I have BR 4 setup on the car. Just wondering if bov will effect the boost setting on a MBC. For instance if you use a different bov will you have to readjust the mbc to read the same amount of boost as before.

I was using a turbo RFL Bov before and the driveability was bad so switch to a 1g. With the 1g the car does not pull as hard compare to the turbo RFL but driveability is 100% better. It looks like the turbo spools faster with the RFL. I guess BOV does make a difference or maybe I might be doing something wrong with the 1g. With the 1g I had to increase the setting on the MBC and I get boost spike to 24-25 psi settling down to 20-21. Is this too much for the stock turbo, 93 octane gas? Anyone else notice difference in power from one BOV to another?

Thks

 

No replys????

 

I think that for that level of boost pressure you may need to "crush" your 1G BOV.

To crush it you put it in a bench vise so that the top is at one jaw and use the vise to literally crush the top down.
What this does is move the top closer to the valve seat, which compresses the spring to hold more boost pressure.

 

1g BOV is crush. I'm going to see if I can find a way to run with both BOV setup. Put both BOV on and switch between the two.

 

Just so you know, a BOV only needs to be configured to hold the amount of boost you intend to use (usually it can hold quite a bit more) and release easily when there is Vacuum present on its diaphragm helping the pressure insite the intake pipe push the spring open..

The trick is to try to get the spring pressure in the BOV to retain the boost pressure without much assistence, and allow the vaccuum/boost on the diaphragm to do the work of keeping the pressure in or assisting letting it out.. If you boost at 19psi, the spring pressure required to keep the valve closed should be around that... the additional "Seat pressure" would be provided by the diaphragm to assist it in staying closed.. and the vacuum on closing the throttle (in the intake manifold) should provide enough assist to the diaphragm to effectively lower the pressure required to open the valve.

It shouldn't directly effect the setting of the MBC at all. If it does, then the valve is leaking and should be adjusted.

Hope this helps..

My experience with the 1G valve is crushing it increases its spring pressure enough to stay closed under pretty much all the boost you can give it when it has an adequate manifold vacuum/pressure signal on its diaphragm.. But at part throttle, I think it has a fairly light spring and seems to leak a bit under neutral manifold pressure (where its close to 0 psi or vacuum) which is ok, but obviously doesn't have the level of adjustability you would need to correct that (aside from crushing it a little more)

The truth is, everyone has a slightly different opinion on how to set up their Diverter/Blowoff valve.. so the key is that it open easy enough so it doesnt cause compressor surge (the turbocharge stalling itself) and not flutter (spring pressure and adjustment a little too high, or blowoff early (spring pressure/adjustment too low))

 

In your case, the valve was probably leaking.. you'd get a very high spike which likely overcame the spring pressure and diaphragm (plunger) and would blowoff.. the result would be poor drivability and unpredictable boost characteristics, additionally you'd have a hell of a time tuning the car because your AFR's would probably be all over the place.

I had a similar issue when running 22psi of boost on a stock blowoff valve.. it would spike at 22psi, and taper severely to 17psi.. Obviously there were several reasons for this happening, the most likely being the stock diverter valve could not hold that level of boost.

 

Oh and anything over 22psi is just way too high.. especially on pump gas. If the boost spikes and tapers severely.. Its likely the DV may still need adjustment..

However there are other things to check..

Make sure the boost controller is getting an adequate signal, if you T'd the boost controller off the Diverter Valve.. you may actually be diverting too much pressure away from the DV therefore lowering the max pressure the DV/BOV can hold.. Keep that in mind.. you could try moving the pressure line to the MBC to a different vacuum source and see if that helps.

Since your stage four, I already know the nipple on the turbo outlet pipe has already been eliminated.. However that nipple on the stock pipe were also a possible reason for boost spiking, but its irrelevent in your case since your stage 4, your running the buschur intercooler and their Lower pipe and outlet..

 

thanks for the inputs. I am using BR intercooler and their lower pipe. Also teeing boost controller off the BOV along with the Boost gauge and will check on this. I crush the hell out of the 1g bov so can't do it no more. I have a feeling the bov could be leaking.

Does the location of the bov on the intake pipe or the location of the recirculation pipe on the mas matter?

 

The location "Shouldnt" matter much.. I suppose in theory if its too close to the MAF sensor on the MAF pipe it can possibly cause problems.. but unlikely.. I have the same basic configuration except I'm still using the stock boost solenoid.. the one advantage is the stock hose as a restrictor on it that prevents too much bleedoff of vacuum.. you could try to adjust a recurculating aftermarket BOV instead of the 1G, Greddy Type-S or something with the same 1G flange..

 

Ya I got buschurs stage 4 on my car , I run 19.5 psi on pump just for safe measure. Are you using buschurs stage 4 map for the s-afc? I am running a type-s and have pushed 23 psi through it with no leaks and great holding power to redline.

 

NO setting on the AFC. I have a custom dynoflash from AL so the AFC is set to 0 for now. Gonna change the plugs and see if they are fouled.

The 1g bov makes a loud whistle after it opens. I hope this is normal.

 

I don't know that its normal, but I get the whistle.. I also get a whistle from the throttlebody..