Oppo car mod help

"Supreme Chancellor and Glorious Leader SaveTheIntegras" (jegoingout) 01/07/2016 at 11:00 • Filed to: HALP

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I never heard of people using different crank pulleys until I bought a TL-S. Anybody have experience with “lightweight crank pulleys”? Acurazine has good words to say about it, but I’m hesitant to believe it as XLR8 sponsors a lot on that site

crowmolly > Supreme Chancellor and Glorious Leader SaveTheIntegras 01/07/2016 at 11:09

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Sure. But why?

Seems like an appearance mod more than anything else. There may be an overdrive/underdrive thing going on but that’s usually a bad idea.

iSureWilll > Supreme Chancellor and Glorious Leader SaveTheIntegras 01/07/2016 at 11:14

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I've heard of people using these as they are usually an under drive pulley and its cheaper than the set for all the accessories. I wouldn't recommend using a non OEM crank philly since the stock would should have a balancer on it. Get the accessory pulleys if you want to under drive them and leave the stock crank pulley.

Future next gen S2000 owner > Supreme Chancellor and Glorious Leader SaveTheIntegras 01/07/2016 at 11:14

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The math behind it says a lower mass pulley will have lower rotational inertia which leads to faster acceleration for a given force. So you could be helping your engine rev faster and slightly lower parasitic drag losses. On a DD, it probably isn’t worth it.

daender > Supreme Chancellor and Glorious Leader SaveTheIntegras 01/07/2016 at 11:17

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I guess, in theory, is to reduce the rotational mass of the all the accessories but, to be honest, it’s a dress-up part with very negligible performance benefits. You’ll get more power per dollar with a K&N intake filter...

...WHAT?! 198$ for just that pulley!?

That’s some overpriced bling right there, it’s almost into Carroll Shelby regions. Treat your car to a new muffler AND intake filter for that sort of money.

Pixel > Supreme Chancellor and Glorious Leader SaveTheIntegras 01/07/2016 at 11:17

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This site gives some seemingly valid reasons why it would be a bad idea on a street motor.

I know there was one sold for the xB, but several people who ran them had the pulley fail and gouge up the end of their crank or do other expensive damage. Dunno if that is due to it being a 1-piece aluminum pulley or just a quality issue with the one company that supplied them for xBs.

Supreme Chancellor and Glorious Leader SaveTheIntegras > crowmolly 01/07/2016 at 11:18

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everybody says to use the stock size, underdrive = horribleness

Pixel > crowmolly 01/07/2016 at 11:18

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Significant reduction in rotating mass, frees up some horsepower and helps the engine rev faster.

Tradeoff is the pulley is less durable(drilled alum vs steel), and you loose the harmonic dampening of the stock pulley, which put more strain on the motor internals.

PowderHound > Supreme Chancellor and Glorious Leader SaveTheIntegras 01/07/2016 at 11:19

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I have a lightweight that came on my car when I bought it. Never drove one without to compare though. Very very marginally quicker to rev though?

Little Black Coupe Turned Silver > Supreme Chancellor and Glorious Leader SaveTheIntegras 01/07/2016 at 11:19

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Meh. I've heard they really aren't worth the bother for the gain. Unless you're super serious about getting every last bit of HP, meh.

Supreme Chancellor and Glorious Leader SaveTheIntegras > daender 01/07/2016 at 11:20

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the underdrive pulley’s were an extra $100

crowmolly > Pixel 01/07/2016 at 11:26

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If this is a harmonic damper delete than it goes from “OK I guess” to “This sounds like a bad idea for a street car”.

That does explain the power gain and loss in rotating mass, though. I’m sure you get a benefit but I don’t know if it would be worth it long-term.

Pixel > crowmolly 01/07/2016 at 11:30

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Yeah. It is another of the mods that started in race engines and filtered down to the street car aftermarket without accounting for the fact a race engine isn’t expected to last for tens or hundreds of thousands of miles without a rebuild.

daender > Supreme Chancellor and Glorious Leader SaveTheIntegras 01/07/2016 at 11:36

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Yikes! There’re better performance parts to buy for that kind of money.

Textured Soy Protein > Supreme Chancellor and Glorious Leader SaveTheIntegras 01/07/2016 at 11:48

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Back in the day it was all about the billet “underdrive” accessory pulleys. Same basic idea. Get a bit more responsiveness out of an NA motor by reducing the parasitic power drain.

I wouldn’t mess with it. The benefits are dubious at best. There are plenty of other ways to make power, and a car like a TL-S is not some highly tuned race machine that you need to go changing pulleys out.

Snuze: Needs another Swede > Supreme Chancellor and Glorious Leader SaveTheIntegras 01/07/2016 at 11:54

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I think a lot of this has been covered already but there are a few benefits and a few drawbacks:

Benefits are from reduced rotational mass, which translates into faster revving and freeing up a couple horsepower. You can also go to underdrive pulleys, which drives the accessories slower, but this has some drawbacks in terms of reducing the output of things like your alternator, power steering pump, etc. For a track car it probably doesn’t matter but for a street car it’s hard on the accessories.

The downsides are two-fold. One, these pulleys are aluminum, not steel as most OEM units are. Aluminum has a fatigue life - I’d be extremely worried about it cracking and breaking on my daily driver. Second is vibration - usually the stock pulley acts as a crank damper to attenuate crank vibrations. This is really important because these vibrations will be increased in magnitude and transmitted to other parts of the engine/car. Hot Rod magazine did a test a number of years ago with a hopped up SBC V8. They compared a stock pulley, aluminum under drive, and a whiz-bang Fluidamper - in this particular application the aluminum pulley came in last in terms of power production despite weighing significantly less than the other two. What they discovered was that (in this particular application) it was transmitting vibrations into the valve train that were so bad it was creating a resonance issue in the valve springs leading to a minor amount of float - not enough to cause piston-valve contact, but enough that the lifters were skipping and causing some valve flutter that affected performance (losing a bit of compression, exhaust reversion, etc.). This probably wouldn’t happen on a mild street motor like your Acura, but it makes you wonder what other damage could possibly be occurring in your engine.