lart951

Hosrom, I have never paided attention to the boost gauge all the way to red line but i see the needlle right at 17 when boost hits. Those two graphs were done much before the dyno day, but i did some tuning which doesn't reflect in those 2 before dyno day.

Jimbo1111, why don't you use wideband anymore?

Tomas L

Check your boostlevel at 6000 rpm with an aftermarket boost gauge (not the stock one).
No matter which boost level you measure you should check your BOV if its the stock one.
If the boost has dropped of much then you should check for leaks around the intake and if none found check your wg.

lart951

I got 2 questions for the experts. Yesterday I found the vacuum line that goes in the top of the BOV disconnected (see picture #1), the questions is could I lose power because of that?

2nd after looking at the Lindsey racing website I happen to notice that my BOV is installed different see picture # 2.

A) Picture # 1 from lindsey racing website showing the line that was disconnected in my car (yellow arrow)



B) Picture #2 showing the way my BOV is installed which is totally different from LR, question could I be losing power because the BOV is installed wrong?

awilson40

I do believe its backwards and the line being off would allow boost to open the valve and bleed pressure bypassing the compressor.
Reverse the install and see if it improves

hosrom_951

If your line was disconnected then you WOULD lose power, estimates ~40whp or so??

I am NOT familiar with the Lindsey DV, but comparing the first and second pictures you posted, the posions are different. Which one is the correct way, i dont know

special tool

The vacuum line pulls the valve off the seat when you close the throttle - you are not losing power. You are, however, blasting your turbo with compressed air which now has no place to go.

Ben Z.

So flip those hoses and let us know how she runs!

Russ Murphy

>>>The vacuum line pulls the valve off the seat when you close the throttle - you are not losing power.<<<

The vacumn line also supplies pressure to the top of the piston in addition to the pressure supplied by the BOV's spring. You need both to keep the piston closed under boost with most blow-off/bypass valves. So yes, you most likely were losing a good bit of boost once your boost level exceeded the spring pressure. What that pressure is depends on how stiff a spring 'ya got.

lart951

I just got a email from Dave Lindsey and he told me that I was a super noob, the BOV was installed backwards. Do I qualified for the Weekly Darwin Awards?

special tool

Russ - yeah man , I don't know about the positive pressure. I get the same minute fluctuations on my datalogs under buildup with vac removed and installed - exactly the same. I don't think the positive pressure does anything, it doesn't look like it on my laptop anyway.

lart951

But what about if the BOV was installed backwards would I lose power because of that?

HoBoJoe

For you to loose power because of your BOV, you would see your boost drop. Now i don't know if having the vacuum leak from the hose unhooked would cause a major problem...

Russ Murphy

>>>But what about if the BOV was installed backwards would I lose power because of that?<<<

Probably not because the boost pressure would be pushing against the side of the piston (which won't move) vs. pushing against the bottom of the piston (which can be moved upward). The open hose is certainly a boost leak but it would be overcome at significant rpms.

special tool - interesting. What BOV do you use and how stiff is the spring. I don't know for sure (I haven't tested it) but I doubt my Forge Dump valve would hold at 18psi without the boost/vac line even with the stiffer "race" spring, at least judging by the piston area.

NZ951

There are many many threads on the LR orientation of their bypass valves. They have had 2 pictures on their site showing 2 different ways of installing it, so dont feel bad about it. LR qualify for the award, not you! PS when I had an LR unit, it worked the same no matter which way I had it in.

NZ951

PS I use a Tial BOV with a 11psi spring. The Tial engineers said the spring rate should equal the idle vaccum, so its very close.