07-13-2018, 02:30 PM | #29 | |
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Sorry - but the skeptic in me has to ask... About that pair of dyno plots that you posted. The plot on the left shows the Toda part resulting in almost 3x the torque of the std part at 3k rpm. Image is fuzzy, but it looks like Toda makes 11.5ish units to a few tenths above 4 units for the factory motor, right? Keeping in mind that the factory bone stock motor is making roughly 135 ft/lbs at 3k rpm, I have to ask - Do You really believe the graph you posted? (hint: the pulley didn't triple the torque output at 3k rpm to 405 ft/lb). There are more than just those two options, and it doesn't really matter which it is - that dyno plot simply makes no sense, the scaling is off, it's fake, who knows. But on this high strung 2.0L 4 cyl engine - That makes peak power at roughly 7K rpm, that graph is meaningless. |
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07-13-2018, 02:40 PM | #30 |
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07-13-2018, 02:43 PM | #31 | |
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1. Yes all vendors lie and over hype their product. 2. Yes the Toda underdrive pulley set does work/make measurable gains. Bcs it’s underdriving alt/water pump, not bcs of its weight or being lighter. I assumed this thread was about weight reduction on pulleys. Not underdriven pulleys. I have posted the math on previous threads. So I’ll just give numbers here. 15% underdriven alt pulley will had .65whp 15% underdriven water pump will add 1whp. Obviously 0 crank hp, but less parasitic leach from the two accessories. I haven’t looked at the % Toda underdrives if it’s diff then the 15% fensport pulleys you can just do the conversion math. |
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07-13-2018, 02:43 PM | #32 |
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07-13-2018, 02:51 PM | #33 |
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There are increased vibrations caused by the light crank pulleys that can lead to spun bearings. I wouldn't take that risk for such a small gain (if any). Installing a performance exhaust header, removing the spare tire, or using lighter rims (and/or others) can make much more difference.
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07-13-2018, 02:55 PM | #34 | |
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07-13-2018, 02:59 PM | #35 |
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07-13-2018, 03:50 PM | #36 |
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I'm not convinced the alternator (at least on the +2017) is consuming engine power under load. My voltage spikes to +14 when I let off the throttle. Other manufacturers run schemes to eliminate alternator load under throttle, so it's not unheard of.
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07-13-2018, 03:52 PM | #37 |
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@86TOYO2k17 You don't have a 1000lbs atlas stone and you shave 4lbs. Your engine revs much faster in 1st and 2nd gears with the same car weight, meaning that the crankshaft drives much less weight in these gears. Have you ever ride a bicycle? Do you understand the basic mechanism of gearing and the effect it has on your foot pedal?
And by the way Toda underdrives only the alternator and the gain is in the range of 1 hp max. The dyno shows more gains and it is not a 0 hp gain for the crank pulley. @Joesurf79 I never try to explain a dyno on the very low RPMs. For the blue curve I can assume that the operator shifted differently from 2nd to 3rd gear and the dyno measured a range of RPMs without full throttle acceleration. What matters for me is above the 3.5k RPM area and the dyno is not fake: http://www.toda-racing.co.jp/en/prod...lley-fa20.html @weederr33 Yes this is what I figured too. Why some people behave so childish on the pulley topic? |
07-13-2018, 04:27 PM | #38 |
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Check the independent tests of lightweight pulley vs. OEM pulley vs. Fluidampr below.
https://motoiq.com/fluidampr-the-independent-test/3/ There is no HP gain from lightweight pulley as @Subsonic has shown in the first post. This has been discussed so many times before. All power gain claims are fake. |
07-13-2018, 04:28 PM | #39 | |
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When the engine isn't tasked with accelerating the huge lump of mass that it's attached to, the weight loss in a pulley may seem to make a difference. Under load, the power required to accelerate the mass of the pulley system is limited to the same rate of RPM increase that is set by the acceleration of the car. That is the key to why pulley mass is trivial beyond the static weight loss. |
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07-13-2018, 04:33 PM | #40 | |
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If youget to assume that the dyno operator wasn't full throttle on the stock plot down low in the revs, I get to assume the were sandbagging and not going WOT from 3K to 7.3K either lol! Where is the arbitrary point in your mind where you assume the dyno op went WOT for the factory pulley set up? Okay - Lets play devils advocate, then. You posted the plot to bolster your claim (which honestly has no bearing as it's for a set of under-driven pulleys and the discussion here is about lightened pulleys), and now we only get to scrutinize the portion that fit's your narrative? Cool - Lets say they were WOT from 5K to 7K we can agree on that then, right? The delta looks like roughly 5% more torque 5K-7K rpm. Are you telling me you believe their motor picked up 7 ft/lbs from 5K to 7K rpm? Sorry man, the math doesn't bear it out. In fact here is a counter article on those types of power generation numbers with an engineering flavored layman terms explanation, vibration analysis (multiple orders), and dyno plot for each crank pulley tested. Factory, light weight, and a viscous type. https://www.enginelabs.com/news/guest-column-fluidamprs-brian-lebarron-on-fr-sbrzwrx-dampers/ When you present a bunch of engineers, physicists, and other generally sharp, Alpha male technical types with a bs argument on a slow Friday at work, well...what more do you expect from the internet? Nothing more or less than what you got, as this isn't the first time we've kicked this car-forum hornet's nest, is it? |
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07-13-2018, 04:34 PM | #41 | |
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07-13-2018, 05:42 PM | #42 |
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But nikitopo says a pulley give 8 WHP.. And that is not a huge gain.. It must be true, you all other guys are lyers.
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