View Full Version : N75 Technical question
I've just been reading an interesting debate about N75 valves on VW Vortex and there seems to be speculation about N75 H and J valves giving different engine responses on modifies ecu's.
Has anyone tried using a H or a J valve and what result did you get?
Finally does anyone know the VW/Audi/Seat part numbers.
Maybe one for Bill to answer?
Blucupra
16-08-2003, 18:36
Hello,
I recently placed the N75 J in my (chipped) Cupra 20vt.
The boost is build up quicker and holds longer. I am very pleased with this part. I have read that the H part has an boost spike wich will put the car in to limp mode. The part has been in my car for a little more then a week.
The partnumber:
N75H - 034906283H
N75J - 034906283J
Jeffrey
Netherlands
sounds good
I'll give it a try and get one ordered and report back
cheers
ibizacupra
18-08-2003, 08:02
The only difference I "believe" between these frequency valves is the orifice diameter on the bleed.
Originally posted by ibizacupra
orifice diameter on the bleed
There may be other differences aswell (like spring strength, restrictor diameter @ inlet, ... ). BTW you can adjust the "virtual size" of that orifice / amount of bleed with the screw on it which is really a nice feature IMO. Pity that some N75s can get completely stuck, so it is not really recommended :(.
How can I see wich one I have?
Blucupra
18-08-2003, 19:39
Hello,
On one side there's an piece of metal. On this you can find the part number. The standard one in an Ibiza 20VT is the "C"
Jeffrey
andy_dea
18-08-2003, 23:14
where can you get the N75H - 034906283H from as my mate has told me to look at getting one so the car holds boost longer is this true and if so where from how much
cheers andy
Well I fitted the J valve yesterday having got it from Wharfedale Audi in Bradford and all I can say is WOW!
It feels like I have just taken a mechanics sock out of the exhaust system.The turbo spins up much quicker(similar to when I had the Dawes on)and it really does hang onto the boost.The Cars Upsoluted and it really does pick up incredibly quickly.
No limp mode/no warning lights............
It has to be a 10/10 modification.
Or maybe my old f valve was nackered
I ordered a J valve the other day, should be here soon. I'll let you know how it goes on a Revo'd Leon
Dormouse
21-08-2003, 12:39
Just out of interest, how much is a J-valve anyway?
Dor.
Originally posted by Dormouse
Just out of interest, how much is a J-valve anyway?
Dor.
its about £40-£50 from your local audi dealer.
got one myself they work well
Mark@VAGWORX
21-08-2003, 13:06
Which is the race valve, H or J??
so whats the best one to go for??
Bought mine from www.vagparts.com came in a £30 and a bit all in.
J is thought to be the best (by the MkIV Golf crowd anyway), less of a boost spike and holds the boost for longer.
The 'N75 Race valve' is a similiar part made by an aftermarket company, i forget the name. The H and J revision N75 parts from Audi, are uprated versions of the wastegate controller that we already have, from higher spec cars. S2 and S4 i think. They are basically the same as the aftermarket 'Race valve' AFAIK anyway..
sportbilly
21-08-2003, 13:48
So what do people feel the overall effect of this new J valve is ?
Would it make a difference in a standard car ?
Was it easy to fit?
Its supposed to hold the boost pressure for longer. It has also been known to solve some peoples surging and hesitation problems.
Not sure it would make very much difference on a standard car.
Its dead easy to fit, just some clips holding it in, a bit like the DV.
Surfer_D
21-08-2003, 13:58
"H" is the most aggressive and this is what people are using the most when replacing them. I found that my bost is higher for about 0.1 to 0.2 bar from 3000 to 4000 rpm.
I actually don't know anyone who doesn't have "H" version in his 1.8T engine. I mean in person.
It costs about 40£ with VAT in Europe.
Mark@VAGWORX
21-08-2003, 14:51
So apart from the higher spike from the 'H' valve, fundamentally both valves are pretty much the same.......so does it come down to personal preference then??
Apparently the J is a higher spec than the H (its form a more powerful Audi model), so is better suited to higher boosting cars. The H gives a sharper boost spike but doesn't hold the high pressure for as long.
Perhaps H is the best for the ibiza and J for the Leon? Depending on what boost you are running of course...
Are there any pictures of where this is located?
Dormouse
21-08-2003, 15:40
Originally posted by DU02
Apparently the J is a higher spec than the H (its form a more powerful Audi model), so is better suited to higher boosting cars. The H gives a sharper boost spike but doesn't hold the high pressure for as long.
Perhaps H is the best for the ibiza and J for the Leon? Depending on what boost you are running of course...
Why?
They both has similar power outputs chipped don't they? (assuming you are comparing the leon and not the leon R).
I for one would rather have the J if it does infact not boost spike as much and hold the boost hence torque longer.
Dor.
Dor, i agree, however i just seems there are a lot of happy Ibiza owners running the H.
The golf owners reported several cars going in to limp mode with the H cos the boost spike was too much. Haven't heard of any Ibiza's going into limp cos of the H valve. If your car is not running too high a boost level, you might want the aggressive spike of the H to give a more powerful kick??
I've seen a few threads on this one but never done anything about it - since I am going to have a full IHI conversion in the next few months is it worth me doing?
If so is there a "how to" anywhere (needs to be Peter and Jane stylee as I am mechanically challenged)
ok... i'm confused... which is best for a standard Ibiza 20vT, H or J? :redface:
To summarise, general current opinion suggests that J is the best, but there seem to be plenty of happy beeza owners running H's
....i'm gonna do a poll in the Ibiza section! :D
Surfer_D
22-08-2003, 08:26
hey hold on, we're talking about a thing that has been discussed for several times on all VAG forums. The general conclusion everywhere was that "H" version is the best. Don't ask me why, but they dyno'd their test and checked the pressure via VAG com.
Everyone interested use "H" version. This is what I read on every forum.
I personally feel the difference, although the weather has changed and this might be it. It's a little colder - that brings up some horse power.
Surfer,
yes that was the situation until someone came up with the idea of using J :)
Originally posted by Surfer_D
Everyone interested use "H" version. This is what I read on every forum.
That's not the opinion on vwvortex/ukmkivs ....
Dormouse
22-08-2003, 10:09
Originally posted by Phill
....i'm gonna do a poll in the Ibiza section! :D
What's the point of doing a poll simply to choose a letter? We simply don't have enough infor to make a decision....:(
Dor.
P.S I'm gonna pinch DU02's for a test when he gets it (although he doesn't knoe yet!!!!) - oops :eek:
Originally posted by Dormouse
P.S I'm gonna pinch DU02's for a test when he gets it (although he doesn't knoe yet!!!!) - oops :eek:
Ok np dor, i'll let you know when its here
Dormouse
22-08-2003, 10:40
Originally posted by DU02
Ok np dor, i'll let you know when its here
WHHHOOOHOOOO!
Cheers Matey!
Dor.
Hi all,
Have recently fitted a 'H' version valve to mine.
Fitting is dead easy, took about 1/2 hour. Just make sure you get 3 jubilee clips before starting.
Engine cover needs to come off and once you have the bought the new part, it's dead easy to match up to the part you want to replace.
On testing it, the difference was noticeable straight away.
Boost kicks in harder and just seems to get stronger as you go through the rev range.
My car is more or less standard (nothing that affects BHP anyway) and I'd say it's definitley worth trying one, it's only £40 odd so you can't go wrong really.
One thing I have noticed is how much smoother it is now.
Well recommended :D
Damo.
Shock_Xe
22-08-2003, 13:36
quick note, I didnt take clips off, just twisted and pulled pipes and they came off and went back on with a bit of patience and elbow grease!
Yeah , if I'd have taken more time, then yes the clips already on there could be used again, patience was not on my side in this instance though, those bloody clips they insist on using are a pain the butt.
Do you not worry that the pipes might possibly come off?
Damo
Shock_Xe
22-08-2003, 13:47
they were a bugger to get off and put back on big time! so cant see em popping off! Been on for 5/6weeks now and no probs
Shock, seen in your sig that you've got a boost guage. How much extra pressure are we talking about from changing the valve?
No such luxuries in mine :( ..........yet.
Damo.
Surfer_D
22-08-2003, 17:12
I second that and mine is chipped with forge p007, larger turbo intake pipe and green air filter in standard box
Originally posted by Damo
Hi all,
Have recently fitted a 'H' version valve to mine.
Fitting is dead easy, took about 1/2 hour. Just make sure you get 3 jubilee clips before starting.
Engine cover needs to come off and once you have the bought the new part, it's dead easy to match up to the part you want to replace.
On testing it, the difference was noticeable straight away.
Boost kicks in harder and just seems to get stronger as you go through the rev range.
My car is more or less standard (nothing that affects BHP anyway) and I'd say it's definitley worth trying one, it's only £40 odd so you can't go wrong really.
One thing I have noticed is how much smoother it is now.
Well recommended :D
Damo.
Surfer_D
22-08-2003, 17:14
Originally posted by Damo
Shock, seen in your sig that you've got a boost guage. How much extra pressure are we talking about from changing the valve?
No such luxuries in mine :( ..........yet.
Damo.
Mine shows about 0.1 to 0.2 bar more boost at about 3000 to 4000 rpm. It definitly holds boost better. Even at higher rpm the boost is staying longer. Before this upgrade at about 5500 rpm I was already on 0.8 bar - now I'm arround 0.9 - 1 bar.
Originally posted by Surfer_D
Mine shows about 0.1 to 0.2 bar more boost at about 3000 to 4000 rpm. It definitly holds boost better. Even at higher rpm the boost is staying longer. Before this upgrade at about 5500 rpm I was already on 0.8 bar - now I'm arround 0.9 - 1 bar.
Cool, thanks for that. I suppose what I'm trying to get at is how much extra power do you think this new valve adds and what does it do exactly to gain this extra power?
I've had mine rolling roaded a few times (pre-new valve) at different times of the year at different rolling roads............
Summer time (not so good tuner/rolling road) = 156bhp
Winter time (decent tuner/rolling road) = 165bhp
Now when I fitted the new valve, the outside temperature was about 26C, but on testing it, the car flew like it was about 14C.
Another thing I've noticed is that on the not so good rolling road, my torque peaks at between 2400rpm and 3000rpm. However on the decent rolling road, my torque peaks at between 3500rpm and 4500rpm. Now, with the new valve in place, it feels like my torque peaks at between 3500rpm and 4500rpm regardless of conditions and the pull feels harder as well, all the way to about the 6K rpm mark. I guess I just want to know what I should expect of it BHP-wise when I come to RR it again. Chances are it hasn't raised peak BHP at all, just given it more mid-range pull.
Anyway, sorry to go on, just wish to understand this valve thing a little better.
:cheers:
Damo
Hi Guys,
I'm running a APR chipped Ibiza 20VT: I've been following this discussion on N75 valves, and I've looked for the codes - 034906283H and 034906283J on the N75 valve, but the only code I can find there is 058906283F.
I haven't seen anybody else talk about this particular version - can anybody tell me the difference between my version and the others, and whether it would be worthwhile changing - anything to be gained?
Cheers,
LB:confused:
I imagine the one you have is the standard fit item that came with the car as new. The ones we've been talking about 'H' and 'J' are from Audi, so you won't find them listed as Seat parts.
Defiately seems like a worthwhile upgrade as to which is best, the jury is still out on that one.... watch this space, my J is going on soon.
:cheers:
Started a bit of a debate haven't I?
The reason I plumped for the j valve was after lenghty reading on VW vortex.It would seem on a chipped engine using the H spec which allows an overboost ,it was just enough to push the whole 'system'into limp mode.
I also considered that Audi would use the alphabet and give the'latest' valve a more advanced letter.
In a nut shell this J valve has really suited my Leon and by christ it really does pick up with phenominal speed***but***** as aggresive as the boost build up is it has made the engine smooth
Its only the price of a tank of fuel(I wish) get one
as above i have an apr chip, what valve shall i get i know the one in there currently is an (F)!
this is so confusing!!:confused:
Mark@VAGWORX
26-08-2003, 10:45
What N75 does the LCR run??
Just out of interest!?!;)
Can someone post some pics of where this thing is and a how to guide for the less mechanically minded... I want to see if it is something I can do but I need to know where it is
Easy job, its very accessible, top right of engine bay. Just a few 'vw special' single use pipe clamps. (You will need 3 small jubilee clips to replace them).
There is a guide from vwvortex here
http://forums.vwvortex.com/zerothread?id=719094
andy_dea
27-08-2003, 20:06
just fitted a j tonight not really tested it but my tyres ripped up big style in first and i had tcs on LOL
for the ibiza owners...
N75 location!
Looks like I'll have to get the J and give it a whirl...
Has anyone actually looked at the difference in plots with VAG-COM??
andy_dea
27-08-2003, 20:30
going to have a look at the weekend ill ask my mate if will do a before and after
Originally posted by smithrc
for the ibiza owners...
N75 location!
Hey, thats my car ;-)
Originally posted by Sim
Hey, thats my car ;-)
Notice the lack of the restrictor though ;)
Actually im using an 1mm restricor before the DawesDevice and no restrictor before N75C. My system is far more complex now ;).
Thread:
http://www.seatcupra.net/forums/showthread.php?threadid=19705
Pic (without 1mm restrictor):
http://www.seatcupra.net/forums/attachment.php?postid=203374
Surfer_D
28-08-2003, 07:41
Here's my review.
http://www.seatcupra.net/forums/showthread.php?threadid=22403
i've got a "J" on order...
what is the best size jubilee clips to use for this?
00 (13-20mm)
or
000 (9.5-12mm)
Can't remember what size exactly, but they are very small, i used the smallest ones I could get at my local shop, smaller than the DV ones.
I'll be interested to see what you make of the J valve. I didn't like it and put my stock one back on after a few weeks.
It smoothed the power delivery out nicely, but reduced my overall boost pressure somewhat and killed the car's acceleration 'kick'
My J valve now resides on Dormouse's Ibiza. *cough*money*cough* ;)
Good luck
well i'm currently suffering from a possible overboost spike meaning i get a flatspot or stuttering at roundabout 4000rpm
if it smooths out the power delivery then it might solve my problem.
lets hope...
my current N75 is "C"
are some people on "F" as standard?
Mine standard one is an 'F'
Must be one of the changes with the AUQ engine, didn't know that...
Dormouse
17-10-2003, 10:23
Originally posted by DU02
My J valve now resides on Dormouse's Ibiza. *cough*money*cough* ;)
Actually it resides in my tool box along with your std DV :D :D
Talk online later about this, having fixed boost problem issues :p
Dor.
i've just been thinking this through. i've got the J solenoid now but not yet fitted it.
i'm thinking to myself if this is really just a solenoid valve then it should still be doing the same job as the standard C or F valve.
as for holding the boost longer, i just can't see how it would do that, it's not doing any thinking itself, it's controlled by the ECU
are there any experts who would care to comment?
There's a bit more to it than that, i'd recommend a search on vwvortex as they've gone into it in a bit more detail than we did here. Don't expect a riveting read though:p
Surfer_D
20-10-2003, 14:55
I see N75 has become interesting again;
http://www.seatcupra.net/forums/showthread.php?threadid=22403&highlight=n75
this "explanation" of the N75 was on the ECS site... i believe they rebadge the H valve as the ECS Race N75 Valve
The Power: The N75 is the VW/Audi part identification number for the wastegate by-pass regulator valve. This valve is responsible for controlling the movement of the pneumatic actuator which drives the wastegate. The wastegate is an internal valve in the turbo-charger which controls the amount of exhaust gas that flows over the turbo impeller generating boost. Under normal operating conditions the engine's ECU sends signals to the N75 valve asking it to open or close which adds or reduces pressure on the wastegate actuator which results in more or less boost. The ECS RACE N75 valve modifies the normal operating parameters of the original N75 valve by delaying the speed at which these ECU signals are interpreted. The result is a higher initial peak boost and an elevated boost curve which tapers back to stock/chipped levels over the engines rev range. Average boost gains are 1-3psi over the rev band.
The Positive Side Effects: As discussed above, the ECS RACE N75 slows the speed at which the wastegate reacts to ECU boost control signals. The result is a smoother boost curve. Many customers who had "jerky" power curves found that not only has the RACE N75 valve added extra horsepower, but has nearly eliminated any irregularities in their engines power curve.
i put in the "J" on saturday. initially good results. the power surge that used to arrive at ~2100rpm is smoother now, and the flatspot at 4000rpm has been reduced. gonna give it some more miles to see how it pans out.
Snoopstah
04-11-2003, 15:11
Can anyone explain to a newbie (i.e., me) how to construct my newly purchased N75 valve?
I've got the solenoid, a spring, a washer, a plunger, and a four-way pipe. Presumably the spring goes into the solenoid, plunger on top, pipe on top of that. Where does the washer go?
Also, what's the best way to attach it to the car? Can I get small enough jubilee clips? Or is it possible to reuse the existing OEM clips?
Ohhh, all i've seen have come ready assembled:confused: Dormouse has my spare one, you could use that as a template if you need?
You can't re-use the existing clips as you'll foul them up getting them off.
You can get small enough jubilee clips no problem, I got mine from a little car spares place near Tesco Express if thats any help.
Snoopstah
04-11-2003, 18:26
Hmm, that's annoying. I think I know how it goes together, I'd just like to be sure...
http://www.alexisbirkill.com/n75.jpg
eeeek that looks like it might have broken in delivery! my N75 came in one piece.
this company below does a comprehensive range of real Jubilee clips (i've found some clips like ones from halfords to have some nasty sharp edges!)
H & D Worm Drive Clips
Hose clip distributors & agents
197-199 Mare St
London
E8 3QF
Tel: (020) 8985 0752
Fax: (020) 8985 3123
:yikes:
It clearly says 1 piece on the bag (albeit in German) not 5!!!
Deffo check its not broken!!!
Snoopstah
04-11-2003, 18:41
D'oh, I should really read the bag, shouldn't I! :redface:
Time to e-mail the guys I got it from tomorrow I think!
ANDY BLUNT
22-01-2004, 18:05
Just fitted "J"valve, seems a bit better in midrange,but its wet and roads are busy so will try tomorrow.For reference mates Leon R has a "k" valve.:cheers: Andy.