin.....dont have have much experience with alternators.....so I wanted to know if theres any way to tell which way its supposed to spin. Reason I ask is cuz I have my stock one in now, but the one I bought from MECHMAN is custom built for a yukon and I dont want to just throw it in and expect it to be spinning in the right direction; find out it isnt and have to rip it back out and get repaired.

[Guest Powered By Hate]

The only thing that matters is if the fan blades scoop air.. the guy at my work rebuilds alt and I was VERY concerned with this.. So I asked him and his dad (whos been doing the alternator game for 30 years) and they told me the same thing. `

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[missinglink]

With the notable exceptions of Honda & Corvair, everything else spins the same direction.

Serpentine drives complicated things when detroit began running things like the water pump from the back side of the belt - making it spin in the reverse. Alternators are driven from the grooved side of the belt, and spin the same direction as the crankshaft.

The only way to drive an alternator "backwards" would be to mount it reversed - that is hanging in front of the belt. Almost impossible without a lot of fabricating.

Some alternators have inclined blades in the fan(s), others are at 90 degrees. An inclined blade is somewhat more effecient if spun in the design direction, but will usually be ok if run reversed. 90 degree blades are completely bi-directional.

'Link

[mbdblue]

With the notable exceptions of Honda & Corvair, everything else spins the same direction.

Serpentine drives complicated things when detroit began running things like the water pump from the back side of the belt - making it spin in the reverse. Alternators are driven from the grooved side of the belt, and spin the same direction as the crankshaft.

The only way to drive an alternator "backwards" would be to mount it reversed - that is hanging in front of the belt. Almost impossible without a lot of fabricating.

Some alternators have inclined blades in the fan(s), others are at 90 degrees. An inclined blade is somewhat more effecient if spun in the design direction, but will usually be ok if run reversed. 90 degree blades are completely bi-directional.

'Link

hahaha shit......Im tryin it in a honda accord......well Ill probably learn tonight if I get to it.....thanks for the replys

[mbdblue]

well maybe not hahaha.....still holding on this due to having to mount my friends speakers and subs down. but we'll see....

[missinglink]

The biggest problem with online help is not enough information.

You never mentioned what vehicle it was going in - only a Yukon as the make of the source vehicle.

Over the years, the Yukon has had several alternators in it - CS130, CS144, CS130D & AD244

Rotating an inclined blower in reverse can cause it to lose performance at one end of the envelope or the other. Most Delco units have inclined or curved blowers. Here is some more information on inclined blowers:

"What is the difference between a backward inclined and a forward curved impeller?

Backward inclined or backward curved blades are constructed of single thickness with 9 to 16 blades curved or inclined away from the direction of rotation.

The air will leave the impeller at a velocity less than its tip speed.

The Backward inclined impeller is non-overloading and if used in an application where the static pressure in incorrecly calculated, it will prevent the fan motor from burning.

The Forward Curved Impeller's efficiency is less than the backward inclined impellers. They are usually fabricated at low cost and made of lightweight construction.

They normally have 24 to 64 shallow blades with both the heel and tip curved in a forward configuration.

The air will leave the impeller at velocities greater than the impeller tip speed. Tip speed and primary energy transferred to the air is the result of high impeller velocities. For the given duty, the wheel is the smallest of all of the centrifugal types and operates most efficiently at lowest speed. "

Your best bet is to confirm that your installation does not void the warranty from your alternator supplier. A reduction in airflow could quickly damage an alternator.

'Link

[MECHMAN]

That is a high efficiency swept blade turbo fan, it moves about 15% more air than a traditional baffled straight blade fan. When designing the profile of that fan, we paid an outside lab for airflow analysis. Running that fan backwards decreases airflow through the back rectifier opening by almost 20%, which can definitely be an issue on a 250 amp alternator. Just make sure you don't run it maxed out for more than short periods at one setting wihtout unloading it and giving it a chance to cool. We will always warranty a burnt stator once, even if it was clearly from abuse. The rectifiers we use will NOT burn up from heat, I've tried to fail them intentionally and have not been able to.

[mbdblue]

thats some great info from both you guys....in that case, I may consider designing my own air cooling system for the alt.....got my ideas flowin about this. Thanks again everyone!

[newls1]

The biggest problem with online help is not enough information.

You never mentioned what vehicle it was going in - only a Yukon as the make of the source vehicle.

Over the years, the Yukon has had several alternators in it - CS130, CS144, CS130D & AD244

Rotating an inclined blower in reverse can cause it to lose performance at one end of the envelope or the other. Most Delco units have inclined or curved blowers. Here is some more information on inclined blowers:

"What is the difference between a backward inclined and a forward curved impeller?

Backward inclined or backward curved blades are constructed of single thickness with 9 to 16 blades curved or inclined away from the direction of rotation.

The air will leave the impeller at a velocity less than its tip speed.

The Backward inclined impeller is non-overloading and if used in an application where the static pressure in incorrecly calculated, it will prevent the fan motor from burning.

The Forward Curved Impeller's efficiency is less than the backward inclined impellers. They are usually fabricated at low cost and made of lightweight construction.

They normally have 24 to 64 shallow blades with both the heel and tip curved in a forward configuration.

The air will leave the impeller at velocities greater than the impeller tip speed. Tip speed and primary energy transferred to the air is the result of high impeller velocities. For the given duty, the wheel is the smallest of all of the centrifugal types and operates most efficiently at lowest speed. "

Your best bet is to confirm that your installation does not void the warranty from your alternator supplier. A reduction in airflow could quickly damage an alternator.

'Link

That is a high efficiency swept blade turbo fan, it moves about 15% more air than a traditional baffled straight blade fan. When designing the profile of that fan, we paid an outside lab for airflow analysis. Running that fan backwards decreases airflow through the back rectifier opening by almost 20%, which can definitely be an issue on a 250 amp alternator. Just make sure you don't run it maxed out for more than short periods at one setting wihtout unloading it and giving it a chance to cool. We will always warranty a burnt stator once, even if it was clearly from abuse. The rectifiers we use will NOT burn up from heat, I've tried to fail them intentionally and have not been able to.

That is some DAMN GOOD info from you guys.....appreciate it....Missing link, heads up, I have an order coming soon...

[missinglink]

That is some DAMN GOOD info from you guys.....appreciate it....Missing link, heads up, I have an order coming soon...

Thanks. We will be looking for your order. Just make sure you give Chris all the info - Year / Make / Model / Engine size / Alternator (OEM or aftermarket).

MechMan:

That sounds like quite a fan. Do you have some pictures of it?

'Link