Should I delete my balance shaft?

Those are good points. But for me, factory Mazda racing teams run the MZR DISI Turbo with balance shafts intact (they're totally stock engines). And those racers aren't taking it easy on those motors. Just food for thought. If any conditions were ripe for oil starvation on main bearings, it'd be the high-G driving these factory race team cars experience, right?

 

Very reasonable thinking, key there is stock engines, which we know work great stock. But start swapping turbos and pounding well maybe it needs an upgrade. However I personally probably wouldn't bother doing BSD on a stock engine, but if I was building an engine I'd take it out.

But BSD should always go hand in hand with a baffle kit being added.

 

But higher-than stock power levels has zero to do with oil sloshing under G's, correct? I may be missing something obvious, but this doesn't add up to me. Is it that the forces the main bearings see are greater and the oil film layer can be compromised due to the extra power, perhaps?

 

Perhaps, I'm not in anyway saying it's a nesicaty. I'm simply saying that while you're there pulling it all apart to build an engine why not add it in? Is it needed I haven't read enough to comment either way, but I do know it won't hurt, will reduce sloshing and will reduce weight.

 

Indeed. My primary concern is vibes, being fully mounted. The concept for the car will be occasional DD/weekend warrior. So I'd still like to have some civility. I think we've all heard the stories about vibes on fully-mounted cars with BSD.

I think I just need to do more homework. I wonder what SP63 would say, based upon my goal power levels and intended use...

 

@Redline definitely talk to sp63, one of my good buddies @Chemmedic has BSD and is fully mounted and I fucking love it! Don't get me wrong there are definitely vibes, but I can't compare fully mounted and no BSD to fully mounted and BSD as he went fully mounted and BSD with baffle when he ZZB. Now as everyone will tell you vibs are very personal as your tolerance level, personally I could handle BSD and mounted as a weekender and occasional DD, possibly even full DD.

 

I deleted the the BSA from my speed thousands of miles ago. I like the added oil capacity, weight reduction, and I didn't feel the vibes were all that much worse. I also did the BSD on my 08 naturally aspirated mazda 3. I didnt buy a bsd kit either. I just threaded the hole and put a socket head cap screw in there. $2 from home depot. Of course I installed a pan baffle as well. Overall, I am a fan of deleting it as well as any other unneeded parts (TB coolan, EGR valve, CATs, et...)
The ford rangers and the 2.0l mazda 3's did not come with a ballance shaft assembly as far as I know. I have seen 2 ballance shaft assemblies fail (made horrible noise) and the fix was to replace it (or delete it). However, both were on NA mazda 2.3l, not the DISI.

 

Right, I know the BS's aren't an issue of engine safety; they're purely for NVH. That's why they're not on trucks (whose owners and driver expectations of the vehicle aren't typically the same). Having said that, cancelling out the secondary forces is nice if you have a lot more NVH anyways due to full mounts, aftermarket exhaust, etc.

It all really boils down to NVH tolerance. I'm somewhere in the middle. A built block with BSD in light of my mounts is desirable. My engine will likely rev more freely anyways due to the Southbend Stage 3 Endurance flywheel I'll have.

 

BSD, prolight flywheel, OG jbr dogbone and epoxied passenger and drivers mounts, vibes aren't that bad but makes the car sound like a diesel with the AC on and clutch out