turbo!!!....hahahaha... that was great

 

my holds great too... I have mine hooked up with turbo nipple.

 

that video cracks me up, "**** that's fast!!"

Well I moved the connection on my hallman from the BOV to the compressor nipple as suggested earlier. The car still loses about a pound or so of boost in gears 1-3 (I didn't test 4 or 5) as it approaches redline, but it's a little different than before. Before in second gear it would hold at 20psi then drop sharply to 19psi at around 5500rom. This quick drop in pressure was very noticable even without the use of gauges, I could feel the power drop. Now it still drops from 20 to 19, but it does it very slowly, much like gottagofaster's video. In fact the higher the gear the slower it seems to drop.

I guess it's true that the stock BOV has trouble holding more than 19psi. We'll see what happends when I eventually upgrade to a 1G BOV.

 

Yeah, the nipple on the turbo is a better location. My theory is that by tapping into the vac/boost line leading to the BPV, when the MBC starts to bleed off pressure to allow the wastegate to open, it affects the BPVs ability to stay closed. The BPV uses both spring pressure and assist from boost pressure to keep it closed. AT least that's my odea, I have no idea if it's correct.

 

That sounds about right. The stock BOV seems to have enough trouble holding higher than stock boost, I'd rather not have to tap into it's vac/boost line.

 

Good point - I concur 100%

This theory has been shown in practice - in fact we saw one like this today

 

Yeah, this is the same thing I've been seeing for a few months on several different cars, but on mine specifically after I upgraded my Intercooler and pipes and had to remove my MBC (put the stock solenoid back on) and needed to find a new place for my Boost controller source.

I think I've mentioned this in passing in several other threads and PM's to people.. Never really posted my observations as a "Tech" thread..

 

I just got my Hallman MBC hooked up and noticed a slight drop of boost at higher RPM as well (it was hooked up the way Al suggested). I think it might be the stock BOV, since when I was running with Works P2 reflash (supposed to hold 20psi to redline), I already noticed some drops at over 6K rpm.
BTW, I'm boosting 1.4 kg/cm, and the boost tapers to about 1.3 at 6.5K rpm.

 

Hmm....how much is the "slight drop"?

Hey Al, what do you think about the new MR bov's that are out?

 

I've got a 1G BPV that's installed as part of a BR hard piping kit. Occasionally it seems that the valve won't shut fully and I'll see taper from a high of 20psi down to 17psi near redline. Interestingly this is the same amount of taper I had until I fixed a leak at my compressor outlet. Most of the time the valve closes fine and might see a 1 psi drop.

 

Hmm, I have a Joe-P MBC, and my boost holds steady at 20.5 PSi to redline with my stock DV. I have it hooked up as al suggested, boost source at compressor.

- Steve

 

my boost drops from 21 to 19 psi at redline, i have the dynoflash and a hallman MBC. I jsut figured that the turbo was running out of steam at high rpms.

i have my MBC hooked up to the turbo compressor nipple and wastegate actuator nipple. I ordered the MR BOV a couple weeks ago and am waiting for it to come off backorder. hopefully this will help a little with the boost dropping off.

 

wow what rpms were u shifting at...and head mods??

 

im kinda worried about taking her that high with hks 272 cams and stock springs......

 

I spike 21psi and taper to 20psi with mine...