New 21 tooth VX Drive Pulleys

[WestonE]

Guys

I have just received 2 new and perfect 21 Tooth VX drive pulleys made for me by Alan Young Engineering to replace my well worn 22 tooth originals. The Spider Europa VX ran the 21 Tooth pulley and they have been sought after for many years. If you would like one for your VX please contact Alan Young on 01387 740404. It really is a beautiful piece of engineering made with the correct and rare gear cutting machinery and a perfect match for the un-conventional Fiat Lancia belt at a reasonable price. Please make sure your VX unit is in good order before this upgrade as it will be spinning quicker producing more boost.

Eric

 

[VXdeMayo]

Dear Eric,
please could you tell me what sort of BHP increase is likely to be gained as a result of fitting this pulley? Sounds like a very simple power upgrade if your engine is in fine fettle. Also what sort of money is reasonable? Is there any problem re-adjusting the belt up to correct tension?
Best,
Chas,
(VXdeMAYO).

[WestonE]

Chas

Less than £100 (it is for Alan Young to set the price and I bought several bits at the same time). I would expect 10 BHP and 10ftlbs earlier in the rev range. Ideally you would want to be using a DCNF 40 in place of the standard lawnmower carb. I have mine bolted to a GC engine with a 3A inlet cam and gas flowed head, but there is more work to do on brackets and finishing the fuel injection before I can put it in the Montecarlo. I would expect the standard tensioner to be fine with a new belt.

Eric 

[VXdeMayo]

Thanks for that Eric, I will check the piggy bank!
Best,
Chas.
(VXdeMAYO).

[WestonE]

Chaps

Alan Young Engineering, Broadforth, Auldgirth, Dumfriesshire, Scotland. DG2 0RS Tel 01387 740404

Cheers

Eric

[spud]

Brilliant Eric, I'll be ordering one no doubt!

Andrew.

[spud]

Hi all and Eric in particular,
Just a random thought... as every component in engine manufacture has safety margins engineered into them I assume it was deemed acceptable by the FIAT engineers to give the Spider VX a 21 tooth pulley rather than the standard and proven 22 on the Lancia engine. If that is so, surely the 21 tooth pulley makes the VX unit spin well within the safety margins of it's design as FIAT aren't known for 'life-on-the-edge-engineering'... making me have the aforementioned random thought... what is the actual limit of the VX supercharger? I mean, I know it is also limited by the size of the pulley and the tightness of the turn the belt has to make around it but... if all the power hungry Lancia owners wanted one less tooth on the pulley then did the FIAT owners wish for the same...? (And also, why did the FIAT get it and not the Beta?) Is a 20 tooth pulley possible? 19 even? Has it been done? Just curious.

Andrew. 

[WestonE]

Andrew

This can get very complex with issues like excess heat removing the performance advantage and having the super charger over rev and kill the bearings or simply have the rotors go out of phase (position on the shafts). Since they are only held in place by friction shock loads can see them smash together and there is one less VX engine and supercharger. The MG conversion folk tend to make that mistake by going for a direct drive from the crank. I would not be happy to go beyond 21 tooth even with a nicely rebuilt VX unit and as it is a relatively small capacity Supercharger the effect of even smaller pulleys would be more boast low down before running out of puff probably creating lots of wheel spin. There might also be issues with detonation from excess heat to deal with plus a DCOE bolted one would have to have a yet smaller chokes to deal with fuel drop out on snap throttle opening.

There is a lot written on this on GC's forum and a number of books on superchargers for light reading if you want to get into this!.

Eric   

[rossocorsa]

also as the pulley gets smaller the wrap on the pulley will get too severe you would have to make the bottom pulley larger instead to gear up further. Personally I am going for one less tooth, 130tc inlet cam and a dcnf40 which will make it a tad more perky but at a passing glance will still look original. I feel chasing big power is a thankless task and a never ending hunt for the holy grail plus the front tyres will probably not tolerate it as traction in a standard VX is borderline at times.  

as regards safe rotation speed decided by Fiat did the spider vx have the same number of teeth on the crank pulley? If it had less that could explain things 

Alan

[spud]

Thanks for the replies you two. Your thoughts are much appreciated.

 as regards safe rotation speed decided by Fiat did the spider vx have the same number of teeth on the crank pulley? If it had less that could explain things 

Alan

Aah, interesting point! Anyone know the answer to this?

Andrew.

[WestonE]

Alan

Yes the Fiat Spider had the same 29 teeth on the Crank Pulley and you are spot on with the belt wrap comment. To spin the SC faster the right way to do it is to increase the size of the crank pulley, but that is much harder to engineer. With my custom tensioner for the FI VX Monte I am being careful to get the tensioner on the drive side to promote as much belt wrap as I can with the shorter 93 tooth conversion belt. At least the new 21 tooth pulley is not half worn away like many well used 22 tooth VX pulleys.

Eric   

[spud]

Hi all,

Does anyone know what this is??

http://www.ebay.co.uk/itm/251413552710?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_101wt_1162

It's not making much sense to me...

Andrew.

[Neil-yaj396]

Is it not what it says? The crank pulley adapted to drive the supercharger (as well as the cambelt)? Or am I missing something too??

[rossocorsa]

It is a normal crank mounted pulley for a vx but has received another larger pulley on top, welded to it as far as I can see, rather more than a single tooth extra by the look of it. From an engineering point of view it is better to enlarge the crank pulley (more difficult) than shrink the blower pulley (easy)because the blower pulley becomes a bit small resulting in a rather tight wrap of the belt around it, however not sure about the gearing on this pulley it looks like it might be a bit OTT and increase the blower speed rather more than is safe, without knowing the number of teeth and working it out difficult to know for sure. Also on a beta rather than a kit car it will spin the ps pump faster too which could be an issue I suppose?

[spud]

It is a normal crank mounted pulley for a vx but has received another larger pulley on top, welded to it as far as I can see, rather more than a single tooth extra by the look of it.

Thanks Rossocorsa, I understand what it is I'm looking at now! I could see teeth where there shouldn't be... and the mention of 1 extra tooth when there's clearly a few more than that... all rather strange. I agree, probably OTT.

Andrew.

[rossocorsa]

On the crank pulley you would need more than one tooth to gear it up adequately, it is just a question of how many. Looking at that pulley I rather suspect they used a cut down aux shaft pulley on it ?? Could be wrong though!

[SanRemo78]

Old thread I know.. back in the day, 20 years ago probably, when I had a Volumex unit (retrieved from an accident damaged car) in my Stratos replica it had an engine built up by Barry Waterhouse. We increased the speed of the supercharger (I forget by how much!) by getting a pulley wheel from a spare power steering pump, machining the centre out for an interference fit on the crank pulley. It avoided any issues with belt wrap on the supercharger pulley and provided a belt guide too. The choke on the standard carb was opened up a little and re-jetted and I think it had cams from a 1600 engine (exhaust only?) and made around 190-200 bhp.
Guy