2% crank pulley , Bigger is better!

With the help of one NAM member DJ1, we have proven our 2% bigger crank pulley to be a great new product for our line up of parts. As you would expect, the 2% bigger pulley gives you the same benefit as if you had a 2% smaller SC pulley. This is great for all the JCW cars out there that already have a 15% smaller SC pulley and want to get a little more power.

As expected, a JCW car with stock SC pulley sees roughly 16PSI of boost (stock is 14psi) which is the same as a 17% smaller SC pulley. The benefit to the JCW guys is the installation is much quicker and simpler than the SC pulley, and you get the benefits of removing all the weight from the factory pulley. You gain HP from the increase in boost and from the lighter rotational weight.

This also will give 17% SC pulley customers another way to gain more HP by upping it to 19%. In this situation we have found that 18PSI is had by the 17%+2% crank pulley.



We can make a 3% larger pulley with no problems also, and we are looking toward the NAM community to make that decision. The room is there to do it, but we thought to keep things comparable to our other SC pulleys, we would stick with 2%. If anyone has any ideas about this please chime in!

This 2% (or 3%)larger pulley will be sold along side our standard size pulley so someone can buy either one if they choose.

We will be releasing the 2% larger pulleys in the next month or so.

 

Looks good

 

If it's easier to do a 2% at the bottom, than why continue to do the SC pulley?

Would you ever combine larger crank pulley and smaller SC pulley?

Hunter

 

Looks nice, tight fit in there, eh?

 

What is the weight of this pulley compared to the stock unit?

Any idea what the load on the crank is versus a stock setup?

 

Can you run the 2% with your 19% pulley, or is that going to far? I haven't bought either yet, so I can go for the idea combo.

Also, I'm willing to be a test case for the 3%.

 

What is the downside to this 2% crank pulley?

Wear on the engine? Heat build up at certain rpms? Wear on the belt?
Wear on other engine parts?

If you can use it with the 15 or 17% SC reduction pulleys then what is the limit? Can it be used with a 19% SC pulley?
Since we know that most ECU software upgrades are not specifically tuned to 17% and 19% reduction SC pulleys if I had a 15% SC pulley then added the 2% crank pulley then what effect would that have on my stock ECU or upgraded (Unichip. MTH, Evotech, Powerchip or GIAC) software?

What is the install time?

 

Alta, since the stock pulley is 5.46", does that mean that your pulley is 5.57" (+2%) vs. the stock pulley?

 

Yes, I have been testing this new 2% crank pulley for about a month now. I was using Alta’s lightened crank pulley (std. size) for about 3 months before that. These two pulleys are virtually the same in weight but now we have the option of the 2% overdrive.
I have tested this 2% crank pulley with different combinations of SC pulleys and found that it truly gives the 2% additive effect. Simply put the +2% crank plus a -15% SC provides the same results as a STD. crank and a -17% SC.
Now I did try the +2% crank plus a -19% SC but I found that performance decreased and detonation increased. Sorry there no dyno tests on this combination as I knew it was going downhill and I believe I reached the limits of my mods.


Dave

 

Very interesting! I'm quite interested, and look forward to hearing more....

It would be nice if Alta can provide for (lend) the special removal tool as well upon purchase. Also, a belt recommendation for the various combos out there would be nice. Thanks much!

 

The standard belt works on all combos except when a -19% SC pulley is used.
The JCW belt can be used with a -17% SC combo.
The required dampener puller and holder (2 tools) are available from BMW/Mini for about $30.00 ea. I am sure your Alta distributors will make these available when the pulley is released.


Dave

 

good idea, i want to learn more....

how aobut other things in line like alt. and compressor. can they take the extra rpm's? i'll have to look up all the numbers and compair, but i am throwing this out there for now...

look forward to more.

 

Remember it is only a 2% increase. When you are racing it is suggested that turn off the AC so as not to waist horsepower, but then maybe you want to be cool. However at WOT the AC is shut off any way. As for the alternator, again only 2%, how long do you plan to run at 7,000 RPM? If it will ease your mind there are under drive alternator pulleys available. I do believe that Alta is thinking of putting out an under drive alternator pulley in the future.

Dave

 

"However at WOT the AC is shut off any way"


I wasn't aware of this; are you sure?

 

YES, this has been programmed into cars as long as we have had computers. The ECU considers WOT as a non normal driving condition. The assumption is that the request for power is needed because you are climbing a hill and passing a long truck at the same time. The ECU shuts down things like AC and EGR so as to prevent power loss. Since the AC cycles under normal operating conditions anyway and the driver is usually focused on other things during WOT this feature goes unnoticed.


Dave

 

My testing showed otherwise:

http://www.mini2.com/forum/showthread.php?t=33585

BTW, there is no EGR in the MCS.

 

We also found out last year coming home from the dragon that with the air on the car has a limit of 130 mph, down from 137 mph.

 

That trick has been around a lot longer than computer driven cars. Several of my 4 cylinder carburated cars had a WOT switch to kill the AC!

It was on the check list of things to look at if the AC was not working right.

John

 

I recall cruising around in an oldsmobile cutlass something or other a few years back and once you hit 110mph, the a/c would shut off...being that this was NewOrleans in August, we decided to slow down

 

Was it on the old pully or is it a separate assembly? Also, does the lightened pully change the freqency of the crank ressonance?

Thanks,

Matt

 

Oh boy, i am so sorry i missed all these posts! For some reason i didn't get any notifications!

Hunter,
You idea is correct, but there isn't any room to do much bigger than about a 4% pulley.

0_mini,
The weight is the same as our other stock sized pulley. Roughly 1lb.

GClemons,
Ya a 21% pulley is what that would make and i would say that is a little much unless you never wanted to REV it past 6400. This would put the SC way past its redline.

minihune,
like i was saying i belive more than 19% would require a lower redline by quite a bit. And yes the 2% would add to your 15% and 17%. Wear on the engine won't be any different than if you had a 17% or 19% pulley on it. The benifit is the gain from boost and from the ligher rotating weight.

62Lincoln,
Yup, our Pulley OD is 2% bigger. This is somewhat up in the air right now, so if people wanted a 3% or whatever we can do it.

agokart,
D1JL is right, the alt pulley is something we may do depending on how many people are interested. D1JL told me the steps in replacing the pulley for the alternator, and it is definatley not an easy task.

D1JL ,JLM, Andy,
There isn't a car i don't know of that doens't shut the AC off if the engine is above a certain RPM, or TPS. I could be wrong with the mini, but the reason being is because the compressor for the AC isn't suppose to spin above a certain RPM. This is to prevent over pressuring the AC system and also not to burn up the compressor. I would find it hard to belive that Mini keeps in on no matter what.

Dr Obnxs,
There are no worries with crank resonence. Many people have asked this question over and over. We responded to this on very indepth thread about a couple months back. A tech from SRT, I believe, even mentioned how the effects of a soild pulley were negligable. If you do a search for the Alta crank pulley you will find the info. There were many good point for and against the Alta crank pulley, but in the end, it really isn't an issue.

Alta

 

For someone like myself who is wavering between the purchase of a 15% and 17%, what benefits would I get from going with a 15% + the 2% crank pulley over a 17% by itself? Is there anything more to be had with the crank pulley besides increased boost?

 

The weight delta is pretty nice for sure; and how that translates into a freer-reving engine is an added benefit...

And from some readings here, it seems that there might be a belt to pulley improvement by going both smaller on the SC pulley and slightly larger on the crank pulley. A 15% SC reduction, and a 4% crank increase might indeed prove to produce less belt failures than what the 19% has shown us. It seems plausible...

I for one am quite willing to try this 2% crank pulley in conjunction with my Alta 15%. Look forward to hearing more!

 

When will the 3% be available? I have the JCW kit, so I assume it will be a nice compliment to the 14.x% reduction pulley JCW uses.

 

I take it the factory one is not a harmonic ballancer also, nor ballanced with the crank & flywheel ? If not, count me in.