In another thread somewhere (I searched for it and couldn't find it), I had asked someone who was talking about how much additional HP and torque was gained by a 19% over a 15% pulley reduction, for a very scientific set of dyno runs. What I had asked for was, using a stock MCS, a baseline with a 15% pulley inbetween each of the pulls on the dyno. A person with good skill can get a pulley swapped out in about 45 minutes, so this exercise would take just over a half day assuming 30 minutes for a dyno run. That way the same car on the same day would be used for all pulls and the car is bone-stock except for the pulley.

8:00AM 15% dyno run
8:30AM install 17% pulley
9:15AM 17% dyno run
9:45AM install 15% pulley
10:15AM 15% dyno run
10:45AM install 19% pulley
11:00AM 19% dyno run
11:30AM install 15% pulley
12:15PM 15% dyno run

The person said they had do just what I had asked for and would post them in the thread. Like I said, I cannot find the thread so I'm unsure if the dyno charts were posted.

Thanks.

 

I think Andy from Ross Tech was going to do it. But it was a very busy day at the shop. It does take a couple minutes to strap the car down, make sure the car is seated on the dyno correctly, and calibrate the speed among other things. You are better off looking at a full day to do this.

 

Thanks for the info Doug!

Dyno Times were only guesstimates from what I've seen done at DynoComp including the set-up and tear down of the car on the machine. Whatever it takes, I was told someone had already done this over a month ago.

Maybe they were posted in the thread, I just can't find that thread. It was a heated thread so it may have been removed from the site. All I remember seeing was dyno charts from two totally differtly prepared cars on two different days, so I requested dyno charts from the same car. That's when I was told they did exist and they would be made public.

 

I tried and failed due to chronological incompetency on my part. I definitely want to do that, but will have to set aside more time.

 

Thanks Andy. I'm sure dynos like that will help all of us be better consumers when choosing which pulley to get.

 

I agree. Plus, I want more POWAH!

 

>>I agree. Plus, I want more POWAH!

Forgive me if I'm confusing you with someone else but I though you got rid of your Mini and bought an Yellow Z3 because the Mini was a lemon?

 

You are SO confusing him! That was Davbret you're thinking of! Andy's our best consumer watchdog!

 

oooooo...sorry my mistake.

 

I'm not the yellow Z3 type ... not that there's anything wrong with that lifestyle.

 

>>8:00AM 15% dyno run
>>8:30AM install 17% pulley
>>9:15AM 17% dyno run
>>9:45AM install 15% pulley
>>10:15AM 15% dyno run
>>10:45AM install 19% pulley
>>11:00AM 19% dyno run
>>11:30AM install 15% pulley
>>12:15PM 15% dyno run

hey Dom - do you have any idea how much work is involved in what you are talking about? Your schedule is totally infeasible. Even the two best pulley men in the business couldn't pull it off...even with Andy's help and chronological incompetency. (: Eric prefers to do a quick jack up to change the pulley and I agree with him. Working on a hot car is no fun and I don't thing the change back to 15% all the time makes sense. One baseline run is sufficient. Besides, the hp #'s aren't what's its all about. It's all in the torque. Remember how much more torque you had when you got the 15%? Well, double that feeling and you're at the 19. In between is the 17.

 

>>hey Dom - do you have any idea how much work is involved in what you are talking about?

Not much work at all, I distinctly remember the other person telling us that they already had done the testing. So, the only work required would be to scan in the existing dyno sheets. Evidently this person was not Andy.

I really appreciate Andy for stepping in and taking up the challenge and helping us all out. He wouldn't have to go thru this if he feel the need to do so. As long as we have someone willing to help out, that's what counts.

>>I don't thing the change back to 15% all the time makes sense. One baseline run is sufficient.

At least a base line at the start of the process and at the end of the process makes sense. The one between would be gravy. Any scientist knows a good experiment should be able to be duplicated. Hence the request to go back to stock. That way you can be sure of no difference in atmospheric conditions, etc. Much easier to see trends that way.

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Happy Motoring!
<a href=http://www.aminivacationinvegas.com>A MINI VACATION IN VEGAS 2004</a>

 

Well apparently, my butt-dyno is right on! I estimated in another thread that the 19% pulley felt about 50-60% of the difference of the 15% pulley. Well Helix has seen the 19% make 6-8lbs MORE torque than the 15%. If the 15% averages 15lbs of torque, that would put the 19% at 21-23lbs of torque (40-53% more torque)!

 

>>Well apparently, my butt-dyno is right on!

No calibration required, right? Excellent.

>> Well Helix has seen the 19% make 6-8lbs MORE torque than the 15%. If the 15% averages 15lbs of torque, that would put the 19% at 21-23lbs of torque (40-53% more torque)!

greatgro, That helps confirm my suspicions. Still would like to see a shootout with dyno charts.

I guess the next big hurdle will be to see what type of heat issues people run into in the hot climates.

 

I spoke with Alta yesterday and that's what he brought up was the heat issue. The internal temps with the supercharger spooling up faster at lower rpm are a concern. He said you would need an intercooler upgrade. Evidently if these temps go up substancially you negate the extra boost due to much higher inlet temps.
The 15% is a given, it works and makes reliable h.p.
The 17%..maybe a good step without pressing it (2-3 psi, 2-3 h.p., 3-4 ft.lbs more torque)???
The 19%..sounds awesome but how about in 100deg plus weather, will you burn up the eaton because the intercooler can't keep up ie too much heat and stress? (3-4psi, 3-4h.p., 4-5 ft.lbs more torque)????

Is the differance even worth messing with going from a 15 to 17, probably not, but 15 to 19 seems to be noticable if you believe what has been posted. To get an ecu mapped for a 19, lower the redline to 6500-6800 etc.. sounds like a worthy cause. We need some miles logged and some hot temps!!

 

Then I'd find some mates down in Oz, and send them some 19's. Their Summer is just beginning

 

minifletch wrote:
Wow, and what a coincidence! Alta sells intercooler upgrades.

Did they provide any data to back up those claims?

 

 

stay at it andy.

 

No hard data as they have yet to experiment with the smaller pulley. I have spoken to others about this though and it does make sense. I am certainly not against the smaller pulleys though. Alta said they would look into it......who knows. I simply don't want to keep re-doing mods, I would like to install the best pulley the first time around.

BTW who offers the 19% pulleys now. Cat/Dog and helix? What is the differance? Is one the heat up type and one not?

 

<< Any scientist knows a good experiment should be able to be duplicated. >>

And that same scientist knows that when you have a dynamic variable called the ECU which will change the result over the next 100 miles, that it is necessary to have a climate controlled facility which could be used to retest under the same parameters after the mods were learned and the computer adapted. Which is why most of the same day mods are right on with climate and totally off on real results, IMO.

The trick is to keep the trend lines going up and the lap times coming down. :smile:

 

Hence the reason to go back to stock, so what ever the ECU tried to learn, it'd have to unlearn for the stock pulley during the dyno run. Going back to stock also provides us with valuable insight into what happens to the car due to atmospheric condition changes thruought the day.

Consider it like troubleshooting a stereo system. You have no output on one set of speakers. So you remove the wires from the amp to the speaker and screw on a new set of wires. Then it works. But before you go thowing out that expensive set of monster cabling, you rehook it up to see if maybe it was just that one of connections might have been loose (which would have been fixed by replacing the wires). I know, lousy example, but it's the best I can think of on a full Christmas stomache.

 

>>I spoke with Alta yesterday and that's what he brought up was the heat issue. The internal temps with the supercharger spooling up faster at lower rpm are a concern. He said you would need an intercooler upgrade. Evidently if these temps go up substancially you negate the extra boost due to much higher inlet temps.

We have heard a couple of tuners bring this issue up, with absolutely no substantiation. To my knowledge, we are the only ones who are systematically testing these pulleys: that means intake temps, boost levels, power gains, etc on both road and dyno. In weather below 65 degrees F., the engine temperatures are not substantially different between the 19% and 15%. We are working on getting hot weather testing done.

BTW, if intake temps get hot enough (80 C.) the boost doesn't get negated, the ECU dumps fuel and dials back timing, which robs power.

 

Thank you oh wise one from Helix. :smile:

 

The data will be interesting to see eric. Thanks for the reply. Everyone is going to push the envelope in 04 and I am excited about it!