who has lightened crank pulley's done?

[boroEF]

I'd like to do this.....IF it isnt bad for the car... i read that the stock crank pulleys have a vibration dampener..and the aftermarket light ones do not. so obviously, this will increase bearing load.. but has anyone actually had experience with them? soo like is there living proof that there wont be any probs when runnin one of these?

[speedemn]

I am running the Unorthodox Racing smaller/lighter crank pulley. On idle, I do hav a light dimming problem, but later on I found that it was mostly due to a weak battery. I have a VERY SLIGHT light dimming problem now. As for drivability, I did feel like the RPMs climbed a little faster, but nothing to write home about. My driving patterns are scattered so I cannot make a definite comment on gas mileage. On the dyno there was a very slight increase in power, but it is more an effect of less driveline loss, than it is an increase in power. A 3-pulley set would have been a LOT better, but alas we do not have that option.

If you have the money to spare, go for it. Then again I might be having a placebo effect now since I've had it for so long that I might not realize how much better it really is.

[boroEF]

On 2002-04-13 18:57, speedemn wrote:
I am running the Unorthodox Racing smaller/lighter crank pulley. On idle, I do hav a light dimming problem, but later on I found that it was mostly due to a weak battery. I have a VERY SLIGHT light dimming problem now. As for drivability, I did feel like the RPMs climbed a little faster, but nothing to write home about. My driving patterns are scattered so I cannot make a definite comment on gas mileage. On the dyno there was a very slight increase in power, but it is more an effect of less driveline loss, than it is an increase in power. A 3-pulley set would have been a LOT better, but alas we do not have that option.

If you have the money to spare, go for it. Then again I might be having a placebo effect now since I've had it for so long that I might not realize how much better it really is.

they claim dyno gains of 8whp...this was on a neon...i figured the car was prolly force inducted... so thats why the gain was magnified? so it actually doesnt help much?

[speedemn]

they claim dyno gains of 8whp...this was on a neon...i figured the car was prolly force inducted... so thats why the gain was magnified? so it actually doesnt help much?

You will not see 8whp with this on your stock 5S-FE. It would be more like 2-4whp MAX.

[DaksGT]

Dennis Grant is a Canadian member of the SCCA and a very active member of the online autocross community. He is an automotive engineer by day, and in his spare time he autocrosses a highly modified Eagle Talon. His name may be familiar to some of you as he was a driving force behind the creation of the SCCA ‘s new Solo II Street Mod fled category. This article was posted to the Street Touring email list in response to questions of why there is a limitation on replacement of crankshaft dampeners in the STS class. It is reprinted with permission. Direct any questions or comments to Dennis at trog@wincom.net
----
The theory behind underdrive pulleys is sane enough: various engine accessories are driven off a belt system taken off the nose of the crankshaft. It takes power to drive these accessories, and the amount of power consumed by each accessory is usually proportional to the speed at which it is driven. Slowing down an accessory thus reduces the amount of power it consumes. Note, however, that is not ‘‘free power’’ but rather “robbing Peter to pay Paul”. The output of an accessory is proportional to the amount of power it consumes, so if you reduce the amount of power a given thingie is consuming by underdriving it, then you are also reducing its output. Go too slow, and you can cause more harm than good.

For example, if your car draws 20 Amps of current at idle, and you underdrive the alternator to the point where it is only producing 15 Amps, then that 5 Amps will come out of the battery so a running car will discharge a battery, not charge it.

Anyway, depending on the design of an individual engine and its accessories, some power may be found by underdriving the accessories.

To do that, you have a choice: just like on a 10 speed bicycle, you can change the diameter of either the driven pulley (gear in the case if the bike) or the driving (crank) pulley.

Reducing the diameter of the crank pulley underdrives all accessories. Increasing the diameter of a given accessory’s
pulley underdrives just that accessory.

So far, so good. This is all just plain Jane high school mechanics here. If you’ve ever had a multi speed bike with a tire driven light generator on it, you’ve experienced everything that’s going on here. But now it gets complicated: Crankshafts flex. One end of the crankshaft (the transmission end) is for all intents and purposes held solid, and the other end is free floating. The crank is then subjected to a series of pulses tangental to the axis of rotation, both in the direction of rotation, and opposite to it (not just power pulses, but compression pulses, inertial loads as the pistons come over the top of their strokes, and so on and so forth)

The crankshaft is being wrung like the neck of a chicken, constantly back and forth, with each crank throw acting like an
additional hand on its neck. No Crankshaft Design Is Immune To This. ALL crank shafts flex. There is no way around it.

The amount of flex does vary in degree though. Cranks that see more torque flex more. Cranks that see higher RPM (and thus higher piston inertial loads) flex more. Longer cranks flex more. (There is an aircraft engine in the Chrysler museum that has a crankshaft about 6 feet long. Crank flex was so bad in this motor that they moved the power take off to the center of the crank, effectively halving the length of the crank) Crank flex is also dependant some what on crank metallurgy.

Thus, a short, slow, low power motor wont see much crank flex, where a long, high revving, powerful motor will see more. But that’s not all...

Each crank has a “natural frequency” that it wants to vibrate at (and higher order frequencies called “harmonics” that are integer multiples of its natural frequency). If a crank sees pulses at its natural frequency, each pulse will re enforce the one proceeding it (like sloshing back and forth in the bathtub, or rocking a car to get unstuck from a snow bank) If this happens, the crank will eventually tear itself apart. Not only that, but due to a law of physics that I can’t explain very well, because one end of the crank is supported and the other not, you get a sort of crack the whip’’ effect that causes the crank nose to move at 90 degrees to the axis of rotation, turning the crank nose into a hammer.

Needless to say, all these effects are bad for motor life.

You cannot get rid of them they are an intrinsic part of the nature of the crankshaft. It is the nature of crankshafts to flex, to have harmonics, and to try and pound out their bearings. But you can control these effects. Enter the “harmonic damper”. The harmonic damper consists of an inertial ring bonded to the crankshaft via some elastic sub stance, usually a rubber of some sort.

The inertial ring is just a circular weight that, thanks to inertia, wants to keep turning in the direction of crank rotation. As the crank flexes back and forth, the inertial ring stays pretty much steady, and the rubber that joins the two together damps out the crank pulses. It is this flexible rubber joint that makes the damper work. Without it, the inertial ring be comes a solid part of the crank shaft, and will flex back and forth with the crank (possibly even magnifying the effects!) No rubber ring no damper. Further complicating the issue, not all engines were internally neutrally balanced; they needed offset counterweights external to the engine to bring the engine into balance. Often, the counterweight was added to the hub section of the harmonic damper (you already had to have the bloody thing, why not put the counterweight onto it?) and so the damper got called a “harmonic balancer”, often shortened to “balancer”.

So the terms “balancer”, “harmonic balancer”, “torsional damper” and “harmonic damper” are all basically interchangeable. They are not all the same thing (depending on if there is a balancing counterweight in there or not) but they all perform the essential function of controlling crank flex.

Now, on most domestic V8s, the balancer and the crank pulley were two separate parts, bolted together. One could thus change the diameter of the crank pulley without disturbing the damping function. But on most modem engines, the crank pulley and the damper assembly are the same unit. What’s more, it seems that the size of the inertial ring has dropped, and the thickness of the elastomer ring has shrunk, so it is often difficult to see at first inspection that a given pulley/damper assembly is in fact an assembly and not just a plain-jane pulley.

If a pulley/damper assembly is replaced with a solid pulley, engine damage WILL eventually occur. The likelihood and se- verity varies from engine to engine, but the physics behind the damage is immutable.
Now there ARE engine builders who will remove damper assemblies. It was common in my drag race days to replace 151b dampers with solid aluminum hubs (in order to reduce rotational inertia) but this was done on engines that were tom down and rebuilt after every event.

If you have the type of operation that has a couple of spare engines, and every week the engines are rotated, and the past week- end’s engine is tom down and inspected, then yeah, you can get away with deleting the damper.

If you have a short-crank, low-torque, low-rpm motor, or your motor rarely sees full-throttle use, then you too can probably get away with a solid pulley. And once and a while, someone will just get lucky. I’ve heard of guys who smokes 5 cigars a day from the time they were 12 dying at the age of 104, but that doesn’t mean smoking is safe.

The manufacturers of underdrive pulleys COULD, if they wanted to, build under-drive combo damper/pulley assemblies, but they have chosen not to. Instead, they will make claims about OEM engineering incompetence, dispute the function and effectiveness of dampers, and generally deny that there is any problem - after all, designing a proper part would take research, and it would cut into their profit margin. I am singularly unimpressed with the underdrive pulley people. They are not people with whom I would do business.
The bottom line is this:

I. Replacing a pulley/damper assembly with a solid pulley as a minimum greatly increases the risk of engine damage.

2. Assuming you are set on underdriving your accessories, the same thing can be achieved with replacement accessory pullies.

[boroEF]

wow thanks daks.
i never would have thought it would be an issue with the crank shaft..i just thought of uneven bearing loads...thats some scary stuff.. no pulleys for me! heh

[JAC91]

Hello Everyone
The only other safe option is to delete your A/C and P/S (AE-92) and have the outer ring of your stock crank pulley lathed off.
The Harmonic rubber ring only goes across the inside ringlet of the stock crank pulley.
It cost me 30 bucks at a machine shop to have this done.
I noticed a nice boost from this.
My two cents!!
Well, gotta go C-YA!!

[boroEF]

On 2002-04-15 08:46, JAC91 wrote:
Hello Everyone
The only other safe option is to delete your A/C and P/S (AE-92) and have the outer ring of your stock crank pulley lathed off.
The Harmonic rubber ring only goes across the inside ringlet of the stock crank pulley.
It cost me 30 bucks at a machine shop to have this done.
I noticed a nice boost from this.
My two cents!!
Well, gotta go C-YA!!

i did exactly that, but i didnt chop off the ring

[Consynx]

Delete A/C and P/S?
does he mean kill your Air Conditioning and Power Seats???
that kinda lost me

[bondobondo]

On 2002-04-15 20:31, Consynx wrote:
Delete A/C and P/S?
does he mean kill your Air Conditioning and Power Seats???
that kinda lost me

power STEERING..

think hard - retard..
hahahahha :grin:

[boroEF]

On 2002-04-15 22:36, trueno92 wrote:

power STEERING..

think hard - retard..
hahahahha :grin:

HAHAHAHAHAHAHA give the newb a break :smile:

[JAC91]

Hello
Yeah if you go ahead and get a spare or get a buddy to give you a ride to the machine shop it should only take them about a hour to do the pulley up. (or at least that's what they will charge ya)
It's a good idea to get your hands on some air tools or power tools to get the pulley off other wise you will be turning the engine over trying to get the da*n thing off.
Well, gotta go C-YA!!

[RERX7]

I have a Greddy Pulley set on my FD, I didn't notice any difference maybe it is just too small to be noticed. But it did ignored the air-pump so there will be an issue when you get a smog test.

[Consynx]

so, you get rid of your Power Steering for some hp?
that's no fun

[JAC91]

Hello
The only reason to have P/S is if your to weak (or lazy) to turn the wheel on your own.
Just imagine living in the 60's ,nothing but top class cars had P/S and they weighted something like 3 1/2 to 4 thousand pounds
I guess it's all what your about though.
I am in to racing so P/S is nothing more than a waste of useable power. (At least to me I should say)
Well, C-YA!!