Pulleys interchangeable?

[CTScott]

The European EPC shows different part numbers for the crank pulley for the 1NZ versus the 1SZ and 2SZ (which share the same part number).

[Swing]

I think the above link is not complete?

Originally Posted by CTScott

The European EPC shows different part numbers for the crank pulley for the 1NZ versus the 1SZ and 2SZ (which share the same part number).

Yes I would expect different part numbers, I guess al that is important if the bolt is the same, and of course the belt width and number of groves.

Originally Posted by cali yaris

The only reason to use an underdrive is to save weight. My pulley is lighter than NST's underdrive, but stock size.
Also, read up on here about NST pulleys breaking and their lack of customer service following such failures.

Why is that the only reason? 10% underdrive means (at least for the water pump) 10% less power needed. (and of course, also 10% less cooling power).
I read about the NST and poor customer service etc.

You are right from the weight point of view, but I also want it to use less power. So lightweight + underdrive is better it seems to me.

[WeeYari]

Originally Posted by Swing

10% underdrive means (at least for the water pump) 10% less power needed. (and of course, also 10% less cooling power).

If only that were true.

It is not really a matter of consuming less power. The light weight achieves that. Going 10% underdrive was a way of making the pulley lighter still, while still providing enough rotation to drive a/c, alt, and water pump.

[Swing]

Ok thanks. Could be because of simply different width of the pulley and length of the bolts,.

Originally Posted by WeeYari

If only that were true.

It is not really a matter of consuming less power. The light weight achieves that. Going 10% underdrive was a way of making the pulley lighter still, while still providing enough rotation to drive a/c, alt, and water pump.

But if it's 10% smaller then it's like a 10% smaller gear. It means that for every revolution of the engine, the waterpump will drive 10% less, costing 10% less energy. The alternator is a different story, I guess the same for a/c if you have it. The alternator will have a certain load to generate a certain amount of current, so that will always be the same amount of resistance.

So why wouldn't underdriving work? Of course I could also put a bigger pulley on the waterpump (might be easier to find) to have the same effect.

Of course, the lightweight idea is straightforward and clear.

[CTScott]

Originally Posted by Swing

Ok thanks. Could be because of simply different width of the pulley and length of the bolts,.

It could be that or it could be that they are different diameter bolts. Unfortunately I don't have enough detail on them to be able to tell. You could go you your local parts department and have them pull the three different MK1 Yaris crank pulley bolts to see the difference. Over here we just get the 1NZ, so we don't have access to the others.

[CTScott]

Originally Posted by Swing

I think the above link is not complete?



Yes I would expect different part numbers, I guess al that is important if the bolt is the same, and of course the belt width and number of groves.



Why is that the only reason? 10% underdrive means (at least for the water pump) 10% less power needed. (and of course, also 10% less cooling power).
I read about the NST and poor customer service etc.

You are right from the weight point of view, but I also want it to use less power. So lightweight + underdrive is better it seems to me.

The bolts have different part numbers as well.