1st Gen R53 Cooper S Most liked posts in thread: Boost Readings

Boost Reading

This should be about right. I have the 'Scan Gauge II' on my R56 MCS JCW (Turbo not Super) still set on MAP and in overboost (3rd gear,pedal to the floor,sport button on) I have attained 30psi briefly which is roughly(30-14.7=15.3 depending upon altitude) 15psi. The r53s don't achieve quite as much boost as the turbo R56 in overboost. So that should be correct. :cornut: Jason

 

Boost Reading

Great! It's gettin up der. Me , I'd be happy. The most important part of the equation is , how does it feel/sound/perform to your heart/seat of the pants gauge ? Does she run and purr or run and growl ?:cornut: Jason

 

We should try not really compare an R56 turbo Minis boost to a MCS R53 Super Charged. Your boost does seem slightly low. Things to consider the cause: a belt slipping, BPV not closing completely,the ic boots are not sealing under pressure,if it is an after market IC this may be inherent for some to have a lower total psi value, the cam was not ground correctly or installed wrong (check cylinder compression) the AFR's are wrong, that's is all I can think of with the information you supplied. You should at least be at 15+psi.@5500rpm under load. Remember also that the size of SC pulley does not mean the boost attained. i.e. 19% pulley does not mean 19psi boost. Also if you engine is efficient it will not necessarily be a high boost to be at a improved power level. You would have had a dyno comparison for that conclusion though.

 

Check the vacuum lines under the IC too. My car had been running fine after I installed a boost gauge, or so it seemed. I noticed my boost was peaking at about 11psi (15% pulley) so I pulled the IC to check the lines and sure enough there was a line under the IC that had somehow come off. Max boost went right back to about 15psi where it should be.

On your car there is a hard vacuum line that goes from underneath the left (PS) horn to the regulator on the fuel rail under the IC. Check both ends to make sure they are connected.

 

Boost Reading

:frown2:No. Exhaust leak(only) shouldn't affect boost in a supercharger. In a turbocharger,depending upon where the leak is, boost could be affected. Jason

 

Remember that there is some variation in boost gauges as well. See if you can datalog what the manifold absolute pressure sensor is reading at your DME.You'll have to use a scan tool with datalogging capability. If you are near our shop, I'll lend you one. If you have a boost/vacuum leak, you probably can hear it just as you shut down the car: listen for a sucking sound.


Edit: I just saw you are in TX...

 

At *almost* WOT @5000rpm, I pull about 12lbs. with 15% pulley. So, I'd expect to get a little more at WOT and winding it on out. I've heard plenty of good things about the DT BPV. Mine's still stock, but I've been considering it.

 

Our BPV is a nice item, with many happy customer. One of things you can do to see if the BPV is a problem is to zip tie it shut and get a feeling of how it drives and your boost numbers. If you like the way it drives and you get more boost, our BPV is the ticket. DT BPV

Chad
Detroit Tuned

 

The various times I have checked the max boost on the AutoMeter gauge installed in my 06 MCS JCW GP, it has been 18 psi which seems a little high. The same gauge installed in my 03 MCS with 15% was usually at max of 16 psi. In any case, you should be around 16 psi or so unless you have a leak somewhere.

 

I'm at 17psi right now with a 17% and other mods.

 

The adjustment on the bpv may be incorrect or to much. The zip tie test works best if the adjusting screw is turned so the valve is completely closed during the test.