Underdrive crank pulley.

[jimlloyd40]

Just curious if anyone has installed an underdrive crank pulley. I have on other brands of cars but I haven't seen anyone mention them in the forum.

 

[GTIfan99]

I think most don't in these engines because of crack walk issues, though likely more an issue with DSG.

I used them on all my Subarus with no b issue. EVO guys always stayed away from them due to crank walk issues.

 

[jimlloyd40]

I think most don't in these engines because of crack walk issues, though likely more an issue with DSG.

I used them on all my Subarus with no b issue. EVO guys always stayed away from them due to crank walk issues.

I thought crank walk was a manual trans problem.

 

[GTIfan99]

I thought crank walk was a manual trans problem.

You're right, I meant to type likely not an issue wish DSG. Sorry, typing on phone and watching a movie.

 

[toothofwar]

What would be the advantages of this? I guess I'm new to this.

 

[jimlloyd40]

What would be the advantages of this? I guess I'm new to this.

Reduced weight and better throttle response. They usually claim about 10 more HP and torque and slightly better fuel mileage.

 

[GTIfan99]

An underdrive pully can't increase hp. It can decrease hp loss.

I've yet to see anyone replicate the manufacturers claims on a dyno, but seat of the pants in my Subarus days says they revved a little quicker, response was better.

I have a 6mt, so won't be doing it on the GTI. I don't know enough about the DSG to know if there's any risk involved or what the other affects of underdriving your accessories will be.

 

[jimlloyd40]

An underdrive pully can't increase hp. It can decrease hp loss.

I've yet to see anyone replicate the manufacturers claims on a dyno, but seat of the pants in my Subarus days says they revved a little quicker, response was better.

I have a 6mt, so won't be doing it on the GTI. I don't know enough about the DSG to know if there's any risk involved or what the other affects of underdriving your accessories will be.

It can't increase total HP but the HP and torque will come on at a lower RPM. I don't know if underdriving the accessories would be a problem with a GTI but it wasn't a problem on the other brands I used one on. That's why I posted this to hopefully find someone who did install one on a GTI.

 

[2slowvw]

Definitely not worth the risk on these engines. Thats why most are going the opposite direction and getting a fluidampr instead

 

[GTIfan99]

It can't increase total HP but the HP and torque will come on at a lower RPM. I don't know if underdriving the accessories would be a problem with a GTI but it wasn't a problem on the other brands I used one on. That's why I posted this to hopefully find someone who did install one on a GTI.

They reduce amount of hp used by engine accessories.

These cars are already pretty finicky when it comes to electronics and vvt, I don't think the juice is worth the squeeze in this case. Look at the fiasco VW ran into adding a tooth to the oil pump and lighter oil.

 

[jimlloyd40]

Definitely not worth the risk on these engines. Thats why most are going the opposite direction and getting a fluidampr instead

What are the risks? Harmonics and vibrations?

 

[Blindeye_03]

An underdrive pully can't increase hp. It can decrease hp loss.

I've yet to see anyone replicate the manufacturers claims on a dyno, but seat of the pants in my Subarus days says they revved a little quicker, response was better.

I have a 6mt, so won't be doing it on the GTI. I don't know enough about the DSG to know if there's any risk involved or what the other affects of underdriving your accessories will be.

I had one of these on my 2.5RS and had similar results. However I have no desire to install one on my GTI.

 

[GTIfan99]

What are the risks? Harmonics and vibrations?

You could be underdriving you oil pump, which could have negative affects on the vvt or oiling.

 

[jimlloyd40]

You could be underdriving you oil pump, which could have negative affects on the vvt or oiling.

Isn't the oil pump driven by the timing gears?

 

[GTIfan99]

You might be right, I'm not an expert on these engines, but I do know they're finnicky.

What specifically will be underdriven and by how much? That might be a good place to start when evaluating if it's worth it.