[supercharger] is this the right hose setup for BOV and gauge

[AntiVenom]

Hi all,

I searched and think I did it right but I am getting a few problems that I expect are related.

First, I went to AAM to have my car tuned. I have the 88mm pulley on a GTM stage 1.5. Since I couldn't get the canned tune from Gamma I went up there without testing the setup. Mike tuned it but surprisingly it was only making 7.5-8 psi. From reading this pulley should be making 10-11psi. I wasn't sure what pulley I had at the time so I went home "happy" with my 420whp thinking I would get a smaller pulley and go back. Got home and measured the pulley on the inside ribs and got 88mm. The sadness set in.

Poking around for leaks I noticed that my BOV was venting/leaking at idle. So I figured this probably explained the lack of boost. Thinking if it doesn't function right at idle no way it is doing what it should under boost.

Not wanting to make any changes without having a boost gauge I could easily monitor I set about installing my gauge. I tee'd off the line running to the BOV think a) if it was good enough for the BOV it was good enough for the gauge b) if there was a problem with the BOV not getting the right pressure to actuate it that I would be best able to diagnose

Having done that I went for a test drive. Vacuum seems good but I am seeing less than .1 bar / 1psi at red line. So I cranked down the BOV as hard as it would go. Got a bit more boost right around .1bar / 1-2 psi.

So before I rip my front bumper off and start searching for leaks I wanted to ask if this was the right spot to hook up the BOV and gauge. I also welcome any other thoughts.

Other factors.
I have HFCs. I think the GTM kit works fine with them from reading
The car was originally throwing a p006a code but Mike tuned it out.

[AntiVenom]

P.S. That's the spot the instructions indicated for the BOV.
Also the BOV on the stage 1.5 vents to atmosphere

Edit: in case the location isn't obvious by the photo it is the line located behind the passenger side throttle body.

[Ghostvette]

A kinda random thought, but you might consider replacing the spring clamps with worm drive clamps. I'm going to presume that the spring clamps are new, but it's been my experience that even when new, they tend to leak some air.

[AntiVenom]

They are new but I will definitely keep it in mind as I doing my troubleshooting.

[TopgunZ]

Well first of all you just put your supercharger at risk of hurting itself. By cranking the "BOV", which is actually a Bypass valve or BPV, completely shut then the supercharger air is getting forced back down its throat which wreaks havoc on its bearings.

Is it open at all at idle? Is air coming out of it?...becuase that is how they are designed to work. It is supposed to be open at idle.

What dyno were you on and did they have the STD correction factor on?

[AntiVenom]

I was aware of the risk when I did it. I only did a couple of 3rd gear pulls and I didn't immediately come of the throttle and let the rpms come down gradually. Stopped the car and backed it off since it only made a marginal difference in boost anyway.

Not sure about the dyno I can find out. I am not really concerned about the number as much as where my missing pressure is. First the missing 2-3 on the dyno and now why I am only getting 1-2 psi or reading that, whichever the case may be.


It does leak at idle regardless of how hard or soft it's set. Meaning you can feel air flowing out of the exhaust port.

Lastly a BPV that vents to atmosphere can be considered a BOV for all intents and purposes. If not please clarify why. Otherwise the correction is irrelevant.

[TopgunZ]

So is the air bypassing the system? Yes? Bypass valve.

Is it only needed to blow off after the system is under pressure? Yes? Blow off valve.

There is a huge difference. Bypass valves are open during idle and out of WOT to bypass the air away from the throttle bodies so the engine is not ingesting forced air when it does not need or want it. Blow off valves are shut during idle.

By your BPV "leaking" at idle it is doing what it is designed to do. If you had a turbo and a BOV and it was leaking at idle then you have serious problems.

[AntiVenom]

Wow insightful.

By that definition a blow off valve would also be a bypass valve since its bypassing the system.

I think you are generally a knowledgeable guy but I think you came in with a "school a newb" mindset.

I am not new to forced induction or cars or terms.

I'd appreciate your help if you are willing to give it but I am not here to learn about basics.

[TopgunZ]

Originally Posted by AntiVenom

Hi all,

I searched and think I did it right but I am getting a few problems that I expect are related.

First, I went to AAM to have my car tuned. I have the 88mm pulley on a GTM stage 1.5. Since I couldn't get the canned tune from Gamma I went up there without testing the setup. Mike tuned it but surprisingly it was only making 7.5-8 psi. From reading this pulley should be making 10-11psi. I wasn't sure what pulley I had at the time so I went home "happy" with my 420whp thinking I would get a smaller pulley and go back. Got home and measured the pulley on the inside ribs and got 88mm. The sadness set in.

Poking around for leaks I noticed that my BOV was venting/leaking at idle. So I figured this probably explained the lack of boost. Thinking if it doesn't function right at idle no way it is doing what it should under boost.

Not wanting to make any changes without having a boost gauge I could easily monitor I set about installing my gauge. I tee'd off the line running to the BOV think a) if it was good enough for the BOV it was good enough for the gauge b) if there was a problem with the BOV not getting the right pressure to actuate it that I would be best able to diagnose

Having done that I went for a test drive. Vacuum seems good but I am seeing less than .1 bar / 1psi at red line. So I cranked down the BOV as hard as it would go. Got a bit more boost right around .1bar / 1-2 psi.

So before I rip my front bumper off and start searching for leaks I wanted to ask if this was the right spot to hook up the BOV and gauge. I also welcome any other thoughts.

Other factors.
I have HFCs. I think the GTM kit works fine with them from reading
The car was originally throwing a p006a code but Mike tuned it out.

You just asked for a clarification so i gave it.

You also state you are a pro but yet look above what i put in large bold letters for you. You were concerned about your "BOV leak" and said " that must be my problem since it isn't functioning correctly because air is coming out of it".... yeah real pro....wtf. Good luck.

[AntiVenom]

Never said I was a pro. Just not a newb. Don't be mad because your definition only disproved your semantics argument.

I did a search on bypass valves staying open at idle and got mixed answers. Never had a SC with a BPV that vented to atmosphere. I understand that they work with the vacuum and boost.

At any rate maybe I opened the field up too much. The only question I really have is

Is this an accurate place to get a reading? If not is there another spot I should use or should I tap the manifold (saw this method used In another thread)

[TopgunZ]

Your right. Your blow off valve is broken because air is leaking at idle. Better go buy a new Blow off valve.

[AntiVenom]

Dude I am not sure why you are so bent.

I apologize if my mistake caused your eyes to hurt and thus required a reply clarifying terms. I understand I am OCD about some things too. If it makes it clearer when talking about supercharger a I will use the term BPV though other than one being attached to a SC and the other to the turbo I am still not clear on the difference since what's on the car is sold as BOV.

Turbosmart TS-0205-1272, Turbosmart Type 5 Series Blow-Off Valves | Turbosmart


All I am saying is you started at the wrong point: definition of words.

The fact that you are saying that it being open at idle is normal is helpful. I appreciate it even though you provided it as a source of argument vs helpfulness.

If you answer my question regarding the placement of the hoses I would have all the info I need for now and will go out to recheck everything.

[TopgunZ]

Lol. Dude.... You clearly stated you thought that was your problem. Again, i have bolded your exact words above. How is this not helpful by coming in here and telling you that, this is not a problem and you need to redo your actions of cranking it shut. Then you aksed for clarification on that subject matter. When i clarified that they are extremely different in how they function, you got all offended. Again, good luck.

[AntiVenom]

Clearly we have crossed signals here.

I didn't mean to state it as the root cause. It was my first suspicion. I sorta scratched it off the list when I had my brother hit the gas and it closed up. After doing the test runs with it cranked down. Newb mistake? Evidently so.

If you have the time to explain the difference between how BPV that vents to atmosphere vs a BOV are different I'd love to hear it. My understanding is when the throttle shuts down they both relieve pressure to eliminate surge. Is the difference due to how they perform under vacuum/boost?

Also I would cite my link above. They are marketed as the same thing so you can see how it might be confusing especially since it doesn't recirculate the air in this case

[AntiVenom]

**** man I just reread your first post. Where you said it was suppose to work that way. Looks like I took it the wrong way thinking it was a bunch of corrections with no info.

Still would love to know why they two are so different. Seems they perform the same function regardless of how they do it.

At any rate, apologies for the miscommunication.

Still leaves the more important question of whether or not that is an accurate hose to get a read off of