Just looking for a quick answer. Street car, 500whp, LS crank, Eagle H beam rods, and CP pistons. Even if the rotating assembly is balanced the flywheel and balancer wouldn't be.

Is it worth $300?

 

Usually aftermarket internals are already balanced within a gram or so of each other across the set of pistons or rods. At least quality stuff is. Some manufacturers like Wiseco even write the weight on the part. You're not likely to have that much variation unless there's something wrong with your crankshaft counterweights(damaged from previous broken rod or something) or some other factor. In all my years of building engines across multiple platforms Honda and otherwise, I've never had a rotating assembly professionally balanced and never had an issue.

If you're planning to rev it to a million RPM it'll probably be worth it, otherwise it's probably money better spent elsewhere for 500whp. I'm sure others will chime in with their experiences as well.

 

I forgot to mention 8500rpms redline. Thanks Aradin

 

Aradin has it spot on. Also, if you're looking to keep it around stock redline, that pro balance is just wasted funds.

 

Ok so no to balancing.

What about Oringing the block?

 

No. Putting an O ring on the top of the cylinder helps with sealing the gasket for ultra high WHP builds but is absolutely not necessary for a street car.

 

I've read it is psi dependent and not WHP related.

 

No to pro balancing. I think balancing is not a waste of money and is a great way to ensure good assembly practices without breaking any bank. 8500 or 10,000. I'd still have it balanced.
O-ringing a block, only if it's sleeved. But, to me, for turbo, I've always o-ringed. Better sealing. Again, just me and how I do things with the motors I abuse.

 

Usually those go hand in hand. So. It kinda turns into a 6 vs half-dozen scenario, you could say if you're running high pressure, you're *probably* going to be upward of 600+ whp.. Can't say I've ever seen a 50+ psi setup only pushing 300whp so you could say high-hp interchangeably ? Although I have seen some high hp running just south of 30psi. So, maybe if you're in a given range? >30psi?

 

For sure balance the crank. If you have rods and they came with a spec card they should be fine. Quality Aftermarket Pistons are usually very close too.
Balance the crank if everything else is new

 

Yes, balance the crankshaft alone. Then weigh match the rods, pistons and pins... if they are within a gram added together as an assembly, then send it.

 

Matching weights of components isn’t really balancing the engine. You might get the weights closer to each other and it could still be unbalanced when spun. A good machine shop/engine builder should have the ability to spin the rotating assembly and balance it. Not sure if these engines are internally balanced or externally. If externally they will also need the crank pulley/balancer and the flywheel/flex plate.

 

Honda/Acura 4-Cylinder inline engines are internally balanced and have a flat-plane crankshaft, so actually, weight matching components DOES improve the harmonic balance of the engine. This doesn't mean that the balance of the rotating assembly cannot be improved by a qualified machine shop, but chances are really good that a typical Honda crankshaft will require less than +/-7 grams on either end, and if you know anything about the balancing process, you know that you will never get it better than about +/- 2 grams... as in never get it to zero... you are chasing weight. Your statement applies to an offset-crankshaft, like what would be found in the V8 engine in your Z28 (assumption from your username), regardless of whether it is internally or externally balanced.