Quote:
Originally Posted by wstar
Yeah, so someone asked on the "visitor messages" thingy here: Nissan 370Z Forum - Conversation Between 12nismo and wstar about whether the engine failure was pulley-related and whether I moved my crank pulley to my new block. The TL;DR answer to that is: I *think* the failure was unrelated to the pulley, but I also did *not* move the pulley over to the new block.
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Our engine is an internally-balanced one, meaning the pulley doesn't play a role in basic rotating-assembly balance issues on this car. It *does*, however, contain a rubber vibration-damping ring on the outer face of it. The core of the real debate here is whether the purpose of that vibration damping ring is purely for aesthetic NVH reduction, or whether it has a real dampening effect that partially reduces some mechanically-important crankshaft vibrations from combustion (and if so, how much longevity are you losing if you eliminate this? It could be 5%, it could be 95%!). |
Have just come across this thread and read selective bits from it ....
To add my 2-cents worth to the pulley debate, on a DD that sees a "big" rev every now and then .... probably not significant, BUT in a competition car, an un-damped pulley is an engine killer in my book.
Back in the 80's, when I built the race-car I have come back to (is an historic 70's sports car, Buick 215 V8 engined), I ran without a crank-damper for the first 3 seasons and lost 4 engines (crank main-bearing failure each time), at which time we moved to dry-sump AND a damper.
We've had engine failures since, but never crank main failure - usually down to running the rod-bolts a tad too long (Carillo's are lifed at 80 hours, but we now replace rod-bolts (7/16" now rather than 3/8") every 40 hours as a precaution.
You only have to speak to the guys in the UK (IES - who prepare the GT3 NISMO GTR and also the 370Z GT4 engines for RJN Motorsport who run these cars in the Euro GT3/GT4 and Blancpain championships for NISMO) and they NEVER run an engine without a damper.
In the USA, talk to JWT who build the Grand Am engines for the Nissan 370Z runners, or Unitech Racing who built the Fontana Racing 350Z's - they all have recent experience of VQ race engines and I am quite confident they will specify a quality damper. In Canada, Sasha Anis also has a wealth of information about the VQ engine in competition-spec.
The NISMO engineer in Melbourne who assembles the VK engines for the Nissan Motorsport Altima's in the V8SuperCar series also specifies a motorsport damper and these are 5-litre engines making 650hp.
If it is good enough for those guys, it is certainly good enough for me, BUT as always, make up your own mind and tread your own path.
RB