2001 Nogaro Blue TT 8N - G25-660 Build

[Byront8]

Hey all

Based in New Zealand, and a sucker for a TT. So a few months ago we found a slightly abused 1.8T Manual Quattro 225 for sale, listed as Pelican Blue and after purchasing and looking at the build sticker found it was Nogaro Blue! Originally imported from the UK, its not been a pretty car at the moment, massive overboost (N249 had failed), terrible tune on the car, clutch slipping etc etc.

So we set about fixing the general crappiness of the car and to use it as a daily whilst we decided what to do. Which lasted about 5 minutes, as I've bene personally dying to do a 1.8T build for a very long time.

Wheels in motion, the BAM engine is still in the car - sourced a lightly used AUM motor and stripped it down - its gone off to the machine shop for hot tanking, decking, honing and maybe an align hone/bore depending on what the ARP bolts change to the main caps. I am also trying to make sure I only build the motor once, and try to make it bullet proof

Currently the build is slated to be:

• JE Forged Pistons - stock bore, stock CR (9.25:1)
• JE Tool Steel Wrist Pins
• IE Tuscan I Beam Rods - 144x20
• Calico main bearings
• Calico rod bearings
• ARP Main Stud Kit
• IE Billet Steel Crankshaft timing wheel
• ARP Crankshaft bolt
• 2.0TFSI Timing belt conversion
• 034Motorsport Rear Main Seal
• Fluidampr Crank Pulley
• All new bolts, gaskets, seals etc

The head will end up:

• Small port head, ported to clean up the casting but will leave it small port
• ARP Head Stud kit
• IE intake manifold
• Grams Performance FBW Throttle body
• IE transitional phenolic spacer
• Supertech springs and retainers
• Supertech valves
• IE Street/Track Cams (new manufacturing run they did in April)
• IE adjustable cam gear
• Ekagrip Friction disc
• All new stems, valve guides
• All new bolts, gaskets, seals etc

Turbo choice is:

• G25-660 .72 A/r External WG - Reverse rotation (annoyingly this was a stupidly good deal, but means I have to make my own manifold vs using a Nortech unit)
• Turbosmart 45mm WG (I can also use an Aeroflow, but I cant find many reviews on them)

Gearbox:

• 02M Manual 6 speed
• Wavetrace LSD
• Darkside Development shifter forks

Rest of the car so far:

• 600x300x76 FMIC fitted - 63mm piping
• All new Powerflex bushings all over the front
• Seat LCR Brembo brakes
• Its been lowered, but will likely replace this with some BC Gold coilovers
• Rear end requires refreshing

My main concerns so far - is the G25-660 on the stock stroke and bore going to hinder my spool, and overall power band usability? I really want the car to react like the existing K04 in the car.
Do I use the locally made LinkTT drop in PNP ECU or the Ignitron ECU? Who here in NZ can support the tuning? Or am a looking at trying to remote link in to guys in the UK to assist whilst on a dyno?
Am I overlooking anything on this list, or should I be looking to do something else? BTW the short block is set in stone - so no chance to change bore or stroke now. Purchasing overseas parts in NZ is stupidly expensive and spare parts for early Audi/VW are almost impossible to come by.

 

[desertstorm]

If you are really keen on low down spool like a K04 then the G25-550 would have been a better choice , All depends on what you are looking for in terms of peak power.
I run a G25-660 in my car and it's just fine tootling around town in 5th /6th gear. If you want acceleration change down and off you go. They are very responsive.

This was my TT around a pretty tight sprint course.

 

[Byront8]

If you are really keen on low down spool like a K04 then the G25-550 would have been a better choice , All depends on what you are looking for in terms of peak power.
I run a G25-660 in my car and it's just fine tootling around town in 5th /6th gear. If you want acceleration change down and off you go. They are very responsive.

Sorry meant to be a little more prescriptive - when I wrote spooling like a K04, it was more that the much larger turbo wouldn't feel lazy when using it during daily use. I'm hoping to be close towards the 450-500whp on the 660 turbo, and if possible, keeping the small port intake and the stock bore/stroke, that the characteristics of the car wouldn't be too far off what they are at the moment (other than the extra silly power/torque)

 

[desertstorm]

Sorry meant to be a little more prescriptive - when I wrote spooling like a K04, it was more that the much larger turbo wouldn't feel lazy when using it during daily use. I'm hoping to be close towards the 450-500whp on the 660 turbo, and if possible, keeping the small port intake and the stock bore/stroke, that the characteristics of the car wouldn't be too far off what they are at the moment (other than the extra silly power/torque)

If you keep a sensible compression ratio as you have, the same as mine, then off boost the car isn't sluggish at all. You won't achieve the 450-500whp figure with a stock size bore and a cleaned up small port head though. If you are going to the trouble of replacing the pistons bore the block to 82.5mm and gain some easy power and torque. Stock 1780cc , 82.5mm overbore uses stock head gasket size etc and gives 1848cc. 1848 / 1780 = 1.038 .
So assuming it makes 450bhp at 1780cc, the same engine will likely make 467bhp at 1848cc and nearly 4% more torque as well. Also a used stock size bore is not going to be as straight as a newly machined bore. There is plenty of material left in a block at 82.5mm as it's the factory top size.
Also I think you will need to remove more than a little flash from the small port head to get enough flow to make your whp targets. I have found that increases in boost pressure say from 2 to 2.2 bar do not give the expected returns in power at high rpm 7K + so I strongly suspect the restriction is with the porting in the head. I wouldn't say fit a large port head or port the small port to look like a large port head. Transmission losses on these cars are quite high taking 18% as a rough figure 500whp would be around 590 crank hp .
Germains stroka motor with all the bells and whistles and Bill mapping it only made 580bhp and that's the highest Bill has seen for a G25-660 engine.
You also ought to look at strengthening the stock 02M box. At these power/ torque levels it's quite easy to break them.