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Lightened pulleys...


Adriank

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afaik it depends on the year of the car, or the engine to be more precise, i think, and i might be wrong that they work on the DE models but the revup engine nees them to be rebalanced (does that sound right?), i might be speaking complete rubbish but i suspect adam from z1 will know as he stocks them :)

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hey guys ;) Thanks Stew for the PM

 

Fitting a lightweight crank pulley is akin to fitting a lightweight flywheel - similar change, but on the other side of the crank.

 

The pullies are offered for all 2002 (I think that's the first year of the Z in Japan, in the US it's 2003) to 2008 Z's. The 2002-2006 cars all use the same exact ones. The HR engine (2007 +, the engine with the dual intakes) uses a totally different pulley.

 

Basically they work by reducing rotational mass. Give me a little while and I'll post the weights on both options. The net change is due to the reduced weight. Overall the engine revs noticeably quicker with the UR pulley installed vs stock. Some people have reported horsepower gains as well, others have not realized these. I'd suspect this is down to the anomolies of one engine vs another - they are like fingerprints at the end of the day.

 

As far as underdriven vs stock diameter, it really doesn't matter unless it's a very, very high revving engine. The underdriving lets the accessories spin at a slower speed, which reduces parasitic drag. Same type of theory as using, say, an electric water pump vs a chain or timing belt driven one. The less things you're asking the crank to spin, the less energy is being lost. Overall on a Z though, the differences between underdriven vs non are basically nill, as most people are not running high enough rpm's to notice the difference. Most of our customers go for the stock diameter unit.

 

As far as the full pulley sets vs the crank alone, as mentioned, the net change is mostly a result of the weight reduction. The factory accessory pullies for the water pump and alternator don't really weigh much. So, the crank pulley alone is the one that effectuates the change. The accessory pullies essentially just look pretty. So for those who want some more underhood "bling", the full pulley set is a nice option and really looks great on the car.

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