Commodore V6

[MRMOPARMAN]

Ummmm, the reason it needs a balance shaft is because the 90 degree (one of the most common, as it is a V8 with 2 cylinders chopped off) V6 configuration is NATURALLY unbalanced. Practically all 90 degree V6s have balance shafts, whilst inline 6s (which are naturally balanced) don't need them. None of this crap about Holden/Buick not bothering to balance the engine. Inline 4s are naturally unbalanced too (2nd order vibration at twice engine speed), but most of them are small enough to not need balance shafts (which is why bigger 4s like the 2.6L Astron needs them)

 

your right, being a Vee engine they are naturally unbalanced.. but so is every over Vee engine. but most manufacturers go to the trouble of balancing their internals somewhat (atleast to a tolerance anyways).. hence they don't need balancing shafts.

astron internals when balanced don't need balancing shafts. I'm going to assume it would be the same with the dunnydore V6. (note, 2nd hand info coming) ive heard of quite a few mild VN V6 buildups, of which the internals were balanced, and the shaft was given the arse. and last time i heard (a few years now) they were running as smooth as when they had the shaft.

 

i stand corrected about the engine capacities though :D

[Hiro Protagonist]

your right, being a Vee engine they are naturally unbalanced.. but so is every over Vee engine. but most manufacturers go to the trouble of balancing their internals somewhat (atleast to a tolerance anyways).. hence they don't need balancing shafts.

astron internals when balanced don't need balancing shafts. I'm going to assume it would be the same with the dunnydore V6. (note, 2nd hand info coming) ive heard of quite a few mild VN V6 buildups, of which the internals were balanced, and the shaft was given the arse. and last time i heard (a few years now) they were running as smooth as when they had the shaft.

 

i stand corrected about the engine capacities though :D

 

Actually, you're wrong once again. 90 degree V8s are naturally balanced, as are 60 degree V6s. You don't seem to know much about harmonic balancing though, do you? Astrons are an inline 4 engine, and it doesn't matter how well you balance individual components it still needs balance shafts because of the firing order. ALL CARS HAVE INTERNALLY BALANCED COMPONENTS, otherwise they would shake themselves to pieces in an instant. A 90 degree V6 is unbalanced because there is uneven pressure on the crankshaft caused by the firing order and the angle of the bank. I seriously suggest you do some more reading, get your facts straight, and actually know what you are talking about before you make any more comments like that

 

Once again, in case you missed it, balance shafts are used to correct the uneveness in some engine designs due to firing order and bank angle, NOT balancing of engine components. If components weren't balanced initially from factory, then for the balance shafts to correct for this it would have to be made uniquely for that particular car as it rolls off the production line. This would be incredibly expensive and time consuming for a mass-produced car.

 

To spell it out in even clearer words, here's a few quotes from Wikipedia:

"A balance shaft is an eccentric weighted shaft which offsets the vibrations in engine designs that are not inherently balanced (for example, most four-cylinder engines)."

 

and

 

"Balance shafts are most common in inline four cylinder engines which, due to the asymmetry of their design, have an inherent second order vibration (vibrating at twice the engine RPM) which, contrary to popular belief, cannot be eliminated no matter how well the internal components are balanced"

[irokin]

90 degree V8s are naturally balanced, as are 60 degree V6s.

 

Wikipedia says:

 

A V6 is not a perfectly balanced engine and benefits from some counterbalancing and harmonic damping. The optimal angle to minimize vibrations in the V6 is 60°

 

A 90 degree V8 is far better balanced than a 60 degree V6 but neither are naturally balanced.

 

Our familys VR commodore (90deg V6) has been through about 4 harmonic balancers.

[Hiro Protagonist]

Wikipedia says:

A 90 degree V8 is far better balanced than a 60 degree V6 but neither are naturally balanced.

 

Our familys VR commodore (90deg V6) has been through about 4 harmonic balancers.

 

Damn, knew I'd slip up somewhere

 

Anyway, there are two kinds of V8s, crossplane and flatplane. Crossplane V8s have inherent natural balance because of the large counterweights used, as they have a 90 degree crankpin offset. They usually do not use a balance shaft. Flatplane V8s don't use the counterweights, and have all crankpins in the same plane. This allows them to rev a lot higher (less rotating mass) so are more common in non-American V8s such as the Dino (and also why have they don't sound like a traditional V8), however they DO need a balance shaft

 

 

So even within V8 design there are different types, with different levels of inherent balance

[MRMOPARMAN]

been doing a bit of reading, and once again i stand corrected on the harmonics issue.. however I'm am standing my ground on the astron and dunnydore V6 balancing shafts.

 

i have seen with my own eyes on astrons how well, smooth and long they run with no balancing shafts when rebalanced internally. and how well they don't PRE balancing. so the shaft may be there for other reasons, but they DO help out internal balancing, or a lack there of.. maybe as a side effect. who knows, i don't care what wikpedia or theat site i read says to the contrary.

 

spoke to one of the guys i know with a mild balanced v6 (sans shaft) and he said it ran like a dream before he sold it 6 months ago, and 16000ish km later.

 

just out of curiosity.. hiro could you tell me some of the V8s that use balancing shafts?

Edited September 22, 2006 by MRMOPARMAN

[irokin]

hiro could you tell me some of the V8s that use balancing shafts?

 

Lotus Esprit, TVR Cerbera & Tuscan Racer are the ones I can confirm....but pretty much any flat plane V8. I believe ferrari V8s are included in this list. Why do they make so much power and rev so hard when compared to american V8s (cross plane)? Because theyve compromised.

 

 

btw...not everything you read on the internet is correct (just incase you hadnt already realised). At least wikipedias information is scrutinised as best they can.

[MRMOPARMAN]

actually it was my trade school teachers that used to tell us that the balancing shafts were to dampen out excessive crankshaft harmonics.. thats also where we were playing with the astrons.

 

i can't remember the site i was at, but it pretty much mimicked what hiro said

[Hiro Protagonist]

I believe ferrari V8s are included in this list.

 

Yep, that'd be the Dino, as I said (the Dino is basically the only V8 apart from the joint Ferrari/MAserate 4300 that Ferrari have used in the last 30 years)

 

 

To MRMOPARMAN

Astrons and most Buicks are getting on in years now (Sigmas are 20 years old), and over time wear and tear will make them run rough naturally, and also make them become unbalanced. From factory they would have been balanced, as you can't have something significantly unbalanced rotating at 6000rpm in a car engine without it shaking to pieces, or at least making the entire front end of the car vibrate like a mofo. The key thing here is that from factory things tend to be balanced as a set - eg all the conrods and pistons will be balanced together. This means that an individual piston may be unbalanced, but because as a set they are all balanced then any vibration is cancelled out. You might be referring to replacing internal components with individually balanced ones, in this case you must replace the whole set otherwise things will still be unbalanced.

[irokin]

Yep, that'd be the Dino, as I said (the Dino is basically the only V8 apart from the joint Ferrari/MAserate 4300 that Ferrari have used in the last 30 years)

 

What about the F360 Modena/Spyder/Challenge Stradale??

[Hiro Protagonist]

What about the F360 Modena/Spyder/Challenge Stradale??

 

Still part of the Dino engine family. The whole family actually encompasses V6, V8 and V12 (the Dino V6 is quite interesting in that it's the world's only 65 degree V6, which allowed for straight intake runners but created a really weird firing pattern)

[irokin]

Well there ya go!

[Dan]

then you talk about eddie tassones car. hardly a buick V6 now is it?? actually how much of that engine is genuine holden? you have to expect that at those sorts of power levels though.

have you read up about that engine and how it makes its power delivery? hardly drivable me thinks.that car is a race/grenade car only

 

f@$king oath it is driveable.

 

Anyone noticed how you don't see that car anymore? And how Eddy Tassone has a f@$kin insane VY SS ute now? Eddy Tassone wrote his VH off here in Perth, taking a mate out for a joyride in it. It was drivable, he raced it, he dynoed it, he drove it.... a 1500hp car. Legend.

 

I have plenty of mates with VNs... while they all say they are generally shitboxes - they are also reliable.

 

But currently I got a hankering for a R31 skyline running a RB30ET.. I'm looking at the costs of doing this at the moment (has anyone got prices for the VL turbo kits, and what exactly is involved.. could ya PM me) and I'm selling my EA to fund part of it (woot).

[ancullen]

Still part of the Dino engine family. The whole family actually encompasses V6, V8 and V12 (the Dino V6 is quite interesting in that it's the world's only 65 degree V6, which allowed for straight intake runners but created a really weird firing pattern)

 

Hmm, who wants to fund my Ferrari conversion? 425bhp F360 Challenge Stradale V8 into an early model (fibreglass bodied) 308 GTB? Now that would be a monster in a straight line!!!

Edited September 25, 2006 by ancullen

[Rolla__Boy]

I wont fund it, but I will take it off your hands when it's done :(

[Jono]

a friend of mine has a GTS1 r31 skyline which is now turbo'd. it hammers even on 5psi.