Crank pulley vibration dampers & harmonics. Update: Lightweight crank pulleys = Bad

full on race engine run special cranks..

The F2 engines are new, and materials inside we dont know about.

On a stock crank, balanced, the lack of damper had catasrophic effect

 

Yes, in this single example.

There are also many examples where it has not had a catastrophic effect.

 

They've done the 2009 season with them, so there's a season's reliability there.

Ref cranks, surely that comes back to whether the crank is balanced or not (Swindon - tick), and the revs involved? (Swindon - 'mid to high 8krpms').

Or are we now in the zone of analysing crank twist on stock cast vs forged vs billet?

 

there are more where crank pulleys fall off, and shear keyways off, as well as shed internal trigger wheels.. Not connected with harmonics?

there is huge evidence of benefits of a damper designed to cope with the engine it was designed for and the rpms its likely to see

some debate on vortex also.
http://forums.vwvortex.com/zerothread?id=4421682&page=3

I am comfortable I have made the right pre-emtive choice for my motor
the science stacks up

 

yes
different animals for which none of us have the data for

I am talking 1.8t factory forged crank, fluid damper and 8k+rpms on a built and balanced engine.

 

Ok, well amongst us is a stock forged 2-litre crank, balanced, swinging to 8,500 rpm, without any vibration damper, and importantly without a turbo.

But Swindon are still no mugs, and the nature of the blow up is so severe.

We were very fortunate to hear about this example. How many examples stay within the dyno rooms, out of sight and adverse commercial impact?

 

I am now afraid to rev mine past 8k rpm, after reading all this!

My engine still runs sandard damper pully, is very smooth tho at high revs

 

intereesting read here:

http://www.vibrationfree.co.uk/Rattler.htm

vibration dampers are made for a specific set of engine components - change anything, and you need to change the damper.

seems there are a lot of engines knocking around with modifications and stock dampers that dont have any problems....

equally, maybe you can just get unlucky with a set of components and a resonance peak occurring within a commonly used power band

 

The OEM damped pulley would probably be sufficient for most of us I would have thought.

Gurds

 

some claimed power from dyno run, presuming gains from less energy losses from dealing with the harmonics etc


I did'nt buy mine because it claimed power as I have more than I need now, but it felt more reassuring

 

Interestingly that's an engine going to 7k, with the most difference from 5-7k.

Are there any graphs for higher rpm motors?

 

not seen any

 

question i find myself asking is:

02a g'boxes
abf engines
single mass flywheels
no rattle or gbox chatter as i recall

02j boxes
1.8t engines
std dual mass flywheels
no rattle or gbox chatter

02a/j boxes
1.8t engines
swap to abf single mass flywheel
rattle and gbox chatter always

why?

balance not what it once was on later engines? dual mass flywheels doing more than we think? cost cutting on engine balance?

 

Are these always in the same types of car (Ibiza/Mk4) or various?

I'm also thinking engine mounts - they help boxes chatter at idle.

 

nope, engine mounts irrelevant

ibizas, golfs, leons, all dual mass before, single mass after = rattle
different engine mounting style

 

Dual Mass Flywheel = low pass filter for torsional vibration to drive train. This system was first used on modern Diesels.
ABF is a non turbo w/NVH quality, amongst other things, not acceptable by todays stds for new vehicles.
1.8T turbo w/NVH closer to what is expected by todays stds for new vehicles.

NVH improved further with newer 2.0, 1.8 and 1.4 TSI engines. All have DMFs.

As vehicles engines become more downsized w/turbo charged and direct injection for petrol, expect the widespread use if the DMF.

NVH qaulity expected for a new car might not be a problem for most of us enthusiasts if the engine is being swapped into something older or we are after more power and torque from std. Plus we would rather have a flywheel that stayed in one piece when we pass huge torque through it!
Still would need a good harmonic damper though

 

Just a related thought: does the behaviour of a harmonic damper change with time (rubber degradation) & use (revs, stress etc) ?

I assume they're not a listed service item?

 

the noise/vibration is only apparent when in neutral and no clutch depressed. It quietens when the clutch is depressed.
ABF dont make this noise why should 1.8t's

single mass and better balanced engine (more costly?)
Vs
Dual mass and worse balanced engine (cheaper?)

My ibiza does'ntt rattle anything like other 1.8t's which just have flywheel clutch change which makes me think its inherant engine balance and cost cutting at vag

 

I wonder what a 9A/6A would do? Block height / rod length etc. Compressions would then be the o/s difference.

Interestingly the TSI/TFSI has twin balancer shafts internally.

All looks like a lot of work - any correlation?

 

ABF code uses a part ally damper, and intermediate shaft, runs a different stroke and rod ratio and different max BMEP to a boosted 06A 1.8T.
These must have an effect on critical speed and the counter measures to reduce the chances of fatigue from the crankshaft.