jeffw
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| posted on 11/11/09 at 07:33 PM |
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Lightweight Alloy Pulleys
I'm looking at a set of lightweight alloy pulleys for my Zetec (anodised red  ) and wondered if anyone had any thoughts on if they are worth
the effort or not.
The engine is 2lt in 45mm Jenveys with 285 Pipercams & vernier cam pulleys
Do we think that crank / waterpump and idle pulleys would make any difference ? Car already has a lightweight alloy alternator pulley
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coozer
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| posted on 11/11/09 at 07:38 PM |
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Lightweight crank pulley may make a difference to engine performance..
You say it has vernier pulleys, are they not ali and already lightweight???
1972 V8 Jago
1980 Z750
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jeffw
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| posted on 11/11/09 at 07:44 PM |
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Yeap...already got Vernier Pulleys. Interested in the Crank Pulley aiding performance...
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Mal
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| posted on 11/11/09 at 07:44 PM |
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The standard crank pulley on a silvertop is of a two piece metal construction with a bonded rubber middle to the sandwich. This may serve a crank
vibration damping function. if it does, it is not a good idea to remove it.
Mal
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goodall
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| posted on 11/11/09 at 08:19 PM |
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As said most modern engines use a torsional damper design, which if done away with you risk snapping the front the crank off. However they arent that
effective and can be done away with, for most older cars didnt have them and considering the limited mileage of a kit I wouldn't worry. Also
alot of tunned turbo engines, which produce alot of torque (ie twist the crank more) do away with the damper and dont fail
Im currently designing my own pulley and had have looked at these issues
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goodall
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| posted on 11/11/09 at 08:50 PM |
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Also, what is they say for every pound of the crank you effectivly get 1bhp. Don't know how much truth is in that how ever
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Bluemoon
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| posted on 11/11/09 at 09:28 PM |
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quote:
Originally posted by goodall
Also, what is they say for every pound of the crank you effectivly get 1bhp. Don't know how much truth is in that how ever
Not true, it increases the rotating mass but the static power (at a fixed RPM) will be the same.. I might increase acceleration mind as you
don't have to spin up the mass but I would think this is negligible (it's a lot smaller than the flywheel, with a lot less rotating
inertia)..
As to the mass damping function of the crank pulley I'd not change it unless you knew it didn't need it. The resonances that it's
stopping are dynamic you might get awaywith it for a while but under certain conditions (load RPM, time held at RPM, missfireing ect) the vibrations
build up in the crank and snap/crack the crank.
Model T had that issue as they had yet to work it out what to do (and hence limited to about 1600rpm!)..
Dan
[Edited on 11/11/09 by Bluemoon]
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clairetoo
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| posted on 11/11/09 at 09:33 PM |
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I read somewhere that 1kg off the rotating mass is the same as 10gk's off the weight of the car as far as acceleration goes - I have ally
pullies and flywheel (something like 10kgs of rotating mass removed....) and it sure does pick up well 
Its cuz I is blond , innit
Claire xx
Will weld for food......
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Bluemoon
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| posted on 11/11/09 at 09:37 PM |
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quote:
Originally posted by clairetoo
I read somewhere that 1kg off the rotating mass is the same as 10gk's off the weight of the car as far as acceleration goes - I have ally
pullies and flywheel (something like 10kgs of rotating mass removed....) and it sure does pick up well
But if the pulley weighs 1kg or so that's not a lot, and you are increasing the risk of unreliability.. You would be better off getting a
lightened flywheel, that will make a bigger difference  ..
Dan
[Edited on 11/11/09 by Bluemoon]
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Danozeman
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| posted on 12/11/09 at 07:40 AM |
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Are they the underdrive things?
I fitted a set of these to my mates st170 it made no noticable differenence but i think he said it should give 2hp more or something.
Dan
Built the purple peril!! Let the modifications begin!!
http://www.eastangliankitcars.co.uk
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dhutch
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| posted on 12/11/09 at 11:01 AM |
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quote:
Originally posted by clairetoo
I read somewhere that 1kg off the rotating mass is the same as 10gk's off the weight of the car as far as acceleration goes - I have ally
pullies and flywheel (something like 10kgs of rotating mass removed....) and it sure does pick up well
Ofcauase with the, it depends where the weights removed.
- Its along the centerline of the crank with will make basicaly no diffrence to the car other then the actual added weight. If its right round the
edge of the flywheel however, obvisouly it will add significat intertia to the flywheel which will mean it spins up slower and spins down slower, or
is otherwise generally more flywheel like in behavoiour!
Again as said, reducing the weight of anything wont increase the horsepower. But i decreases the intertia/weight of it so will (to a greater or lesser
extent) improve accelatation.
Daniel
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jeffw
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| posted on 12/11/09 at 11:07 AM |
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Certainly a reduction in rotational mass should improve engine response which, in turn, will aid acceleration. I would be very surprised if there was
a increase in actual power output.
Lightweight flywheel is already on the list and the pulleys anodised red would be very bling
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fatbaldbloke
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| posted on 12/11/09 at 01:13 PM |
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quote:
However they arent that effective and can be done away with, for most older cars didnt have them and considering the limited mileage of a kit I
wouldn't worry.
Acknowledging I'm more-or-less admitting I should get out more...not so, Sir. The TR2 first produced in 1953, and most subsequent 4 cylinder
TR's, had torsional damper type crank pulleys. These had a long nose which took a 4 bladed fan plus a socket to take the starting handle which
was inserted through a hole in the radiator. Many owners fitted Kenlowe fans to take away the power consumption of the fixed fan and at the same time
removed the long pulley (so the fan could fit). And lo and behold, crank breakages started to appear, usually at the clutch end which is where the
undamped vibration was at its worse.
[Edited on 12/11/09 by fatbaldbloke]
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snapper
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| posted on 13/11/09 at 08:25 PM |
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If you did remove the Ford designed damper you would need to balance pistons and rods to get them even then rotationaly balance the crank, flywheel,
clutch cover and front pulley of your choice.
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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