Underdrive crank pulley

[TOYO-GT-T]

Has anyone fitted one of these and/or know much about them?

How does this upgrade differ from a lighter flywheel as far as performance gains are concerned?

Found some info on the net about them:

- You will notice that the motor tends to spin a little more freely, and acceleration feels faster.

- An UDP alone has had different opinions varying from yes it feels good to no it doesn't have any effects.

- A good brand pulley is definitely the way to go if you get one. Cheaper pulleys tend to make noise and also eat up belts for some.

- An UDP does not create HP it only frees up HP, so do not expect tremendous gains.

- An UDP works better with most all bolt-on mods and it is a catalyst to everything else.

- An UDP is not really recommended if you have a system in your car or multiple electronics as it will deplete the life of your alternator faster.

- An UDP seems to be fine without any additional accessories or systems in the car as far as my experience has been.

- I did notice that my revs climbed ever so slightly faster.

- Again a combination of other mods will see more benefits from the UDP vs just the UDP alone.

- A few members have had the UDP along with their systems and not noticed any detrimental effects from it. That might be from having a healthy car or the effects haven't hit yet.

[Bling]

Sounds like a have? Keen to hear others thoughts though on it's potential...

What is it for, the Vitz? Are you just looking for cheap ways to gain power or what?

[Girvs]

Got one on my NA 2J. TBH didn't notice a huge difference. People complain about the fact that your engine will grenade because the harmonic balancer is not there to counteract vibrations, blah blah. I've not seen any damage in the 30,000K's that I've been driving.
Well that and the 2J is meant to be internally balanced. Either way. Unless you're after that last little bit of power its probably not worth it. It definitely wouldn't compare to the responsiveness from a lightweight flywheel.

[Girvs]

And for more spam, taken from the Unorthodox racing website

What is underdriving/underdrive?

Underdriving/underdrive is slowing the speed of the accessories, or the driven component, from their original factory speed. Underdriving can be done in two ways. First is by increasing the diameter of the accessory pulley/s. The problem with this method is it increases the size of the accessory pulley/s which increases their weight. Weight reduction is the most important key to increasing engine performance and response. This method also eliminates the ability to underdrive the a/c that robs alot of horsepower. The second, which we use, is reducing the diameter of the crank pulley. This allows us to achieve the best ratio of underdriving, and most importantly maximizes the reduction of weight on the crankshaft. This reduction in weight reduces the moment of inertia allowing your engine to respond faster to throttle inputs and perform better at all RPM's. This method also allows underdriving of the a/c we can maximize the performance of our kits by not leaving any accessories to rob precious horsepower from your engine.

Is my crank pulley a harmonic/torsional/vibration damper or a harmonic balancer?

People are getting their crank pulleys confused with the harmonic dampers found on some domestic V6 & V8 engines. "Harmonic Balancer" is a term used loosely in the automotive industry. Technically, this type of device does not exist. The "balancer" part comes from engines that are externally balanced and have a counterweight cast into the damper. None of the applications we offer use a counterweight as part of the pulley, as these engines are all internally balanced.

The pulleys on most of the new import and smaller domestic engines have an elastomer (rubber ring) incorporated into the pulley making them look similar to a harmonic damper. The elastomer in the OEM pulley serves as an isolator, which is there to suppress noise from the engine accessories; the A/C compressor, P/S pump, and alternator. This is what the manufacturers call NVH (Noise Vibration & Harshness) when referring to noticeable noise and vibration in the passenger compartment. It is important to realize in these applications, the elastomer is inadequate in size and durability to act as an effective torsional damper. If you look at the pulleys on some imports there is no rubber to be found at all. We have samples of these, mostly from Acura/Honda B & D Series engines, Nissan Altima, 1.8L Eclipse, 2.3L Fords, Chrysler 2.2L's, and 1.8L VW's just to mention a few. Most owners who have installed our pulleys notice the engine actually feels smoother. This is result of replacing the heavy crank pulley with our crank pulley. NVH is variable and unique to every car. NVH will increase with the installation of an aftermarket intake and/or exhaust, for example. Think of OEM intake systems in newer cars, they use baffles and resonators in the intake to quiet all the intake noise. Aftermarket intakes eliminate these resonators and create dramatic increases in engine noise from the throttle opening and closing. So to most tuners, certain types of NVH can make the driving experience more enjoyable.

The purpose of a traditional harmonic damper is to protect against crank failure from torsional movement and frequencies of high amplitude. This is not necessary in most modern engines because of the many advances in engine design and materials. Factors such as shorter stroke length, smaller displacement, piston dwell time, piston pin off-set, power output, etc., do determine when and how these harmonics and torsional movements occur. More importantly the actual tune of the engine, espcially with modified vheciles, is the biggest factor in potential engine damage. Poor tuning leads to detonation which is an engine killer that no damper can stop.

Again, there is a lot of internet hearsay about solid crank pulleys. When engine problems occur, too often people are quick to blame the pulley first, rather than taking the time to look logically into why there was a problem. We hope that after reading this you will understand our crank pulleys better. T

[wde_bdy]

The only real benefit from them is not killing accessories with too many revs when you live in the top of the rev range more than normal, most of the other stuff you read is placebo effect.

Callum

[TOYO-GT-T]

You got it, its for the Vitz again

Just been hunting through the off-shore forums to see what owners have been doing.

As we all know - not much you can do with the Vitz engine and equally you would not want to spend much on it.

Looking for some basic bolt on upgrades post exhaust,headers (could be hard to source) and panel filter.

The ones which spring to mind - and I say generically as they are common on engines such as 4AGE's and in no particular order or preference are:

* Lighten flywheel
* Enlarged T.B
* Pulley upgrade (not so common)
* Cams (not an option on the VVTI)
* Custom tune

Possibly, the only one worth while doing on this list is a custom tune (if that) as the engine power output is minimal and accordingly it will only respond minimally to each upgrade.

Maybe, I need to change my focus back to the handling and like someone said appreciate the car for what Toyota designed it to be.

[Bling]

I'm not sure any of it is really going to be worth the money. Which is half the reason I haven't modified my blacktop. To get good gains you need to spend up large. So my theory is I may as well buy a fast car if I want one.

Not bagging doing the upgrades, just don't expect much improvement and you won't be disappointed

When you say custom tune, how do you intend to do that? After market ECU and time on the dyno?


tl;dr if you want a fast car, buy one. Or do it properly and super charge / turbo it.

All of the above is obviously just my2c.

[TOYO-GT-T]

I'm not sure any of it is really going to be worth the money. Which is half the reason I haven't modified my blacktop. To get good gains you need to spend up large. So my theory is I may as well buy a fast car if I want one.

Not bagging doing the upgrades, just don't expect much improvement and you won't be disappointed

When you say custom tune, how do you intend to do that? After market ECU and time on the dyno?


tl;dr if you want a fast car, buy one. Or do it properly and super charge / turbo it.

All of the above is obviously just my2c.

Agree with your comments -

re custom tune - was going to spend some time on the dyno and see if the ECU can be "re-flashed" to suit the exhaust and intake and possibly adjust the fueling.

I know this can be done for the Holden at Speedtech - not sure if they can do it for the Vitz.

[gt4dude]

are you guys saying, when building an engine, dont bother sending your parts away with $300 to have a little (m) stamped on your crank, crank pulley, flywheel & clutch cover along with a couple new holes drilled in your crank pulley?

[Bling]

What? I'm confused lol