How long does stroked engines last without silent shafts

[flav]

We generally remove them and re-balance the whole thing. (There are many ways to do this mod) I can say that the engines do feel smother with them in there but we have had no failures and problems so far. However, we have rebuilt a bunch of engines due to pemature balance shaft bearing failure, these will fail when abusing the engines...mainly a long burnout or hard track time.
End of the day, if your going to give it a hard time then take them out. Theory is one thing, but practice is proven here.

[Barney]

We generally remove them and re-balance the whole thing. (There are many ways to do this mod) I can say that the engines do feel smother with them in there but we have had no failures and problems so far. However, we have rebuilt a bunch of engines due to pemature balance shaft bearing failure, these will fail when abusing the engines...mainly a long burnout or hard track time.
End of the day, if your going to give it a hard time then take them out. Theory is one thing, but practice is proven here.

Have you built the strokers without the balance shafts yet?

We will see how long my race engine lasts with balance shafts! I hope its a while :)

[kiwieurospec]

We generally remove them and re-balance the whole thing. (There are many ways to do this mod) I can say that the engines do feel smother with them in there but we have had no failures and problems so far. However, we have rebuilt a bunch of engines due to pemature balance shaft bearing failure, these will fail when abusing the engines...mainly a long burnout or hard track time.
End of the day, if your going to give it a hard time then take them out. Theory is one thing, but practice is proven here.

Have you done up engines and then had balance shaft bearing fail?
Or do you mean they spin bearings and there is nothing else wrong with the engine?

[MrBishi]

A good mate of mine went to Mitsubishi 'school' as a mechanic. The class was shown an old video of when the original balance-shaft motors were designed circa 1978 when the astron 2L (4G52) was the 'new' technology. The video showed a 'shafted' engine running beside a 'shaft-less' engine on an engine dyno. They apparently gave an extended session at full revs and the shaft-less unit failed well before the other.
(bear in mind I didn't see the film so don't take any of this as fact)

They do spin at 2x crank speed, so if you are going to leave them in, remember to be extra careful about bearing condition and tolerances. I suspect that some failures after rebuilds are due to overlooking the bearings and perhaps even re-using the 20 yr old parts.

[airbats801]

leave the balance shafts in? you should just walk away rofl

Balance shafts cause more actual engine faulures in mitsubishi engines than anything else. We wont count bhg :D

I remove them on all my g54b engines, they use a meaty long stroke, almost as long as the 4g64. No ill effects, just better oil pressure, more power and response :) No 2ft long oil pump chain all dependant on those bs guides not breaking

Any falure after a rebuild is gonna be builder or operator roots doing something wrong.

My only g54b related failure was with a broken upper balance shaft guide, which obliterated my oil pump gear byt he chain skipping links off of it. After that, I have not used a balance shaft since, and never had any problems with bad vibrations up to 8krpm on a g54b.

Even the mitsubishi imsa starion team here in the states removed them from their engines, and they were running endurance races. On another side note, some engines like the g54b had a cast without balance shafts, like those old 2.6l forklifts.

[ROCKETMAN]

leave the balance shafts in? you should just walk away rofl

Balance shafts cause more actual engine faulures in mitsubishi engines than anything else. We wont count bhg :D

I remove them on all my g54b engines, they use a meaty long stroke, almost as long as the 4g64. No ill effects, just better oil pressure, more power and response :) No 2ft long oil pump chain all dependant on those bs guides not breaking

Any falure after a rebuild is gonna be builder or operator roots doing something wrong.

My only g54b related failure was with a broken upper balance shaft guide, which obliterated my oil pump gear byt he chain skipping links off of it. After that, I have not used a balance shaft since, and never had any problems with bad vibrations up to 8krpm on a g54b.

Even the mitsubishi imsa starion team here in the states removed them from their engines, and they were running endurance races. On another side note, some engines like the g54b had a cast without balance shafts, like those old 2.6l forklifts.

Why would the starion team care? They have an endless supply of funds
Read: $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

You have said "Balance shafts cause more actual engine faulures in mitsubishi engines than anything else." yet you fail to mention why, perhaps they have been hammered in which is not the correct way to install them LOL.

[flav]

A good mate of mine went to Mitsubishi 'school' as a mechanic. The class was shown an old video of when the original balance-shaft motors were designed circa 1978 when the astron 2L (4G52) was the 'new' technology. The video showed a 'shafted' engine running beside a 'shaft-less' engine on an engine dyno. They apparently gave an extended session at full revs and the shaft-less unit failed well before the other.
(bear in mind I didn't see the film so don't take any of this as fact)

They do spin at 2x crank speed, so if you are going to leave them in, remember to be extra careful about bearing condition and tolerances. I suspect that some failures after rebuilds are due to overlooking the bearings and perhaps even re-using the 20 yr old parts.

Yeah, i went to that school too! Thats where we did all the Starion training.

[flav]

I can also vouch for the early days of all the competition engines having shafts removed. I think the failure is in the clearances. They seem fine when not abused but when u crank these engines the oil gets thin and you have this meaty chunk trying to continually press on the bearing in a rotation single area. This also wipes the bearing face dry as the oil gets hotter and thinner. I can remember my apprenticeship days when the cordia was released, then we were doing balance shaft rebuilds like common services. From memory the factory came up with a bearing that was grooved from one side to the other like a wide thread. Mits might have money, but at the end of the day they do want to win and finish races..hence the shafts removal.

[Alspos]

From memory the factory came up with a bearing that was grooved from one side to the other like a wide thread. Mits might have money, but at the end of the day they do want to win and finish races..hence the shafts removal.

I was speaking to a courier who was an engineer working on Starion race cars in the day. They ran the shafts but modified the bearing with a groove as Flav said. Never had a problem with the bearing running out of oil once they figured out that mod.

[Chryzla]

umm.... they were only there as 'counter balance shafts' spinning the opposite direction to the crank to reduce engine movement and the like, it isnt a performance part, and i only noticed minimal vibration while revving in my old sigma... as for them saving engines... anyone who believes that shit is a moron. if they sieze they take the whole engine with them, and as for the oil pump, at least in the 2.6 engines, the kit i bought gave me a shaft to replace the balance shaft.

[toysrus]

From memory the factory came up with a bearing that was grooved from one side to the other like a wide thread.

Are you sure they re-designed the Bearing with the a groove and not the shaft itself with the Full groove ?

Reason I say this is because I went to the local Mitsubishi dealership and ordered a set of Genuine Mitsubishi JD Balance shaft bearings the other week. They had to come from Sydney as they only had one bearing here in S.A. left and suffice to say they didn't feature the 'groove' in them........

So I had the groove cut out in the shaft on the lathe and the shaft re-nitrated. We'll see how it goes.....

Mark, mrb1, stated the issue being the clearnace at the Front bearing not proving enough pressure for the oil at the back bearing........which makes sense, and is why I can't understand what you mean by 'when you crank these engines, it gets too tight'. So possibly upgrading the Oil cooler would be a wise solution ?

[flav]

Groove in the bearing matey, but i cant see why u cant cut a groove in the shaft. Upgrading the oil cooler is a great idea. So is using an oil that can withstand extreme pressures.

[toysrus]

The problem with any Full groove in the back bearing/shaft is if that has any Oil Pressure issues, the extra volume now from the Full groove is going to drop the oil pressure down even further......

[flav]

Then cut the goove about .3mm deep and 5 mm wide going around and out but stop it before the end where it would otherwise spill out the bearing. I would also polish it.

[toysrus]

Then cut the goove about .3mm deep and 5 mm wide going around and out but stop it before the end where it would otherwise spill out the bearing.

The oil Feed into that rear bearing comes from the block through the Bearing, and the only way for the oil to escape is out the bearing sides and down the insides of the block. So why would you want to only do a 3/4 groove ?