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Discussion Starter · #1 · (Edited)
Not sure if anyone has tried this - I currently have less than a year before I'm going to need a new timing belt so I figured I'd upgrade the crank pulley while I was at it. The ARD project didn't work out - unfortunately I didn't want to risk such a small amount of material around the hub failing on a hard accel/decel since the masses of the compressor AND the alternator come into play.

That being said tonight I started searching and found that the 2008-2012 Ford Duratec RS/ST has the same stock crank pulley (Ford PN 1388487) which makes sense given it's the same engine.

That being said I found that Anembo engineering has an anodized (104.99 GBP) and unanodized (99.99 GBP) solid aluminum crank pulley. It is located here: https://anemboengineering.co.uk/engine-2/?sort=featured&page=4

It is also on Ebay for those that wish to shop through there sold by various resellers of their products.

Says it's made from T6 6082 billet. Anembo doesn't do shoddy work so I plan on upgrading when time comes. Gotta remove the old one anyways. I did the math and the difference in weight comes out to just under 1/4 use of energy to rotate the lightweight one. I'll do a rough HP conversion tomorrow. Gotta go to bed.

Update - I did the math today - A stock crank pulley uses up just over 4HP to turn at 6500rpm and 1/2HP to turn at idle. The lightweight unit will use ~1HP to turn at 6500rpm and about .05 HP to turn at idle. This is a rough estimate, using the math of an evenly distributed cylinder, not properly measuring the inside/outside radius of the primary weight, so it will vary slightly, but this is a close enough ballpark for the time I had available today.
 

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Not sure if anyone has tried this - I currently have less than a year before I'm going to need a new timing belt so I figured I'd upgrade the crank pulley while I was at it. The ARD project didn't work out - unfortunately I didn't want to risk such a small amount of material around the hub failing on a hard accel/decel since the masses of the compressor AND the alternator come into play.

That being said tonight I started searching and found that the 2008-2012 Ford Duratec RS/ST has the same stock crank pulley (Ford PN 1388487) which makes sense given it's the same engine.

That being said I found that Anembo engineering has an anodized (104.99 GBP) and unanodized (99.99 GBP) solid aluminum crank pulley. It is located here: https://anemboengineering.co.uk/engine-2/?sort=featured&page=4

It is also on Ebay for those that wish to shop through there sold by various resellers of their products.

Says it's made from T6 6082 billet. Anembo doesn't do shoddy work so I plan on upgrading when time comes. Gotta remove the old one anyways. I did the math and the difference in weight comes out to just under 1/4 use of energy to rotate the lightweight one. I'll do a rough HP conversion tomorrow. Gotta go to bed.

Update - I did the math today - A stock crank pulley uses up just over 4HP to turn at 6500rpm and 1/2HP to turn at idle. The lightweight unit will use ~1HP to turn at 6500rpm and about .05 HP to turn at idle. This is a rough estimate, using the math of an evenly distributed cylinder, not properly measuring the inside/outside radius of the primary weight, so it will vary slightly, but this is a close enough ballpark for the time I had available today.
Would be interested to see if there's any difference. For the cost I don't think it would be worth 3hp though
 

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Discussion Starter · #4 ·
Jamatron over at c30crew installed this.

Here's the link to his build: http://www.c30crew.com/forum/showthread.php?10446-Building-the-Bosses-Car/page4

It's not on the thread, but I asked him if there were any noticeable gains and he said "not much."
Yep, really isn't and the math confirms - I'm not particularly fond of bonded rubber and have seen what it does to a diesel engine when it comes apart at 120k mi so I am not risking it with this car. The liquid filled ones would be AMAZING if they weren't $800 per.
 

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Discussion Starter · #6 · (Edited)
How did you figure this? Requires 0hp to keep any object spinning at a constant rpm, 1lb or 1000lb.
Sarcasm first: Perpetual Motion Police! Stop right there! You are violating the laws!

But in all seriousness - if this was space you'd be correct. But until we Ol' Musky one of these bad boys into space, we're subject to the physics of gravity and friction on this planet. It requires SOME amount of energy to keep an object at a given speed to cover parasitic forces.

That being said, ignoring the rest of it, KE possessed by an object is measurable using KE = 1/2 * m * v^2 - making energy required to upkeep a spin at a given speed not a factor in this problem.

The math I used was KE = Iω^2 from there that gives us a result in kilograms-meters squared per second squared - from there you can convert it to joules and from there you can convert joules to mechanical horsepower. It's less representative of a hollow cylinder with different internal and external radii, but it gets us a ballpark if it was a universally distributed cylinder spinning about it's axis.
 

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Discussion Starter · #9 · (Edited)
Joules is energy, horsepower is power tho
Now if you say you want to spin from 800 rpm to 6800 rpm and you get some power "savings", but you need a time input there somewhere.
https://www.traditionaloven.com/tut...le-j-per-s-to-mechanical-horsepower-hp-i.html

"First unit: joule per second (J/s) is used for measuring power.
Second: Mechanical horsepower (hp I) is unit of power."
There are more reputable sites, but this is the basic unit of conversion.

Horsepower (hp I) is (Force * Distance)/Time = Ft-lb/sec
Joules/s (J/sec) is (Force * Distance)/Time = Joules/sec

Sounds to me like you're referencing:
"The formula that links energy and power is: Energy = Power x Time. The unit of energy is the joule, the unit of power is the watt, and the unit of time is the second."
https://www.ufba.org.nz/images/documents/calculationofelectricalenergy.pdf
In this case - joules is energy.
In the case above, it's power.

Now I'm not a smart man, and I'm not the best at explaining things, but does this make sense? Been a couple years since Fissics.
 

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Joules is energy, Joules per second is power - in fact, one joule per second is the definition of a watt. In the same way, "miles" is a measure of distance, but "miles per hour" is a measure of speed.

If you are estimating the horsepower drain in getting the pulley up to speed, you need to include some time factor. I'm guessing it takes about 2 seconds to rev up when accelerating in first gear. So you'd take the difference in kinetic energy (joules) for a light vs. heavy pulley, divide by 2 and get joules per second (watts). Then convert watts to hp. (746 watts in a hp).

It makes sense that decreasing the inertia of the engine will give the biggest improvement in accelerating when you are starting in first gear, and not really help at all in the upper gears.
 

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Discussion Starter · #11 · (Edited)
Joules is energy, Joules per second is power - in fact, one joule per second is the definition of a watt. In the same way, "miles" is a measure of distance, but "miles per hour" is a measure of speed.

If you are estimating the horsepower drain in getting the pulley up to speed, you need to include some time factor. I'm guessing it takes about 2 seconds to rev up when accelerating in first gear. So you'd take the difference in kinetic energy (joules) for a light vs. heavy pulley, divide by 2 and get joules per second (watts). Then convert watts to hp. (746 watts in a hp).

It makes sense that decreasing the inertia of the engine will give the biggest improvement in accelerating when you are starting in first gear, and not really help at all in the upper gears.
Ok, so my original post is wrong, and my second post is wrong. I have made two attempts and been corrected on issues in both. I guess I am just not that good at either the math or the explanation or both, but either way I am not really up for trying a third time.

If you guys want to know how to figure this stuff out, refer to these two people here, they clearly know more than I do and are much better at it than myself. If you two want to quantify the benefits for these people between the two pulleys please take the time to do so. I tried and clearly didnt do all that great of a job so there is plenty of room for you two to fill in the gap for inquiring minds instead of just spending time correcting my attempts at explanations.
 

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No need to complicate things, just find the energy required to spin the two pulleys from 800 rpm to 6800 rpm, the divide by the expected time (2nd gear 10-60mph maybe 6 sec?). Should be a lot less energy to spin up the lighter pulley. Then by comparing the two you can get a expected power savings.
 
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