UK-POLOS.NET - THE VW Polo Forum

APR seems to be the better choice, but none close to my area. I'll have to take a long trip to Manchester.

with the remap does it make the sound from the dump valve sound louder by any chance?

Remapping doesn't make the DV woosh any louder, yes there's more charge going through hence the air might be getting diverter into the airbox more often. I recommend changing the DV same time as the map. I'm using the APR one, so far so good.

I've managed according to vag com 6.2 seconds - 100% sure it can be reached quicker (not ideal trying to drive and log at the same time)... take Jeff's e.g. under 6 seconds at times. Granted we both have turbo back exhausts + a little more to improve breathing. A standard car mapped should easily be less than 7secs all day long.

I'm also London based. Do you have your GTI yet?

When I bought my GTI it had already been revo'd....

Performance was very good and really smooth with boost approx 1.1 bar max..

Now I use a stronger more aggressive file which has superb throttle response and quick developing boost with max 1.2 bar... this makes it quicker again than when revo'd..

Sacrifice is a little boost smoothness, you can boost spike at approx 3200rpm so ecu pulls back slighty then goes again. If you look at power graphs of other software you can see this happening. You can see it with VAG-COM logging - It happens with the revo software aswell but not quite as obvious.

I try N75J and N75H soon to see if boost can be smoothed out. As very often it is inability of the N75F to control boost properly on remapped 1.8T.

Will let you guys know how I get on.

what do them n75j and n75h replace and do exactly please?

na mate im going to get it soon tho

The N75 valve controls the amount of boost using signals from the ecu.

There are different versions of the N75 like N75C, F, H, J, K some are used on other models like S2 or other models in the VAG range.

The different valves respond differently to the signals from the ecu, the J valve is often used to smooth out boost on remapped 1.8T. The H valve (known in some places as RACE valve) can sometimes smooth out and give a few PSI more boost.

Jeff when you put on your TIP you would habe handled the N75, a small cylindrical part plumbed to the TIP with two small hoses connected and electrical connection.

J

is it that part right at the very bottom of the TIP nearby the turbo?

or is it at the top?

which is best to smooth out boost then n75J or n75H?

and how much are they roughly and are they hard to fit

not sure in the polos but it was behind the DV in my quat, i have the J version, reportedly the more aggresive of the bunch, never had a chance to test it but i will come thursday night! woo

theres 2 on e bay at the min, and its the h valve saying its the race one, not the j valve mate

im interested in smoothing out my power delivery mate, but a little more boost would be a nice bonus too, which it says is offered by the h valve, where the j just smooths it

but which is best, does one get a better rating that another? which is the valve of choice, also, we know the advantages, whats its disadvantages?

just pulled this off the e38 forums, this guy says he is having a sudden loss of boost in his 20vt...
The n75j is a common fault on the 20v and will create boost problems

can anyone else elaborate or know if the h valve is better?

yet on uk mkiv's, it seems the n75j is the valve of choice????

also someone on uk mkiv's mentions it gives the feel of more power but you actually lose power as although you get more initial boost up to 4000 rpm, boost is backed off by the ecu so meaning a loss in power overall

i cant grasp a simple answer from any of it, ouck my head hurts, im confused

im defo feeling boost spiking though and would like to eliminate it without losing power overall !!

Try this forum Jeff. Put N75 into there search facility and a few threads come up. Or the guys at Awesome maybe able to advise you.

http://www.vag20v.net/forums/index.php?

Ive heard mixed stories about them, i still believe the J is the more aggresive, it causes a lot of cars to go into limp mode because of the boost spike

putting the car in to limp mode is hardly a desirable feather though eh

yes lol just a bit, but on some cars it works fine and holds peak boost really well, seeing as there about 30 quid it might be worth buying both, or you buy a H version and ill put my J on tomora night and we'll talk b*******s about them after giving them a go lol