[GTT 280]

Hi,

I have been comparing the Max Torque value of the MCS with that of some other vehicles.

The MCS has a Max Torque of 210 Nm
A vehicle with a Max Torque of say 250 Nm with a turbo would not necessarily be faster from 0-60 because a turbo has a secific range that it perfoms at. So, although the turbo vehicle may have a higher Max Torque than the MCS, the MCS having a consistent (supercharged) Torque would be as quick to accelerate, if not quicker.

Is this a fair assumption ie. you can't compare the Torque of a supercharged vehicle to that of a Turbo'd vehicle ?

Pleased to hear of knowledgable comments...

Cheers,
EB.

[Mugami]

I can say thats both true and not true at the same time. True that at the starting line in idle with two equaly prepared engines before both super or turbo charging. the supercharged engine would have slightly more torq than the turbo. But as stated lets say both engine are now at 3k rpms the max psi for both super and turbo is 12 psi. At this point the Supercharged mini may have 6psi of boost while the turbo can have the full 12psi of boost. Which means it will have more torq and power at this time. This is were the term call Turbo Lag comes from (the time it takes a turbo to spool up and give the desired boost). the lag time for moderen turbos are nowhere near as great as they use to be (almost non existance). but they are still there and this is where i like supercharging better its instant when you hit the gas power where the turbo does take maybe a half second for the true power to kick in. Hope this helps in some way.

[GTT 280]

Not sure I understand the fact that the MINI would only have 6psi and the other vehicle 12psi if the Max for both is 12 ??? Would the MINI not be providing 12psi throughout the range and the turbo only 12psi at the 3000 rpm ?

Sorry for appearing stupid !!

EB

[FONTAL]

Quote:

Originally posted by EB03_MCS
Not sure I understand the fact that the MINI would only have 6psi and the other vehicle 12psi if the Max for both is 12 ??? Would the MINI not be providing 12psi throughout the range and the turbo only 12psi at the 3000 rpm ?

Sorry for appearing stupid !!

EB

Forgive me if this is wrong but this is what I think, the supercharger is run of the crank so at 3000 rpm it is only running at half power the faster the crank is running the faster the supercharger is spinning so to get 12 psi the engine would have to be at max torque.

[Mugami]

Fontal is correct .. as for the turbo.. it has waste gates that regulate the amount of psi.. so it can reach its max psi early and maintain it.. this is also how they can increase the psi without haveing to chang anything but the waste gate setting. A single turbo can be set anywhere from 5 psi to 15 psi or more depending on the turbo

[dukesantos]

You are correct, the supercharger speed is linear with the engine speed, at 6950 rpm max engine speed, the supercharger is turning 14,317 rpm. At that speed, under ideal sea level and fuel conditions, it produces a maximum of 1.9 bar pressure (not sure of the psi).

Because the supercharger power is always available with no lag and offers good fuel economy, MINI engineers felt that for engines up to 1.6L in size it was preferable to turbo charging.

This information is from an excellent article on the MCS powertrain by Thomas Bruener, published 7/8/2002 in MTZ Worldwide, volume 63. There is a link to this article in a previous thread, I'm sure you can find it with a search.

[friedduck]

Man, tough call. You have to know gearing, consider that the turbo car can slip the clutch to keep it in the power, etc.

Math-whiz types could probably confirm, but wouldn't you have to solve for the area under the curve (Integral equation?) to get the full picture?

The WRX I test-drove had pretty serious lag up to 3,500, but then...hang on!!! Great fun once you were in the power.

Jeff

[Andy@Ross-Tech.com]

Turbocharged and supercharged vehicles have completely different feels. Anyone local to Philly is welcome to take a ride in my GTI 1.8T and/or my MCS.

Here's a MCS boost chart courtesy of macncheese:



Here's my GTI 1.8T (chip and 3" downpipe/cat):

[jlm]

my contention is that if you use the 15% pulley, Mac"s boost graph would shift to the left, so that the previous reading at 4000 rpm would occur at 3,400 rpm, for example thus giving that midrange an earlier kick in the butt. It would also give you a higher max boost when you really peg it, but since 90% of performance driving is 5-6000 rpm the shift is of more use than the max reading.

[Andy@Ross-Tech.com]

I hope to prove or disprove that contention in a couple weeks.

[minimini36]

I think if you look at the graph of the boost in the MCS powertrain article it is about .4 bar (5.88 psi) at 2000 rpm. I suspect the MCS graph was maybe after a shift or full throttle was not until 3000 rpm. I have recorded 5 to 6 psi of boost at low engine speeds.

[911ETR]

JLM,

Didnt you design the 15% pulley yourself?

[jlm]

Yes; that is to say, i personally engineered it and personally fabricated it. I don't think the concept of the two part hub/pulley is that unique; what really counts is that it is out there and in production.

As far as the %, the hub constrains you to no less than 15% diameter reduction; the testing will reveal just what % to shoot for. Serendipity allowed for pulley access when back in the car
and the option for going back to stock seems logical.

[noahe]

A Supercharger will generally start to deliver boost at lower RPM. The Supercharger, being mechanically driven by the engine, creates a drag, which on the MINI can suck 4-6 HP from the engine. Fortunatly, it makes much more than 4-6 HP. A Supercharger's boost will vary with engine RPM. Typically, a supercharger is more reliable and maintenance free than a turbo.

A Turbocharger will generate boost when spools up to it's operating range. Depending on the size of the turbo, this will happen at medium-low to high RPMs. A smaller turbo will generally spool up faster than a large one, but produce less boost. Since the exhaust gas is a waste product, the turbo get's it's power almost for free (it does increase exhaust back-pressure somewhat while spooling up). A Turbocharger's boost will also vary slightly indirectly with engine RPM, based on exhaust gas pressure, but since most turbos come with a boost pressure controlled waste gate, the turbo can be set to spool up to X,XXX RPM, and then overboost for the rest of the band. The wastegate will release the excess pressure, to keep the boost pressure constant. Turbo's generally require more maintenance due to to the heat & corrosive gas environment of the exhaust stream, and the incredible RPM's they run at. A turbo often requires more frequent engine oil changes, due to it sharing the engine oil supply to cool the turbo's bearings.

They are both pretty cool technology.

[911ETR]

Quote:

Originally posted by jlm
Yes; that is to say, i personally engineered it and personally fabricated it. I don't think the concept of the two part hub/pulley is that unique; what really counts is that it is out there and in production.

As far as the %, the hub constrains you to no less than 15% diameter reduction; the testing will reveal just what % to shoot for. Serendipity allowed for pulley access when back in the car
and the option for going back to stock seems logical.

You stated that "the hub constrains you to no less than 15% diameter reduction" I guess I am a little confused by this statement and cannot picture why you would have to go at least 15% unless its due to the Serendipity access. As far as numbers... what is 15% in mm? How big is the stock pulley? Are there weight differences?

I saw the pulley in Portland yesterday and it is a very nice piece. You do nice work.

[jlm]

thanks.

in brief: the shaft is about .780" dia; the hub has about a .187 wall the od of which has to clear the head of the #10-32 shcs which will hold the pulley on. That sets the minimum bolt circle radius. The Vee depth for the pulley has to not break into the bolt area from the exterior. The smallest pulley that would work was about 2.25 (aprox 57mm) dia, (15% reduction); the stock size is about 2.6 (approx 66mm). Any size between 2.25 and 2.6 will obviously work, like 10% (2.47 dia). Stock belt length has enough tensioner travel available to still work with the 15%.

[911ETR]

will you design different sizes and if so what ones?

[jlm]

Right now, testing of 15% 1n 10% is happening. Hp gains vs hp loss driving the blower are being evaluated as well as fuel/air ratios.
As far as production goes, any size can be made.
My guess i the bsic package would be a hub and one pulley, size of your choice. Extra pulleys, like a stock size, would be optional.

to change your pulley, once the hub is fitted and the blower installed, you need to release the belt tension and remove the pulley-to-hub screws, a tight, but do-able operation.

[GTT 280]

This thread has become far to technical for me.

This usually happens on forums like this. They get taken over by technical wizards who forget not everybody is in the field of work they are.

Now, if you ask me about horizontally fragmented partially replicated databases I could talk for hours !!

Cheers,
EB MINI

[911ETR]

Positively charged SQL databases of course, right? ļ