U have to use a spline socket like the pic below, with a long spline that goes in on the inside of this socket. One spanner and a Power bar and you’re sorted.
http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/Tq0AAOSwxH1T24HQ/$_35.JPG
So it is cheaper to make the alternators and then use the same pulley on multiple cars.
One more post and you can edit posts.
Great information all around guys. Really good stuff.
For reference:
The pulley for the Crank is part 06E105251F Cost is $350-470 depending on where you get it from.
Since your in there already, the new serp belt is part 06E903137Q ~$50
Here is a little sneak peak for those of you in the future that run into OEM Crank Pulley failure or are looking to go with a Lightweight Crank Pulley for added performance.
Pics of our prototype that was installed and a little while ago:
http://jhmotorsports.com/RandD/B8/30T_HD_LWCP/JHM_B8_30T_Crank_Pulley_Prototype_Vs_OEM.jpg
http://jhmotorsports.com/RandD/B8/30T_HD_LWCP/JHM_B8_30T_Crank_Pulley_Prototype_Installed.jpg
Very cool. I am interested in hearing how much lighter the new crank pulley will be.
Quite a bit lighter ;D
Looking good Jake. Any boost logs or Rolling Road figures ?
After I had my issue I fitted all the OEM parts back except the IBF pulley and Charger belt. I had a new belt that came with the IBF pulley and i stuck that on. After 2 days I had a noise coming from the engine and it gradually became worse.
Last weekend I got a bee in my bonnet and dropped the front end and took the belt off. No more noises.
Ran it without a belt.
Then I stuck a new OEM belt on and no noise. Guess the so called improved belt was crap.
I bought a CTS Turbo Pulley a month back and fitted it. I can feel an improvement with the pulley alone.
Car is due for a Pump file and Octane Booster file next week. I’ll post up some figures when I have a gap.
http://i17.photobucket.com/albums/b89/DirkieUys/IMAG0209_zpsqfkifa3g.jpg
http://i17.photobucket.com/albums/b89/DirkieUys/IMAG0223_zpsfouzraix.jpg
All closed up and ready to go
http://i17.photobucket.com/albums/b89/DirkieUys/IMAG0235_zpsn89i9e68.jpg
The pulley that I posted is the same diameter as OEM so boost will be the same. The lighter weight of the pulley will help with reducing rotating mass for quicker engine acceleration!
Looks great! Wish i could have been without my car for longer to pick one up instead of buying another factory one.
No worries, there is always time to upgrade in the future!!
Final products will be Hard Anodized Black like our other pulleys ;D
Interested in the crank pulley 
Wow great product Jake you guys were able to not only make the pulley but reduce the weight. That’s a big plus. Performance and preventive parts
I will post up once people are able to order!
Thanks! It truly is a win win situation. You are doing preventative maintenance AND adding performance at the same time.
I am not super familiar with lightweight crank pulleys. How much power could you realistically expect from one?
There’s some estimates out there for 1.5hp per lb dropped (reduced parasitic drag). idk if its necessarily something you can measure on a dyno, in normally just makes the engine more responsive/rev happy. You’ll also see under drive pulleys (spins the accessories slower) but with the blower thats a more involved option beyond the concerns of under driving the alternator.
So what about negatives regarding LW crank pulleys? I’ve heard these reduce torsional damping, which is needed to attenuate higher order harmonics from the crank, especially with an inherently unbalanced engine like ours.
Not trying to drive the discussion in a negative direction, just interested about the technical discussion. Maybe there are some good threads here? If you search the web on this subject, you can probably find plenty of information to support either stance.
But we do know now that the factory crank pulley can fail relatively early on, so it is a welcome choice to have aftermarket solutions. Wasn’t there already another LW crank pulley made for our engine? I’ve seen it discussed on AZ, where people were pretty negative. It might have also been a larger radius.
Generally speaking, the front pulleys are heavy OEM because they are acting like a small flywheel- dampening torsional vibrations like you said. It stands to reason that if BMW and Audi among others have stated they use aluminum fasteners on the engine to save weight, they wouldn’t have put a 5lb mass on the crank snout if they could have put a 2lb aluminum one. It’s there because they think it’s necessary. How bad is it if it’s not there? I dunno but as you said I’m sure there’s engineering docs on it somewhere.
If I were racing a car it’s probably a great idea to go with a solid pulley if the OEM one is known to come apart. But for a street car I think there’s no real need for it.
On the “it makes HP” front, it’s easy enough to calculate using formulas how much power you’d get from a lighter crank pulley. It’s an inertia calculation so it’s HP freed up based on how fast the engine is accelerating, therefore gear dependent with the greatest amount in the lowest gear.
There are some decent calculators out there which can cover the basic simplified calcs to give you and idea of the ballpark HP you could gain by swapping to lighter pulley damper or brake rotors etc.
- http://www.w8ji.com/rotating_mass_acceleration.htm (good basic explanation of HP stored/gained etc from different rotating masses)
- calculator used in the above URL: http://www.botlanta.org/converters/dale-calc/flywheel.html
- http://hpwizard.com/rotational-inertia.html good one for calculating gains from lighter brake rotors in particular (equivalent mass is about 1.2x static mass for a typical brake rotor)
Looking at the data for a 5-7lb and 7 diameter inch (guess) pulley damper, it looks like the gains are going to be pretty small using the links in #1 and #2 as Hp/sec is less than 1 to begin with. Just not enough mass and too close to axis of rotation for it to amount to much.
No offense, but this is a poor argument. I noticed your car is stock, so that makes some sense. Here’s why.
Audi also puts a restrictive set of cats on your car, as well as a restrictive intake. Does that mean those can’t be improved? Hell look at the 1320 supercharger…it is not being used anywhere near its capabilities. People replace their blower pulley and ECU tune all the time in the pursuit of performance and don’t say ‘oh well Audi must have done this for a reason, so we shouldn’t change it’. Audi makes the stock exhaust super quiet on all of their cars. Some like it a bit louder…but Audi’s market isn’t the 2nd and 3rd buyers of these cars. They’re the people who pay $100,000 or $80,000…the first buyer. Those people usually like it quiet as a church mouse.
Reality is that Audi isn’t after 100% maxed out performance on all of these cars. Especially the entry level sedan’s midrange option (S4). Perhaps Audi recognizes that they need to maintain a delta between the S4 3.0T and the RS4 4.2 FSI thus they hold back in a number of areas.
Another factor is that a lump of steel is far cheaper than a balanced aluminium piece. On the aluminium vs. steel debate, my RS4 has aluminium fenders, aluminium hood, aluminium trunk. The S4 has none of that. Does that mean that the steel parts on the S4 were made in steel for a reason, and that it must be better? Or does it mean that Audi just frankly doesn’t give the S4 all of the toys. Going further, the R8 has an aluminium frame, whereas my RS4’s is heavy steel. Which one is ‘right’? Or is right not the answer…budget, power delta and model positioning being the main factors driving these decisions.
On my B7 S4 I had a JHM lightweight crank pulley. It stands to reason that taking 5.5 lbs of rotating mass off at the crank will help the engine rev, and if the stock part is shit, why the heck wouldn’t you do this instead of replacing it with the steel lump that is apparently prone to failure (that’s shocking in itself)
[quote]There are some decent calculators out there which can cover the basic simplified calcs to give you and idea of the ballpark HP you could gain by swapping to lighter pulley damper or brake rotors etc.
- http://www.w8ji.com/rotating_mass_acceleration.htm (good basic explanation of HP stored/gained etc from different rotating masses)
- calculator used in the above URL: http://www.botlanta.org/converters/dale-calc/flywheel.html
- http://hpwizard.com/rotational-inertia.html good one for calculating gains from lighter brake rotors in particular (equivalent mass is about 1.2x static mass for a typical brake rotor)
Looking at the data for a 5-7lb and 7 diameter inch (guess) pulley damper, it looks like the gains are going to be pretty small using the links in #1 and #2 as Hp/sec is less than 1 to begin with. Just not enough mass and too close to axis of rotation for it to amount to much.
[/quote]
Calculators are fun. Reality is that feeling your engine rev freer is more compelling. A LWFW and crank pulley in combination really feel fantastic and while putting an hp number on it is impossible (we’re talking about reducing loss, not making gains) it is one of those things like LW brake rotors that people say doesn’t help when they use a calculator (even though the cars accelerate faster with them).
Jake - how much for the crank pulley?