Boost gauge noise and psi

[Snuff]

So i fitted a boost gauge to keep an eye on things and the needle makes a ****** vibrating noise when i boot it also what psi should a mapped 07 S3 pull , ineed to check that the pipe to the gauge is in the right place under the bonnet so will do that asap.. any ideas would be good
Thanks in advance

 

[bennyball]

Does the needle actually vibrate? If so it's likely you need a restrictor, an inline filter should do the trick

 

[Snuff]

yep it does , i have checked everything else ... what is a restrictor and where can i get one

 

[S3Alex]

Peak boost will depend on what stage mapping you're running,and which tuner.

Also will depend on what turbo,i.e. are you running an aftermarket big turbo or the stock K04/

 

[Snuff]

Dont know who mapped it ( was done when i bought it ) its got stock turbo and also turbo back decat and CAI. im only after a rough figure , my mk 1 s3 pulled about 19psi tops

 

[S3Alex]

Here's a useful link....


http://www.audi-sport.net/xf/threads/revo-stage-2-vs-apr-stage-2.244782/#post-2462139

What you'll see is a stock S3 will run around 1.2-1.2 bar peak(the figures shown are absolute BTW),and a Stg1 car will run around 1.3bar,with Stg2/2+ coming to around 1.5-1.6bar.

There isn't much point in trying for more,as the K04 is mostly blowing hot air by then.....a bigger turbo will allow you to run lower boost pressures but get higher air flows,at lower temps.
My old GTX3076 would just about get to 2bar with some surge issues,at 500bhp,whereas the bigger GTX3582 will hit 550bhp at 1.9bar.

 

[Snuff]

Dont know whats going on with mine then because my gauge is spiking at 35psi when i give some , if im right it should be around 25psi... had it checked by a vag technician today and it showed no faults other than the led lights and that the battery had been disconnected.. its just had a new diverter valve (which had a hole) , n75 and a forge uprated actuator as before these parts were fitted it was only pulling about 11-12 psi and boost was coming in at nearly 4k , thanks for the info and help too

 

[S3Alex]

2.5bar (35psi) is way too high,and may have something to do with the new actuator.

If it isn't opening the wastegate at all,then you would see massive boost levels....get it checked quickly before some lasting damage is done.....

 

[Snuff]

yeah was thinking the same , got someone taking a look this week so fingers crossed

 

[S3Alex]

yeah was thinking the same , got someone taking a look this week so fingers crossed

Definitely.

When I bought my old Escort Cosworth(an ex GpN car) the previous guy who raced it had wound the boost up to 2.5bar,by altering the wastegate actuator.
We removed the GpN restrictor,and got obviously a lot more power,but at lower peak boost....yours is behaving very much as if the wastegate actuator has either a fault,or is wrongly adjusted.

 

[Bazzle]

An cable tie pulled around the hose to the guage will work as a restriction. So will a piece of pipe/fitting with a soldered in washer and a small hole drilled thru solder.

 

[Snuff]

fitted a restricter into the gauge pipe and its problem solved , bought it off ebay £3

 

[Broken Byzan]

bin the "uprated" actuator and put a standard on e on before you blow her up. I bet the actuator spring is set up at around 15 PSI where as OEM was 8. If this was fitted after the remap then it would explain the simply ridiculous 35PSI that you are seeing.