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Discussion Starter · #1 ·
well as many of you guys know after i came back from the dyno, i lost more power when i came out than when i came in...my car is running super rich and a/f is everywhere. i am at 150whp now with an m62 supercharger pushing 5-6psi. with my n/a setup i would say i was at around 140whp, lol so WTF?!?
anyways, i also lost the whining on my supercharger after the dyno session...

fast forward to now:
today i accidentally filled up with 87octane instead of the regular 91 octane, well i was getting late for work and i drive about 30 miles to get there....after 15 miles, i noticed that my car began to have more power?!? :einstein:
well i went to pass someone and BLAM !! my supercharger was whining and the car pulled hard :3_vliegen...
i thought it was a flaw, but i started to pass people and it kept pulling hard and whining.

so what's causing this?!?
i bought another wideband to help me tune, but i would like to know
-what causes the supercharger to whine and not whine?
-if i buy an OBd2 scanner what will i be looking for to pull timing? knock?
-also will this work? http://cgi.ebay.com/ebaymotors/ws/e...260455648887&viewitem=&_trkparms=tab=Watching

i am currently using the 5-6 psi pulley because it slips less...
 

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Well, first off I would never recommend driving around with low octance fuel while boosted.. that is a bad idea. As for the supercharger to whine or not whine, its the boost actuator. Make sure its operating correctly and check the vacuum line going to it isn't too soft and crimping. Hopefully this helps! :)
 

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Discussion Starter · #4 ·
when i was at the dyno everything seemed to be working alright, boost was up at times and actuator worked,etc.
what about for guys with lower stages, how come some s/c v6 have stronger whine than others?
thanks for the advices! keep em coming1
 

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The whine will come from when the supercharger is actually working. Its the rotary vanes that whine they are like straight cut gears. Only roots style superchargers whine really.
Spinning the pulley and shaft with the rotors makes the noise. Whether or not the actuator is working right determines how much boost you see in the combustion chamber. If the engine is running at a high enough rpm, is when you'll hear the twin screw rotors "whine", regardless if your actuator is working.

So working is a broad term, you mean forcing air "boost" into the intake and combustion chamber.
You probably don't talk about that stuff on the "subie" forums, thought I'd help out.
 

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what about for guys with lower stages, how come some s/c v6 have stronger whine than others?
Not true, a mp62 will sound similar whether it's spun by a 2 Liter 4 cylinder, or 7L V8 at equal rpm.
differences in sound probably come from the video quality, or where the sound is coming from.
 

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Whooty what are you talking about? I said the rotary vanes (or rotors if you prefer to dumb it down) are what make noise. They make noise for the same reason straight cut gears make noise in a transmission. Thanks.


stronger whine comes from more boost because of what I just described above.
You said only when it's working "properly". It will still whine when the actuator is not working right and no boost is seen due to the valve not opening. I'm sure you knew that, just clearing up the statement for everyone else.
 

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Sorry for getting on the wrong track OP.

That's the trouble with the i4's, their serpentine belt is very narrow and may cause slipping on smaller pulleys if the belt is not tight enough.

I suggest getting a larger crank pulley, with a bigger blower pulley to keep the rpms on the blower consistant with the levels of boost you want to see.

Please do not ever boost again on less than 91 octane either, do you have a boost gauge to confirm you're actually seeing boost?
 

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my fic tells me i am at boost....
Have any graphs? The FIC is a very useful tuner, not many people have that advantage. If you don't, I'd suggest recording some data next time you do a few pulls(when you run out of low octane of course).
 

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Also i highly recommend to get a scangauge2 or something that you can use to see your STFT and LTFT in realtime once you get your wideband.

If i were you, i wouldn't even be driving the car without either of those things in place.
 

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My MP45 SC does not whine unless it is producing boost no matter what the RPM is.

At high RPM and light load, no boost = no noise from the SC


Are you running a Goodyear Gatorback belt?

When I have tried other belts I had problems with belt slip.

The Rpm would come up and boost would start then the boost gauge would drop for a few seconds then boost start to come back up.
 

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Discussion Starter · #16 ·
yea my boost will fluctuate 1-2 psi with the 5-6psi pulley

on the 10psi pulley i use a gator back belt and the psi will still fluctuate 2-3psi...sometimes it will even drop to 4psi.

i bought an a scan obd2...
what exactly am i looking for beside the STFT and LTFT?
how would i know my car is in open or closed loop?(when the o2 vts fluctuates?)
how do i know when to pull timing?
 
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