what components would I need to convert a 90bhp tdi to a 110?

**wacky77** · 24-10-2009,06:51 PM

hello all, having just bought a very tidy 1996 A4 for the missus with the 90bhp pre PD 1.9 tdi lump in I'm wondering which components I would need to convert it to the 110bhp as standard in the 'red I' pre PD models?
I have a 1999 A6 with the 110 version and it just pulls a lot better, as they're the same basic engine and its only 20bhp difference is there much to change?

Cheers-Steve

**sbt** · 25-10-2009,01:48 PM

i would not imagine you would have to change any components just get it chipped

**Copiertech** · 26-10-2009,02:26 AM

90hp is wastegated turbo, 110 is vnt. different mapping and different and incompatible means of boost regulation, without investing too much time and money anyway. the fuel pump resistor mod is cheap and cheerful.

**wacky77** · 26-10-2009,10:41 AM

Originally Posted by Copiertech

90hp is wastegated turbo, 110 is vnt. different mapping and different and incompatible means of boost regulation, without investing too much time and money anyway. the fuel pump resistor mod is cheap and cheerful.

Thanks for that, yeah going the plug in mod route anyway but as its gain is a percentage of standard power I would have prefered to 'start' with 110 rather than 90 had it been relatively simple to upgrade, 90 + mod is around 110 but 110 + mod is around 135 (ish)
Obviously it would have been preferable to start with a 110 bhp engine anyway but this A4 was too tidy to pass on just because its only 90bhp lol.
Excuse my ignorance but what is 'vnt.'? vented?
Thanks for the swift replies-Steve

**Copiertech** · 26-10-2009,10:58 PM

a vnt is a variable nozzle turbo, instead of just a gate that opens once a predetermined boost level is reached which then regulates the boost level on a wastegated turbo the vnt has variable geometry inside to spool up very quickly from low rpm where the exhaust gas is slow then once the flow of exhaust gas and boost picks up the geometry of the turbo hot side is changed to allow better flow and to regulate boost, it allows for more boost from low rpm and a wider powerband.

**vinrex7** · 28-10-2009,01:23 PM

Hi guys, i'm new to the site. Can someone tell me what the fuel pump resistor mod is? and how much more bhp will i get from it? cheers Dan

**wacky77** · 28-10-2009,06:45 PM

Hi mate click the link below for a cheap one for PD engines, they simply connect between the fuel pump to loom connectors and slightly alter the signals to/from the ECU.
The gain you get tends to be a percentage of your standard bhp/torque, ie the more you start with the bigger the gain this'll give you.

http://cgi.ebay.co.uk/TDI-PD-Tuning-...item2ea8bbd5d5

the link below is for pre PD engines ie 90/110 bhp early A4's.
http://cgi.ebay.co.uk/TDI-Chip-Tunin...item56365c3792

**Copiertech** · 28-10-2009,11:32 PM

http://forums.tdiclub.com/showthread.php?t=257122

**wacky77** · 29-10-2009,08:18 AM

theres a similar mod for petrol injection engines where you use a resistor across the terminals of the ECU temp sensor, fooling the ECU into thinking the engine is colder than it is causing it to inject a little more fuel and advance the timing slightly.

**I_am_stealth** · 06-11-2009,01:38 PM

wacky77, there is another topic somewhere on the difference between the two engines and whether or not is worth the conversion...
Briefly, fuel pump, ecu, injectors, turbo. And it just crossed my mind that the 90hp AHU has a single mass flywheel, whilst the AFN 110 has a dual mass.