Audi AAT 2.5 TDI power increase / limits

shone190

Member
Joined
Nov 12, 2019
Location
Belgrade
TDI
Audi AAT 2.5 TDI
Hi guys, I have Audi AAT 2.5 TDI 115HP engine and thinking about power increase.

I know that this engine has cast pistons (AEL 140HP has forged) and want to know what is the HP/Torque limit for AAT pistons?

I would like to make about 250HP/500Nm, but to be on the safe side with the engine.

So is it safe to go with AAT engine or still with AEL?

Thanks a lot in advance.
 

jhax

Veteran Member
Joined
Jan 24, 2012
Location
Golden, CO
TDI
96 Passat B4V, ALH engine out of a 2002 Jetta, some IE Rods and ASV Pistons. Nothing drivable yet though
The car, the motor. I am certainly intrigued
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
Hi guys, I have Audi AAT 2.5 TDI 115HP engine and thinking about power increase.
I know that this engine has cast pistons (AEL 140HP has forged) and want to know what is the HP/Torque limit for AAT pistons?
I would like to make about 250HP/500Nm, but to be on the safe side with the engine.
So is it safe to go with AAT engine or still with AEL?
Thanks a lot in advance.
For what they cost nowadays go for the AEL swap, its cheaper in the long run...
 

Markus L

Veteran Member
Joined
Feb 12, 2015
Location
Finland
TDI
Caddy (14D) 1.9TDI 2-stage 400+bhp, Passat 3BG 4motion AVF
Why do you think AEL has forged pistons? Cast pistons can be made to bear 200 bar peak cylinder pressure.
 

Markus L

Veteran Member
Joined
Feb 12, 2015
Location
Finland
TDI
Caddy (14D) 1.9TDI 2-stage 400+bhp, Passat 3BG 4motion AVF
Then it must also have piston replacement scheduled with every oil change due to lack of steel reinforcement for top ring groove.
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
Most c4 audis in europe are pieces o s*it as they old and rotten however you get the odd one thats been loved and cared for but its rare ! I had a c4 a6 and it was a really well put together car, mine was auto and gave me some trouble... The 6 speed gearbox and the 140 Bhp engine really does go well together ! I would keep modding minimal as the 5 speed box in the AAT is kinda weak and clutch will slip with minimal modds...Also the archaic ECU is hard to work with, i know of a few that had later EDC15 ECU from 2000-on transporter 2.5 tdi as the wastegated k14 is difficult to mod due to old tech. However using the wiring harness from t4 150 Bhp opens a whole load of posibilities to tune the old inline5 lump !
 

p0wer

Veteran Member
Joined
May 21, 2009
Location
Jyvaskyla, Finland
TDI
Golf 3 -94 1Z 377hp, Golf 3 Cabrio 4-Motion 1.8T 620hp, Golf 3 Syncro 2.9 VR6 HX52, Bora AJM 4-Motion 2260vk +120% Firad, Passat 3B Syncro AFN 2260vk
Old ecu does not NEED to be used with k14, you can use what WG turbo you ever want. It´s bit idiotic to use and modify that old k14. We have made several 8 bit tunes for old ecus also here without problems and works well. EDC- and MSA-ecus from T4 can be also used with WG and VNT setups on C4, no need for 151hp ECU.

Where do you know you have different pistons on your AAT than AEL has? As I remember, european AAT´s have same pistons than AEL. Baybe here´s same issue than in some 1Z´s pistons between states and EU.
 
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