Confirm understanding of lightweight mods

[Smalaihollo]

Originally Posted by mrg666

So, are lightweight pulleys nonsense or helpful? I was wondering ...

My butt dyno and right foot love the lightweight racesceng crank pulley. It might be all in my head but it feels more responsive and quicker.

[tomm.brz]

the point is: of course a lightweight pulley would make rev match/neutral revs quicker and more responsive
but saying that lightweight pulleys make car faster when on gear is pure bullshit

[86TOYO2k17]

Originally Posted by mrg666

So, are lightweight pulleys nonsense or helpful? I was wondering ...

Short answer, they are nonsense.

Longer answer, In neautral it will rev up to redline and freefall down to idle each about a 1/5th sec faster. However once you apply the rest of the drivetrain in gear. It’s practically zero gain. People have broken down the math and it’s basically the equivalent of 1/8th hp, with it diminishing more and more with higher speeds and higher gears.

The main gain is just the static overall weight loss from the vehicle.

Now as I’ve outlined in earlier posts underdriven accessories can add a little bit of gains.

And the fluidampr crank pulley being a much better dampener then stock especially in the 4000k+ range (where vibrations are most dangerous) has been shown on numerous tests on various platforms to actually add some HP/torque in the 4K+ hp range. Vibrations cause energy loss (HP/torque) through generation of heat. So in theory reducing vibrations should cause less energy loss through heat resulting in more power being able to pass through the drivetrain to the wheels. Even if in practice this doesn’t help much in gains still seems like it’ll make the engine run safer. Most people note much smoother quieter engines at idle.

[SuperTom]

Originally Posted by Smalaihollo

My butt dyno and right foot love the lightweight racesceng crank pulley. It might be all in my head but it feels more responsive and quicker.

I'm on your side. My car definitely revs and responds quicker especially in the first 2 gears

[humfrz]

Originally Posted by 86TOYO2k17

Short answer, they are nonsense.

Longer answer, In neautral it will rev up to redline and freefall down to idle each about a 1/5th sec faster. However once you apply the rest of the drivetrain in gear. It’s practically zero gain...……….

It seems to me that your short answer and longer answers are about the same …


humfrz

[nikitopo]

Aftermarket part or Porsche's 993 RS pulley?

[Joesurf79]

:shrug shoulders:

[Subsonic]

Originally Posted by nikitopo

Aftermarket part or Porsche's 993 RS pulley?

I guess if you're building a new engine from scratch then it makes sense to reduce as much rotational inertia as possible, but modifying the FA20? See the new thread I created here:

https://www.ft86club.com/forums/show...48#post3109548

[why?]

Originally Posted by 86TOYO2k17

Short answer, they are nonsense.

Longer answer, In neautral it will rev up to redline and freefall down to idle each about a 1/5th sec faster. However once you apply the rest of the drivetrain in gear. It’s practically zero gain. People have broken down the math and it’s basically the equivalent of 1/8th hp, with it diminishing more and more with higher speeds and higher gears.

The main gain is just the static overall weight loss from the vehicle.

Now as I’ve outlined in earlier posts underdriven accessories can add a little bit of gains.

And the fluidampr crank pulley being a much better dampener then stock especially in the 4000k+ range (where vibrations are most dangerous) has been shown on numerous tests on various platforms to actually add some HP/torque in the 4K+ hp range. Vibrations cause energy loss (HP/torque) through generation of heat. So in theory reducing vibrations should cause less energy loss through heat resulting in more power being able to pass through the drivetrain to the wheels. Even if in practice this doesn’t help much in gains still seems like it’ll make the engine run safer. Most people note much smoother quieter engines at idle.

vibrations are absolutely meaningless in a non forced fed 2 liter vehicle. Even subaru states the engines are internally balanced, so you don't have to worry about it unless you add a turbo or supercharger. This is not an old school big block v8.

[churchx]

there are also EJ & FA engines that had crank bearings fail in relatively low mileage on cars with both lightweight flywheel & lightweight crank pulley installed, requiring engine rebuild. So feel safe to compromise reliability of your car and your engine according to what subaru states. subaru, which most probably mentioned that for engines with stock flywheel and stock dampened crank pulley, not for one with aftermarket ones.
Boxer opposite engines may have least balancing/vibration issues and need least heavy flywheels/dampeners and no need for balancing shafts/weights, but still firing is not happening at all cylinders at same time and each firing twists crankshaft and puts extra load on bearings. Least need != no need at all. Going past reasonable may work on race engines where high budget and well equipped teams don't expect to last them past 10-15K miles prior rebuild/overhaul/replacement, but will not work for car daily driven or lightly tracked, but still owned by someone expecting it to last for 100K or more.

[86TOYO2k17]

Originally Posted by why?

vibrations are absolutely meaningless in a non forced fed 2 liter vehicle. Even subaru states the engines are internally balanced, so you don't have to worry about it unless you add a turbo or supercharger. This is not an old school big block v8.

Yes on FI it will matter more. And bone stock the car should come from factory perfectly fine, although they still put a dampener on for a reason.

However even NA after tossing on intake, bpb, full headerback, a tune, engine mounts, trans mounts, diff inserts/bushing, Fd swap, accessory pulleys, CF driveshaft, changing the cars factory weight distribution/reduction. All these would have effects on vibration that wasn’t originally intended/calculated from factory.

Not saying to the point of being detrimental to the engine. But possibly enough that adding a better dampener with a wider frequency of dampening could be beneficial.

[why?]

Originally Posted by churchx

there are also EJ & FA engines that had crank bearings fail in relatively low mileage on cars with both lightweight flywheel & lightweight crank pulley installed, requiring engine rebuild. So feel safe to compromise reliability of your car and your engine according to what subaru states. subaru, which most probably mentioned that for engines with stock flywheel and stock dampened crank pulley, not for one with aftermarket ones.
Boxer opposite engines may have least balancing/vibration issues and need least heavy flywheels/dampeners and no need for balancing shafts/weights, but still firing is not happening at all cylinders at same time and each firing twists crankshaft and puts extra load on bearings. Least need != no need at all. Going past reasonable may work on race engines where high budget and well equipped teams don't expect to last them past 10-15K miles prior rebuild/overhaul/replacement, but will not work for car daily driven or lightly tracked, but still owned by someone expecting it to last for 100K or more.

every single one had forced induction. There are no vibration issues in a rev range our engine can actually hit, that is what internally balanced means.

Besides I did it to piss people like you off. All your theoretical bs is just that. Someone needs to actually test this stuff out in the real world.

Originally Posted by 86TOYO2k17

Yes on FI it will matter more. And bone stock the car should come from factory perfectly fine, although they still put a dampener on for a reason.

However even NA after tossing on intake, bpb, full headerback, a tune, engine mounts, trans mounts, diff inserts/bushing, Fd swap, accessory pulleys, CF driveshaft, changing the cars factory weight distribution/reduction. All these would have effects on vibration that wasn’t originally intended/calculated from factory.

Not saying to the point of being detrimental to the engine. But possibly enough that adding a better dampener with a wider frequency of dampening could be beneficial.

there is no damper on the car, that is a myth. Any vibration issues are going to be tuned for rpm's that the engine cannot possibly hit. That is what internally balanced means.

Any car that is as heavily modified as you mentioned could have issues that have absolutely nothing to do with vibrations.

[churchx]

why?: theoretical? That was from posts i've seen on this forum from guy from tuning shop that did those several engine rebuilds. Of course you can ignore his "non real world" experiences as he must have dreamed about doing rebuilds and just scammed customers for work they didn't do, as you surely know much better practical statistics.

[why?]

Originally Posted by churchx

why?: theoretical? That was from posts i've seen on this forum from guy from tuning shop that did those several engine rebuilds. Of course you can ignore his "non real world" experiences as he must have dreamed about doing rebuilds and just scammed customers for work they didn't do, as you surely know much better practical statistics.

every single one was forced induction. There is zero proof or statistics of any of these mods damaging a normally aspirated engine. Subaru engines have issues stock, so there is zero proof any of these mods had anything to do with the issues the forced induction engines had.

Unless you are arguing that all subaru engines are total pieces of garbage.