Engine balancing

[cjames]

How many of you L-series engine builders have the rotating assembly balanced for a build? Its something I do with out even thinking about it when I build any engine. This is my first L-series though. I FINALLY got all my parts together for my L28ET build, and the entire rotating assembly is with my machinist now for balancing. I'm curious to see how much work it will take for him to balance this stuff up compared to other engines I've built. I did a quick search, and found a few posts, but not many regarding L-series balancing. I'd love to hear thoughts on this from some of you other engine builders here.

[Mr.INSANE]

Most of the people who go turbo don't really bother with balancing the bottom end, Unless there making upwards of 400+hp. At which point the stock bottom end starts to have trouble holding up anyways.

 

Also consider that turbo motors aren't usually revved that high so balancing isn't as important as it would be in a high strung high revving N/A l series.

 

Regardless as to what others think, I myself would have my motor balanced if I was doing a N/A build or a high power turbo build. I would not trust a 20 yr old motors internals.

[Dayz]

There is a post that talks about balancing, It seems that Nissan did a great job rotating the assembly at the plant, I haven't balance mine and it seems to work well. It is not a high power build N/A.

Dayz

[katman]

If you're using aftermarket pistons then it isn't a bad idea. But as Dayz says, the factory did a great job in the beginning. Back in the Z heyday's of SCCA Showroom Stock the difference between a bone stock bottom end and a balanced and blueprinted bottom end was about....drum roll .... 1 hp.

[Doug71zt]

I recently balanced a bottom end with an LD28 crank, L24 rods, single row damper and a 240mm factory flywheel that had the back shaved out of it- this combo was out by a whole 4 grams. I balanced the rods with a scale and the pistons were Ross, so they were 0 before the assy was balanced.

[cjames]

I'm using ITM pistons, I doubt the quality control, and I debated myself for weeks before I even bought them in the first place, but I havent heard many bad reviews. I weighed my rods, they were close, but the "hung" weight of the small ends varied quite a bit. Could have been the way I hung em too when I weighed em, very un-scientific. I'll post results when I get the final word from my machinist.

[1 fast z]

You have to be EXTREMLY carefulll when balencing rods, no to get any friction involved on the stand, and make sure they are dead strait.

[z-ya]

I've used the ITM brand on a couple builds now, and the quality is decent. The last motor I built I had balanced with ITM pistons, and it wasn't too far off (can't remember exact amount, but it was close).

 

I think balance is also important for engine life if you are going to run it at high RPMs (6500+) for long periods of time.