3400 Connecting Rod Weights

[SappySE107]

This is for a pulled set, with the stock rod bolts/nuts and no bearings.

592.6
592.4
591.2
591.0
589.1
587.5

5.1 gram variation across the set.

[SappySE107]

SCAT I beam set modified by WOT-Tech are all 595.7g

[3400-95-Modified]

I'm guessing if you go with the SCAT rods then you should really re-balance your crank to match right?

I've been reading up on balancing my setup and I have read if you change anything about the piston and rod you will have to recheck the weight of your bobweight on the crank to ensure its correct for what piston and rod your running.

[SappySE107]

You should balance any setup, factory or modified, if you want the best performance and longevity. With the variance in the stock rods alone, you are looking at an improvement from matching those, and then having the rotating assembly balanced.

[ForcedFirebird]

I'm guessing if you go with the SCAT rods then you should really re-balance your crank to match right?

I've been reading up on balancing my setup and I have read if you change anything about the piston and rod you will have to recheck the weight of your bobweight on the crank to ensure its correct for what piston and rod your running.

You should balance any setup, factory or modified, if you want the best performance and longevity. With the variance in the stock rods alone, you are looking at an improvement from matching those, and then having the rotating assembly balanced.

Right. GM especially has tolerances, so the rotating assembly isn't balanced from the factory, so even a quality rebuild should be balanced anyways. Ben and I were surprised when we weighed some rods from a 20yr old BMW, they were less than a tenth of a gram off 0.o

Also, Ben will tell you about the head decks on BRAND NEW GM heads, they are usually right on the edge of the tolerance from the factory

[3400-95-Modified]

Yeah and to think I'm running 6700 RPM with all of that stuff as is... LOL

I do plan on doing a much more in depth upgrade in the near future on my bottom end.

[Z26-T]

Right. GM especially has tolerances, so the rotating assembly isn't balanced from the factory, so even a quality rebuild should be balanced anyways. Ben and I were surprised when we weighed some rods from a 20yr old BMW, they were less than a tenth of a gram off 0.o

Also, Ben will tell you about the head decks on BRAND NEW GM heads, they are usually right on the edge of the tolerance from the factory

Not to bash anyone.. But who's engine costs more? The BMW or the GM? Or who's car..? I don't think GM plans on these engines being high performance.. Though we like to make them that way . I'd be curious to weigh the rods on an LS engine. I'd hope they'd be closer.

Ben, that's awesome with the Scat rods! Just a random question.. Will you be offering rods for 3500s eventually? 3500s are just a lot easier to locate locally for me.

[3400-95-Modified]

I think thats the point that Forced was trying to make... The tolerances are much wider than what BMW produced since their engines were planned to be pushed to the limits, at least depending on application, as well as much more time and money invested in building them. I think he's really just trying to show how many corners are widened to accommodate mass production of these engines and that we should really pay attention to that when we are building them up.