Not too long ago I went from a 3.1 to 3.0 pulley and it made quite the difference. The car would now throw me back into the seat and fly. I would see around 13 - 14 psi all day long. Now it's been slowly diminishing. Less and less of a jump. The gauge now only reads 10 psi on a good day. I am getting stomped by cars I use to devastate.
My questions is what could cause boost loss on such a severe level?
One thing I do question is that I have a phenolic spacer from OEM (m62 to IM) and I had to use siicone to properly seal it. The Master Mechanic I work with said the silicone could of given out. I sprayed carb cleaner to see if it would show anything and I got nothing.
Any input or tips would be greatly appreciated, thanks guys.
P.S. also did a compression test to day. got 180-175-180-180.
Bypass solenoid? Gauge bad? You checked for VAC leaks?
P&P Tuning
420.5whp / 359.8wtq
a sudden loss in restriction. cat blown out, muffler blown out, exhaust leak, vaccum leak, intake leak, bad bypass valve, bad blower gasket or intake gasket. a restriction in the PCV system maybe. lots it could be.
Sounds normal to me with the SCer system and the ambient heat increase for AZ. The increase in heat here has a dramatic affect on boost pressure on the SCer setup. Has a dramatic affect on anything forced induction here. Run meth.......... Oh by the way IAT temps pull butt loads of timing so that is going to also be taking affect since the temps have started increasing a lot here as of recently. Onlything to counter it is to get a good heat exchanger setup and run methanol.
ASE Master Certified Automotive Technician
CaliforniaDomestics wrote:Sounds normal to me with the SCer system and the ambient heat increase for AZ. The increase in heat here has a dramatic affect on boost pressure on the SCer setup. Has a dramatic affect on anything forced induction here. Run meth.......... Oh by the way IAT temps pull butt loads of timing so that is going to also be taking affect since the temps have started increasing a lot here as of recently. Onlything to counter it is to get a good heat exchanger setup and run methanol.
I think this hit it on the head.
Meth is your friend.
FU Tuning
Jesus Jacobo wrote:
One thing I do question is that I have a phenolic spacer from OEM (m62 to IM) and I had to use siicone to properly seal it. The Master Mechanic I work with said the silicone could of given out. I sprayed carb cleaner to see if it would show anything and I got nothing.
I don't think this test would rule out a leak after the blower since anything after it is under boost therefore pushing away the carb cleaner instead of sucking it in
SilvrSunfir wrote:Jesus Jacobo wrote:
One thing I do question is that I have a phenolic spacer from OEM (m62 to IM) and I had to use siicone to properly seal it. The Master Mechanic I work with said the silicone could of given out. I sprayed carb cleaner to see if it would show anything and I got nothing.
I don't think this test would rule out a leak after the blower since anything after it is under boost therefore pushing away the carb cleaner instead of sucking it in
unless he's manually closing the bypass valve while idling the manifold will remain in vacuum.
ASE Master Certified Automotive Technician
I honestly haven't look at the bypass, hmm.
Gauge is bad, reads off by 2 psi, so when I say 10 psi the gauge actually shows 8 psi, but I've checked it with my two shop gauges and the numbers are right.
I thought I may have a vac leak at the s/c to IM or even IM to head and at boost was causing the pressure to seep. That is why I sprayed Carb Cleaner at idle to see if it would suck it in and cause a change in the tone. Got nothing.
But the belt has crossed my mind.
Originally I had the 3.1 and stock belt.
Then added the spacer.
Then went down to the 3.0 and after time began noticing a loss in power.
Recently switched the 2.5 tensioner pulley with the 3.0 pulley off the idler after I noticed I could free spin the charger pulley, belt and all accesories, excluding the crank.
Last thing I did yesterday was pull the charger off, remove the spacer, and temporairly silicone it until I get the gasket next week.
Boost went down some more to 9psi and i can hand spin the accessories again.
Today I'll be switching back to the 3.1 to see if I can get some more tension on the belt, but it looks like I'll need a stage 2 belt.
I took into consideration the change in temps, but this was happening before the suden temp change. I want to say some time in the winter. When I first got the 3.0 last fall I saw 15psi, then winter came and only saw 12 psi and the beggining of March only 10 psi.
Interesting note though. Yesterday when I pulled the charger and removed the spacer and restarted it I was playing with the throttle while in Park (i.e. reving it) and for some reason it jumped to 18 psi, whined like a beast, then engine stalled out and I got a nice big plume of black smoke. Turn it back on and acted normal. I was so weird, it is still registered on the peak on the gauge. Any idea why the big jump?
The only thing that will cause a spike on that SCer would be a sticking bypass valve or perhaps something plugging the vac/psi lines to the bypass. If the belt is slipping you will see glazing on the pulleys and/or the belt.
ASE Master Certified Automotive Technician
Not a slipping belt. Replaced the belt again with a stage 2 belt on a 3.0 charger pulley and 2.5 tensioner pulley. More than enough tension. Now seeing 9-10 psi
I'm going to take a second look at the bypass valve again.
Ive been at 8lbs since i installed my supercharger on my 04 cavy. it literally hits 8 and just stops like hitting a wall. Always has.
I had the stock idler pulley and tensioner pulley but i also have both phenolic spacers. 3.0" pulley on the blower.
I was having MAJOR belt slippage on the stage1 belt especially at the track on DR's. It would peak at 8lbs constantly. Even on the road at WOT, so belt slippage or not, my boost doesnt seem to go up much. even when its sticking.
So i had to grind down the head, and tensioner bracket quite a bit, but eventually got the stage2 belt on. Then the tensioner was so tight, it wouldnt allow the tensioner to go back up (the top of the tension hydrolic arm was too far forward to go back the other way).
So I put the stage 1 belt back on, but to make up slack, i swapped the stock tensioner pulley out with an idler pulley (larger diameter). it seemed to help the tension a little, but if anything gained maybe .5 lb more boost (and i think thats all in my head).
Im running around beating cars i probably shouldnt be beating on only 8lbs. My friends s/c 4dr cavy was supposedly running 17lbs on the same stock blower with a larger pulley (no h/e working) and i pulled pretty hard on him.
Ive run some decently turboed vehicles including a well modified turbo WRX and pulled pretty good against a few Mustang GTs. so its got the power, but seems to be low still. I do hear the belt slip at start up sometimes though briefly and when i shift hard under acceleration i feel it slip (like tries spinning, which is also a problem lol).
either my boost gauge is off, or my vac lines are run incorrectly. but i think the belt is only part of the problem.
how do i test the bypass valve on the s/c someone mentioned? Im interested in this thread too, as i want to see the boost this thing is capable of making!!
04 Cav. 2dr. 5spd. My DD. 'Nuff said.
blu04DD wrote:how do i test the bypass valve on the s/c someone mentioned? Im interested in this thread too, as i want to see the boost this thing is capable of making!!
Vacuum/pressure pump. You can get em from pretty much any auto parts store and even harbor freight. I personally use mighty vac systems.
Mityvac
Useful for a million different things such as testing everyone's boost gauges which seem to be notoriously off haha. Remember most gauges everyone runs are not precision instruments but rather somewhat accurate guides per se.
ASE Master Certified Automotive Technician
