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For anyone interested in some info on the N75 valves, i can cofirm as of tonight that the "H" versions, does not work well with a standard Gti, it throws it into limp mode requesting too much boost from the map.
However, after J (more-bhp) remapped the car, the valve was fine with a really smooth boost, and a really good map too cheers J, so ill have a play and swap the H valve with the original F and see what happens when i bung 98 rons in the tank, watch this space
looks likely the H valve was really good on my car, really smooth, no surging, it just asked for too much boost, its definately the most aggresive valve for sure
I'll put the MBC findings here as slightly more related to the topic..
This morning I have been up and down the local roads many many times...laptop on passenger seat enjoying the ride..lol
So re-routed some pipes to use the MBC, n75 blocked off but electrically connected.
1st run we are at max 0.8 bar - lovely and smooth - but feels a little slower.
2nd run we are at max 0.9 bar - still lovely and smooth - but still want more speed.
3rd run we are at max 1.0 bar - almost smooth - you can feel slightly feel the transition of the mbc opening and allowing pressure to reach the actuator and so opening the wastegate.
4th run is at 1.1 bar - still quite smooth but feels like timing is being pulled a little..explain why later
5th run 1.2 bar .... LIMP MODE
So for the moment I leave it at just over 0.9 bar and see how it goes.
Limp at 1.2 bar happens at the higher revs because the map is trying to tail boost off but the MBC keeps it at what you want... so the gap between requested and actual gets too big... and LIMP.
The ecu can also pull the timing a bit if it sees that same gap getting too large - and you feel it a little. However using vagcom torque readings and various calculators max power achieved was 222bhp.
At the smooth 0.9 setting it see approx 205bhp.
Max torque shown by Vag-com 331NM at 1.1bar with MBC.
More later - got to go and do some real work now...lol... motorway test this afternoon.....hehehe
Ok been on motorway and power is good, its completely smooth throughout the rev range and because its max boost is 0.9 bar I can get plenty of traction in the lower gears....
BUT.....
I kind of find it too smooth, I think I prefer the strong onset of power with the N75F fitted.
With the N75F I see overboost of 1.3 bar at 3200 rpm so the car feels very quick - bad for traction in the wet - but much more fun.
With the MBC boost is held for much longer compared to using the N75 but the interesting thing is MORE power is actually made with less boost at the high revs.
With the N75 boost is tailed of to 0.5 bar high in the rev range whereas the MBC was holding 0.8 bar +.
Enjoyed playing but think the N75F will be back on tomorrow...maybe try a "j" sometime.... lol
remember you would need vag-com to log whats happening..
if you were to try its very difficult to knacker the car because the ecu can look after things..
thats part of the problem.. the ecu is too damn clever... even without the N75 it can still sort of control boost...if it sees to much it just opens the DV and dumps it, it pulls back on the fueling and timing..
with the j valve fitted, my boost still has the strong caracteristics as the standard f valve did, but all moved higher up the scale if that makes sense, more aggression, still got the long lasting hard power and pull to the redline and smoothens out the way boost is delivered
i aint had a single blip with it in the slightest, seems to just work in harmony with the map and mods
i ran 214 bhp with my car before the following mods
Forge I/C-TB hose
Forge TIP
N75J
and the difference made by these mods feels like a mini remap, im sure it will be close if not in to the 220 hp now, but obviously rr proof is yet to be done so cannot be confirmed
more-bhp wrote:Ok been on motorway and power is good, its completely smooth throughout the rev range and because its max boost is 0.9 bar I can get plenty of traction in the lower gears....
BUT.....
I kind of find it too smooth, I think I prefer the strong onset of power with the N75F fitted.
With the N75F I see overboost of 1.3 bar at 3200 rpm so the car feels very quick - bad for traction in the wet - but much more fun.
With the MBC boost is held for much longer compared to using the N75 but the interesting thing is MORE power is actually made with less boost at the high revs.
With the N75 boost is tailed of to 0.5 bar high in the rev range whereas the MBC was holding 0.8 bar +.
Enjoyed playing but think the N75F will be back on tomorrow...maybe try a "j" sometime.... lol
have you been looking at the equivalent torque curves? This might be better for estimating the best setting but I realise you'd have to take readings throughout the rev range and I'm not sure what VAG-COM does.
Hi guys, i've been reading what you wrote... and i stil don't understand which N75valve works better with the engine... the J or the H version.
I have a remap ... if this counts.
cheers J, so ill have a play and swap the H valve with the original F and see what happens when i bung 98 rons in the tank, watch this space 
