>>if you have intake temps for the different pulleys then yes, i would like to now what kind of temps you are seeing.... :smile:

Unfortunately, I only have the intake temps from the 19% pulley. I didn't get datalogger until after the 19% pulley was installed.

 

>>1) just wondering about the gas economy tradeoffs in going to any of the pulley reduction schemes.
>>2) i have seen threads about changing the ECU chip.
>>any serious downside to not making the change?

1 - Reportedly, you have the potential to get better mileage but should be having so much fun that your mileage will suffer. If you are sincerely concerned with gas mileage than you should be questioning your desire to make any performance modifications to your car, IMHO.

2 - I have had a 15% and a 19% for over 10k miles and have not yet modified my ECU. A/F ratios very close to stock. Power and torque way up. Driveability very close to stock (better than some stock). No mechanical problems.

 

Andy stillmaking stabs eh, nothing better to do..... Anyways I said that i consistanly run around 19psi, not to far off from your test, im sure i ve done other mods that you haven't to help air flow, as well the 25 psi i can hit, but not consistanlty only on real cool nights, and i have admitted that and i dont have an explination why other than cool temps, anyways have fun with your stabs, like the comparison was made i think i do see the bad apple in the NAM bunch, but i it doesnt bother me, have fun!!! And i though things were getting better from some actuall agreement on some good reading, hey keep contesting everyone, its fun to see your reaction.... I also did noticed you used different cars for testing, Why? Thats against scientific theory of keeping a good controlled test.....

 

Based on the discussions here I created a chart showing the air density based on temperature in Celsius and pressure in PSI. The higher pressure created by the smaller pulley maintains a higher density of air up until a 35degree Celsius difference. So based on these graphs, unless I am way off on my calculations of

Pressure = (R) x (Density) x (Temperature)

The temperature issue that people are bringing up may not be an issue as far as the performance of the smaller pulley. This doesn't account for any other issues relating to the temperature and it' affect on the engine. Therefore, the smaller pulley will allows provide more denser air than the larger pulley, up to at least 40C, unless the supercharger starts becoming inefficient because of it's design, but no one has shown that. The pulley continues to increase boost even past the redline.

Here is a link to the actual data numbers and the graph is attached below:


Temperature vs. Density

 

My goal in going 19% was to see the results greatgro descibes. Move the performance down from the top of the rev range. My thought is that you don't need to be pushing to the redline to make the car perform. And, then, when you really are looking for the 10/10th, you have it under your foot.
If you are using lower revs, aren't you relieving some of the stress that would be associated with high rpms?

 

Does anyone know the volume capacity of the supercharger?

 

> Therefore, the smaller pulley will allows provide more denser air than the larger pulley, up to at least 40C, unless the supercharger starts becoming inefficient because of it's design, but no one has shown that.

 

>>Does anyone know the volume capacity of the supercharger?

Its listed on th eaton website, under the MP45, in my opinon its a little small, for race applications, as being discussed here the 19% it at he superchargers limit, rpm and efficiency, there for to get more gains than a 19% pulley you must upgrade the supercharger, which several have already done or in process of(myself, BBR, Minipilo, and several others)

 

>> I also did noticed you used different cars for testing, Why? Thats against scientific theory of keeping a good controlled test.....


As andy stated: "The above plot is a bit of an apples to oranges comparison since BlueMCS' car and mine are different. It still gives a rough idea of the difference between 15% and 19% pulleys"


And from what I have seen the uprated charger (modifying a stock MCS charger) has not shown a siginifacant gains for the cost.

 

Andy said:
No, I'm not talking throttle step-response and subsequent boost gauge mechanical overshoot; I'm talking about DYNO PULLS where boost gradually rises over the RPM range. Any hypotheses why the MAP is reading lower than the mechanical gauges? Are Caddman and I using poorly calibrated units?

Fun story here: Omori North America

 

Upping the boost Psi also ups the compression ratio right? If i'm right, what kind of numbers are we talkin with the different pullies?
Whats the max for the stock bottom end...?

or am i wrong about the compression?


Mike

 

The S with stock ECU redlines at 6850 RPMs. And you call shifting at 6800 RPMs playing it safe???

 

slight tweak to your info greatgro; the redline is 6950RPM

_________________

 

vdubdoug, im not talking about modifying the supercharger im talking about a whole new one......as well if he willing to critisize everyone elses testing he better be prepared and make sure his testing is done correctly any flaw in his will be pointed out as he does to everyone elses......

Ryphile, i dont believe our guages are wrong, i have two seperate sources and they agreed on boost level, now mind i do believe in a possible +/- 1 Psi in any type of testing is possible.....

 

>>> Therefore, the smaller pulley will allows provide more denser air than the larger pulley, up to at least 40C, unless the supercharger starts becoming inefficient because of it's design, but no one has shown that.
>>
>>
>>
>>
>>

This is a nice graph. I wonder if anyone has done any temperature measurments at the higher boost levels (specifically a measurement for 15psi and 18psi). This would indicate the pressure and temperature, and based off of those numbers you can easily calculate the density of the air and thus the oxygen molecules present.

 

Caddman,
Well from following the VW world for a while i have seen a few different chargers run on G60 cars, such as the Lysolm and the Mecedes benz slk charger. The cost involved for one of these units and the power made was not worth it to me. And as anyone knows when you remove stock pieces with custom one's the chance for error is greater and not everyone will want to touch a highly modified MINI.

If you are running 25psi of boost what will your Air fuel ratio's look like? I would want to know before I bolted up a different charger. Plus with a custom charger won't new software or different engine managemant be needed for optimum performance? I have seen many software programs out there make some power and compramise driveability but the producer of the software claims it as the best (VW and MINI tuning). Powerchip stated not to use there software on 17% and 19% pulleyed cars(mini Cooper). So you can not safely use there software on a car producing more boost!!!!

 

>>Ryphile, i dont believe our guages are wrong, i have two seperate sources and they agreed on boost level, now mind i do believe in a possible +/- 1 Psi in any type of testing is possible.....
>>

Caddman,
Are you sure you're seeing this under acceleration? Could it be between shifts or when you lift? My initial hunch would be its bypass related.


--
Cheese

 

GREATGRO I do push my rpms but its just hitting 6800 and off to the next gear. I'm not sure if there is in fact a water pump cavitation problem but I'm not staying at 6800 rpms long so I'm not too worried. I like to push all my toys to the limit while playing it safe, its an art. I have a 1984 yamaha rz350 in my garage that will blow the doors off a 19% reduced mini any day. I also have an aprilia with a modified 1000cc v twin motor that redlines at 11500 rpms.
I just like to play!
I'm running a 15% reduced pulley on my mcs but all the talk about the 19% have sparked my interest. I want to learn a little more about it before my next visit to helix. I've been waiting like some of you for the GIAC ecu.
BLUEMCS had mentioned an on off type response at 3000 rpms with the 19% pulley, any comments on that?
Thanx.

 

>>BLUEMCS had mentioned an on off type response at 3000 rpms with the 19% pulley, any comments on that?

As I said before, with the 19% you have a significantly higher boost at low RPM's. So when the bypass valve opens there is a much higher pressure to release than stock or even a 15%. It's not offensive, but you know its there and learn to just accelerate through it. The minor "Yo-Yo" at 3,000 rpm that my car has had since birth is exacerbated a bit by the 19% as it was by the 15%. Again, it was there when stock, with a 15% and now with a 19% so you again learn to accelerate through it. Feels a bit like a car with Webbers running a bit rich. Hoping that Garrett will take it all away (nobody else has).

These are very minor drivability issues and you forget about them very quickly when you push down with the right foot.
:smile:

 

>>Upping the boost Psi also ups the compression ratio right? If i'm right, what kind of numbers are we talkin with the different pullies?
>>Whats the max for the stock bottom end...?
>>
>>or am i wrong about the compression?
>> Mike

the compression RATIO doesn't change - it's still 8.3:1, but you go from compressing one atmosphere (14.7psi?) to compressing 14.7psi + boost.
The bold ones will be able to tell us what the max is - after they exceed it...

 

>>Wow GreatPro...you seem to be impressed with it...I haven't done the pulley yet and would like 19% but some of the stuff I have been reading concerns me as I know it does others as well...I wanna go 19%..but is it safe?



Greatgro is my brother. We both got our 19% pulleys the same day at Helix. It's worth it and it's safe. Both of ours have been extremely reliable, no problems whatsoever, and we both drive a lot of miles and dirve our cars hard.

RaceCarDriver

 

>>folks,
>>finally pulled the trigger.
>>i am a new soon-to-be owner of a 04MCS (just placed my order last week).
>>
>>i have been perusing this forum for awhile now and i find the pulley mod to be the most fascinating mod for my upcoming MCS.
>>two questions i have about the pulley change:
>>1) just wondering about the gas economy tradeoffs in going to any of the pulley reduction schemes.
>>2) i have seen threads about changing the ECU chip.
>>any serious downside to not making the change?
>>
>>appreciate any light those of you in the know can shed on this matter.
>>
>>a mod newbie,
>>-spirit16-


Gas economy with the pulley is actually slightly better.
Both myself and Greatgro have not done the chip. It's runs fine without it. But we plan of getting the GIAC chip just to give us even more power and torque.

RaceCarDriver

 

I got 37mpg on my way home from Helix.


--
Cheese

 

BLUEMCS, thank you. I do a 22 mile each way hwy comute and spend a lot of time in that just under and just over 3000 rpm range. I'm thinking the condition you describe is not something I want. I wonder if VDUBDOUG can comment on the driveability characteristics of his 17% reduced pulley. I can live with a condition described by BLUEMCS after 3500 rpms, no problem. Thanx for all the information shared here, I find it very useful in finding the right modification level for my car. At this point I've decided to not go for a 19% reduced pulley but the 17% is still a possibility.

 

>>I got 37mpg on my way home from Helix.
>>
>>
>>--
>>Cheese
>>

How the heck did you get 37mpg? The most I have gotten was 27mpg and that was better than Car and Driver. I don't think I have heard anyone getting 37 mpg. That is 4mpg greater than BMW claims and those are always high.

Not necessarily doubting you, just want to know how you are doing it? Is this an MC or an MCS?