Compound turbos on a 1.9td

[jimbobpolo]

Hey guys I'm looking to put together my mk2 compound setup, previously I ran a t15 (standard 1z tdi turbo) and a t2 from a landrover 2.5 and had various issues with boost spiking and some high turbine back pressure, the sound of the two turbos was amazing but performance wasn't as I expected, even at 30psi! I put it down to mismatched turbos.
I'm now running a k14 at 18 psi (was running a k24 at 22 psi) and I'm thinking of Plumbing in the k24 after the k14, what you guys reckon? Engine is a 1.9 aaz with 1.6 gtd ip and injectors, 2.5" turbo back exhaust and a huge alloy fmic. Am I correct in thinking 10 psi on the k14 and 10psi on the k24 would give decent total boost?

[RabbitJockey]

Yes you are right but keep in mind you will still be limited to the amount of air that the larger turbo can flow so I would not expect anymore than 150hp from this setup.  Which is a decent amount especially considering it would probably be quite powerful through put the rev range but nothing outrageous.  Also the boost doesn't just add like 10 and 10 makes 20.  It's a bit more complicated.  If both your wastegates are set to 10psi and referencin their own inlet as the atmospheric side of the wastegate you will actually have nearly 27psi

[Alcaid]

Pick a newer, more efficient and more flowing LP turbo, or even better, throw both the K14 and K24 in the bin and change both

[jimbobpolo]

I'm aware of the 10 psi plus 10 psi doesn't equal 20 psi, more like 27 psi, obviously due to the HP turbo pressure ratio...

Ok what turbos would you suggest??

[Alcaid]

Depends on your goals, will you keep the pump unmodified?

[jimbobpolo]

I'm looking for 160-180ish whp, I already have done the governor mod, wound in the max fuel screw about 3/4 turn and a custom LDA boost pin, I get a fair amount of smoke but clears when on boost,

[Alcaid]

You will be nowhere near your power goals with a pump like that...

[RabbitJockey]

here was andy2's old thread, he eventually ditched the aaz and built an insane compounded tdi with custom cast iron head, i think maybe alot of andys problems were from too small of turbos or simply too old of turbos or maybe too restrictive of manifolds.  who knows since he moved on to another platform

http://www.vwdiesel.net/forum/index.php?topic=2538;

[jimbobpolo]

My gtd pump isn't standard... I had it built up by a Bosch diesel specialist and setup for 20psi with double the amount of stock fuelling..
I think 160 whp is attainable and I'm looking to make it reliable power as its my daily driver.

Shame none of those pics in that thread work

I'm trying to use the k14 and k24 as I already have them to hand

[Alcaid]

Double of stock fuelling is in the region of 80cc. Not enough for your power goal... But hey, build it and give it a go. Pump can (and needs to) be upgraded later on

[jimbobpolo]

I have another gtd pump which I'm planning on sending over to giles at performance diesel, when funds allow!
I'm wondering if I should enlarge the wg on the k14, I'm using a 110hp peugeot k14 not the Vw unit....

[RabbitJockey]

K24 will not make your goal as the large turbo, I can't say much about your k14 I don't know anything about its size. If you are staying cheap the k24 as the small turbo would do ok, although I'd prefer the vw t3 over it because it has a larger exhaust side.  then for the large turbo you could something like a 60 trim t3 with .48 ar exhausy or basically any medium sized turbo that flows atleast 250 hp worth of air.  That'd be a cheap route can't guarantee it would work well but itd be a good start

[Alcaid]

K24 will not make your goal as the large turbo

True

120whp as maximum have I seen in dynos with the K24 or T3 1.6TD turbos. Compounding does not help the LP turbo flow more...

[RabbitJockey]

Compounding does not help the LP turbo flow more...

As in k24 as the larger turbo will not flow anymore?

I say vw t3 would be a good cheap option but my over al opinion of that turbo is that it was a turd, I believe at the time it was Garrett's smallest turbo they could make but only a few years later they started producing the t2 stuff, smaller and faster spooling more efficient and flowed as much air as most t3 series.  Anyways it has a narrow band of poor efficiency boooo. But it works haha

[Alcaid]

As in k24 as the larger turbo will not flow anymore?

Correct, compounding gives you more boost but not more air mass than what the biggest turbo can flow by itself. Well maybe a small amount more since you can run the big turbo with a lower pressure ratio and the compressor map might give you some extra there instead of running as a single turbo with a higher pressure ratio and being limited by rev limitation or choke.