Extra weight on the crank pulley

[daxtojeiro]

Hi all,
Ive been wondering wether the extra weight Ive stuck on the end of my crank pulley will cause problems with the crank. Its an RV8 which Ive supercharged, in order to drive the blower Ive had to extend the length of the pulley by 30mm with an round aluminium block. Ive bored it out to reduce its weight but just wondered what it might do long term to the crank?
Heres a picture of it:
www.replica-cobra.co.uk/Pics/Pic84.jpg
Phil

[greenv8s]

That looks like a lot more than 30mm! I guess in principle it should be OK as long as it is absolutely straight and central?

[BogBeast]

My new pulley had to be balanced prior to fitting to my Griff. I would suggest that it would be a good idea to get yours balanced...

[350matt]

It all depends on what you're using the car for, if its just for racing then don't worry too much as doubtless you'll be regularly stripping the lump anyway.
However the front pulley incorporates a inertial damper which is a tuned chunk of iron rubber mounted. This damps out the natural frequency of the crank and helps to reduce crankshaft twist and 2nd order harmonics ( crank whip). If the inertia of this piece is changed you'll change the frequency of the damper and probably no damp out the crank natural frequency as well.
If the engine feels more vibratory or you start knocking out mains shells then you'll no something is amiss.

[daxtojeiro]

Hi,
thanks for the replies, it sticks out 33mm from the edge of the alternator pulley to the edge of the blower pulley, then theres 36mm of blower pulley, so in total it sticks out 70mm.
As its made from billet alluminium and turned centrally on a lathe I didnt bother having it balanced, but I think i'll play it safe and get it balanced,
thanks
Phil

[greenv8s]

My new front pulley is simmilar but much shorter. As I understand it the front pulley is in two parts with the inner part being rigidly connected to the crank and the outer weight flexibly mounted to that. The pressed pulleys for the drive belts bolt on to the inner, fixed part so adding extra drive pulleys here shouldn't have any effect on the damper frequency. It still needs to be balanced, just as any rotating part would, but I don't think it will affect the damping.

[v8 racing]

providing you had the pulley re balanced i cant see a problem, in the past i have run extras pulleys for blowers/power steering/and an external oil pump all on the same engine and the pulley was massive, worked ok though.

[daxtojeiro]

Thanks for the replies, will be getting it balanced very soon, good to hear youve added extra weight and got away with it,
Phil

[Boosted LS1]

I've added a viscous fan to the crank of an rv8 in the past and had no vibration problems. It was the best cooling mod I ever did