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H valve
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If you comapre the two plots above, you will see similarities.
The lower pic is my S3 making 332 lb-ft of tirque, with the H valve fitted (along with a very aggressive map...and other mods)
The shape of the boost curve is the same... (the black line that peaks soonest is actual boost recorded on the dyno - not VAG Com boost...but measured at the inlet manifold)
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The solid straight line is due to boost sensor not being able to read above 1.55bar.
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This is roughly true...although MAP sensors do vary in theit accuracy and range...mine read slightly higher.
The bottom line is...they do saturate...and when they do...you'll risk limp mode.
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but looking at the rate of clime its easywell into 1.6 and probably above 1.7, when i originally posted these charts others said using the H valve they have seen upto 1.8 bar of boost.
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This is VERY dependant on the map you have installed...you will NOT get 1.6+ bar on a standard ECU map!
I was running 1.6 to 1.65 bar peak boost on a standard N75...adding the H valve increased this by approx 0.2 bar peak...roughly 20 lb-ft of torque.
I was running 1.85 to 1.89 peak boost with the H valve fitted...and to do this you need the trigger point for limp mode raising substantially, in the ECU map.
Some tuners raise it higher than others...the answer seems to be that they raise it proportionally to the increase in boost (peak boost up by 0.4 bar, limp trigger up by 0.4 bar) but to run the H or J valves in all weathers and temperatures, you'll need one with the limp limit raised further.
I could run the H valve perhaps 50% of the time...in cold weather and high ambient barometric pressure (both of which effect the limp trigger point) I would hit limp if you didn't drive round it.
So, don't go thinking you'll get 1.8 bar from a H or J valve...you won't.
But if you are running a 1.4 bar map, you may well see 1.6 / 1.65 bar peak - if there isn't a restriction elsewhere!
With regard to the H and J valves...I dyno's both...back to back, and back to back with standard...on high boost and standard boost maps...and saw no noticable difference on my engine - despite expecting big differences!
Peal torque on both occasions was 332 lb-ft.