The most powerful 2.5tdi V6

ben0069

Well-known member
Joined
Oct 15, 2012
Location
wales
TDI
allroad 2.5 tdi v6
I've had that pipe out to check and it does move freely where it lays.
The head shop down the road that first changed the guides said that material had been removed from the area where the bottom of the guide is located and that a part of the guide that protrudes downwards had also been removed. Is there anything like a galley up in that area?
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
You dont have any pictures? I would say get a pair of stock BAU/BDG/BDH heads and new bolts and fit them instead, you can try one at the time... For your power goal they are good enough Ben...
 

ben0069

Well-known member
Joined
Oct 15, 2012
Location
wales
TDI
allroad 2.5 tdi v6
I have two stock heads ready, just didn't want to ditch the ported ones as it was not cheap to get them done, plus you know more than many that stripping the front end down on these engines isn't a 5 minute job and that's before starting on the heads.

I will take some photos once stripped, it's difficult with the lack of space even with an inspection mirror and torch. Apart from the internal leak the engine is dry as a bone and power is all there !:)
 

diffas

Veteran Member
Joined
Jun 25, 2008
Location
Finland
TDI
B5q A4 Avant 2.5TDi+, B7q A4 Avant 3.0TDi
I have again something to update to this topic. Not sure if most powerful but at least most powerful here in myt town as far as i know.
After the last post I've changed a lot. It used to be 380hp single wg turbo setup, +120% nozzles, bigger pump, stock compression, cams .. etc

Now it has +90% nozzles, stock AKN pump, custom cams, decreased compression and more boost by compound setup. Only 3.2bar but still more.
Runs way leaner on max power and delivered more power with the same ecu map. Weird stuff to be honest. I did expect something like 340-350, but it delivered 394. Lost few hp after installing cat.

First ever dyno with the new setup, 100% same ecu than on my post earlier here with 380hp. This power run was needed for inspection to register my car full street legal. Now it is.


Few weeks after that dyno I had to install cat to the exhaust before inspection. And we had surprise dynoday so was happy to see that the cat actually
didn't hurt power that much. Few horses only. Okey its a different dyno so it might be that there is no loss at all, its so close numbers.



Latest video on 0-100kmh
 

diffas

Veteran Member
Joined
Jun 25, 2008
Location
Finland
TDI
B5q A4 Avant 2.5TDi+, B7q A4 Avant 3.0TDi
Thanks! Funny thing is that it had 8mm bolt hole on intakemanifold on those dyno runs, since i didnt notice it missed one bolt.
I think it runs bit better and leaner when on full boost. Still too much exhaust pressure for my taste, 0.4-0.5bar over the boost pressure.

Target is to run high 12sec quarter for this summer ... should be possible.
 

diffas

Veteran Member
Joined
Jun 25, 2008
Location
Finland
TDI
B5q A4 Avant 2.5TDi+, B7q A4 Avant 3.0TDi
Oh man! I crashed the car on June and bought new car and built it in super fast schedule for the last drag events.
First test run with the just few hours after starting new car resulted my new best on quarter 12.74/180. It was 8.30 1/8mile.
I've managed to get 8.10 on 1/8mile with very slippery track and that basically means car is capable atleast 12.5 or even 12.4 on quarter.
Super happy with the results! I have not touched ecu at all.... well okey only launch limiter is adjusted.
I made video montage from the clips I did recieved from my friends:

Went few days ago to the dyno to check if the car has all the ponies in house. Ecu is the same as last year. Only difference is it
has no boost leak, boost is turned up a bit and cat is removed. It made ~403hp!! Finally over 400! Lambda is 1.4+ / afr 20+ so it should be pretty smokeless but I think the nozzles I have cause excessive smoke that cant be turned down. Maybe. Pump is low mileage stock 2plunger AKN pump.

- dyno videos


Dyno graph:
 

diffas

Veteran Member
Joined
Jun 25, 2008
Location
Finland
TDI
B5q A4 Avant 2.5TDi+, B7q A4 Avant 3.0TDi
Interested to learn and see more of your compound setup!
It is estimated setup that should be working pretty good. And to be honest it works quite good as it is now. I have two K03-029 (BFB stock) working as HP turbos and bigger S362SXE as LP. The thing is, currently S300 is making too much boost, so it is slightly too small. It delivers 2.6 - 2.7bar now. I'd rather see 1.5-2bar max for now. I have bigger exhaust housing already ready to be installed. Going from 0.91 to 1.10 should give some drop on boost.
Max boost is now 3.8bar on top of the revs, so it means HP is doing about 1.3 PR. I'd rather see something like 1.7-2 PR. EMP is 0.4 - 0.5bar over boost, so not that bad.

I have uploaded some build photos to my facebook page https://www.facebook.com/media/set/?set=a.2308809885819769&type=3
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
Yes. Larger A/R LP and larger HP-stage wastegate opening area (external?) will help balance the PR contributions of the HP and LP stages. You ARE using the wastegate on both the HP and LP, right? If not, that explains why you're overboosting overall. You shouldn't leave it to size and turbine A/R of the LP alone to hope for correct overall boost.
 
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TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
HP wastegate(s) should be controlled by interstage PR and overall boost by LP wastegate by the N75 or however you're controlling it.
 

diffas

Veteran Member
Joined
Jun 25, 2008
Location
Finland
TDI
B5q A4 Avant 2.5TDi+, B7q A4 Avant 3.0TDi
I don't have wastegate on LP turbo. No need to waste gas which i is already has lost energy. High overall boost level is not really my concern, probably need to go 4+bar when starting to add more fuel. I'm only after decrease boost made by the LP and add more to work to HP turbos. Overall boost from the intake is currently controlling wastegates of the HP turbos and it works just like it should. I have 2 bar springs on gates. Idea is to keep the setup as simple it can be, so there are no electronics currently. Maybe later I will add maxxecu and mac valves for control, but for now I'm pretty pleased with the setup.

One other upgrade I want to make is to add intercooler some kind, that should give nice bump on HP compressor efficiency. Problem is with packaging. Maybe some small w/a intercooler is possible to fit.
 

adamss24

Veteran Member
Joined
Nov 2, 2005
Location
Great Britain
TDI
audi a4 2.5 tdi 98 quatrro 6speed
Nice youre keepong us posted with the power updates ! I also noticed you went for a quattro model...nice !
 

diffas

Veteran Member
Joined
Jun 25, 2008
Location
Finland
TDI
B5q A4 Avant 2.5TDi+, B7q A4 Avant 3.0TDi
No problem. I like to keep people updated on some forums I still use. I'm active only on few forums. Have longer build topics on finnish forums and on my fb page. Lots of people find this kind of builds quite interesting and thats keeps me going :)
 

TDIMeister

Phd of TDIClub Enthusiast, Moderator at Large
Joined
May 1, 1999
Location
Canada
TDI
TDI
One other upgrade I want to make is to add intercooler some kind, that should give nice bump on HP compressor efficiency. Problem is with packaging. Maybe some small w/a intercooler is possible to fit.
An inter(stage) cooler is definitely a good thing to have but doesn't have any material effect on HP compressor efficiency; the latter's value as a percentage remains essentially the same at the same operating point. It is a fixed property of the turbo design and not on external factors (although you do apply a correction factor √T/P which will shift your operating points on the map depending on inlet conditions).

However, I do understand what you mean: lowering the HP compressor inlet temperature will indeed reduce the outlet temperature, but in your case that's not a function of a changed compressor efficiency per se for having an interstage cooler. HP compressor work, which translates to EMP as well as shaft stresses, would also decline with lower inlet temp.

The control strategy I outlined in my previous post does not involve adding any additional electronics or complexity. It just shifts what controls what.
 

diffas

Veteran Member
Joined
Jun 25, 2008
Location
Finland
TDI
B5q A4 Avant 2.5TDi+, B7q A4 Avant 3.0TDi
...
However, I do understand what you mean: lowering the HP compressor inlet temperature will indeed reduce the outlet temperature, but in your case that's not a function of a changed compressor efficiency per se for having an interstage cooler. HP compressor work, which translates to EMP as well as shaft stresses, would also decline with lower inlet temp.
...
Ah good you figured out my idea. Not so good always on word. Easiest way to intercool between stages is probably water or water/meth injection.
My only concern is that it destroys HP comp wheels pretty good when having too big water droplets. Maybe using higher pressure and very fine multipoint injectors to great fine mist of water helps with that? It's not daily so adding water time to time is not a problem.
 
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