[urq] AAN or 3B swap

[Steve Mills]

Again, I'm not saying the increased intake tract length is a huge problem. However, the engineer in me hates the 3B/ABY/ADU packaging both in terms of intake tract length/volume and how the compressed charge is routed back over to the hot side and passed over the exhaust manifold only to be rerouted around the back of the engine to the cold side. Like most designs, I'm sure the tradeoffs were made for sound reasons, but my preferred solution is still the SQ-style intake manifold, which eliminates both issues.  

Doesn't mean the 3B and it's variants won't run great and transform an UrQ- it's just my preference. 

Steve 

> On Feb 3, 2014, at 7:55 AM, "Martin Pajak" <martin at quattro.ca> wrote:
> 
> For what its worth my old '85 with 3B and a huge 944 turbo intercooler had
> no issues building instant boost (with stock K24).
> Throttle responce was excellent as well.
> 
> HTH
> Martin Pajak
> 
> http://www.quattro.ca 
> 
> 1981 VW Scirocco, all original
> 1982 Audi Ur-quattro, SQ project
> 1983 Audi 80 quattro, Euro 2-Tür
> 1993 Audi 90 CS quattro, 2.5 TDI with 6-speed
> 1993 Audi 80 quattro Avant, 2.5 TDI with 6-speed
> 1994 Audi S2 Avant, stock
> 
> 
> -----Original Message-----
> From: urq-bounces at audifans.com [mailto:urq-bounces at audifans.com] On Behalf
> Of David Glubrecht
> Sent: 3-Feb-14 00:36
> To: s.b.mills at gmail.com
> Cc: urq at audifans.com
> Subject: Re: [urq] AAN or 3B swap
> 
> That is what I thought the concern was, but being as how a turbo is not a
> positive displacement devise, I don't see how it could have much of an
> effect.  I suppose it could affect where the turbo is in the compressor map
> while spooling up, but in practice (in an extreme case) Huge volume and old
> school turbo motor (MC) that is known to have significant lag, I do not see
> any effect.   I mean this vehicle really does have about the same post
> compressor intake volume as a remote mount turbo.
> Perhaps it might have a noticeable effect on a newer motor with minimal
> lag.
> 
> This is somewhat academic, as I can't/won't change this vehicle and will try
> to minimize the 3B UrQ anyway.  
> But I do want to understand the significance of this.
> 
> 
>  David Glubrecht
> 
> 
> 
> 
> Intake tract length is a major factor in turbo lag. The turbo has to work to
> compress and maintain pressure on the intake volume, and the larger it is
> the longer it takes. It's not the end of the world, but it's desirable to
> minimize it. 
> On Feb 2, 2014, at 4:13 PM, David Glubrecht <daveglu at hotmail.com> wrote:
> 
> 
> 
> 
> Another 3B swap here.  Will definitely be doing the 3B as I have two of
> those and no AAN's.
> I also plan on going stand alone with the adaptronics 1280 and this will run
> COP.
> While I feel free and able to modify mostly anything I want, intake track
> length is only a concern due to room constraints.
> I was concerned a little on my last project about intake track length
> (volume) as it is very long/large.
> This is a MC running CIS with 3' cis to turbo, 2' turbo to intercooler,
> large intercooler, 3.5' intercooler to intake. All plumbing is ~2.75id.
> I have not seen anything with this much post airflow meter volume and was
> concerned, but I have not noticed any adverse effects.
> What is the concern with intake volume?  
> 
> 
>  David Glubrecht
> 
> 
>> I do believe the AAN is a better engine, but the AAN can require a lot of
> fabrication to install. I personally would go with an ABY (late S3) or ADU
> (RS2) sourced from Europe, or installing an SQ style intake on the AAN that
> moves the throttle body to the front of the engine. This should minimize the
> required modifications and also minimize the length of the intake path. 
> 
>                         
>                         
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