[Jason@JacFab]

So while tearing down my spare engine I was hoping to find a way to pick up some free power with a balance shaft modification, or maybe be able to have some neutral balance shafts made...

My hope was that the shaft would be an actual shaft (circular), that I could machine the weighted areas off of in a lathe...

Nope, gm screwed us. The weighted areas are not built into a circular shaft, but more so like the weighted areas hang way out there, and there is basically a support rib. I wouldnt trust taking the weights OD and just leaving the thin rib, I feel like there would be too much stress and the remaining shaft would break at some point.

Looking at the design of these factory balance shafts, I'm sure they would be pretty ridiculous to have new shafts made as far as $$$ goes, mainly do to all the gears built onto the shafts. Not as simple as an older engines... Might be possible to convert to chain drive rather than gear, much easier if something new were to be made to save mfg cost...idk

Anyway, here's some random pictures






Notice the thin "back bone" here?


The weighted side of the shafts.


2lb 4.3oz


2lb 15.1oz

Oh! And can't do a balance shaft delete, because the oil pump bolts to the back of the balance shaft housing and is driven off the backside of the smaller shaft. I thought about a single simple shaft to drive the oil pump, but the pump drive is offset from the shafts so it wouldn't be a straight shot through either of the balance shaft journals.

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[SUN]

maybe a answer why at idle the 2.0 is so rought and shake

[geoffchad]

I have heard from multiple individuals that the LTG was intended to reduce cost of the LNF and improve reliability. GM knew full well the thing would go into a bajillion cars eventually so they needed something easier (and cheaper) to chuck together and would hold up better under GM's warranty terms.

Reducing cost was first priority, reliability gains were secondary.

I can only assume integrating gear-driven balance shafts into the bottom of the engine was done because they are sub-assembled and can be slapped onto the engine in Tonawanda quicker and then it's easier to pull the assembly off the bottom of the engine while the engine is still in the car than the traditional method (remove engine THEN remove balance shafts).

Originally Posted by SUN

maybe a answer why at idle the 2.0 is so rought and shake

If they skipped a tooth (unlikely, but possible) that could make the engine worse - but I suspect the primary reason is the engine just isn't balanced tightly from the engine plant as a means of cost reduction - then use active motor mounts to try and hide it. But being how the motor mount system is driven, a hiccup in one of many systems creates a cascading loop of the ECU adjusting variables to mitigate the hiccup and ends up making it worse.

[Corner carver]

This is unfortunate... Makes building a 'big power' LTG pretty pointless until someone figures out a solution.
Like to get into rebuilding with a stroker kit... Why until this is solved? Damn...
Back to the drawing board lol.
Irritating after spending the money on supporting equipment already :/

[Corner carver]

What about a work around for the oil pump, like a dry sump set-up or something (belt driven oil pump?)...then a nice crank dampener or something?

[Jason@JacFab]

Originally Posted by Corner carver

This is unfortunate... Makes building a 'big power' LTG pretty pointless until someone figures out a solution.
Like to get into rebuilding with a stroker kit... Why until this is solved? Damn...
Back to the drawing board lol.
Irritating after spending the money on supporting equipment already :/

Well, ZZP think that it's not really an issue. But they said at some point they may look at them

Also gotta remember, you aren't spinning the whole 5lbs of off balance weight around. I'm speculating the weights themselves could probably only be about 2ish lbs. still seems like a bit though.

I happened to find another complete balance shaft assembly w housing on eBay, so I bought it this morning. I have a couple ideas I might try. 1) try to turn some of the weight off in the lathe, leave just enough to not compromise the integrity of the shafts. 2) had a thought this morning of a way I could make neutral balance shafts with straight cut gears. Might introduce some noise similar to gear drive timing on a v8 engine, but some people are into that, but would be affordable to manufacture, and completely cut the offset rotational weights out.

Problem with belt drive oil pump is due to its location and the fact that it mounts to the balance shaft housing, is that you can't really get a belt or any other drive mechanism to it, and because all of the proper oil passages are built into the housing , it doesn't seem feasible to get rid of the housing. It would take a lot of thought and $$ to come up with a proper working dry sump that eliminates the shafts and housing.



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[Corner carver]

My fingers are crossed you can figure something out! Thanks for explaining the issue with a dry sump; I was just spit balling to get some ideas flowing
After seeing this post and on the facebook group I was feeling pretty defeated about the whole thing lol

[Adp2017]

What kind over hp are you talking before this thing is the cause of failure? 500+ whp?

[Jason@JacFab]

Originally Posted by Adp2017

What kind over hp are you talking before this thing is the cause of failure? 500+ whp?

Not sure of the question? I doubt it will fail as is, it will just rob power. If I take too much material off the weights in a lathe, it's questionable when or if the shafts would break, but the stock shafts can never be taken to a neurtal balance due to their design, they can only be lightened... It which point, they will no longer cancel out the vibration that they were designed to cancel out as they will have been changed, but either cancel out a different vibration or maybe even amplify another? It's hard to say, but I'm willing to try if I can shave some weight off, or come up with the straight cut gear neutral balance shafts.

[Adp2017]

^ got it, thanks Jason. very interesting

[Ashium]

It's a double edge sword. It would be beneficial if we're reving to 10,000+ rpms. Otherwise it might just do more harm then good on 99% of the streets driven Camaros. I would look into a fluid damper or similar to help reduce any increases in damaging harmonics after such a mod.

[EagleRS]

Jason and other I4 Camaro peeps,

I know that you didn't mention longevity of the engine (Geoffchad) but I agree that quicker to build and cheaper is what GM does best. But based on what Jason uncovered, was this engine meant to stand up to not just DD but also spirited driving and occasional foot races? Or was the wicked, awesome autopsy performed by Jason of the LTG was to clarify that (Heavy Mods) may not be possible? I just got a little concerned and was starting to kinda regret buying the I4 Camaro instead of the V6.

Thanks guys, I appreciate everyone's feedback.

EagleRS

[ChicagoTommy]

Originally Posted by EagleRS

Jason and other I4 Camaro peeps,

I know that you didn't mention longevity of the engine (Geoffchad) but I agree that quicker to build and cheaper is what GM does best. But based on what Jason uncovered, was this engine meant to stand up to not just DD but also spirited driving and occasional foot races? Or was the wicked, awesome autopsy performed by Jason of the LTG was to clarify that (Heavy Mods) may not be possible? I just got a little concerned and was starting to kinda regret buying the I4 Camaro instead of the V6.

Thanks guys, I appreciate everyone's feedback.

EagleRS

The LTG is still reliable. Deleting balance shafts are typically done in race only applications. So, unless you're looking to start making 10000rpm drag passes, you have nothing to worry about. Your LTG will still run 250k miles.

[EagleRS]

Thanks ChicagoTommy,

I was hoping that was the case but again...I was just concerned. Yeah, not to keen on pushing the little LTG past 6K rmp.

Not to sound like a douche but I may be the first guy on here with the LTG to achieve 100K miles + in a short matter of time.

Bought my little RS in May2016 and I have ~44,300 miles on my car thus far.

Thanks again guys....