Howdy partners,
I need some help from the much wiser, greater MINI community.
I have recently installed a P&Ped Head, Piper 285 (rotation) cam as well as a GRS IC (oh, and an ALTA O% LWCP). Now, it could be a faulty sensor that I have running thru my logger and dash system but I doubt it, but I am running 29Psi/ 2.0 Bar of Boost.....Yes, 29Psi!!!!!!
I recently had the belt tensioned as it was loose after the rebuild as well as removing the AC system but have left the AC puley on the belt path to avoid further complications.
Now, my question to the wise is why so much boost and how can I avoid this as it is strictly a track car and I dont want to blow the engine.
Im installing a 17% pulley (this week) instead of the 19% I have on at the moment ( I know a 19's not recomended but Ive had no probs before with it).

What could it most likely be so I can start searching the right places:

Faulty sensor?
AC removal?
Can the head and cam affect the boost?
SC is screwed?
MTH Tuner Program fault?
Suggestions please....

Dont get me wrong, its got more punch than Lennox Lewis but I fear the little pinging sound feared by all.

p.s. I also use a GoodYear Gatorback belt on the SC.

:impatient :impatient :impatient :impatient :impatient :impatient

 

Could it be the logger is reading (perhaps due to miscalibration: 14 (or so) atmosphereic pressure + 15 psi of boost?

The # just seems unsually high for a head, 19% and 0%. If the IC is larger that should reduce boost. Guess the first thing is to check the sensor. Can you view the boost live, even just to see if your readings are making sense with what you'd expect?

 

I can, its all connected up to run live as well as log. Its peaking at 2.0bar but as you said it could be a faulty sensor. I think thats definately one thing to check/ replace.

Thanks

 

It is probably not a faulty sesnsor but rather one that starts at 1 bar. Interestingly, Porsche 911 turbos and 944 turbos have different style boost gauges; one starts at 0 bar, the other 1 bar.
It is a wise move by you to go with the GRS IC for your track car!

 

AC removal would result in less drag i'd imagine, so maybe a tiny bit of extra boost. A P&P head would result in less boost due to better flow (less restriction) and slightly greater volume. I doubt the SC is screwed, as that would probably make less boost if that was so. Also doubt it's the MTH. I'd suggest a faulty gauge/sensor.

 

What does it read at idle?

What does it read when the engine is not running?

What does it read at moderate accelleration

 

It might be a good idea to check your catalytic converter. One of the folks in our local MINI club (www.metroplexmini.org) had an overboost situation that started on his MINI one day and it turned out that his cat was clogged / ruined.

 

The sensors read Manifold Absolute Pressure (map sensor). Substract atmospheric pressure to get you boost level.

 

Thanks guys, I'll chech it all out as soon asap. By consensus, it does seem to stem from the actual sensor and/or its calibration.
Will post back to fill in the blanks.

Thanks again.

 

As Motor On and 002 suggest... if you're pulling your info off the factory sensor, be aware that it senses absolute pressure. That would be: atmospheric pressure at your altitude + SC boost. If you were to read the sensor with the motor off, it would read about 1 bar (14.? lbs) which equals 1 atmosphere.

Oddly enough, you're a little low for a 19% pulley. I routinely get 17lbs of boost, which off of the factory sensor would read as about 31lbs of boost, or 2.2ish bar.
Hope that helps?

 

It does, and you are very correct.
I checked it all out today and did find it was at 1.0BAR when the engine was off and 0.7 when Idle.
Im happy with the boost as it is, as its quite a punchy little car now and pretty much perfect HP for the tracks I frequent. Now that I know nothing is actually wrong except me having a worry spell I will confidently give it all.

BluMinimeDo, you have a larger IC as that could be the culprit of the boost drop if you are reading higher levels..........:impatient I go from posting about too much, now I want some more

Thanks all for the advice,
really appreciate it

 

Does anyone know how to display boost pressure on the OBC screen? And does it display the boost real time or only momentarily....

 

Yer quite welcome. I'm sure my GRS IC is causing a small bit of pressure drop. I believe Graham measured it at slightly less than a pound. Still, 17lbs on an aftermarket boost gauge is nothing to sneeze at. If I were to measure it off of the factory sensor, I'd predict 31lbs/2.2bar.

.7bar is normal at idle... and is caused by engine vacuum that occurs when the engine is not under load.

I did an overhaul on my bypass valve some time ago, realigning the valve in the bore, and turning out the stop screw so it would seal completely, and picked up roughly a pound of boost. I still think you're a little low and the bypass valve is many times the likely culprit of low boost numbers. Recommend you have a look at it.