N75J on a standard 1.8T?

[No457 Snowy]

Thanks Seb, it's good to get some straight talk in layman's terms on this stuff. It sounds like you really need someone who knows what they are doing to see how an individual motor is going to react to something like changing the N75, otherwise you risk not really knowing what the hell is going on inside the engine?

Especially on a chipped car, by changing to a different N75 that it wasn't tuned for, wouldn't you be just messing up the remapped fuel/boost/ignition tune you just payed for? (Assuming you have a chip from a reputable company that is).


Snowy

[No457 Snowy]

Further interesting boost sensor related comments and photos in this thread for those interested:

http://www.vwwatercooled.org.au/newf...t=20021&page=2


Snowy

[spj]

Well decided to go ahead, against the advice on here...

Finally installed it this afternoon, cause i finally got around to wiring up my boost guage... lazy!

After a few runs and varying the type of driving my findings are as below...

Before, N75C (stock)
Boost - 8psi
Spike - 9psi
Boost would fall away in the top RPM range (4200rpm>) to 6.5psi.

After, N75J
Boost - 10psi
Spike - 11psi
Boost slightly falls away in the top RPM range, but then zips back up to 9.5-10psi.

22 degrees and sunny in Melbourne this afternoon, and had been driving the car alot so heat soak would be a factor (standard car other than Remus rear box), but have noticed an increase in power (as much as can be expected...).

Will have a nice drive tonight, in the cooler, turbo air =]

Worthwhile mod for $100 IMHO.

[gpk_gti]

I told ya!!!! just checked my dyno sheet and I was getting 9.5psi without and 11psi with it on.... cheap and easy power mod!!!

[spj]

I told ya!!!! just checked my dyno sheet and I was getting 9.5psi without and 11psi with it on.... cheap and easy power mod!!!

Finally some good advice... TRIED AND TESTED.

What where your power figures from those dyno runs? Mods?

Cheers,
Sonny.

[gpk_gti]

they were before chip ,just with exhaust and k03s.

[glidn]

Snowy i know what you mean, but the fact is N75J does actually come standard on the GTI as i have seen many here in New Zealand.

Also now the N75J is the only replacement unit you can no buy from VW in New Zealand.

SPJ - As for the replacement DV, do that, dont think. JUST DO IT.
Get the 710N DV. It comes from the Audi S3 unit, it should set you back around $80ish tops. It's even cheaper than the standard replacement unit.

I'm sure that the 75J is the difference between my gti and the girlfriends gti.
Hell her car is making almost 10Wkw more.

[spj]

SPJ - As for the replacement DV, do that, dont think. JUST DO IT.
Get the 710N DV. It comes from the Audi S3 unit, it should set you back around $80ish tops. It's even cheaper than the standard replacement unit.

I'm sure that the 75J is the difference between my gti and the girlfriends gti.
Hell her car is making almost 10Wkw more.

Hey mate,

So whats the difference with the S3 diverter? Will that stop my boost falling off in the top end more? will it run more boost just replacing the DV?

I have been told that the $350 APR DV wont do anything extra... just wont fail... Bit of a waste of money IMHO if my diverter is fine...

Your thoughts?

Cheers.

[No457 Snowy]

I think everyone agreed there would be some more boost, but as Seb pointed out weird things start to happen inside the engine when it dumps more fuel in to protect from the extra heat but at the same time it's trying to trim it back because it thinks the mix is too rich. Sounds like a recipe for problems without proper tuning.

My worry would be that you could damage the engine here because things are no longer tuned properly to account for the extra heat and boost you've just added. With a proper chip tune you get the timing adjustments the fuel maps and the boost all tuned to complement each other and not cause issues.

I'm not sure if this is the case, but just being "not sure" is enough to stop me from guessing and playing with a complex system and maybe running too lean and smoking my engine for 2 psi.

Maybe it's completely safe, I don't know.


Snowy.

[spj]

Well i found out today, my findings above were all written with a faulty diverter valve!

Car is in at Volkspower for a few things and they advised me of this after i requested them to check over it. Replacment one being fitted, will update when i get the car back.