MBC/Bleed Valve On Stg2

[__B3NNY__]

After doing some reading and talking to phil on MSN, its got me thinking about these bleed valves. Would fitting one of these help my k03s to hold boost longer up the range? Ive seen this cheapo ones on ebay and i thought about trying one to see if it helps, if it did then i`d get a better quility one from forge.

Im not that clued up on them hence my question, Am i right in thinking that you just fit into the hose that runs from the N75 to the actuator? The ones ive been looking at have 3ports would you just leave the 3rd port running into the atmos.

Any pros and cons would be great, i havent brought one yet but i might do if its possible to get abit more out of the turbo without casusing limp mode or the likes.

Currently running k03s stg2 with all supporting mods.

Cheers.

 

[m0rk]

what deviation are you getting from requested to delivered boost?

if that gets too large it'll limp (but I don't know what "large" is on revo stage 2)

Assuming you set it just a bit higher than the minimum requested it'll be OK. I imagine lots of running up & down a dual carriageway testing.

 

[__B3NNY__]

Yeh i assumed it would take a fair few runs to set it up to the best without hitting limp mode.

Heres a recent log from about a week ago. Looking at this do you think a bleed vavle would be of any good?

	Group A:	'115			
		RPM	Load	Absolute Pres.	Absolute Pres.
	TIME				
MARKER	STAMP	 /min	%	 mbar	 mbar
	0	1760	104.5	1710	1410
	0.34	1840	106.8	1790	1460
	0.74	1920	111.3	1930	1510
	1.25	2040	117.3	2030	1580
	1.75	2160	124.8	2070	1660
	2.15	2240	136.1	2100	1770
	2.55	2360	151.1	2120	1930
	2.95	2480	165.4	2160	2130
	3.35	2640	185	2170	2360
	3.75	2760	191.7	2180	2520
	4.15	2880	191.7	2170	2540
	4.55	2960	191.7	2160	2540
	4.95	3120	191.7	2150	2540
	5.35	3200	191.7	2140	2540
	5.84	3360	191.7	2140	2530
	6.24	3440	191.7	2130	2510
	6.76	3600	191.7	2120	2470
	7.25	3760	191.7	2130	2440
	7.64	3880	191.7	2130	2390
	8.05	3960	190.2	2140	2370
	8.45	4080	182.7	2130	2300
	8.85	4200	179.7	2120	2250
	9.24	4320	176.7	2120	2210
	9.65	4440	174.4	2110	2160
	10.04	4520	173.7	2100	2130
	10.45	4640	169.9	2090	2080
	10.85	4720	169.2	2070	2070
	11.35	4880	169.2	2060	2050
	11.75	4960	169.2	2080	2030
	12.15	5040	167.7	2060	2050
	12.66	5160	166.2	2070	2030
	13.15	5280	163.2	2070	2010
	13.55	5360	162.4	2070	2030
	14.05	5440	160.9	2060	2010
	14.45	5560	159.4	2050	2010
	14.85	5600	157.9	2040	1990
	15.25	5680	157.1	2030	1980
	15.65	5760	157.1	2010	1970
	16.05	5840	154.9	1990	1960
	16.45	5880	154.1	1990	1940
	16.85	5960	154.1	1980	1950
	17.25	6000	152.6	1980	1940
	17.65	6040	153.4	1970	1940
	18.05	6080	152.6	1960	1930
	18.45	6120	151.1	1960	1940
	18.85	6160	151.1	1950	1940
	19.25	6200	150.4	1950	1950
	19.65	6240	150.4	1940	1950
	20.05	6280	149.6	1940	1940
	20.45	6280	150.4	1930	1950
	20.87	6880	41.4	1020	2010
	21.35	5080	116.5	1640	1220
	21.84	5080	142.1	1430	2340
	22.24	5040	54.1	1110	1440
	22.64	5040	71.4	1140	1390

There not a lot of deviation from requsted to actualat the top end, so would uping the boost with the valve threw it into limp stright away or is stg2 limp mode set a fair bit higher than requsted? if that makes sense?

Am i right in assuming, when setting one of these up it would be slightly like adjusting the actuator with logging etc.? Would i have to keep and eye on cycle duty as it would go threw the roof if set to much, or would it go the other way?

 

[ibizacupra]

bleed valves by nature that they continually bleed can make things seem laggier.. a continual leak which has to be overcome... where N75 can be off completely, no flow/pressure to actuator

from memory ~250mb is in the "limp" zone

 

[__B3NNY__]

So would it be worth trying one to see if i could get more boost up the top end? Or would it cause me more trouble than its worth? If i did get one what sort of numbers should i aim for further up? If it was to cause me any problems i assume it would just be a case of removing the valve and putting the stright threw pipe back in place?

Is it just a case of joining it into N75 to actuator line and leaving the 3rd port running into the atmos?

 

[DPJ]

I have an MBC which I'm going to try at the end of the week, running it in parallel with my N75. This is to try to squeeze another 0.1 bar....................

 

[__B3NNY__]

I have an MBC which I'm going to try at the end of the week, running it in parallel with my N75. This is to try to squeeze another 0.1 bar....................

Do you mean run it in the same line as the N75? What valve did you get, would be nice if you could report back if it made any differance and how easy it was to set up etc...

 

[DPJ]

Do you mean run it in the same line as the N75? What valve did you get, would be nice if you could report back if it made any differance and how easy it was to set up etc...

I'll report back at the weekend. I'm going to Tee the 'boost' feed so it goes to the N75 and the MBC. The actuator lines from both devices will then Tee back together before they get to the actuator.

 

[__B3NNY__]

Pics would be great also then if its not to much trouble?

 

[PhilW]

It seems the deviation is larger than 250mb as i hold 2550 for a couple of time stamps where requested sees max of 2190.

One of the reasons i'd like to run one is due to HB9 only requested 17.2psi at its max on stage 2 and i see low 70% at redline after dropping below 60% mid range WG duty. Its will also help what i seen on the rollers before where the ECU seems to be pretty slow to react to the initial quick overboost but cutting the power/boost, possible due to the extra load on the rollers.

Now whether the deviation reduces further up the rev range remains to be seen.

 

[ibizacupra]

duration of deviation also a factor?

 

[m0rk]

it all assumes that bluffing it will still make it pump more air.

As bill says it'll still leak off, so 1psi gained at the top end, will be 1psi less it can produce at the low end.

 

[PhilW]

Yeah thats unknown really bill, as i said it might reduce further up the rev range.

I'd like to try a proper EBC like the apexi for this, but for how cheap bleed valves are its worth a bash even if it doesnt work well.

Part throttle issues look to be a concern as well.

 

[__B3NNY__]

Sounds abit of a catch 22 situation to me..


think im just going to try one of the cheapo forge ones and log it and see how it goes. Can always revert easily back to standard surly?

Am i right in saying whenfitting the bleed valve you would just basicly cut the N75 to actuator hose and insert the valve in between or is there abit more too it than that?

 

[m0rk]

http://www.rtec.ch/prinzip4t.gif

http://www.rtec.ch/turbo_basics.html

 

[__B3NNY__]

Kind of got my head around that, not to great with those sort of diagrams. Looking at that its abit more complex than just 'cutting' the hose and inserting the valve in the middle.

 

[PhilW]

Yeah put the bleed valve inline from the N75 to the actuator.

 

[ibizacupra]

N75 has 3 ports.. from turbo, to actuator, and to inlet ( the bleed vent)
simple enough. just remember how the N75 ports were plumbed before you remove it, as you will want to refit it again correctly afterwards.

bleed before n75 if inserting with n75.... else replace n75 (mechanically, leave it electrically connected so ecu does'nt get a strop on) - twiddle with caution