Hey all, like the title says, I recently installed a new 15% WMW supercharger pulley to go along with my 2% overdrive pulley which should effectively equate to close to 17%. These are my only mods by the way.

However I am only seeing a peak of 11.5 psi to redline. From what I've seen in other posts I should be hitting at least 16-17 psi but I'm nowhere near that and honestly the gains don't seem like much.

My thoughts as to the lack of boost are either a massive boost leak (not likely), a slipping belt (also not likely but not ruling it out, but I did install a new belt) or possibly a bad bypass valve. I am leaning toward the bpv as of right now but I'd like to test it before I drop more money on a DT bypass valve. I thought I've read on here that you can zip tie the bpv shut to see if more boost can be created, thus ensuring that it is leaking boost. Does anyone have a diagram/walkthrough on what to zip tie? I'm assuming there is an actuator rod like on a turbo wastegate?

Finally, any other thoughts as to why I am missing 5-6 psi?

Thanks in advance for any help!

 

what size belt did you use? how many holes in the tensiorner do you see as well? belt can be slipping in the higher rpms thats why you dont see much boost. and peopel with 17% pullys should be seeing that much boost. even with a 2% crank you arent that close to a 17% pulley 2+15 does not = 17 in the pully world

 

Thanks for the reply. The belt is a Contitech 6pk1374. Quick Google search looks like its a Mini belt but its not the usual belt I've seen people use on here. I have a 2% crank pulley so I wasn't sure what size belt I needed but Way at WMW said he'd send the correct belt.

I have one full hole showing on the tensioner and when I put the belt on it seemed to be a tight fit (I had to put a socket on the crank pulley and walk the belt on). I don't think its slipping but I can't be certain.

Another reason I don't think the belt is slipping is when I am monitoring boost it increases smoothly up to redline where it will stay rock solid at about 11.5 psi. I think if it were slipping the boost would fluctuate a little, no?

I know my setup isn't a true 17% but I should be hitting at least 15-16 psi. I'm nowhere close to that.

 

Your belt IMO is too long
JCW is 1374 (6PK 1374) which would be equivalent to 060541.
Stock is 1388 (6PK 1388) which would be equivalent to 060547.

You should be using a gates K060535 or even a K060532 belt.

 

i agree with bram, your belt imo is to long, go to napa and pick up a smaller one.

 

So you think I should be running the Gates K060535 or 532 even with my 2% overdrive crank pulley? I have read about people using the 535 with the 17% pulley and 0% crank pulley. But wouldn't I need a slightly longer belt than that since my 2% crank pulley is bigger than stock?

Forgive me but its my use of the larger crank pulley that is throwing me off on what belt I need.

Also you guys think that the belt is the cause of my loss of boost? Shouldnt the boost be fluctuating a little if the belt is slipping? My boost is solid, just really low.

 

Some of these guys know more than I do, but I thought showing One Full Hole was the indicator that the belt was correct size.

I only have one hole showing on my car, I don't think my belt slips (I have stock pulley if that's relevant to you). I ordered the tensioner-tool from Way, so I just got the belt from him too -pretty sure he sent me the right one.

Let me know if you find more info on the zip tying the valve. I can see it when I open the hood, but haven't tried to tie it because i had questions that I couldn't find answers to:
When the car is off, does the valve rest in an open or closed position?
Boost is created when the valve is closed, correct?
Will tying it shut cause a check engine light which will need to be cleared with a scanner?

 

There are no lights associated we the bypass valve....it has no sensors...
If the vacume diafram in it is leaking badly, you could get a code (it has both a spring AND a vac line to help it close).
You loose/op....first check for the belt..look for the holes on the tensioner...
Next listen...a big boost leak makes a big sound usually....look at you sc boots...
Then I would mess with the bypass valve...with just swapping it out, or ziptie it for a test...
How many miles on the car? And where are you? elevation DOES effect boost of a sc at about an inch per 1000 feet above sea level....no quite, but close enough to guess if that is your issue.

 

I have exactly one hole on the tensioner (meaning the hole is right at the point where it will be covered by the tensioner body if it goes any further). I was also under the impression that that is enough tension...maybe that is only the case for a stock pulley?

I'm pretty sure I dont have a major boost leak. My IC boots are on properly as well. I did take the supercharger off to change the oil and the pulley so I guess it's possible but I made sure to properly secure everything and use new gaskets when putting it back together.

I want to zip tie the bpv but I want to be sure it's in the closed position when I do. The bpv should be in the open position when off boost so I need to manually close it then zip tie it correct? I was also thinking about doing the VGS mod to help it close.

Car has only 77k and my elevation is only 2k feet. Shouldn't be effecting it by 5-6 psi.

 

What are you using to measure you boost. Also throttle position has a lot to do with boost make sure you are floored at redline.

 

I'm using the Torque app so it's reading straight from the ecu so it should be accurate. I would like to hook a mechanical boost gauge up but money is tight after buying a house. Besides I doubt the difference between the two would be 5-6 psi.

I definitely have the throttle floored when taking the boost readings :-)

 

I dont think it would be that much either. I know the obd port is a little slower(because of refresh) than an acual gauge. I use the SC2 and run around 15.5 psi with a 19%. Does the torque app save the high boost reading or do you have to be watching it the whole time

 

It will save the peak reading. And its always exactly 11.5-11.6.

 

Did you do pre pulley boost runs if so what was the reading. I haven't run thst app but is there settings to compensate for elevation or stuff like that?

 

There are settings for boost but as far as I've researched I have them correct. I'm not really concerned that the Torque app readings may or may not be off because seat of the pants doesn't feel like Im hitting the boost level I should.

I have used the app to read boost before both pulleys and I was consistently hitting about 8-9 psi. Stock is 10'ish?

 

Oops, wrong thread, Re Posted my question on the Boost Gauge Thread

 

I actually had the same question regarding the BPV. I can see it and touch it from the engine bay but am not sure what is supposed to be zip tied. I am running a 15%, stock crank and am seeing psi in the 12.5-13 range.

 

Just an update on what I've done.

-I did the VGS mod, didn't help increase boost.
-Adjusted the atmospheric pressure on the torque app while the car was off so the gauge reads 0. As a result my real boost reading is still only 13.5 peak. Still missing 3-4 psi.

Going to hook up a mechanical boost gauge just to double check boost and also going to zip tie the bpv shut to see if its leaking boost.

Any other ideas while I have time to tinker this weekend?

 

Double post

 

Not sure how the Torque App works.... Did you set it so Boost reads zero when car is off, or so that Atmospheric Pressure reads zero when car is off? There's a good Wikipedia article on atmospheric pressure I read a while back... I think it's 14 something pounds per square inch at sea level, then of course variances for humidity, temperature and elevation.

 

Sorry, I should have been more clear. I adjusted the atmospheric pressure so that the boost reads zero when the car is off. Before I did this it was sitting around -3 in hg. After I adjusted it the boost sat dead zero. I went for another run and Im still only seeing about 13.5 psi.

 

I see. Cool that you can zero the guage like that.

I'll be curious of your test results from tying the BPV closed.

I'm sure there's all kinds of things posted about the boost increases from pullies ... Really I thought 13.5 would be a good number. Wouldn't it be stock 10psi, add 2 psi for the 15% and a little more for the 2%. .... Maybe I read wrong somewhere a while back.

Let us know about the BPV. Good luck

 

Yeah I'll report back on what happens after I zip tie the bpv. I'm no expert but from what I've read people with 17% pulleys are seeing 16-17psi. I know I don't quite come to 17% with my 15% and 2% crank pulley but I shouldn't be far off. Any experts want to chime in on how much I should be seeing?

 

That sounds like you are in the ballpark so to speak....
13.5 + about 2 psi for the rough elevation correction....gives you 15.5, and it is not a "fresh" SC....within about an inch or so if what might be expected....
Please remember boost numbers are not universal...they are really on good for monitoring one car...
An example....if you had a stock exhaust, you might see higher boost due to more resistance ....think of it has a measure of how hard your car is resisting "drinking" your air from the sc....if it flows better....so installing a freezer flowing head or exsust will result in lower boost numbers but MORE power....

 

Being that the SC only has 70k on it and has been maintained I don't think I should be giving up 2-3 psi. I still maintain that something isn't right. I will zip tie the bpv and see if that nets me any boost