Engine balancing

[aelred]

I would say yes you need to balance everything, you cannot balance the crank without pistons and conrod assembly, unless you know the weight of this

[Bram]

Previously I have changed to Scat rods. The engine runs fine at this moment. Now I am about to put on a alloy FW, but is this now the moment to do a complete engine balance??

I could consider to balance the front pulley, crank, FW and clutch. This will be doable, since I will have to place a new clutch anyway. Is it also good enough to do it like that and leave in the pistons and rods? Because removing them is a hell of a job!

Please let me know what you think is smart. And yes I know taking out everyting is the best option

[Jamo]

The benefit is smoothness, the ability to reach higher rpm and therefore create more power. A reduced rotational mass provides less of a load on the engine. The smoothness improves reliability too... If you visualise an extreme case where components are out of balance then there is uneven loading on the bearings, conrods and so on.

It is true that you don't want to go extremely lightweight on a roadcar as you need a certain amount of rotating mass for smooth idle and silky power delivery.

Bassett Down have plenty experience of these engines - they will know how far to go, but it would be worth getting some reference weeights from others who have BTDT before you - I'm thinking of MarkH, Terrybullwon and others.

From memory I think approx 1kg can be safely removed from the crank as part of dynamic lightening and balancing. But please check with others who have done it.

Paul

I think 1K is good, IIRC some have had 1.5 kg removed. Terybullwon had his done via Aelred which wasn't BD

Volcano RS also had a very nice knife edge job.

Aelred has mentioned this other place in passing on the forum but not named it.

[Pirvu Eugen]

I saw on previous threads that ...iff done wrong...will distroy the engine...
Nobody wants this...
Better done by pros...
Thanks!
Eugen

[A80Avant]

i have changed the pistons and rods,but kept the crank,double mass flywheel and pulley.Car feels nice and there was no need of balancing.
The problem is that not everyone knows how to balance a 5cyl engine...

[Pirvu Eugen]

Thank You!
I will take in consideration this...for sure..
All the best!
Eugen

[S2central.net]

The benefit is smoothness, the ability to reach higher rpm and therefore create more power. A reduced rotational mass provides less of a load on the engine. The smoothness improves reliability too... If you visualise an extreme case where components are out of balance then there is uneven loading on the bearings, conrods and so on.

It is true that you don't want to go extremely lightweight on a roadcar as you need a certain amount of rotating mass for smooth idle and silky power delivery.

Bassett Down have plenty experience of these engines - they will know how far to go, but it would be worth getting some reference weeights from others who have BTDT before you - I'm thinking of MarkH, Terrybullwon and others.

From memory I think approx 1kg can be safely removed from the crank as part of dynamic lightening and balancing. But please check with others who have done it.

Paul

[Pirvu Eugen]

wow...!!!
Wich are actualy the benefits from doing this, in place off using heavier components?
will not affect the idle or something else?
I have tried to find a definitive answer about this...heavy crank versus lighter one...
Thank You!
All the best!
Eugen

[volcano rs]

you need to send clutch cover ,crank,flywheel ,rods, pistons ,and front pully.

[Pirvu Eugen]

Thanks guys!!!
This means i need gather everything and send everithing together to Basset Balancing...No?
i have skimmed pistons, scat rods, lightened flywheel...
Another expense....but better to be done by somebody good..here i dont trust enibody.
All the best!
Eugen

[S2central.net]

Dynamic balancing is certainly best practice, but if you are retaining stock rods, pistons and other rotating parts then you should be well within tolerance.

The benefit of a perfectly balanced (and lightened engine parts) is the way they really want to rev and rev so nicely. Its probably not worth your while unless you have some other lightweight parts you wish to attach to this new crank, but it is best Engineering practise on all engine builds.

[Pirvu Eugen]

Ahhh... So for 400hp is neccesary balancing?
What you think?
Thank You!
Eugen

[volcano rs]

Hello!
Maibe a stupid question... but...iff the rotating parts on the engine have to be balanced together, how the stealers sell the crankshaft separate?
Is not so important to balance the engine with all the new internals together?
Or i dont need to worry to much..
Thanks!
Eugen

dealers sell it to people who they think will using it for standard spec .for that it dosen't need balancing .

[Pirvu Eugen]

Hello!
Maibe a stupid question... but...iff the rotating parts on the engine have to be balanced together, how the stealers sell the crankshaft separate?
Is not so important to balance the engine with all the new internals together?
Or i dont need to worry to much..
Thanks!
Eugen