BLue NoTe

iTrader: (4)

Boostins thread got me wondering: Has anybody had problems with the stock balance shafts when routinely going above 7000 rpm? Id like the peace of mind having the neutral shafts but the install looks like a bitch to me. Wanted to know if its worth it

laser_racer

Had a friends cobalt that ran stock shafts from day one and reved it to 7500 to 8000 all the time on the weekend. Six months ago he blew the motor from a bent rod so balance shafts didn't break it so not sure.

kxrida2000

iTrader: (12)

watever u do dont do a balance shaft delete..it rattles my car to death

ItalianJoe1

iTrader: (10)

I spun mine to 7600 after the valve spring change, never had a balance shaft issue.

Karlen89

iTrader: (1)

There was a car that made more power than any car here is going to see, and it was stock balance shafts. No problems.

Frew

iTrader: (9)

zombie thread revival, does anyone know how much more vibration over stock one would experience?

advise

iTrader: (3)

x2

Staged07SS

iTrader: (25)

I have been spinning my car over 7000rpm for 3 years now. Stock balance shafts. No issues.

Anything over 7500rpm it's "recommended" to install balance shafts.

distillion

what valve springs are you running?

Staged07SS

iTrader: (25)

Stock.

I shift at 7,100rpm. The stock springs are perfectly fine to 7,250rpm.

I'm installing supertechs this winter though.

Frew

iTrader: (9)

Well I wanted some opinions because I was gonna see if I consider them driveable daily, I have a motor out of my car and I thought it would be a good way to pick up 10in hp and not have to worry about installing then later

Frew

iTrader: (9)

I spun my motor to 7400 rpm for about 2 years and now I got a tapping lifter at cold start

distillion

good to know.
got a link on the supertechs for the lsj?

hhrfreek

iTrader: (6)

I have been spinning my SC 2.4l to 7200 for the past 4 months with no problems and another member said he has been doing it for 3 years. The LE5 balance shafts are heavier than the LSJ shafts as well:

http://zzperformance.com/products_img/1143_2.jpg

I would think the LSJ engine will handle high rpms much better with the lighter shafts/shorter stroke/forged parts. In a 2.4l Pontiac Solstice stock tune file, the stock rev limit is 7200 and that car has the same springs as the LSJ and heavier shafts. If I had an LSJ, I'd rev 7400 with stock shafts and not worry.

On a side note, if you have performance engine/trans mounts you may not want to do neutral shafts. The vibes I get with my poly mounts are pretty heavy for a dd under low rpm load.

newt

iTrader: (2)

I've done the LZM Balance shaft delete (not neutral shafts) on both a 2.2 and a 2.4. The vibs are slightly increased, but I also have a solid urathane engine and trans mounts and no interior...which makes it much worse.

My car is not my daily, but I take it to work often enough it might as well be, it also gets driven on 10+ hour trips to the drag strip on weekends. Its not unbareable by any means IMO.


GM recomends removing them or installing neutral shafts after 7000rpm I do believe. Remember they spin at 2:1 the engine RPM, so at 7000rpm they are spinning at 14,000rpm. Thats alot of RPM for a significantly unbalanced mass to be spinning at.

I removed mine for peace of mind, as I rev both motors out to 7600rpm. They also free up a considerable amount of power, which is never a bad thing.

As for the guys looking to get Supertech springs, they don't fit into an LSJ head without clearancing the valve spring pockets. The spring contacts the cylinder head casting at the back of the spring (closest to the lash adjuster).

You will need to remove material from the head in order for the springs to fit....just a heads up.

Also, all Ecotec variants (L61, LE5, LSJ, LNF, LAP) all use the same valve springs, GM PN#90537032.

Just wanted to clear up some information.

Staged07SS

iTrader: (25)

After 7500rpm.

I have all the info in from my GMR Stage 3 kit.

On a side note:

I have heard of many people installing the supertechs in the lsj head w/o any modification. There could be casting variances though, and that could have been your issue.

LNF's on the other hand def need some modification.

Staged07SS

iTrader: (25)

If you have the motor out I say do it.

If I ever decide to remove my motor for a build I'm def installing the NB shafts.

newt

iTrader: (2)

You are correct, I just double checked, for some reason I thought it had the same 7000rpm rating as the valve springs do.

My bad.

Staged07SS

iTrader: (25)

Cobalt & Ion ---> ZZ Performance

mrbelvedere

iTrader: (3)

if it was aera47 he had nbs in his engine

im getting rid of them id rather have the extra 10 to 20 hp at 7500 to 8000 and you all should be more concerned with the stock pos harmonic balancer it does nothing for the ecotec after 6800 rpm

Boosted05

Thought it was 6500 that the stock on was crap, no?

EXsoccer1921

iTrader: (14)

i took my old lsj on a completely stock internal engine to 7500 rpms every weekend. never had a problem. got rid of the balance shafts on this build and take it up to 8,192

mrbelvedere

iTrader: (3)

its around that area 65 to 68 it dosent do ****

hawlyns711

iTrader: (2)

I've deleted mine and retained the water pump chain setup. I have an lsj. on stock mounts the vibs really aren't even there. I can't notice anything rumbling or vibs really at any rpm. I have a full exhaust, that may be my sound resonation, but overall it is very driveable. I've got the zzp springs and spin 8k.

AjSS

Same here, and I have the rotated mounts. The vibes arent as bad as I expected, its only at idle that you notice, driving I dont even notice any vibes, its smooth.