Fitting an underdrive pulley, worth it?

[phazed]

I was going to remove and shelve the A/C compressor for now, (A/C not working atm) and fit a shorter belt. Had a lightbulb moment and thought while everything is apart, why not fit an underdrive pulley.

Is there anyone with experience of this? Any noticeable improvement?

[edc]

I've done this on both my 986. I don't see any real down side. This is a reliability mod more than anything else and the theoretical reduction in drag loss and minor increase in wheel horse power is a by product. Don't forget the original aim of this is for the track where high rpm keeps the ancillaries spinning faster. The original aim was to stop the PAS pump overheating. 

[Nobbie]

I fitted one mainly to stop overworking the ancillaries as in my 2.5 I tend to use the upper end of the rev range. Never noticed any difference once fitted which is hardly suprising as my backside isn’t calibrated to within 1%😀. Sadly it didn’t stop my newly fitted oe water pump failing after 20k mikes, but maybe it would only have lasted 10k without.

[phazed]

Thanks for the responses. Where would one be available?

[bally4563]

11 hours ago, phazed said:

Thanks for the responses. Where would one be available?

Try the usual culprits D911 or 9apart , you will have to grind a boss off to fit

[phazed]

Watched a couple of YouTube videos last night and saw the methodology. I think Design911 do them for 129+ VAT and delivery.

[edc]

Design911 have most of the UK distribution for the US products. 

Looking back through my old posts my first was I think a 4.25" from a small business called Motordrive. I think they do seats too and were somewhere in the Mids. They sold up and all their product and stock went to SVP. Next up and on current car was the @jimk04 design, 4" from memory. Both were much cheaper than the import Design911 stuff.

I recall the one to avoid is the US Mantis one which has the spoked design. One example proven to have shattered. 

 

[T911UK]

We have them as a complete kit for £136

https://type911shop.co.uk/epages/de867ca1-377e-432e-84fd-bdccf2206766.sf/en_GB/?ObjectPath=/Shops/de867ca1-377e-432e-84fd-bdccf2206766/Products/22422

https://type911shop.co.uk/epages/de867ca1-377e-432e-84fd-bdccf2206766.sf/en_GB/?ObjectPath=/Shops/de867ca1-377e-432e-84fd-bdccf2206766/Products/22421

[EXY]

58 minutes ago, T911UK said:

We have them as a complete kit for £136

https://type911shop.co.uk/epages/de867ca1-377e-432e-84fd-bdccf2206766.sf/en_GB/?ObjectPath=/Shops/de867ca1-377e-432e-84fd-bdccf2206766/Products/22422

https://type911shop.co.uk/epages/de867ca1-377e-432e-84fd-bdccf2206766.sf/en_GB/?ObjectPath=/Shops/de867ca1-377e-432e-84fd-bdccf2206766/Products/22421

These look excellent value, would be difficult to go past them IMHO.

I am on record on here as stating an under-drive pulley is in the top five modifications on a Boxster.

In my opinion if you can't notice the difference after fitting you probably shouldn't be driving a sports car.

Also I wouldn't recommend removing the ALLOY boss with a grinder, WTF is it with power tools, it would be like using a sledge hammer to crack a nut and using a hack-saw blade won't plaster the car interior with filings.

Let us know how you get on 

[phazed]

The “no air con” one will be perfect. I will order that. I guess I will need or should I need a new crankshaft bolt?

[EXY]

17 minutes ago, phazed said:

The “no air con” one will be perfect. I will order that. I guess I will need or should I need a new crankshaft bolt?

I reused the old one with a drop of Loctite.

[phazed]

👍

[bally4563]

For the Boss removal I use a diamond burr done 3 or 4 of these now and as for the fillings didn’t take more than a couple of mins to vac up.

[EXY]

2 minutes ago, bally4563 said:

For the Boss removal I use a diamond burr done 3 or 4 of these now and as for the fillings didn’t take more than a couple of mins to vac up.

Let me guess, it wasn't your car 

I believe the easiest way to keep something clean is not to let it get dirty in the first place.

When I done mine I also utilised the damp paper trick whereby you place a dampened piece of paper (so it moulds into place) anywhere you want to keep clean or where detritus might gather.

Took less than 10 sec to clean plus there's no vac to get or put away AND I didn't have the worry of loads of metal filings buried in carpet or nooks & crannies that the vac couldn't lift, like your lungs fer instance 

Reminds me of my Engineering Manager days. You asked one of the apprentices to remove a cover or device and off he went to get a cordless drill, bit holder and invariably the incorrect bit. It was inconceivable he would carry a hand-tool in one of his many pockets. I always gave them one opportunity before removing said item myself with the terminal screwdriver I always had on me. 

I'm all for power-tools but sometimes it is ultimately faster with a hand-tool, at least in my experience, plus I don't have a diamond burr