Cause of blown motors?

[suaveflooder]

Originally Posted by ZDan

Don't be so credulous that you just take everything people say to you at face value when they are trying to SELL you something...

Here's what you said Perrin said, which is patently absurd:

This is total and utter horseshit. The required tolerance for the pulley is the same whether you make it out of one part or two. If you make it out of two pieces with a rubber piece between them, you have to have *tighter* tolerances on the two metal parts to account for the tolerance stackup of the assembly.

It is most certainly NOT made as two steel parts with rubber in between them to save money, it certainly costs them more to make it that way.

The REASON is that a dual-mass damper (effectively two rotational masses with a spring between them) controls vibes better over a broader rpm range.

A one-piece with the same net shape and total mass would definitely be cheaper.

Of course Subaru would never waste money making it a pretty shiny anodized aluminum piece. They know what they want the two masses to be, if they made them out of aluminum they would have to be bigger, and they would cost more. That would be dumb...

Highly doubtful, and I'm 100% certain whoever wrote this has no data to back up the claim.

Not a chance you would be able to measure any difference on a rear wheel dyno or at a dragstrip. The effect of such a *tiny* reduction in effective overall mass would be well below repeatability of the measurements.

lol, read the rest of the thread, there tiger. This has all been covered. Thank you for your participation and as always, thank you for playing! I'm done in this thread. I'll poke in if people quote me, but not really in the arguing mood anymore.

[ZDan]

The rest of the thread contains piles of more horseshit. Repeating bad info doesn't make it more correct.

If you want less engine rotational inertia, the flywheel is the place to do it. A lightweight flywheel can remove a significant amount of rotational inertia, which will make upshifting and particularly heel/toe downshifting easier and quicker. With a very small benefit to acceleration times as well. While also potentially reducing peak cyclic stresses in the crank.
A lightweight single-mass pulley isn't going to make a real difference, and can lead to greater stresses in the crank due to torsional modes being peakier. If you don't track the car or spend a lot of time at high revs, it might not be an issue (but then again it might...).

[FirestormFRS]

Originally Posted by PMPB

There is also a huge different in machining steel vs. aluminium. Aluminium might as well be butter compared to the expense of tools, cut speed, and machining fluid required to make our stock crank pulleys.

I'm not sure how much a set of stock pistons cost, but an aftermarket set of FORGED pistons is around $600. Our OEM pistons are sandcast, and spend a lot more time in machining than a relatively simple pulley. I'm just pointing out that a sandcast part that requires extensive machine time, can still be made cheap. Just because the Perrin part is machined from billet, doesn't make it better than what Subaru could make using a cheaper method.

Also, before you start saying that billet is some mythical alloy production methods, it's just a cast aluminium rod (a billet) that is cut into round blanks. 6061 aluminium is the most common plain aluminium ever. T6 is also the standard tempering used. Often a part could be treated to T4 sent for machining, and then retempered to T6.

If Subaru wanted to make lightweight aluminium crank pulleys, they could produce them for about $12-15/ea, possibly cheaper. (I wanted to be conservative)
It would be an extruded part semi-hollow, which would subsequently be cut into blanks, bored on both sides, turned on the outside, and then reamed for concentricity. Pretty fast machining operations which would be automated.

(Myself and a few family workers have or still work in the manufacture of aluminium parts for several car makers, ATV, snowmobile, aircraft, manufacturing equipment, jet boats etc.)

I believe the stock crank pulley would require more manufacturing time. Each piece is likely sand-cast. Additionally, due to the design of the stock pulley, it requires balancing, the manufacturing time alone for that step is not insignificant. A one piece pulley would not have to be balanced after the turning is complete.

Which part of economies of scale did you not understand. The crank pulley isn't designed for the car. The crank pulley is designed and built for the engine, which goes in many different cars.
These large manufacturers know exactly when and when they can not save money on parts. They try to eek suppliers out of $.01 per unit. They can not machine a lightweight pulley reliably for less or they would.

[suaveflooder]

Originally Posted by ZDan

The rest of the thread contains piles of more horseshit. Repeating bad info doesn't make it more correct.

If you want less engine rotational inertia, the flywheel is the place to do it. A lightweight flywheel can remove a significant amount of rotational inertia, which will make upshifting and particularly heel/toe downshifting easier and quicker. With a very small benefit to acceleration times as well. While also potentially reducing peak cyclic stresses in the crank.
A lightweight single-mass pulley isn't going to make a real difference, and can lead to greater stresses in the crank due to torsional modes being peakier. If you don't track the car or spend a lot of time at high revs, it might not be an issue (but then again it might...).

I've had a performance shop here say do one or the other (pulley or flywheel), but not both. They've had bearing fail when BOTH were swapped out, as well as the CEL light, but said things were fine if it was just one or the other.

There is just so much conflicting information out there on this. It's crazy.


Sent from my iPhone using Tapatalk

[continuecrushing]

Is there info out there for how many members were wearing hats when the engine blew? I'm trying to decided whether or not to wear a hat while driving.

[gramicci101]

Originally Posted by Shutter

Is there info out there for how many members were wearing hats when the engine blew? I'm trying to decided whether or not to wear a hat while driving.

Does the hat have a flat brim and/or a sticker and are you wearing it at an angle? If so, then there's a risk of you blowing up your car; they're not designed to handle that much swag. Yolo. Idkmybffjill. Other meaningless acronyms.

[billwot]

Originally Posted by Shutter

Is there info out there for how many members were wearing hats when the engine blew? I'm trying to decided whether or not to wear a hat while driving.

Wearing a ballcap backwards is a known risk factor for catastrophic engine failures.

[continuecrushing]

Originally Posted by billwot

Wearing a ballcap backwards is a known risk factor for catastrophic engine failures.

engine failure or increased traffic stops?

[ZDan]

Originally Posted by suaveflooder

I've had a performance shop here say do one or the other (pulley or flywheel), but not both. They've had bearing fail when BOTH were swapped out, as well as the CEL light, but said things were fine if it was just one or the other.
There is just so much conflicting information out there on this. It's crazy.

Funny... The word on old Nissan L6 engines (a bit different from an H-4) from those who competitively race them (including at 9000+rpm at Bonneville) was that a lightweight flywheel with a dual-mass damper (heavy relative to "lightweight" aftermarket 1-piece pulleys) was the way to go. And guys that tried to race with a lightweight pulleys (expecially in conjunction with heavy flywheels) had crank failures.

[suaveflooder]

Originally Posted by ZDan

Funny... The word on old Nissan L6 engines (a bit different from an H-4) from those who competitively race them (including at 9000+rpm at Bonneville) was that a lightweight flywheel with a dual-mass damper (heavy relative to "lightweight" aftermarket 1-piece pulleys) was the way to go.

EXACTLY. It's all over the place. Oh well. Life goes on

[billwot]

Originally Posted by Shutter

engine failure or increased traffic stops?

Oh yeah...that too!

[ZDan]

Originally Posted by suaveflooder

EXACTLY. It's all over the place. Oh well. Life goes on

The impressions of shops and race teams don't necessarily reflect the underlying analysis/test data that drove the design. The fact is that the engineers who develop OEM cars are paid to minimize the risk that stuff breaks. Particularly expensive stuff like engines. The engineers develop requirements for components to mitigate risk of major failures. This leads to things like (relatively) heavy and expensive 2-mass dampers for pulleys where a lighter single-piece would have been simpler and cheaper. The increased probability of an engine surviving past warranty with a 2-mass damper at the front of the crank is worth it overall according to the analysis and testing that the OEM has done, otherwise it wouldn't be there precisely due to the lengths OEMs will go to to save even 5 cents. I kind of doubt that it's an NVH thing, as the car is so uncompromised otherwise in this regard in the interests of light weight and responsiveness.

[Celadrielas]

Originally Posted by Gords_zenith

Did you even read the article? You can't argue physics. I thought I would post the article and you can come to your own conclusions, but if the OEMs put a harmonic balancer on the engine, and race guys that build professional engines include one, don't you think that they may know more than you? By all means do what you want but I was only posting it to enlighten the uneducated in automotive terminology, and design. I myself have come to the conclusion after many years of denial that yes OEMs are smarter than me....and so I don't bother with modifying anymore. I just enjoy driving without worry and completely covered by warranty. Case in point my dad has a completely stock 2003 Yamaha R1 with 60k km, including track time. That to me is justification enough to not mess with harmonics of the engine.

I'm late to this party, so forgive the early post quote. In the article, there was a quote that caught my attention. "—in this instance an average 9hp at the crank across the rpm range on a modified S2000 making over 300whp: The theory behind the power increase is that reduced vibration will allow an engine to spin more freely, transferring more power to the wheels."

My question is sort of based on theory and is as follows: Wouldn't this not be a "Gain" in power but more of a "Freeing up" of existing power the engine is already making. IE: Engine is running 9hp more efficiently and suddenly gained 9hp?

Maybe that's a noob question. I dunno

[Poodles]

Because of how dynos work, you can get it to read as more power because it spins up a bit faster, but this isn't REALLY power at all and in a true race isn't going to show it.


That or it's simply an underdrive pulley and you're causing issues (alternator not charging, etc)