There is no real issue with an aluminum pulley on a steel SC shaft. They work fine, don't slip, and last approximately forever. If you want an aluminum crank pulley, you might as well have an aluminum SC pulley.

BTW, no-one is really saying that a larger pulley will cause a problem, or a lightweight aluminum pulley either - the issue is all about the lack of damping material to kill potential resonances which might be causing damage.

If there was a damped-core lightweight crank pulley available that avoided the issues with single-piece offerings, I expect it would sell well.

 

x2

 

As to the steel vs aluminum sc pulley I have seen 2 alta sc pulleys on the same car spin on the sc shaft due to the different thermal expansion rates of steel and aluminum. The car was being tracked when it happened so the conditions were extreme. It is only anecdotal evidence and there are thousands of cars with aluminum pulleys that haven't slipped so take it as it is.

For the record they were both Alta v1 pulleys and they were installed by ase certified techs at 2 different shops. The Alta v2 pulley on another friends car has never done it and it is aluminum. Like Jans numbers its a small percentage but it happened. I got a deal on the M7 16% so I went with it.

 

Yeah - I'd get an aluminum pulley that uses six Grade 10 or better bolts to hold it together, rather than only four bolts, which I believe was all the Alta v1 used.

50K miles on mine no problem, for what a testimonial is worth.

 

I personally know of one car that has both the M7 16% and the M7 2% plus a first gen. Cossi with 100k miles SINCE they were installed 0% problems. Regulary brought to redline Belive the car has 130k miles on it now.

 

Jan - if you got 15 people interested in the oil pump what would be the cost each? How are you going with your dampened Crank Shaft Pulley, will it be available soon?

 

It is my understanding (right or wrong) that S/C = pulsing hence why the Cooper doesn't have a harmonic damped CP as its not needed.

I've heard of 3 cars that have had oil pump failures and all 3 were attributed to lightweight undamped CP's transferring vibration to the oil pump causing failure.

That's why personally I'd never fit one on the MCS.

 

I was unaware that the Cooper did not have an unbalanced crank pulley, but if true my take would be that the Cooper just doesn't make enough power or torque to cause any significant torsion/twist/harmonics in the crank with each power stroke.
Guess the test for the supercharger pulsing theory would be to have one of the turbo guys run a solid CP. Any takers? I wouldn't.

 

The Cooper crankshaft pulley is three piece, a hub, thin rubber band (a tad over 2mm), and ribbed pulley; balanced also BTW.

 

The Alta V1 is all steel, the V2 has a steel shaft clamp, with aluminum pulley fastened to it.

 

Cheers... So is it damped or not?

 

With only a 2mm rubber band, the answer would be "kinda, not much". Subjective things like NVH must be viewed in shades of grey instead of black and white.

 

Just some food for thought.

Every engine made has a bad spot, some more then others. If you do not operate thus said engine in those areas the chances of having problems are slim.

There is something interesting about Mini's that you might consider before going light. Running a Mini at 60 mph in 6th gear can put you in the 2300 rpm range. Depending on your set up you can land right in the middle of the area that the stock damper is doing most of it's work in smoothing out the engine.

Those that connect with an engine understand the soul that drives it.

John

 

good thing I only go 60 on highway on/off ramps

 

Becareful saying things like this Allblack, or Krut and Motor On will close down the thread.

 

LOL

If the plows take out the speed limit signs doesn't that mean they don't apply?

 

[quote=mach schnell;2612668]...is this like changing the oil without changing the filter?

I am no expert by any means, but I like to read and love to hop up. I considered doing my crank pulley too since I was already going to have the belt off and was set on the 15% anyhow. After reading more and speaking with the people at Alta, I decided I did not 'need' to do my crank. From what I understand, the crank is usually done when you do the alternator pulley and a larger % SC pulley like 17% or 19%. For 2%lighter on the crank, I decided it was more work than was worth. Having done the 15%SC pulley alone, WOW, what a difference. I also have a CAI and will have exhaust soon, but the SC pulley is BY FAR the gnarliest upgrade, biggest bang for the buck. If you are mechanically inclined and have an "ultimate set of tools," (and a partner) you can probably do it yourself.

Not that I addressed any of your points, but just wanted to say DO THE SC PULLEY! It is amazing.