Advice on modded AUDI TT purchase

Wow that's pretty sucky timing - I guess the "weak stock rods will break/bend when you turn it up" is pretty accurate with the 1.8t. 

Ya when i rebuild the motor i'm going to go forged everything incase the future has bigger hp plans. it put down just over 300whp before it blew up.

As @docwyte mentioned, careful!

30psi is way too much UNLESS you have a bigger gt28. It's way off the compressor map on the smaller ones. 

And UNLESS you have a newer ecu that has a factory wideband O2 sensor. 2000 model tear tt does not. 

And UNLESS the boost sensor has been upgraded to one that can read more than 22psi. This also requires a lot of changes in the tune. 

If these are not all addressed, at the least you have a very dangerous suboptimal tune, but more likely a ticking time bomb even if all the metal bits are top-notch. 

bradyzq said:

As @docwyte mentioned, careful!

30psi is way too much UNLESS you have a bigger gt28. It's way off the compressor map on the smaller ones. 

And UNLESS you have a newer ecu that has a factory wideband O2 sensor. 2000 model tear tt does not. 

And UNLESS the boost sensor has been upgraded to one that can read more than 22psi. This also requires a lot of changes in the tune. 

If these are not all addressed, at the least you have a very dangerous suboptimal tune, but more likely a ticking time bomb even if all the metal bits are top-notch. 

I am by no means a 1.8t expert yet but I am learning as I go.... I do know that the turbo is a GT2876R which I think is one of the bigger GT28's? I believe it replaced the GT2540r which does not seem to be a well regarded turbo on most 1.8t applications.

the ecu's is from a newer 1.8t Jetta and was tuned to support the big injectors, no maf and the rest of the mods. 
 

I also know that this car was driven by the original owner for about 5-6 years after getting built. I suspect that at a "conservative" 20-22psi everything should be pretty safe based on its history at 28-30 psi as a daily.

it is currently uninsured and I am waiting till spring is fully here to insure and drive it. From what I have read it would likely be a better experience with the turbo swapped to a GT3071 unit? Any opinions on that? In the brief amount of time I spent driving it before it was parked  it felt like it wasn't making full boost till about 4500rpm. Would be nicer to spool a bit quicker but it didn't feel horrible all things considered.

Pierre

If the ECU doesn't know how much boost there is beyond 22psi (the way it is stock), and the tune is hacked so it's ok at 30, if you turn it down to 22psi, there will be too much fuel and not enough timing. The wideband is gonna be working hard to correct the fueling, maybe out of range even, but nothing will correct the ignition advance. Putting a MAF back in would be a good idea if you want the ECU to know what's actually going on. But that's a whole other rabbit hole!

More learning to do for sure on the tuning side of things. Would you suggest it would be better to just leave it at 28 psi then and just try and drive it's bit nicer...

Any input on a different turbo choice vs current? This is not a daily driver and was bought cheap enough that some fairly major changes can be made without much anxiety 

You need to figure out what the tune is for and what its doing before you drive it, period.  Once you figure that out you can start to try and optimize the setup.  A GT3071 is a huge turbo for a 1.8t, it's not going to spool faster, that's for sure...

docwyte said:

You need to figure out what the tune is for and what its doing before you drive it, period.  Once you figure that out you can start to try and optimize the setup.  A GT3071 is a huge turbo for a 1.8t, it's not going to spool faster, that's for sure...

The tune is for the car as it is now - has been driven semi daily for about 5 years as is by the previous owner. 

Have a google at the part number of the boost sensor to see if it's stock (max 22ish psi). It should be post intercooler but pre-throttle somewhere.  There aren't many people who can tune these ECUs in true speed density. Most just try to get the boost pressure vs throttle opening limp maps dialed in a bit better, and call it good. But since the ECU probably can't read over 22psi anyways, even that is running pretty much blind.

And is the car running properly?  I'm confused, I thought you were saying its not running right?

docwyte said:

And is the car running properly?  I'm confused, I thought you were saying its not running right?

No - it ran great the 2 times I drove it. I don't have enough seat time yet to give proper feedback though. While it was winter and uninsured I thought I would update certain things I did not like about it. Gauge location, stereo, suspension height etc. 
 

As for the turbo questions.... everything I have read about the gt2540 or newer equivalent on a 1.8t is really bad. Like I said though, I haven't really driven it enough or that hard to agree/disagree with others experiences. The gt3071 on a built 1.8t however seems to get a lot of positive praise online. And, since this car was so cheap, I don't mind spending some cash updating the turbo to something better if it seems worth it or if it has better manners. 

I've never heard of  a 2540 from Garrett. Maybe HKS, but I think it doesn't follow the same naming conventions, so isn't comparable. 

It is the GT2876 that is often considered  a bad match for a 1.8T.

Where do you want your torque or boost to hit, rpm wise? And what are your power goals? Depending on hotside, spool on the 3071 and 2876 should be similar.

At  a pressure ratio of 3+ and 55lb/hr of air you are going to be flying right off the map on a GT25 and borderline on a GT3076. 

I punched the numbers into matchbot and it looks like an EFR 7163 is a pretty good fit. 
http://www.turbos.borgwarner.com/go/20XWD4

They aren't cheap, probably $500 more than the Garrett but it should spool faster. Do you have a divided manifold?