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Here's my dilemma: Running 15% pulley, PRW damper, fresh belt tensioner, new Gates 060535 belt, new BPV. Installed boost gauge a few days ago and, after warming it up, only getting approx. 8 lb. boost at WOT. Have checked for leaks with starting ether and propane at the usual spots. Gauge responds normally, 18 lb. vacuum at idle. No codes thrown. Performance is strong, just not the expected boost at WOT. S/C is not unusually noisy but am ready to change it out. Anything else I should check? What would cause a S/C to underperform after only 57,000 miles? No, the car hasn't been abused.
Check all possibilities for a vacuum/boost leak. The BPV would be obvious, but that is a new part. I would doublecheck it anyway. Also check for ruptures on the snoot boots
BPV working properly. Boots checked and double-checked. Am in the process of rigging up a smoke test to eliminate any leaks from the equation that the ether and propane didn't find.
Autometer boost gauge. Possibility it may be faulty? Line isn't kinked. No leak at either connection. Smoke test showed no leaks but hard to get past closed throttle. If I turn on ignition but not start, can I open it by depressing accelerator?
No but great minds work in the same circles! I'm going to either borrow or buy something to do just that...Even attach another boost gauge for comparison.
My boost is back! Since I did a number of things while the car was in VOR status, I can't tell you if one or a combination of things solved it. I can say for sure that it wasn't a faulty gauge. I changed I/C boots, re-routed the vacuum line T to below the FPR and used a 1/8-inch plastic T, rather than the supplied AUTOMETER T-fitting, used a short piece of 1/8-inch fuel line to connect to the FPR and ty-wrapped it securely in place. I changed pulleys to ensure no slippage on the shaft. In addition, I replaced the non-resonated center section with the resonated version in order to create a little more back-pressure. I also checked my PCV valve. FWIW, here's an article from KenneBell that helped me the most: http://kennebell.net/tech/supercharg...-causes-cures/ Clear, easy to understand information from folks who've heard it all. I also learned that, if you have significant mods like cam, header, tune, free-flow exhaust, etc., don't expect the higher boost numbers as those without these mods. Their engines don't breath as well, hence the higher numbers. High boost values don't necessarily equate to higher horsepower.
Last edited by NC TRACKRAT; Mar 23, 2021 at 06:10 AM.
Postscript: Just got back from instructing for a BMW CCA event at VIR and pleased to report I consistently saw 14-15 lb. boost at WOT up to 7000-7200 rpm. The GP performed flawlessly all week-end.
I don't have any pictures, but I drilled and taped a takeoff location on the aluminum duct on the left side of the intercooler.
There's a boss that looks like it may have been there for a screw location, but never used. I drilled and taped it for an 1/8 NPT, installed a 90° fitting and ran the line into the car and also am using an Autometer gauge.
When I drilled and taped the hole, I removed the intercooler, stuffed a rag into the tube, below where I'd be drilling, and made a "diaper" out of duct tape to catch all of the aluminum chips.
That way, the small diameter vacuum line is as short as possible. Length will make a difference. The longer the length, the less accurate (speed to show a value) the reading will be.
Postscript: Just got back from instructing for a BMW CCA event at VIR and pleased to report I consistently saw 14-15 lb. boost at WOT up to 7000-7200 rpm. The GP performed flawlessly all week-end.
how many students does bmwcca give you? And do they give you the option to pay to have less?
I find it hectic having two students and I do not get to spend enough time with them
Different chapters have different procedures. You may get two students, you may get just one. Luck of the draw. Tarheel doesn't charge instructors for instructing, Tarheel arranges its run group schedule such that you never have back-to-back students. If you choose to attend Friday "Orientation/Test & Tune day", you pay a fee. At Carolinas PCA, instructors pay, even to instruct but can reduce the fee by taking two students.
I don't have any pictures, but I drilled and taped a takeoff location on the aluminum duct on the left side of the intercooler.
There's a boss that looks like it may have been there for a screw location, but never used. I drilled and taped it for an 1/8 NPT, installed a 90° fitting and ran the line into the car and also am using an Autometer gauge.
When I drilled and taped the hole, I removed the intercooler, stuffed a rag into the tube, below where I'd be drilling, and made a "diaper" out of duct tape to catch all of the aluminum chips.
That way, the small diameter vacuum line is as short as possible. Length will make a difference. The longer the length, the less accurate (speed to show a value) the reading will be.
Mike
Mike-
Thanks for a very good suggestion. By "Left", I assume you mean as you're standing at the front of the vehicle, i.e. the passenger side. I concur that keeping the diameter of the fittings and tubing as small as possible and as short a run as possible will help accuracy. Next time I have the I/C off, I think I'll do your mod. Putting grease on the flutes of the drill and tap helps catch the chips, too.
Mike-
Thanks for a very good suggestion. By "Left", I assume you mean as you're standing at the front of the vehicle, i.e. the passenger side. I concur that keeping the diameter of the fittings and tubing as small as possible and as short a run as possible will help accuracy. Next time I have the I/C off, I think I'll do your mod. Putting grease on the flutes of the drill and tap helps catch the chips, too.
No, left vs right, is always, as sitting in the seat. Or that's the way that I've always understood it to be, and I'm working on being ancient !
Check your PM. I'll try to take a picture tomorrow afternoon. Will let you know.
Finally.
The air horn on top, I did first to make sure there was going to be enough threads, both for strength and to seal the threads. Then I removed the intercooler, stuffed the rag, and made the diaper out of duct tape to catch the chips.
If you need to use an angled fitting as I did (brass 90° fitting below the cooler cover), you can cut the threads deep or shallow enough to set the angle of the 90° fitting. Tap, check your "tight" angle, tap more, check, etc.
I DO NOT recommend using teflon tape. I just use oil, that's all I've ever used. If you feel that you need a sealer, use a gasket sealer on the threads.
Doing it this way, removes about 1/2 of the line length from the system, than if you go over to the intake manifold fittings on the other side of the engine like many do. You get a full open source of airflow for the gauge to register from.
Different chapters have different procedures. You may get two students, you may get just one. Luck of the draw. Tarheel doesn't charge instructors for instructing, Tarheel arranges its run group schedule such that you never have back-to-back students. If you choose to attend Friday "Orientation/Test & Tune day", you pay a fee. At Carolinas PCA, instructors pay, even to instruct but can reduce the fee by taking two students.
I'm in NC, vir/cmp are my home tracks. The clubs I instruct with are the same except for tar heel sports car club, they let you pay to ensure you have one student.
I spray meth in almost the same location, but I come in from the side to it sprays across the full width of the horn. I use teflon tape on all three that I've done. I run a analog PSI gauge in the car, I caught a plugged nozzle last week with the gauge the pressure was not dropping after I lifted throttle. I spray 300ml/min (175cc nozzle at 200psi) works out to about 1 gallon per tank of fuel on the street, almost 2 gallons per tank on the track. I edited my wide open throttle fuel table, 11.8 and some knock correction without meth 11.3 with meth. I do not advance timing with meth but there's lots of room there if I ever want to, the risk is if the tank runs dry, nozzle clogs, line pops, pump fails etc etc
