06noscobaltss

Hey guys, as some of you know I am working with Bill Hahn over at Hahn Racecraft and I have a set of neutral balance shafts for my motor. Anyway, the engine builder did not realize there was indeed a difference between the stock balance shafts and my neutral balance shafts so they were not put in. Does anyone have a exact answer to if I need to put these in?

A little background, I have a full built motor, Staged Race Head, Stage 2 cams, and other goodies not to mention the Garrett GT35R turbo. We are shooting for 600hp. I know the motor can handle a lot but I believe I heard stories of the crank snapping around 450whp without the neutral balance shafts or a balance shaft delete kit in the motor.

I need help asap so if you know or have any imput that would be highly appreciated!

Thanks guys!

Kaisoboy

PM Spaz. He rebuilt his cobalt and I believe he also had nuetral balnce shafts in his. He is a GM tech. and a really great guy.

hope this helps

freakta

iTrader: (1)

balance shafts to my knowledge are there if you are running high rpms? dont take this as gold but if you have them why not have them in your engine

Witt

I'm using them.

They are to run the engine to 8k+ reliably. If you are looking for big horsepower numbers, you will have to run the engine up pretty high in rpm to achieve it due to the small displacement of our engines.

Kaisoboy

Well when Spaz was running his, his redline was 8000 rpm. So I would think that with that kind of HP and build I would presume you will be runnin like that also.

Witt

I also just noticed the OP is using a GT35. Your dyno is going to look like the rocky mountains. Without driving the engine up to high rpms, it will be a dyno queen and probably slower on the track than most GM stage 2 cars. I'm not flaming or being a dick, its just I've been down this road for the past year with a close friend of mine.

The reason you read so many sources replacing balance shafts at a set horsepower number is simply because to achieve that horsepower (aka airflow) the compressor required won't provide as much pressure down low while also achieving a high pressure ratio. Simply put, unless you shift at 8k rpm+ you will drop the boost pressure to below levels that you want after shifts.

I'm currently helping a friend who runs a fairly large size turboed LSJ achieve decent track times this year. 8k rpm+ and a two step are bare minimum to run decent times.

2K5SS/SC?

RiceEater on the redline forums learned the hard way about balance shafts and high rpms. Get them in there ASAP man if you'd like to keep that new built engine together at high RPMS!

06noscobaltss

Thanks for the feedback guys! I guess we will be putting them into the motor!

WSFrazier

I would toss them in. Motor can stay in the car, so it isn't that much of a hassle. Should be a 1 night job.

06noscobaltss

Haha anyone have a HOW-TO???? This is going to get done asap!

syP

how long is it gonna be down now joe? another 8 months??

lol

just playin

Witt

Nothing hard about it, just a bit of labor.

Remove the passenger side axle and drop the ball joint from the control arm. Remove the engine oil pan and all the mounts except the one underneath the fuse box (support the engine with a cherry picker). Allow the engine to rest on the subframe and the exhaust side shaft should be able to slide out. The intake side will have to be pulled halfway out, then place a pair of vice grips on it and remove the sprocket from it while its still half in the engine, the rest of it should slide out after the sprocket has been removed. Install is the opposite of removal with the exception of the vice grips on the neutral, I used the water pump chain to provide resistance while I tightened both bolts on both neutrals at the same time.

BCobaltSS

Well the GM Build Book states : pg 107, The stock balance shafts are scalloped so when they spin , the forces generated by the movement of the internal components are offset to smooth the operation of the Ecotec engine. Racing -oriented engines aren't concerned with this " comfort", so a tube is installed to replicate the balance shaft, but not to lose the 10hp it takes to spin them.