Vlad's rides thread

[v6bucket]

Balance shaft in or out?

[immortality]

Will be out with a double row timing chain set.

Not a huge issue, my old s1 VN never ran better/smoother than when I took out the balance shaft and fitted a powerbond race balancer. Got rid of that nasty vibration it always had around the 2300rpm that was bad enough to rattle the clutch fork against the slot in the bellhousing.

[psyolent]

see thats interesting.
back when i was a kid, lol, i had a v6 built for my old S pack. the entire lot was 'balanced' incl flexplate and balancer, berryman engines IIRC.
it revved out absolutely smoothly / beautfiully, however, it had a strange harmonic - not a vibration per se but it was definitely noticeable during normal driving.
when it was put together, we left out the balance shaft and the bellmouth in the manifold. i liken the reason for it was the lack of balance shaft due to the design of the v6.
i found a really good pic which explains it i might have in my archives somewhere.
just for consideration vlad.

[psyolent]

yes . here it is . http://www.fullthrottlev6.com/forums/sh ... park-knock

[vlad01]

I dont run a balance shaft in my VR and thats still at stock 36.5% balance. Only slight vibration at 1450rpm 50rpm either side, other than that its quite smooth and revs cleanly.


This engine however has been balanced at 50% so should be much smoother again.

[ejukated]

vlad01, psyolent, what sort of revs are you spinning to?

[immortality]

I think another one of the big issues is the POS factory harmonic balancers. A harmonic balancer needs mass to be able to absorb/dampen those harmonic vibrations. The OEM balancer lacks mass.

Balancers is one of those areas where lighter is definitely not better.

Been a 90° V6 the engine will never balance properly (as described in the link above) and will always have some strange harmonics. It's just a matter of minimising as best you can.

[vlad01]

vlad01, psyolent, what sort of revs are you spinning to?

Ill be spinning up to a max of about 6K for this engine. all my other stock engines I normally push them up to 5500


Im contemplating on going for 3.45 diff when I put in a trutrac.

Ill make the call once the engine is tuned on the dyno so I can see what if anything for the diff will need altering to suit the torque curve.

[vlad01]

I think another one of the big issues is the POS factory harmonic balancers. A harmonic balancer needs mass to be able to absorb/dampen those harmonic vibrations. The OEM balancer lacks mass.

Balancers is one of those areas where lighter is definitely not better.

Been a 90° V6 the engine will never balance properly (as described in the link above) and will always have some strange harmonics. It's just a matter of minimising as best you can.

agree on all of this.

[psyolent]

ejukated, i stopped at 5500rpm on the old girl. i'd not made any other changes to inlet and it ran out of breath up there. IIRC i had a 'commsport' throttle body on it 70mm jobby, which, was had been inaccurately 'bored out' so had way too much air going past at idle anyway. ah commsport. jeez i was young back then.