Fiat Coupe Club UK

Balance shaft in 20VT - remove or not?

Posted By: PabLO20VT

Balance shaft in 20VT - remove or not? - 26/05/2014 21:38

With forged rods and pistons, new shaft, etc. I put the original new oil pump. I had disassembled the engine.

It makes sense to remove the balance shaft in 20VT? I saw on the forum that some users in the description of the car had a "Balance shaft remove".

It must be completely removed or just cut off the "fin" drive?

Crankshaft with pistons, connecting rods, pulleys, flywheel, etc. will be balanced.
Posted By: Per

Re: Balance shaft in 20VT - remove or not? - 28/05/2014 23:29

On the 16vt they have a point, but on a 20vt I cannot see why.
Posted By: szkom

Re: Balance shaft in 20VT - remove or not? - 29/05/2014 07:47

I suspect it's to deal with the 5 piston arrangement on the 20 valve.

Do people delete them on the 20 valves?
Posted By: Ferrarist

Re: Balance shaft in 20VT - remove or not? - 29/05/2014 18:32

Removed mine, there is different opinions how wise is to use balancer shaft together with oil pump "train".....
Saw many 5 pot Alfa JTD engines that becomes quieter when balancer shaft removed.
Posted By: lenzoferrari

Re: Balance shaft in 20VT - remove or not? - 29/05/2014 18:37

To be honest I would speak to barbz but iv never heard him say about removing it
Posted By: Stichl

Re: Balance shaft in 20VT - remove or not? - 31/05/2014 20:51

You can remove it because it is balanced to original weight of the rods and pistons. But I recommend additional balancing of the crank. Original crank is unbalanced with about 30g, adjusted to the balancer shaft in combination with the original rods/pistons. Fiat engineers did really much work in balancing complete engine.
Juergen
Posted By: Anonymous

Re: Balance shaft in 20VT - remove or not? - 01/06/2014 19:30

I've been down the removal path as has someone I know not on this forum but who races a 20vt

Neither of us are currently racing with our engines, there are issues with the oilpump when the shaft is removed that leave lovely bits of metal flowing round the engine

Looks like I'm going to be investigating dry sumping, so more delays for me

My recommendation is leave it in
Posted By: Stichl

Re: Balance shaft in 20VT - remove or not? - 02/06/2014 15:38

Originally Posted By: nyssa7
I've been down the removal path as has someone I know not on this forum but who races a 20vt

Neither of us are currently racing with our engines, there are issues with the oilpump when the shaft is removed that leave lovely bits of metal flowing round the engine

Looks like I'm going to be investigating dry sumping, so more delays for me

My recommendation is leave it in


Can you explain me why?! This does not make any sense?! The oilpump drives the shaft with help of a chain, which has no load any more after removal of the shaft. Therefore the stress for the complete oilpump theoretically even becomes less?!
I have no problems after removal and the people I know (with the same change) do not have any problems, too?!
Where do the metal bits coming from?!
Thank you
Juergen
Posted By: Jopa_zgd

Re: Balance shaft in 20VT - remove or not? - 02/06/2014 15:53

Stichl, how much RPM you turn your engine?
How much KM have you done with balance shaft removed?
little ot smile yours grale coop drives? smile

I'm doing a dry sump conversion and removing balance shaft gives me much easier job but people here tells me not to remove it because the engine will become unstable in high rpms smile
Posted By: Anonymous

Re: Balance shaft in 20VT - remove or not? - 02/06/2014 19:26

If I could explain it to you, I would. To be fair, its not my engines that have suffered this, but someone else who's engine was built by same people at the time - and they have warned me of this

Quite possible none of my engines has ever lasted long enough to suffer!

I have engaged a new company to rebuild my car, they are looking at the oil pump design to see if they can understand the issue without me having to run it up and damage it

Maybe the other person has other issues they are blaming on the oil pump - I honestly don't know. But am pleased that you are not having any issues
Posted By: Anonymous

Re: Balance shaft in 20VT - remove or not? - 06/06/2014 12:21

The harmonic imbalance on a 4 cyl remains the same throughout the rpm range whereas a 5 cyl engine has an imbalance that get progressively worse as the rpm rises, that's why 4 cyl engines are better ;-p
Posted By: Solouko

Re: Balance shaft in 20VT - remove or not? - 15/06/2014 17:57

Originally Posted By: 1NRO
The harmonic imbalance on a 4 cyl remains the same throughout the rpm range whereas a 5 cyl engine has an imbalance that get progressively worse as the rpm rises, that's why 4 cyl engines are better ;-p


And why 6 cylinders are better than 4cylinders and the smoothest engine ever made was a V12.

I think volvo, fiat and VW audi are the only 3 companies that even make a 5 cylinder engine because they're so hard to balance.
Posted By: Ferrarist

Re: Balance shaft in 20VT - remove or not? - 15/06/2014 18:59

Porsche running V4 engine on LeMans and V4 engine is almost impossible to balance.....
Posted By: Solouko

Re: Balance shaft in 20VT - remove or not? - 16/06/2014 22:15

I think single cylinder engines are harder, but that's the point of balance shafts, you can always stick a counterweight in there to smooth things out. but with a V engine you stick the shaft between the cylinders so it's at the center of mass, but on an inline engine it has to go on the side like the coop engine.

Also, are you sure it's not a V Reihenmotor 4 cylinder configuration, a VR means that it's a staggered inline engine lettng you use only 2 camshafts for a DOHC V engine.
http://en.wikipedia.org/wiki/VR6_engine

This is how the cylinders are in the bently W2 and the bugatti W16, technically they should be called WR engines.

The 5 cylinder engines that VW do are also VR5s derived from the VR6 used in the R32 golf.

You cant put the balance shaft where you normally would on a VR type engine, it's got to go at the side, but on the WR type engines then it can go back in the middle. but then, they probalby balance well enough without them.
Posted By: Anonymous

Re: Balance shaft in 20VT - remove or not? - 17/06/2014 18:30

Almost, v5 was dropped before the r32 engine was launched, you meant it was derived from the vr6 (2.9) of ye olde skool hot vw's.
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