Lightened flywheel and pulleys
 

Do you know if fitting both lightened flywheel and pulleys (all of them) can cause any issue?
Thanks!

Why do you want to have a lighter fly wheel? It's gonna rekt your engine in the long run

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In my old FRS, I had the lightweight crank pulley installed & ran it for about 2 years. Though revving it was easier, I found that it was causing some slight idle dips. When I reinstalled the stock, the engine ran smoother throughout the power band & the idle dip was gone too.

There might be some merit in LWCP or LWFW .. on mostly tracked only car. For most of us driving car both on track and street (and usually 90% of time/mileage on street. Or for even more of owners - never on track) imho cons of extra inconvenience with LW FW or CP, such as easier to stall, rougher idle, harder to revmatch and so on, outweigh slight gain for track for more responsive revving. Better not, purely from usability and enjoyability of driving viewpoint.
As for "issues" .. while boxer layout engine is one of most internally balanced, it still has multiple of vibrations. It can get by having less flywheel mass and without balancing shafts unlike eg. some inline-4, but it still needs some to dampen vibrations and reduce wear on crankshaft bearings, as it's just part of vibrations/harmonics of how pistons move in-out simultaneously, firing still doesn't happen on all of them at same time, so uneven small twisting of crankshaft will happen anyway, even on such more "internally balanced design". If you still are set on going for lightweight CP or FW, suggest doing just one of them. Recall reading here posts from shop rep that had dealt a lot with rebuilding subbie engines with this advise, that he had seen several subbie engines with medium mileage and failed crankshaft bearings with both CP&FW lightened, and imho worth err on safe side, at least if you like the car and want it to last.
Also "gains" on dyno from LW pullies are more of fooling how power/torque is calculated in them. Extra energy to spinout heavier flywheels/pullies is relatively small as to what power needs to accelerate mass of whole car, so at the end it's less of "free power gain", more just quicker to rev engine .. only with clutch disengaged, when all that power goes just to spin now lower spinning mass just in engine. And if you happen to go later on forced induction route, which adds lot of extra load/stress .. i'd rather think of going opposite route to LW CP/FW, for eg. fluidampr pulley.

I had light weight flywheel. I loved it. Made my shifting smoother. The crank pulley is a damper and shouldn't be replaced because it does reduce vibrations. I've never heard of a flywheel causing or reducing vibrations.

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And i had seen people hating easy to stall in stop and go traffic in city .. and sometimes reverting back to stock that "upgrade", due not liking feel of result. Possibly subjective thing. There had been oh so many flaming threads regarding LW pulleys, i voiced my view/impression that cristalized from many, often opposite views from there, that gains seem often overstated and cons may matter to me more, leaving impression that it is mod not worth doing on mine, at least in context how i use the car. I still spend a lot on car, but in other areas, on mods that look less controversial, less for specialized use case, and/or of better price/performancy.

Thanks, I already have LWFW as in all my previous car, and it's absolutely an upgrade.
Reducing rotational mass doesn't give anything on the dyno, as it doesn't add torque, it just makes the engine revs faster. And I don't care of dyno, but just of driveability.
Regarding the harmonic damping, using a LWFW changes things, so the stock damp pulley is not damping the correct harminic, probably.
Regarding my question, LWFL causes a little chatter with cold engine (and no hardware failure).
Adding LW pulleys, what causes? Irregular idle perhaps?

EDIT: the damper is just for harmonics, and not for vibrations, those are 2 different things. I don't expect bearings failure due to harmonics.

Weren't there a bunch of threads a few years back trying to link lightweight pulleys paired with lightweight flywheels as causing engine failures? Yet one or the other was fine?

I remember that also. Thought the info came from a reputable engine builder.

I have the lightweight flywheel and drive in traffic, does not bother me any. There are some idle/AC on harmonic issues with it in the transmission. The flywheel will have more effect than the pulleys.

In theory it is an issue. But let's be honest, is an FA20 really going to run long enough this is an issue :iono:


:D

Lol I'm sure there are plenty. I don't mind the FA20 TBH

I'm mostly joking.

Not gonna claim any benefits other than faster revs, but I have had a LWP on my EJ205 for 10 years and 80k with no ill effects at 147K. Put one on the BRZ just because, have to admit I did not feel as much of a faster rev as I did on the EJ. Just saying.

I have both of them (Toda Racing) for the last 3+ years. No issues at all and no engine light. Older Subaru engines was confirmed to give an engine light, but this engine looks to be fine. The car has traveled across Europe (Germany, Italy, Greece).