Performance Underdrive Pulleys - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

PaulG · 07-18-2001, 07:07 AM

I understand that installing a smaller, lighter underdrive pulley can free up some extra hp from an engine.  I have also heard that they can shorten the life of an engine (which doesn't sound right to me, but better to check before jumping in with both feet).  Anyone know whether this is true or not?  Also, What kind of hp gains could I expect if I did this?  How much of a pain in the @$$ would it be to install one of these things on my '95 s14?  

**West** · 07-18-2001, 10:55 AM

The chances you will ever see the ill effects of the underdrive pully is VERY slim. I have ran UD pulleys on all my cars and always will. The gain isnt great though. But its worth the $ to me.

*Jeff240sx* · 07-21-2001, 11:57 PM

From my understanding, Unorthodox Racing Pullys are horrible for the KA engines.  The KA has suck a huge stroke, and causes a lot of crankshaft vibration.  Nissan put a harmonic balancer on the main pully for a reason.  The Unorthodox pullys have no harmonic balancer on them, allowing the crank to wobble, causing stress on the bearings, mis-aligning things, and causes other damages.  Not all pullys are bad, but I wouldn't go without a harmonic balancer on my car.

PaulG · 07-23-2001, 09:19 AM

Ah, that's the issue.  I never quite understood why someone said that they could damage the engine, but that makes sense.  Well, since the decision is still at least a few months off, I'll have some time to think about it and look into what's available.  Thanks.

07-18-2001, 07:07 AM	#1
PaulG Join Date: Jul 2001 Posts: 2 Trader Rating: (0) Feedback Score: 0 reviews	I understand that installing a smaller, lighter underdrive pulley can free up some extra hp from an engine.  I have also heard that they can shorten the life of an engine (which doesn't sound right to me, but better to check before jumping in with both feet).  Anyone know whether this is true or not?  Also, What kind of hp gains could I expect if I did this?  How much of a pain in the @$$ would it be to install one of these things on my '95 s14?

07-18-2001, 10:55 AM	#2
West OMNOMNOMNOM Join Date: Dec 2000 Location: Denver, CO Age: 43 Posts: 6,456 Trader Rating: (0) Rides Gallery: West Feedback Score: 0 reviews	The chances you will ever see the ill effects of the underdrive pully is VERY slim. I have ran UD pulleys on all my cars and always will. The gain isnt great though. But its worth the $ to me.

07-21-2001, 11:57 PM	#3
Jeff240sx I hate you too... Join Date: Jul 2001 Location: Tampa, FL Age: 41 Posts: 5,828 Trader Rating: (0) Rides Gallery: Jeff240sx Feedback Score: 0 reviews	From my understanding, Unorthodox Racing Pullys are horrible for the KA engines.  The KA has suck a huge stroke, and causes a lot of crankshaft vibration.  Nissan put a harmonic balancer on the main pully for a reason.  The Unorthodox pullys have no harmonic balancer on them, allowing the crank to wobble, causing stress on the bearings, mis-aligning things, and causes other damages.  Not all pullys are bad, but I wouldn't go without a harmonic balancer on my car.

07-23-2001, 09:19 AM	#4
PaulG Join Date: Jul 2001 Posts: 2 Trader Rating: (0) Feedback Score: 0 reviews	Ah, that's the issue.  I never quite understood why someone said that they could damage the engine, but that makes sense.  Well, since the decision is still at least a few months off, I'll have some time to think about it and look into what's available.  Thanks.