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The mkiv Supra Owners Club

Front Pulley part number


dandan

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Anyone let me know what the part number is for the front pulley and if possible any bolt/washer that may be needed?

 

This is for a 1996 manual non vvti facelift jap RZ, not sure if all pulleys are the same?

 

Anyone got a rough idea of cost?

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Originally posted by leett

i wouldnt be surprised if the uprated pulley from boostlogic was a similar price to the toyota one.

You think underdriven and/or lightweight pullies are a good idea? I I'd stick with the stock one for a road car.
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Originally posted by Jake

You think underdriven and/or lightweight pullies are a good idea? I I'd stick with the stock one for a road car.

 

im quite sure the bl crank pulley is a quality bit of kit with no downfalls. im sure terry will be along to add to this shortly

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Originally posted by Jake

You think underdriven and/or lightweight pullies are a good idea? I I'd stick with the stock one for a road car.

 

Read my TVD post in the FAQ thread at the top of technical and make up your own mind. :cool:

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Sorry chaps but no chance I'll be fitting a Boostlogic one.

 

I don't doubt the workmanship or quality, but I value my engine longevity too much to sacrifice it for the small gains a lighter pullet MAY give.

 

Too many risks for my liking, especially given the relatively long stroke of the 2JZ and the harmonics that can be generated.

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I'm not a convert, I'd never fit lightened components such as flywheel or front pulley to my motor unless it was a dedicated race engine or underwent regular strip downs and checkovers.

 

At the very least I want the whole engine stripped and the rotating assembly balanced dynamically as one. - Hopefully to go some way to extending the life and promoting some smoothness. I'm sure the balancing must be thrown off by just throwing on a aftermarket flywheel and front pulley.

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Originally posted by dandan

At the very least I want the whole engine stripped and the rotating assembly balanced dynamically as one. - Hopefully to go some way to extending the life and promoting some smoothness. I'm sure the balancing must be thrown off by just throwing on a aftermarket flywheel and front pulley.

 

It's got nowt to do with rotating balance. The crank pulley is there to damp out oscillations. These are a function of the crank stiffness, pin layout, inertia and firing order.

 

It might help with NVH and it might give the bearings an easier time, but it won't alter the affects of using a light pulley or flywheel.

 

Likewise, fitting a light pulley or flywheel won't affect the engine balance. Vibration / bending and balance are two separate entities.

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  • 2 weeks later...

I know that Darren.

 

I was trying to make two different points.

 

1. The damping side of things provided by the Toyota pulley and the dual mass flywheel.

 

2. I'm sure the stock rotating assembly is designed be balanced to a certain degree once assembled even if it is not dynamically balanced as one (as it's a mass produced engine). There are no guarantees that the balancing will be as good as stock when an aftermarket pulley is thrown on. Hence my comment about maybe fitting it if the engine was fully stripped and the rotating components all balanced as one. Even then I'd still have the original concerns about the lack of damping.

 

But if all the stock pulleys are totally neutral as far as balance is concerned so as to have no effect on the balance of the rotaing components then this wouldn't be true. Assuming the Boostlogic was the same a swap shouldn't cause any balance issues.

 

The light weight wasn't what concerned me with regard to balancing, it was the possible mismatch of individually balanced components however the damping would definitely be my first and greatest concern.

 

Make sense? - not sure if explained myself well enough there? :)

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Originally posted by dandan

1. The damping side of things provided by the Toyota pulley and the dual mass flywheel.

 

Yep. The flywheel, torsional damper and bending damper will all be tuned to each other and the stock cranktrain.

 

Originally posted by dandan

2. I'm sure the stock rotating assembly is designed be balanced to a certain degree once assembled even if it is not dynamically balanced as one (as it's a mass produced engine). There are no guarantees that the balancing will be as good as stock when an aftermarket pulley is thrown on. Hence my comment about maybe fitting it if the engine was fully stripped and the rotating components all balanced as one. Even then I'd still have the original concerns about the lack of damping.

 

Each component will be maunfactured to tolerances which will, when randomly assembled, always result in a total level of dynamic rotating balance that will be acceptable in terms of bearing life, NVH, fatigue, etc. The crankshaft itself will probably be balanced my selective machining of holes around the edge of one of the counterbalances. The flywheel may well be balanced the same way, and perhaps even the front pulley. The rods might be graded for end-to-end balance and then selectively assembled - I have certainly seen this approach on engines designed around the same time as the 2JZ. Nowadays with sintered rods in a lot ofhigh-volume engines the individual parts are sufficiently accurate that no grading is necessary. The pistons, pin and rings will be accurate enough off the shelf so as not to require selective assembly. I agree that the entire rotating assembly would not be balanced as one, although its not outside the realms of possibility. IIRC the Lotus 4-pot was balanced this way from the factory, but that was hardly mass production.

 

Therefore if an aftermarket pulley was put on that was machined to the same level of balance as the stock one, simply swapping them over should not have any effect on the total balance (at least it should not suddenly make it "unacceptable").

 

Originally posted by dandan

But if all the stock pulleys are totally neutral as far as balance is concerned so as to have no effect on the balance of the rotaing components then this wouldn't be true. Assuming the Boostlogic was the same a swap shouldn't cause any balance issues.

 

Since a pulley is basically a turned part it should be pretty hard to make it anything other than perfectly balanced, straight off the lathe. It is usually only large, rough forged or cast parts (crank, flywheel) that require specific machining operations to balance them up.

 

Originally posted by dandan

The light weight wasn't what concerned me with regard to balancing, it was the possible mismatch of individually balanced components however the damping would definitely be my first and greatest concern.

 

Make sense? - not sure if explained myself well enough there? :)

 

The light weight in itself would not be an issue for pure rotational balancing, and hopefully the mismatch of any swapped out parts would not be an issue either. However, the weight (end hence inertia) would be an issue for damping, as it will alter the resonant frequencies in the cranktrain.

 

Good enough explanation for me! :)

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