[presurized mini]

with the stock airbox

1st gear 8psi
2nd gear 9psi at top rev's 9 1/2
3rd gear about the same

then i insatlled a 3in ID K&N filter to the end of the stock pipe which is pretty much what everyone else is selling but this cost me what $30 for the filter,and here is what i get.I teed of the back of the intake just under the intercooler.I dont understand where some people are getting 12.5psi what am i missing

1st gear 8 1/2psi
2nd gear 9 1/2psi at top rev's 10psi
3rd gear 9 1/2psi

[jonturner]

Quote:

Originally posted by presurized mini
with the stock airbox

1st gear 8psi
2nd gear 9psi at top rev's 9 1/2
3rd gear about the same

then i insatlled a 3in ID K&N filter to the end of the stock pipe which is pretty much what everyone else is selling but this cost me what $30 for the filter,and here is what i get.I teed of the back of the intake just under the intercooler.I dont understand where some people are getting 12.5psi what am i missing

1st gear 8 1/2psi
2nd gear 9 1/2psi at top rev's 10psi
3rd gear 9 1/2psi

Have you controlled for changes in barometric pressure, humidity and temperature? A cooler, damper day, may give the engine management computer more room to raise the boost which could explain the ~7% difference you're seeing. I would be very surprised to see any difference in boost pressure as a result of a change in the upstream, except at very, very high RPMs because this engine is does not behave as if it's air starved. Consider also that most of the super's boost is being bled off by the wastegate. (Which, I suspect, in concert with ignition timing changes, contributes to the yo-yo acceleration effect we're experiencing but that's a different subject entirely...)

-- JonTurner

[presurized mini]

I agree with you i dont see how puting on a little air filter that you get more boost,i've had other cars with blowers and never seen it

[jlm]

i've been watching my boost gauge and have noted that you only get 11 psi when you redline the engine with the throttle full open and pulling. third and fourth gear on an open road are good; you won't be in first gear very long at red line with the throttle fully open...timid use of the throttle will show as a reduced manifold pressure, all other things being equal. (the autometer elecric boost gauge will store the max boost reading, a handy thing.)

the blower increases the pressure in proportion to the rpm subject to the factors limiting air supply. if the throttle is not open, you will limit the air; if the intake filter is limiting the air, you will get more manifold pressure by using a free flow unit.

i wasn't aware the mini had a wastegate?

[RSAmerica]

What is the point of a boost gauge? Unless someone has figured out how to put in an adjustable boost dial in a MCS, like a 911 Turbo, in that application with adjustable boost, the gauge is used to adjust the boost and watch for an over boost condition. All you need to do in a MCS is keep the car 4000-6000 rpm to get some power. You drive the car with the tach.

MCS @ LRP
911 RS America @ WGI

[thepilo]

Boost is able to be changed from minimizing restriction. This is because if you try to suck throught a restrictive intake, the turbine can spin the same speed, but get less air, due to the restriction, when that is opened up, the turbine has access to more air, and is able to push more of that air into the intake manifold, his readings are about what it should be by removing restriction, it's only going to be a bit, but should be noticable.

[jonturner]

Quote:

Originally posted by RSAmerica
What is the point of a boost gauge?

It's fun to watch.

[pzaxis]

If the engine has a wastegate would it be possible to ad an HKS EVC or similar device.

[thepilo]

No, You can't control the boost really, via the HKS EVC or anything, that is because there is nothing that electronically controlls the Boost, it's only a function of mechanical force, and air pressurization. sorry

[macncheese]

Heres a little romp I did tonight from 2nd gear to 3rd gear. Sorry its so wide, i hate when graphs are really small





--
Dave
Alchemy Engineering

[pzaxis]

What a great look at the boost pressures at different RPM.
Now what can be done to get some high boost at low RPM!!!!

[minimini36]

I am curious how everyone is measuring the boost pressure. I have run a few tests using my scan tool connected to the OBD2 connector. I have recorded the RPM and MAP (manifold absolute pressure in inches of Hg) during various runs. The highest pressure I have recorded is about 47.7 inches of Mercury. The barometric pressure at the time was about 28.7 in HG. This gives a boost of 19 inches which translates to about 9.5 lbs of boost. (1 BAR = 14.7 psi = 29.92 in of Hg) At about 2000 rpm there is already 5 lbs of boost. At 3k 6lbs, 4k 7 lbs, 5k 8.5 lbs and 6.5 k 9.5 lbs. These are all approximate since in first or second the number of samples from the scan tool is low because the rpms rise very quickly. The scan tool can only read 9 or 10 parameters per second. I was recording the rpm, MAP and intake air temp. These tests would be better if done in a higher gear on the freeway and may be only recording MAP and rpm to get more readings. The great thing about the scan tool is the data is recorded to the Laptop for later review. In 3 runs I have never seen more then 9.5 lbs of boost not the 11.75 that equates to .8 BAR boost being reported by MINI. The first link below is to an article about the MCS drivetrain and the second link is to the German version which has all the figures including figure 2 that show the boost. The boost is on the left side in BARs. (remember 1 bar is atmospheric pressure) the yellow curved lines are engine rpm starting at 2000 rpm and with a line for each 1k rpm increment to 8000 rpm. The boost line ends just past 7000 rpm. The higher boost line is out of the supercharger and the lower boost line is out of the intercooler. This article is good reading for MCS fans. If anyone else has a scan tool could you post your results. One of the intake manufactures reported his boost went from 11.5 lbs to 13.5 lbs of boost after installing his intake system. It makes me wonder about the accuracy of the MAP sensor or his gage.

Many of us have also noticed a lack of power when starting off in first gear with our MCS. Many have complained first gear is too tall and there is not enough low end torque. I live in Arizona and got my MCS in July when the temps were near 110 to 115 degrees F and I always ran the Air Conditioning. Now that it is cooling off there is no shortage of low end torque. After looking at the scan tool I think I understand most of the reasons why this is occurring. To me it is always worst when setting at a stop light for a long time. I believe the large amount of engine heat given off, the high outside air temp and the extra heat given off from the AC condenser have raised the intake air temp to a very high level. This is aggravated because the car is not moving and there is no air flow over the intercooler. The first night I connected the scan tool the outside air temperature was about 75. After the car had set idling the intake air temp had risen to 162 degrees. Now imagine if the outside air temperature was 35 to 40 degrees higher. The intake air temperature could easily be 200 degrees. I think the computer is reading this temperature and is changing the timing and mixture to prevent damage to the engine. After you start off there is a big inrush of cooler air and the computer returns to more normal settings after a few seconds. It makes me wonder is a fan blowing on the intercooler would help reduce this effect? It would have to be very thin. The alternative is to move to a cooler climate.

I have also looked at the TP (throttle position) sensor which has never indicated a value over 92%. I saw a post on a BMW board and that person indicated his BMW never indicated over about 70% max on the scan tool. Someone earlier mentioned a waste gate to control the boost on the MCS. There is no waste gate on the MCS. I have wondered if the ECU would try controlling the boost using the throttle position which is controlled electronically by the ECU. This is known as fly-by-wire. Any comments?

http://all4engineers.de/all4enginee...z/m07-02-11.pdf

http://all4engineers.de/all4enginee...z/m07-02-08.pdf

For anyone interested in the operation of an ECU and the operating modes should check out this link to info about the Chevy LS1 engine. The only major difference is in the fact that the MINI does not have a MAF (mass air flow sensor). It calculates the air flow based on pressure and rpm I believe. Good reading.

http://www.vetteguru.com/mods/howto/

[macncheese]

Quote:

Originally posted by minimini36
If anyone else has a scan tool could you post your results.

The graph above was generated via a performance oriented scan tool. The Cooper S OBDII interface is capable of sampling rate of 20 readings per second, one of the fastest I've seen. You're probably limited by your interface. Let me know if you want me to run any other tests for comparison.


--
Dave
Alchemy Engineering

[Coati1]

No discussion of supercharger boost and throttle position/manifold pressure is complete without this:

http://www.jacksonracing.com/pages/howorksh.html

[jonturner]

Quote:

Originally posted by jlm
i wasn't aware the mini had a wastegate?

You're exactly right, it doesn't. I think I was having a "senior moment" there. Either that, or I've been wrenching on Turbo cars waaaaaaay too long and my brain can't conceive of a stupid-simple air pump without a bunch of other junk to keep it from overboosting.
I think I'll go take a nap, now.

[macncheese]

Quote:

Originally posted by minimini36


I have also looked at the TP (throttle position) sensor which has never indicated a value over 92%. I saw a post on a BMW board and that person indicated his BMW never indicated over about 70% max on the scan tool. Someone earlier mentioned a waste gate to control the boost on the MCS. There is no waste gate on the MCS. I have wondered if the ECU would try controlling the boost using the throttle position which is controlled electronically by the ECU. This is known as fly-by-wire. Any comments?

I verified this on the way home from work. WOT results in 91.55%.

I dont think there is any external boost control, only the mechanical bypass valve. This engine is barely ever boosted as you can tell from watching the manifold graphs. Im interested in knowing if you see anything odd when looking at timing while cruising at speed (55-70mph).

--
Dave

[minimini36]

Quote:

Originally posted by macncheese


I verified this on the way home from work. WOT results in 91.55%.

I dont think there is any external boost control, only the mechanical bypass valve. This engine is barely ever boosted as you can tell from watching the manifold graphs. Im interested in knowing if you see anything odd when looking at timing while cruising at speed (55-70mph).

--
Dave

The throttle position agrees with what I was seeing. I was not implying there was any kind of external boost control, just that it could be possible for the ECU to control the boost level using the electronically controlled throttle.

I am not sure what you were seeing while cruising at 55 to 70. I am new to using the scan tool and viewing the data. I did go for a drive tonight on the freeway. At a steady cruise speed the advance was about 30 degrees at 2000 rpm and maybe 37 degrees near 3000 rpm in 6th gear maintaining a steady speed. As the MAP would increase the timing would retard. This was for slight changes in throttle position.

I will have more time to look closer at the data tomorrow.

[minimini36]

I did an experiment this morning using my scan tool connected to my MCS's OBDII port. I used the scan tool to record the engine RPM and MAP (Manifold Absolute Pressure). The first run shown in the first table was with the stock MCS. The first column is the elapsed time of the RPM measurement with the RPM in the second column. The third column is the elapsed time for the MAP measurement in the fourth column. The maximum pressure was 47.7 inches of mercury, which is about 9.5 psi of boost. This is the highest I have ever recorded in multiple runs. For the second run I opened the air filter box and removed the filter element before re-closing the air box. I then made a second run around my neighborhood. This included 2 more full throttle accelerations in first gear. The highest pressure recorded was 48.3 inches of mercury. Removing the filter element only resulted in about .3 psi increase in boost. This tells me switching to just a K&N replacement element is not going to result in much of an increase in boost. The 1.7 psi increase in boost reported for the BMP air box appears to at least in part be the result of the opening in the back of the unit. It appears as if the cold air intake in the front grill and the opening into the air vents in front of the windshield are not supplying enough air. I think the opening to the air vent is actually there to increase the sound from the supercharger. In previous tests I was able to run to the fuel cutoff (6950 rpm) in both first and second gears on an up hill grade and there was no further increase in boost above the 9.5 psi level. I did the short runs without the filter in first gear only because I could do this on a road near my house with a 45 mph speed limit. I did not want to travel far without the filter installed. Previous runs had been done entering the freeway which is in a dusty agricultural area about 10 miles from my house.

Air filter element installed

111.06 2037 111.22 28.4 first gear
111.39 2242 111.55 32.6
111.77 2559 111.93 38.2
112.10 2956 112.32 41.2
112.48 3453 112.65 42.3
112.81 3988 113.03 44.1
113.20 4503 113.36 45.6
113.58 5035 113.75 45.9
113.91 5551 114.08 46.5
114.30 6033 114.46 46.2
114.63 6492 114.79 47.7 Peak pressure for run
115.01 6960 115.18 32.6
115.34 6789 115.56 9.8
115.72 6148 115.89 16.0
116.05 5065 116.27 46.2 second gear
116.44 4888 116.60 46.8
116.82 5054 116.99 46.8
117.15 5285 117.32 47.1
117.54 5457 117.70 16.3

no air filter element first run
141.66 2224 141.82 20.4 first gear
141.99 2387 142.15 19.8
142.37 2592 142.54 40.0
142.70 3050 142.87 41.2
143.09 3559 143.25 42.9
143.42 4089 143.64 44.4
143.80 4614 143.96 45.6
144.13 5137 144.35 46.5
144.51 5678 144.68 46.5
144.90 6192 145.06 46.8
145.23 6682 145.39 48.3 peak pressure
145.61 6975 145.78 24.9
145.94 6991 146.11 10.7
second run with no filter
177.96 3071 178.18 31.1 first gear
178.35 3435 178.51 41.2
178.73 3939 178.90 43.2
179.06 4406 179.23 44.7
179.45 4945 179.61 46.2
179.78 5482 180.00 46.8
180.16 6021 180.33 46.5
180.55 6510 180.71 48.0
180.87 6975 181.04 13.0
181.26 6430 181.42 10.1
181.59 5425 181.75 46.8
181.97 4742 182.14 46.8
182.30 5054 182.52 43.2
182.69 5068 182.85 8.6

[ElectronMan]

If the TPS is reading 92% at WOT, is it reading negative % at fully closed or is it reading 0? Also does anyone know the voltage output range of the TPS?

[jlm]

here's an update:

i'm now getting 13.5psi boost at WOT, pulling hard.

same gauge as before when i got 11psi. (electronic Ultralite boost/vac reading intake manifold pressure; this gauge retains your peak reading.)

here is what has changed:

rogue induction;
ECU chip upgrade;
rogue cat-back exhaust;
today ambient temp is about 55, last time it was about 70

...the sucker goes!