Installed the Evosport Underdrive Pulley Today

[King Tut]

I did this with a buddy in my driveway. First I jacked up the front of the car and put it on jack stands. Then I removed the bottom panel as it says in the Evosport instructions. Those instructions state you can do the install without removing the fan shroud, but you would have to be crazy to want to do that after struggling for 30 minutes before removing it. It is well worth the time and less frustration to remove the fan shroud. It is a little difficult to get it out and then back in (only casualty of the install was the clip that locks in the driver side of it). Anyway the install went fine. I got the 09+ and DCT package. After the install, I noticed that all the pics of pulleys I see look different than the one I installed today. Most pictures show a pulley where both the front and rear are the same diameter. Well on mine the rear of the pulley for the water pump and alternator was a smaller diameter than the front for the A/C. I am assuming this doesn't affect the power I will see and that is the difference of the new double sided belt setup that is used now. I should have taken some pics, but we were fighting the light, and I didn't get time to put the bottom panel back on yet. If anyone has any questions about the install let me know. I also drew a belt diagram for each belt that I can post up if anyone needs it. I hope to possibly dyno it this Friday or the next on the same dyno that I did my baseline in the same conditions. As requested by PencilGeek I will be posting both dyno files and the Dynojet software to view them at that time.

[naveenb]

what are your intial impressions? i am considering the AA pulleys.

[King Tut]

I havent driven it yet, but I dont really put a lot of stock in butt dynos. I will wait to see what the real dyno numbers are.

[808MGuy]

I was considering a pulley upgrade until I thought about what it actually does. You're slowing down the rotation to decrease parasitic drag. Now, I assume slowing down the rotation also affect power output of the alternator which could have negative affects if you run electrical accessories that will draw high loads like an upgraded stereo.

Is this true or does the upgraded pullet somehow compensate to keep the alternator output up.

[King Tut]

No that is very true that if you are running a couple large aftermarket amps this might affect your charging system. That isn't a big concern for me right now.

[MrHarris]

Butt dynos are important, especially if it's like a 5-10whp gain. Sometimes you really can't feel it. I assume you can with the pulleys though as the power is gained throughout the rev range and not just certain parts like many other power mods.

[King Tut]

Well after driving it I don't feel anything under full throttle when accelerating, but it feels like when cruising in 5th or 6th that partial throttle has more go which is expected. Anyways the dyno will confirm it. I will also be installing the Macht Schnell air filter on the dyno and getting some pulls on that as well.

[King Tut]

Originally Posted by King Tut

I got the 09+ and DCT package. After the install, I noticed that all the pics of pulleys I see look different than the one I installed today. Most pictures show a pulley where both the front and rear are the same diameter. Well on mine the rear of the pulley for the water pump and alternator was a smaller diameter than the front for the A/C. I am assuming this doesn't affect the power I will see and that is the difference of the new double sided belt setup that is used now.

Okay this has me really bothered now. Can anyone confirm the reasoning behind this?

[John@BMW]

Originally Posted by 808MGuy

I was considering a pulley upgrade until I thought about what it actually does. You're slowing down the rotation to decrease parasitic drag. Now, I assume slowing down the rotation also affect power output of the alternator which could have negative affects if you run electrical accessories that will draw high loads like an upgraded stereo.

Is this true or does the upgraded pullet somehow compensate to keep the alternator output up.

you alternator has a voltage regulator that keeps the car at approx 13.6 to 14 volts while driving. The alternator is always making more power than what it is showing- slowing down the alternators RPM will not cause in charging issues.

[J08M3]

Originally Posted by John@BMW

you alternator has a voltage regulator that keeps the car at approx 13.6 to 14 volts while driving. The alternator is always making more power than what it is showing- slowing down the alternators RPM will not cause in charging issues.

all alternators have a voltage regulator. Are you saying that BMW oversized the alternator and in can produce enough amps to charge the battery when there is a heavy load on it and the RPM has been slowed down?

[King Tut]

Originally Posted by King Tut

Okay this has me really bothered now. Can anyone confirm the reasoning behind this?

Well I confirmed the reasoning myself by talking with Brad at Evosport:

There are currently 3 companies selling pullies for 2009 6MT and all DCT equipped cars. All three companies took different approaches to dealing with the change to a double sided belt. I will explain each approach as I understand it:

1) Evosport decided to leave the front of the pulley the same as the OEM pulley thus allowing use of the stock belt and not changing anything on that side of the engine so no worry about DCT issues. The downside is it doesn't underdrive the crank pulley nearly as much as the other 2 setups thus theoretically resulting in less horsepower gained. They are the only company where the pulley for newer cars and older cars is different.

2) Active Autowerke decided the best solution was just to find a supplier for a proper length double sided belt. This belt apparantly is somewhat proprietary to AA and thus could be difficult to find a replacement if it snaps (some have) without going back to AA to get a new belt. AA has apparantly corrected their original belt design/length so snapping belts should not be a worry anymore. They use the same pulley for newer and older cars.

3) Rogue Engineering decided the best solution was to redesign the way the pulleys are utilized on that side of the engine. This invovles swapping out an additional pulley to allow utilizing a non double sided belt just like the 2008 6MT cars. This belt can be easily sourced at any parts store should it snap or get damaged. They use the same pulley for newer and older cars.

I have talked with representatives from all three companies this week, and I have gotten an insight from each. If I made any mistakes in my analysis please let me know.

[rbk1115]

Originally Posted by King Tut

Well I confirmed the reasoning myself by talking with Brad at Evosport:

There are currently 3 companies selling pullies for 2009 6MT and all DCT equipped cars. All three companies took different approaches to dealing with the change to a double sided belt. I will explain each approach as I understand it:

1) Evosport decided to leave the front of the pulley the same as the OEM pulley thus allowing use of the stock belt and not changing anything on that side of the engine so no worry about DCT issues. The downside is it doesn't underdrive the crank pulley nearly as much as the other 2 setups thus theoretically resulting in less horsepower gained. They are the only company where the pulley for newer cars and older cars is different.

2) Active Autowerke decided the best solution was just to find a supplier for a proper length double sided belt. This belt apparantly is somewhat proprietary to AA and thus could be difficult to find a replacement if it snaps (some have) without going back to AA to get a new belt. AA has apparantly corrected their original belt design/length so snapping belts should not be a worry anymore. They use the same pulley for newer and older cars.

3) Rogue Engineering decided the best solution was to redesign the way the pulleys are utilized on that side of the engine. This invovles swapping out an additional pulley to allow utilizing a non double sided belt just like the 2008 6MT cars. This belt can be easily sourced at any parts store should it snap or get damaged. They use the same pulley for newer and older cars.

I have talked with representatives from all three companies this week, and I have gotten an insight from each. If I made any mistakes in my analysis please let me know.

Thanks for this information.

[powertrip]

+1....great info. I think PG got almost 10 WHP out of the Evosport Pulley; I wonder if the Rogue and AA produce any power above and beyond that...

[King Tut]

Originally Posted by powertrip

+1....great info. I think PG got almost 10 WHP out of the Evosport Pulley; I wonder if the Rogue and AA produce any power above and beyond that...

Remember PencilGeek has a 2008 6MT so his pulley is just like the one that comes with the Rogue and AA kit. I am sure it makes the same power as all the others. Only the new Evosport pulley for 2009 6MT and DCT cars is different, and that is the only one I question how much power it makes.