98 A3 with AGU engine: are people putting in boost gauges?

luckymacy

Registered User
If so, where/how? Yep, I admit it, this is my first turbo experience and there's no other similar cars here that would have had to do this so I want some handholding before I do it. I'm not convinced I'm getting much boost but hard to really tell w/o a gauge, right? Got any better ideas on testing out the turbo?

Not finding an AGU engine DIY and I recon I should be able to do this if I can see how it's done prior.:sos:
 
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Mattfaced

Registered User
You can buy a cheap guage range up to about 1.5 2 bar, then t of any vacuum tube under the bonnet. Prob on an agu just t from the plastic d/v valve, ether bring the vacuum feed for the gauge through the bulk head, or just bring it in you window for temp reading your boost.
 

Welly

335D Driver :-)
Easy as pie mate..... DIY all the way.

Get a kit, pref in PSI.

Decide where you want to put the gauge in the car (personal preference).

Take T Piece and install it into the pipe running to the top of the DV somewhere - wherever best to suit you engine bay.

Consider buying some of this http://cgi.ebay.co.uk/4mm-x-3M-BLAC...arts_Vehicles_CarParts_SM?hash=item45efe1c0dc for piping into cabin.

Run pipe for boost gauge from T Piece, through/under scuttle panel and run along to the DRIVER's side of the scuttle area.

Run into cabin through the grommet. (See this link http://www.audi-sport.net/vb/showthread.php?t=59639&highlight=fitting+boost+gauge - Second post)

Run pipe to back of boost gauge.

Voila.

I have an AGU engine with one of these at home, can take pics if required.
 
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luckymacy

Registered User
Yep, I could use a picture of exactly where you T'd into and where/how you routed into the car, how u secured it, etc. The links are interesting and helpful. Plus, what pressures are you getting for the typical operational situations (idle, moderate acceleration, full acceleration, etc)?
 
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Welly

335D Driver :-)
Well, my boost readings will be a little different to yours to be fair. Is your engine hardware/software standard? My AGU has a lot of mods, so boost levels will be different, mainly because I'm using a manual boost controller set to 15.5 PSI.

I'm not convinced I'm getting much boost but hard to really tell w/o a gauge
Standard AGU, or any 1.8T 150/180 engines don't make much boost. They are designed to be a gentle engine that provides smooth power delivery. Typical standard boost pressures for a K03 are around 8-9 PSI - which isn't a lot...

Standard boost under hard acceleration should be 8-9 PSI. At idle you would be expecting to see the gauge reading vac pressure. Around and about 20 InHG is normal.

Anyway, I'll take a few snaps when I get home, although pics may not be great as it will be dark :(
 
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Welly

335D Driver :-)
Pictures as promised, sorry for the delay but the weather has been awful here!! Have added a pic of the A3 with 4 inches of snow on top!

I have tried to be concise in labelling this, should be easy to follow. Standard pipe to Dump Valve from inlet manifold is generally about 4mm and is cloth braided.

gauge1.jpg


Engine bay

gauge2.jpg


Close up of area you need to be looking at...

gauge3.jpg


Hope this helps?
 

Sandip

Registered User
You'll get a more accurate reading if you connect it to the fuel pressure regulator :)
 

Welly

335D Driver :-)
I wouldn't do that personally for 3 reasons.

Firstly, with respect Sandip, I disagree. It's a feed from the inlet manifold which carries vac/boost pressure. Whilst there may be a minor (and I mean minor) difference, it's not enough to be able to tell the difference from a boost gauge, which are difficult to get a super accurate reading from anyway due to size of gauge vs size of needle. It's a feed from the same place, so in all fairness it's never going to be that diferent, if different at all.

Secondly, boost gauges vary from gauge to gauge anyway, so the reading isn't likely to be 100% accurate.

Thirdly, it has always concerned me with piping into the FPR pipe in case of fault/split in the hose or T Piece. If this happened (likely that it won't but thats never certain), this means that, aside from boost loss, the FPR wont be fuelling the engine correctly as it won't be getting correct pressure reading from the inlet manifold. This in turn causes fuelling issues (generally makes the mixture lean - Lean = Ultimate enemy) which in turn could cause running problems/loss off power/detonation. All of these things being side effects of boost gauge installation I would image that you wish to avoid. A split in the DV vac hose will only ever cause loss of boost and cause a sluggish response from the DV which you would notice immediately. Low pressure to the FPR isn't so easy to spot and can cause much worse problems.

Not slating you Sandip, I'm really not, just that I reviewed all of the options for Boost Gauge install when I fitted mine, and chose to pipe mine to DV pipe. Just giving my 2 cents....
 

Sandip

Registered User
Thanks for that welly, you could be right, my car is running lean so this might be the cause, Thanks bud, i'll try connecting it to the dv and see if i get a little bit more power :)
 

Welly

335D Driver :-)
No problemo.
 

Sandip

Registered User
I'll do it after work tomorrow, its boosting 19psi and 221bhp running lean, so should i notice a big difference in power if the connection is causing it to run lean?
 

Welly

335D Driver :-)
Deffo worth a blast. it would normally only run a bit bad if there was a leak, but I guess the pressure used to pressurise the DV pipe to the cabin might be causing it.
 

Sandip

Registered User
No harm in trying it i guess, i'll post up the result tomorrow lol
 

HTC

Registered User
As mentioned, on the AGU engine tap into the DV vacuum pipe. There is no need to tap into the FPR vacuum pipe as there is none of the N249 stuff to worry about.

Just to add, if the vacuum feed to the FPR is leaking it wouldn't cause the engine to run lean due to a fuel pressure discrepancy. High vacuum acts at idle or overrun to lift the spring to reduce pressure. On WOT or with a leak the spring wouldn't lift and the FPR would remain at 3 bar. It's a fail safe system.
 

Welly

335D Driver :-)
Did you do this over the weekend Lucky?
 

Welly

335D Driver :-)
I'll do it after work tomorrow, its boosting 19psi and 221bhp running lean, so should i notice a big difference in power if the connection is causing it to run lean?


Not really, it should just fuel better. Maybe a touch more go towards the top end, but not a great deal. What fuel do you use?
 

Sandip

Registered User
Not really, it should just fuel better. Maybe a touch more go towards the top end, but not a great deal. What fuel do you use?

Always v power bud, haven't had the time to do it yet though
 

will.f_1.8t

Registered User
Is the fitting for the boost gauge the same for an aum engine! i want to fit one also and connecting to the dump valve looks very straight forward cheers
 

Welly

335D Driver :-)
Is the fitting for the boost gauge the same for an aum engine! i want to fit one also and connecting to the dump valve looks very straight forward cheers

Yes mate, should be next to identical.
 

luckymacy

Registered User
Did you do this over the weekend Lucky?


Nope, got sucked up bright and early Saturday morning into the black hole known as FIRST Robotics competition where I mentor a high school team and it's been a constant user of my free time throughout this entire week. I doubt I'll get to it now until the robot is built and tested out thoroughly over the next 5 weeks before the competitions start. I've this bookmarked and I'm coming back ASAP.
 
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Prawn

My other car is a MINI!!!!
Just to add, if the vacuum feed to the FPR is leaking it wouldn't cause the engine to run lean due to a fuel pressure discrepancy. High vacuum acts at idle or overrun to lift the spring to reduce pressure. On WOT or with a leak the spring wouldn't lift and the FPR would remain at 3 bar. It's a fail safe system.

Can you explain that one again Kev? I always understood it to be the other way round.....

On my AGU, at idle, the fuel pressure stays at a constant 3 bar. On boost, the fuel pressure rises directly inline with boost. Fuel pressure is always 3bar +boost so at 1 bar boost my fuel pressure is 4 bar, this is why I had fuelling problems running a standard pump and 1.6 bar boost, the pump couldn't keep up with the spike, and **** itself.

On idle when under vacuum though the fuel pressure stays at a steady 3 bar and never goes below.
 

Welly

335D Driver :-)
Nope, got sucked up bright and early Saturday morning into the black hole known as FIRST Robotics competition where I mentor a high school team and it's been a constant user of my free time throughout this entire week. I doubt I'll get to it now until the robot is built and tested out thoroughly over the next 5 weeks before the competitions start. I've this bookmarked and I'm coming back ASAP.

Post pics of the robot!! I don't blame you, thats MUCH more fun than working on an engine. I'm jealous!! :(
 

HTC

Registered User
Can you explain that one again Kev? I always understood it to be the other way round.....

On my AGU, at idle, the fuel pressure stays at a constant 3 bar. On boost, the fuel pressure rises directly inline with boost. Fuel pressure is always 3bar +boost so at 1 bar boost my fuel pressure is 4 bar, this is why I had fuelling problems running a standard pump and 1.6 bar boost, the pump couldn't keep up with the spike, and **** itself.

On idle when under vacuum though the fuel pressure stays at a steady 3 bar and never goes below.

Forget my ramblings, I was thinking NA FPRs. Boosted cars get 1:1 FPRs.......doh :)
 
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