# 1.8t twin turbo project



## abacorrado (Apr 5, 2005)

http://forums.audiworld.com/showthread.php?t=2814265 
what do you guys think?


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## TBT-Syncro (Apr 28, 2001)

all aboard the fail train.


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## abacorrado (Apr 5, 2005)

nice comment, could be a fail but how about a little explaination? otherwise your just jerkin.


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## AJmustDIE (Dec 22, 2010)

Otherwise known as a Compound Turbo Setup, actually kind of interesting.. because I don't think I've ever came across somebody doing it on our cars, other than a few VR's. 

Totally braced for fail when I opened this thread.. but now I'm enthused. :thumbup:


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## Pat @ Pitt Soundworks (Nov 14, 2008)

Only problem using a ko3 in a compound set up is the wastegate is not big enough. Even ported, there will be too much pressure in the main exhaust manifold. If he made a custom manifold with an external gate then it would be alright.

That other poster in that thread is thinking of a sequential set up. For compound, the larger unit feeds in to the smaller unit with no bypass valves or dual intakes or anything like that. Turbo 1 exhaust and wastegate exhaust feed directly in to turbo 2.


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## abacorrado (Apr 5, 2005)

Pat @ Pitt Soundworks said:


> Only problem using a ko3 in a compound set up is the wastegate is not big enough. Even ported, there will be too much pressure in the main exhaust manifold. If he made a custom manifold with an external gate then it would be alright.
> 
> That other poster in that thread is thinking of a sequential set up. For compound, the larger unit feeds in to the smaller unit with no bypass valves or dual intakes or anything like that. Turbo 1 exhaust and wastegate exhaust feed directly in to turbo 2.


 So if you had say a hybrid ko4 feeding into a ko3s, with an external wastegate at the pipe feeding into the ko3s, would you still have the quick spool of the ko3s, with the 400 hp potential of both turbos? The second turbo would be mounted at the muffler location btw. I hate lag.


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## Mr Roo (Aug 8, 2006)

A few years back i emailed back and forth with a guy that did a compound turbo on a ford focus. Do remember the turbos he used, but set it up so a diverter valve switched to the larger turbo. He said it much quicker than the one turbo set up, but was done more for a conversation piece. It was cool looking at the turbos plumbed together under the hood. If done correctly, this certainly has benefits. I saw a few of these set ups on a bunch of drag race diesels recently. Those turbos were just big feeding monster size!!!!!!!


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## TBT-Syncro (Apr 28, 2001)

abacorrado said:


> nice comment, could be a fail but how about a little explaination? otherwise your just jerkin.


 you asked us what we think. 

prove me wrong. :beer:


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## abacorrado (Apr 5, 2005)

Its not my project. And the comment was definitely jackwagenesque.


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## Pat @ Pitt Soundworks (Nov 14, 2008)

I think a k04-020 non-hybrid would probably be about right, but you'd end up around 40psi with each charger running a 2.0 pressure ratio. You'd need to run the both turbos at a 2.0 pressure ratio (about 14 psi boost) to get full flow and compound set-ups multiply pressure ratios.


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## Dowski12 (Nov 2, 2011)

I know this thread is kinda old but for all who say this is a fail I can assure you its not. Im currently have a built 01 Audi TT225Q with a compound turbo setup that makes 518awhp and spoosl at 1800rpm. I usied my stock K04-022 that I had made into an external wastegate with better internals, and a custom made 64mm Garrett turbo. Did all this on a 2.0 Stroker 9:1, AEB port and polished head w/ IE drag cams, oversized Supertech valves, IE titanium springs/retainers, SEM intake mani w/ 80mm TB, custom exhaust manifold, tial 38mm wastegates...and so much more. All in all I'm into it about $12,000. I could have done it cheaper but this doubles as my daily driver so it has to be reliable. Was it worth it? Hell yeah...I have a daily driver that produces 518awhp and spools a 1800rpm, cant beat that. If you have the money, DO IT.


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## Big_Tom (Aug 19, 2007)

Dowski12 said:


> I know this thread is kinda old but for all who say this is a fail I can assure you its not. I currently have an 01 Audi TT225Q with a compound turbo setup making 518awhp and it spools at 1800rpm. I used my stock K04-022 that I had made into an external wastegate with better internals, and a custom made 64mm Garrett turbo. Did all this on a 2.0 Stroker 9:1, AEB port and polished head w/ IE drag cams, oversized Supertech valves, IE titanium springs/retainers, SEM intake mani w/ 80mm TB, custom exhaust manifold, tial 38mm wastegates...and so much more. All in all I'm into it about $12,000. I could have done it for cheaper but this doubles as my daily driver so it has to be reliable. Was it worth it? Hell yeah...I have a daily driver that produces 518awhp and spools a 1800rpm, cant beat that. If you have the money, DO IT.


:bs: pics or it didnt happen


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## DIRTYJERZ201 (May 28, 2009)

who the f*u*c*k use's audi worldopcorn:


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## abacorrado (Apr 5, 2005)

Hey dow, on your setup, do you have the bigger turbo feeding the ko4. And do have any pics. My other options are nos or a 4kw electric turbo. Thanks for sharing your project.


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## GTijoejoe (Oct 6, 2001)

DIRTYJERZ201 said:


> who the f*u*c*k use's audi worldopcorn:


I think ppl only on the west coast or Canadians? 

I too was like whaaaaaaaaaaaaa? twin turbo? those arn't twins :laugh:


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## Dowski12 (Nov 2, 2011)

The K04 is mounted on the exhaust mani and then feeds into the larger turbo. The larger one feeds back into the K04 and then into the engine. My exhaust manifold is a top mount behind the motor and the larger turbo is mounted on the driver side of the engine bay behind the battery. I originally was going to hide the second turbo underneath the top mount mani, but the erge to show off got the best of me. I have pics of the entire build, and I am going to do a step by step build post...which forum would you like it on being as that I am not on the West Coast and not from Canada:laugh:


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## Big_Tom (Aug 19, 2007)

Dowski12 said:


> The K04 is mounted on the exhaust mani and then feeds into the larger turbo. The larger one feeds back into the K04 and then into the engine. My exhaust manifold is a top mount behind the motor and the larger turbo is mounted on the driver side of the engine bay behind the battery. I originally was going to hide the second turbo underneath the top mount mani, but the erge to show off got the best of me. I have pics of the entire build, and I am going to do a step by step build post...which forum would you like it on being as that I am not on the West Coast and not from Canada:laugh:


post some pics of your car! i must have missed the thread if u have one


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## GTijoejoe (Oct 6, 2001)

Big_Tom said:


> post some pics of your car! i must have missed the thread if u have one


he's not asking, he's telling


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## ExtremeVR6 (Sep 6, 2001)

A compound setup with two of the same turbos set to a pressure ratio of 2:1 will result in approx. 60psi... A pr of 2 doubles ambient pressure with is 14.7... The first will add 14.7psi to ambiant pressure resulting in 29.4psi absolute... Since that is ten compressed to a pressure ratio of 2:1 you double it... 58.8psi absolute. 

More often than not a supercharger and turbocharger are used for compound systems. Since you're using the waste from the engine to feed the supercharger which is a source of parasitic loss, it theoretically possible to get pretty close to a mechanical efficientcy of 100%. Obviously you cant actually achieve 100%. If the right cooling and fueling is done there's some great power in this. 

Tractor pull vehicles will use up to triple compounded turbos to achieve rediculous torque as well...

Just some information


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## Pat @ Pitt Soundworks (Nov 14, 2008)

40, not 60. Multiply base pressure ratios.


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## ExtremeVR6 (Sep 6, 2001)

How does two times 29.8 equal 40? The pressure ratio is applied to the absolute pressure entering the intake which is the charged air from the compressor outlet...


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## Pat @ Pitt Soundworks (Nov 14, 2008)

turbo 1 pr = 2
turbo 2 pr = 2

2*2=4

4*14.7-14.7=44 at sea level

edit: you're forgetting to subtract atmospheric pressure from total pressure to get boost pressure.

edit again: yes, ~60 absolute. The way you had it written in the first post makes it looks like you're talking about gauge pressure.


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## sdezego (Apr 23, 2004)

OT, but does anyone know what that intercooler is from? Looks like it could be some SAAB or Volvo, but the ones I have seen in the past do not have down facing inlets and outlets (or up depending on how you look at it  ).


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## Big_Tom (Aug 19, 2007)

GTijoejoe said:


> he's not asking, he's telling


:laugh: :beer:


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## ExtremeVR6 (Sep 6, 2001)

Re: boost pressure vs absolute... Okay ya got a point there... If you're considering the resultant pressure after the static compression ratio of the engine it's the 60psi you'd consider... But I'll concede ... 40 something depending on distance above sea level...


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