Its how 99% of our motors go together, they are fine.

 

Thread summary: balance shafts still are not needed.

?

 

Its always a good topic & great to have one of our best builders chime in w/the good news

Im sure English Racing would be aware of this fretting damage if it were occurring

Sure would like to interview one of the 4G63 engineers & ask them some questions as to why all that engineering was done to develop these BS

Its not just Mitsu, its basically all of the larger displacement I4's that have them

If its just NVH & marketability im OK w/the BS delete

 

Thinking about this, I think BS are not affected by piston position because BS are rotating in tune with cranshaft. So the BS is in tune with the pistons at over half way with pistons.

 

The OEM BS is lopsided so it reduces power to rotate this mass. The GSC race shaft is centered, so it doesn't take much energy to spin it. To be technical the lopsided weights take more energy to spin. To me, the full shaft is just insurance to keep the oil pump happy. The extra cost is worth my down time and repair time. Maybe it will be wasted money where it only buys me peace of mind.

 

Do what makes you happy, IMO. It all works out the same.
No sense in trying to reinvent the wheel here.

 

My thoughts exactly, it just seems weird that they'd spend so much time and money on comfort in a vehicle that was never meant to be comfortable. However after seeing the input from our many knowledgeable members I may start leaving them out in future builds... Haven't really decided yet. Our builds at the shop would always leave the BS in 4G builds, and we haven't had issues with them, however I certainly wouldn't mind added simplicity when assembling the engine and doing timing.

Thanks, Don, for making the thread and thank you to everyone who contributed their thoughts. You guys are the reason I always come back to this forum

 

2. Agreed. I just wrote my thoughts because of Jack's site.
3. Agreed. It is like a buffer/stabilizer/equalizer
4. Agreed. I was just saying that it helps to reduce the power spikes (or harmonics as you refer to). But it isn't what you want because of the momentum changing directions at extremely high cycles. Personally, I feel that too light of pistons do increase harmonics since it transfers more of the energy spikes on combustion.

 

It's nice to get a group of experience gathered together.
When I build my spare engine, I want to use AEM 12 tooth wheel for my infinity so I have to delete my BS. So far, I only found mounting kit that requires removal of BS.

 

Trade the Infinity for an Elite 1500, problem solved haha.
In all seriousness though, I could have sworn there was at least one company back in the day that allowed for the BS to be kept with their 12-1 tooth wheel. I presume you're gonna be running the TriggerDisc.com wheel?

 

Info in here is very interesting, especially with experienced engine builders like Aaron. Another interesting fact is the increased oil pressure with BS delete. Although I never personally logged the oil pressure before and after to confirm it, it is reasonable that a delete will increase oil pressure. Another interesting fact is the purpose of the engine. For example let's just say you have a 2.3 with 8.500 rev limit. The engine seems to be more sensitive to vibrations and produce more vibration than 2.0, therefore if the theory is correct and the BS spins double the speed, consider that you will have a rotating part which will spin 17.000rpms. It seems that highly modified evos delete the balance shaft and there is no need for it. However, for a midly street daily car i would personally keep them. And this is the reason that i stated earlier that GSC solution seems to be the best of both worlds.

 

No idea what to use. I have 508 infinity and spent a lot on it.

 

I know haha, I was just messing about :P
Don't wanna clog the thread with unrelated talk, but I like the TriggerDisc wheels. Worth looking into.

Cheers!

 

JohnBradley (Aaron) is a mechanical engineer. He has extremely thorough understanding of what the bshafts do, how they do it, and why.

Many 4 cylinders don't come with balance shafts Honda K, B, and D series. Nissan KA and SR's, Mitsu 4b1X, etc.

The balance shafts are "in tune" with literally neither of those things.

When the crankshaft is at exactly mid stroke, the piston is below the middle of the bore, this means means the piston travels faster on the top half of the stroke than the bottom, which mean there is more force required to accel/development the piston on the top half of the stroke than the bottom. This creates a second order vibration. The balance shafts are tuned to make an equal/opposite 2nd order vibration and they cancel each other out.

Most of the power loss from them is the friction of the bearings. The counterweight isn't that heavy, and it's very close to center.

2.3's vibrate a lot because of the ****ty rod ratio.

The race shaft does the same thing as BSD, except you still have an extra bearing to fail, so there's not point to keeping it,

A BSD definitely increases oil pressure. There are several ways to deal with this. As Kaj said, you can leave the rear shaft in with the bearings not rolled and just leave the belt off. ER also makes an underdrive pulley for the oil pump, you can do some light porting in the bypass on the oil filter housing. Etc.

 

I was thinking it might be possible to drill a small hole in the bs bearing on the opposite side. So that when you spin it there is still an oil return path. I have no idea how big that hole would need to be, or if it would even work correctly. Has anyone heard about this being tried / done?