I know that Helix and a few other companies are now offering pulleys that are smaller than the %15 pulley. Are there any REAL disadvantages to using these smaller pulleys?

 

First of all, and after talking to Randy Webb about the 15% pulley, I'd have to say that it's been tested to death and has been proven to be rock solid reliable. That is why you see it in the JCW and DINAN kits. They offer solid warranties from two to four years on the pulley upgrades because it is well within the limits of design for the MCS engine.

Now the question is when and where is it appropriate to push the performance limit and consider the 17% and the 19% reduction pulley.

Lets look at them separately. The 17% pulley gives some benefit in power but it isn't going to be tremendous. It will create some additional heat but it doesn't require a larger intercooler. It doesn't have the same level of testing that the 15% pulley upgrade has endured. So far the early reports are that it is doing OK but the long term results are not in yet. If you have any reservations about reliability and warranty issues it seems that the 15% pulley is a safe bet. The stock belt can be reused.

(Edited)
The 19% pulley upgrade is a different horse. A vendor has "claimed" quite a bit of extra power (I've read how much but I'm not sure if I can believe it) and it "could create much more heat" and that is bad. So this vendor suggests that to use it safely requires addition of a larger air to air or water to air intercooler. More than 19% would be more risky. I'd say 19% "might be" about as far as is possible without a bunch of other changes. Long term safety is unknown but some MCS with it are doing OK so far. The pulley belt needs to be slightly smaller. Randy Webb(being conservative) has some reservations about the 19% as he has discussed this option with technical people that know the Eaton Supercharger.

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Aloha

 

Damn, you always have the answer hune...thanks. I am thinking about getting the Helix pulley, and was wondering what I would need to do if I ever wanted to go smaller. Thanks for the help once again!

 

I have 20k+ miles on the 15% pulley and I'm going smaller. We have a number of cold months ahead to think about what to do in the warmer months to keep the temps down!

 

the 19% pulley at 6700 rpm is doing what the 15% pulley does at 7000 rpm.

likewise, at 3300 rpm the 19% is doing what the 15 is doing at 3500.

as far as heat and reliability and overdriving the blower, you have to consider how much time you spend at greater than 6700 rpm.

As far as performance, do you want the affect of extra boost to start earlier in the power band?

 

I have almost 6k miles on my 17% pulley and there are no issues. Have not had a chance to Dyno it yet but will soon. When my car just had the 17% and no exhuast it had a little more power on the road than a car with 15% and Magnaflow exhuast.

 

>>I have almost 6k miles on my 17% pulley and there are no issues. Have not had a chance to Dyno it yet but will soon. When my car just had the 17% and no exhuast it had a little more power on the road than a car with 15% and Magnaflow exhuast.

Was that the frosted pulley or the jelly filled pulley?

--
Cheese

 

>>I have almost 6k miles on my 17% pulley and there are no issues. Have not had a chance to Dyno it yet but will soon. When my car just had the 17% and no exhuast it had a little more power on the road than a car with 15% and Magnaflow exhuast.
>>
Doug
how do you know that??


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Koolmini - I believe in his earlier thread about the 17% pulley he mentions he raced a friend with the 15% pulley and magnaflow and madness intake. Vdubdoug only has a drop in filter and 17% pulley. He noted that his friend got the initial jump on him but he would pull on his friend soon afterwards.

I had an idea that I'm strongly considering. Since changing pullies through Helix is fairly easy and inexpensive, I'm CONSIDERING using a 19% pulley from October through April or so and going back to a 15% or 17% pulley from May through September. Also when the warmer weather comes, I plan on moving down a temperature range in spark plugs to colder plugs. In fact, I may go down TWO ranges depending on which pulley I use during the summer. I will also use Mobil 1 racing 15W-50 oil in the summer months. And when the GIAC chip finally arrives I will either keep the redline at 6850 RPMs or maybe even lower it to 6500 RPMs if that is an option. What do you all think????

 

^^^^
greatgro,
will the 17% & 19% pulleys (Helix type) bolt to the 15% pulley back hub thingy?

btw: i was hinting to Doug that i'll race him with my 15% pulley & Magnaflow
if i did that sort of illegal street race thing

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Oh I got ya!
Yeah - I believe that the 15% pulley/hub thing we have from Helix is the one where others can just be screwed on so to speak in a couple of minutes. I'm going on the 17th. The only question is the 17% or 19%.

 

any headlight flickering issues with these pullies as na motors do?

 

>>Yeah - I believe that the 15% pulley/hub thing we have from Helix is the one where others can just be screwed on so to speak in a couple of minutes. I'm going on the 17th. The only question is the 17% or 19%.

I just got an e-mail from Eric @ Helix and he said he hasn't done any warm weather testing on the 19% pulley -- which could indicate the need for a change to the intercooler (since the 19% runs hotter). I'm awaiting an answer to my question of what I'd net in added HP with the 19% over my existing 15% pulley. If the gains are substantial, I'll consider adding Randy Webb's Water-to-Air intercooler upgrade. My guess is that would address any heat issues.

 

^^^^^
will you need to change to a smaller belt for the 17% & 19% pulleys?

 

>>^^^^^
>>will you need to change to a smaller belt for the 17% & 19% pulleys?
>>
Eric from Helix13 told me that for the 17% you can use the stock belt but for the 19% you can change to a smaller belt to get the belt tension correct.

 

No. You're talking about underdrive pullies that increase HP by saving horsepower by providing less power to the electronics on your car. We're talking about a pulley for the supercharger. This makes the supercharger spin faster and create more boost. Other than the water pump which is attached to the supercharger belt, nothing else is run off of it. And it seems that the water pump is ok up to a 19% pulley reduction.

 

>>The 19% pulley upgrade is a different horse. It gives quite a bit of extra power (I've read how much but I'm not sure if I can believe it) and creates a ton more heat and that is bad.

Minihune:

Not true. It doesn't create a ton more heat, in fact the IATs are similar to the 15% pulley on both road and dyno. We have done, and are doing, extensive datalogging of 19% cars. The net effect of the 19% is actually not dramatic. The power and torque output is greater, but not dramatically greater. The OBD2 numbers are, as I said, essentially the same. As stated in this thread, we haven't done all of the hot weather testing, but what is clear is that intake temps, even on days above 100 degrees F will not be dangerous for the engine. What is still yet to be determined is whether the intake temps go above 176 F, which triggers an engine protect mode in the ECU. In that mode the timing is dialed back and the mixture goes full rich, which, of course, robs the motor of power, defeating the purpose of the 19% pulley in the first place.

We do offer the 19% pulley now, with the above caveat attached. Never have we stated or believed that it can in any way damage the motor when properly used. I have seen several claims of huge power increases over the 15%, and have also seen warnings that the 19% pulley is radical, untested equipment. Both are false and probably based upon vendors who don't know what the pulleys do, or don't have access to them and want to scare all of MINIdom. We will continue to dyno and road test various pulleys, and as we get more good, scientific test results, we will make them available.

 

>>We have done, and are doing, extensive datalogging of 19% cars. The net effect of the 19% is actually not dramatic. The power and torque output is greater, but not dramatically great.

Helix13, how about 17%? Is it relatively "safe?"
:smile:

 

>>The net effect of the 19% is actually not dramatic. The power and torque output is greater, but not dramatically greater.

Eric,

Can you comment on what you have found the power and torque increases to be, typically speaking? Are the gains worth the effort of switching from a 15% pulley to a 19% pulley for the power hungry?

(Regardless of your answer, I will be switching, but the answer might be helpful for those that are still on the fence.)

Kev


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Eric,

Do you plan on creating a version of the GIAC chip that is tuned for the 17% & 19% pullies?

Also, do you have a pulley-removal tool available for rent/deposit for your pulley customers that wish to install their own pulley?

 

>>>>The 19% pulley upgrade is a different horse. It gives quite a bit of extra power (I've read how much but I'm not sure if I can believe it) and creates a ton more heat and that is bad.
>>
>>Minihune:
>>
>>Not true. It doesn't create a ton more heat, in fact the IATs are similar to the 15% pulley on both road and dyno. We have done, and are doing, extensive datalogging of 19% cars. The net effect of the 19% is actually not dramatic. The power and torque output is greater, but not dramatically greater. The OBD2 numbers are, as I said, essentially the same. As stated in this thread, we haven't done all of the hot weather testing, but what is clear is that intake temps, even on days above 100 degrees F will not be dangerous for the engine. What is still yet to be determined is whether the intake temps go above 176 F, which triggers an engine protect mode in the ECU. In that mode the timing is dialed back and the mixture goes full rich, which, of course, robs the motor of power, defeating the purpose of the 19% pulley in the first place.

I'm glad you think otherwise on the heat of the 19%. I've seen posts at Webbmotorsports that indicate the the heat buildup from the 19% pulley can be "much greater" from the 15% and 17%.

I think that Helix is reasonably comfortable with the 17% pulley as an upgrade but I am not sure that other vendors are equally comfortable. I'm glad you are doing lots of testing to sort out the pulley upgrade picture.

>>We do offer the 19% pulley now, with the above caveat attached. Never have we stated or believed that it can in any way damage the motor when properly used. I have seen several claims of huge power increases over the 15%, and have also seen warnings that the 19% pulley is radical, untested equipment. Both are false and probably based upon vendors who don't know what the pulleys do, or don't have access to them and want to scare all of MINIdom. We will continue to dyno and road test various pulleys, and as we get more good, scientific test results, we will make them available.

Power gains claimed by various vendors are all over the map for the 19% pulley so some independent testing of the various sizes all done at one time comparing 15 vs 17 vs 19% with same intake/ECU/exhaust setup or even just a stock setup would be good. Opinions are conflicting quite a bit. It's difficult to tell who is closer to the truth.

 

As someone who has been running a 19 for about about 1,500 miles including a track day and several autocrosses, maybe I can shed additional light on the subject.

I have had no problems with the 19.

The only thing I have encountered is a rougher transition from an unboosted to a boosted state. When the bypass valve opens due to low vacuum, the boost is higher than the 15 and significantly higher than stock. This makes small changes in vacuum (read: pedal position/bypass butterfly position) allow much higher boost levels. It's particularly noticeable when driving in third at about 3,000 rpm. Under this condition the engine sees no boost and then 15 lbs of boost within a very small pedal throw. So, the pedal acts kind of like an on/off switch in this range. It's kind of fun and you quickly get used to pushing down and transitioning into a fully boosted state.

The only other issue has been traction. With about 15 lbs of boost at 3,000 rpm tight corners on the street or autocross require modulation of the throttle. Now you're back into the issue in the previous paragraph. And the cold weather has only made it worse as hp has noticeably increased. So you learn to drive a little differently. On the track, the 19 allows you to stay in a higher gear where you didn't have the torque at 4,500 with the 15.

With regard to the "heat" problem, Eric is totally on top of this and has promised us that he will have his new ECU software customized for a 19 to aleviate the retard/rich mode before the roses bloom next spring. Eric? (:

I wouldn't trade my 19 for a set of PSS9's. Remember the grin on your face when you first drove the 15? Remember how you thought "this is how BMW should have made this car"? When you drop in the 19 the same thing happens all over again except that you are going a lot faster. And look how much you spent. If you are into all of this it is a must have!!!

 

BlueMCS:

Have you looked at your intake temps with the 19%? You seem to be relatively independent. What are your results?

 

>>Have you looked at your intake temps with the 19%? You seem to be relatively independent. What are your results?>>

Well, I'm not selling anything.


I have looked but I got the 19 and the software just after the weather broke here in NY and it hasn't been above 60 degrees so the information isn't very meaningful.

I think we start to run into problems at 80+ ambient.

Here's the last run I did at 55 degrees ambient.

 

I had Helix do the 15% pulley a while ago and I remember it being quite involved. How difficult would it be to switch between that (or possibly the 17%) and the 19% pulley? I mean in a DIY at the track type of thing. 15% or 17% for daily driving, 19% for the track?

I mean I can see the pulley but that doesn't mean it's easy to change.
-Chris