It depends on mapping really.. SCN peeps seem to think that the J valve gives non-mapped cars more boost.. (mainly by being slower to react giving a bigger boost-spike and maybe a couple of psi extra boost thats within the engine tolerances)

My Jabba map is very mild, the J apparently makes the turbo spool up quicker, which i think would help me, as im struggling to get used to not having a decent wad of power when i boot it.. coming from a remapped TDI you understand

It depends on mapping really.. SCN peeps seem to think that the J valve gives non-mapped cars more boost.. (mainly by being slower to react giving a bigger boost-spike and maybe a couple of psi extra boost thats within the engine tolerances)

My Jabba map is very mild, the J apparently makes the turbo spool up quicker, which i think would help me, as im struggling to get used to not having a decent wad of power when i boot it.. coming from a remapped TDI you understand

I don't think it will make it spool quicker. All of the valves lock shut when you boot it, vag com duty cycle will register something like 95.3% shut. They then open up to bleed the excess off. As you say i think the general understanding is that the J valve does take a little longer to react.

I did comparisons between the f valve and J valve with boost logs via vag-com. The results were that the J valve did hold on to the boost a little better but it was very marginal.

Well, i fitted my J valve today.. and blimey!

Its like having a remapped car again!

The boost builds sooner, spikes about 3psi higher and holds it right to the end of the rev-range (this is all my scientific data recorded from looking at my boost gauge lol)

It does seem a bit smoother low down, no sign of surging either.

Edit: i got the N75 valve and my Aero wipers from VWspeed.. its cheaper than vagparts and free delivery

Well, i fitted my J valve today.. and blimey!

Its like having a remapped car again!

The boost builds sooner, spikes about 3psi higher and holds it right to the end of the rev-range (this is all my scientific data recorded from looking at my boost gauge lol)

It does seem a bit smoother low down, no sign of surging either.

Edit: i got the N75 valve and my Aero wipers from VWspeed.. its cheaper than vagparts and free delivery

3 Psi higher :eek:

What does it peak at now then?

3 Psi higher :eek:

What does it peak at now then?

It peaks around the 19/20psi mark... previously it was very mild up to 16/17 at 3krpm and started to tail off pretty much straight away.

It goes like a ****ing rocket now!!

Its got me thinking that maybe the J valve works better on some maps than others.

Here are two boost plots the first one was made with my old remap.

and this was with my new remap, (ignore the first glitch) .

There looks to be a fair amount of difference between how the two follow the specified boost

What gear did you do those runs in? think ill get me some logging done:)

3rd gear.

Just done a couple.. now to try and get a graph lol

OEM parts and VWspeed are the same price with free delivery.

I am thinkin now coz my map seems to have stages of boost lol

accel reasonably hard and there are 3 noticable stages of boost that come in, i am hopin that the J valve sorts it.

we shall see.

there arnt diff varients of the n75j are there? depending on where you get it?

OEM parts and VWspeed are the same price with free delivery.

I am thinkin now coz my map seems to have stages of boost lol

accel reasonably hard and there are 3 noticable stages of boost that come in, i am hopin that the J valve sorts it.

we shall see.

there arnt diff varients of the n75j are there? depending on where you get it?

No, a J valve is a J valve, and they are brown.

That doesn't look like a mild map to me Neo.

Seems to hold boost alot better than me lil ol generic one lol.

That doesn't look like a mild map to me Neo.

Seems to hold boost alot better than me lil ol generic one lol.

Well.. its a jabba map and i have nothing to compare it against.

will the engine/turbo mind having that extra boost pressure?

the wastegate actuator setting pressure is there for reason after all.

i guess it's all a comprimise though...

Well, i fitted my J valve today.. and blimey!

Its like having a remapped car again!

The boost builds sooner, spikes about 3psi higher and holds it right to the end of the rev-range (this is all my scientific data recorded from looking at my boost gauge lol)

It does seem a bit smoother low down, no sign of surging either.

Edit: i got the N75 valve and my Aero wipers from VWspeed.. its cheaper than vagparts and free delivery

So would an N75J offer any gains on an unmapped car? I like the idea of it holding boost longer

dont think there is a point mate, only get one when ur standard one goes t1ts up.

Oh well I ordered one after making that last post so guess its too late :thumbdwn: will fit it anyway and see now its on the way

lol

oh well ne mind mate, let us know if it makes a diff...

have fun

Apparently they have best effect on a standard car.

mmmm i will be interested to know.

Apparently they have best effect on a standard car.

Here's hoping

Well, having followed this thread with interest, I think I am going to try one of these as I am getting the mentioned hesitation / stutter under mild to mid acceleration, one thing that seems strange on mine is that the effects seem to be worse when the car is warmed up? :confused: Although I have been told that the rubber boost pipes under the inlet manifold probably need replacing.

That's going to be sorted on Thursday, so if it arrives before that I can do a quick check to see if it sorts the problem out. Will still have the pipes done, as I've already had the "y" shaped one off the rocker box perrish, so probably want replacing anyway.

will post my results once it's been done.

I had to replace 2 of these pipes under and on the way to the inlet manifold. mine had the same jerkiness that you describe. You can often hear a hissing on tick over. Car is perfect again now and jerkiness has gone.

IIRC the 'J' valve is from an Audi S2

Well I've the same issue and I just tried to order the n75j from oem parts and vwspeed..... They both don't deliver to Ireland :(