New Zetec Under Driven Pully

[STEVE GILBERT]

Just fitted my Raceco Under Driven Pully. What a top bit of Kit and probably the most nicely made thing on the whole car. Difficult to tell fron my run across town to collect the 3 year old but It does feel a bit crisper. Im going on the rollers again in a couple of weeks so I will be able to tell better the exact saving for any one who is interested. It does weigh two parts of bugger all and the finish is much better than other offerings I have seen

For once, well chuffed with something and a bargain at £90

 

Splurb and picture now on my website

 

See My Zetec Power 7 Here

 

Edited by - STEVE GILBERT on 11 Oct 2002 20:51:00

[simonbell]

I was considering this modification on my own zetec. A discussion about doing on another list suggested that the original pulley acts as an harmonic balancer for the crank and that the new pulley (by Esslinger USA in this case) did not.

 

Now I`m not exactly the most knowlegable when it comes to engines but I assume this means that at a given frequency the crank requires this pulley to remain balanced. Therefore if the new pulley does not fulfil this function is this a problem?

 

The guys were suggesting that the ultimate life of the engine may be shortened but given the mileage most se7ens do then it wouldn`t be a problem.

 

Can anyone else shine any light on this

 

Simon

[AMMO]

Simon

 

There was a discussion about this some time ago on Tech Talk. I did a search but was unable to find it. The conclusion I came to was that there would be no problem as long as the crank is in balance. Various firms I know and (some that I have worked for) who build Formula Ford Zetecs say that the Ford production cranks as standard have very good balance.

 

The other potential problem is with torsional vibrations. I spoke to two very well esatablished crank balancing firms (one I have been using for almost twenty years, the other works with F1, amongst other things). The conclusion was that once the Zetec is removed from a passenger car mated to a different weight flywheel, gearbox, drive shaft, diff and different wheels all the torsionals have changed. In view of the fact that components like the flywheel and wheels are lighter they could not see a problem fitting a lighter, smaller pulley. In simple terms if you remove weight from the back of the engine it is OK to do so from the front as well. The heavy vibration damper fitted to a passenger car is to make it comfortable at school run type speeds so you can hear the traffic news on the radio.

 

Another fact that reasured me and made me go ahead with the production of these pulleys is that there are several firms in the USA making them. In the land where people sue you at the drop of a hat the fact that anyone sells them at all makes me think they are OK.

 

The only problem I have heard of is engines throwing belts. This happens on a regular basis on rally engines due to high rpm. If anything the reduced belt speed may reduce this. Sometimes this happens simply because the alternator pulley is not aligned. Care must be taken when fitting.

 

On the plus side weight is reduced by 1.1 kilos (the pulley weighs just over 400 grms.) It reduces the alternator speed by 15% and reduces the water pump speed to 1:1 (Formula Fords reduce this further but they spend all their time at high rpm). This avoids cavitation of the coolant at high rpm and drag. I'm hoping to do some back to back tests on the dyno to see if there are any power gains. The yanks say 8 bhp but this is for Ford Focuses with aircon. So maybe there is a couple of bhp to be had.

 

I looked into importing the Esslinger ones but did dot like the open design which might let debris into the cam belt cover. Also by the time I paid carriage and import duty it was better to have them made here where I have some control over what is made. I also wanted them to be hard anodised rather than have the pretty colours of cosmetic anodising. The price of the pulley is the same as the Esslinger one in the US, only you don't pay carriage and import duty.

 

If there is any interest I am thinking of making some for the K series as well.

 

AMMO

[simonbell]

Thanks for the explanation....you`ve got mail