# c5 2.7 swap advice needed



## s4logic (Sep 9, 2007)

i have an c5 auto , 2.8 , wanna put an 2.7 and manual trans and desperatly need some direction and advice in how too go about doing this .... thanks !


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## Snowhere (Jul 27, 2007)

*Re: c5 2.7 swap advice needed (s4logic)*

I hate to say it, but it is not worth it unless it is an Avant, and even then, it is dubious.
It will be way easier, and cheaper, to just sell it and buy a C5 with the 2.7TT and a six speed already in it. 
You do know they made them that way in the sedan?

On the Avant side, you can get a S6 Avant with the 4.2 V8. 
Or you can get an Allroad, with the 2.7TT but the six speed is rare, but they are out there.
I would love the six speed swap myself, and that is a lot easier then swapping everything.

If you just happen to have a complete donor car, 2.7TT and the six speed, it is possible, but you need everything!
Complete wiring harnesses and all. Then there is the labor factor. 
Once again, with a complete car and lots of time on your hands, and you could do it. 
But in the end, you will have a lot less headaches if you just buy it assembled from the factory. 
You pretty much need to strip the recipient car down to a bare shell, then do the same with your donor and swap them. 

I know of one person on audizine that I believe is trying this swap, but I do not remember his sign in and I have not seen a post in a long time. 

If you do go ahead with it, I will watch it and help where I can. However you will be figuring 
most stuff on your own, as I do not know of any one that has accomplished it. 
Most of us would love to watch, and cheer you on. 
You just need to be fully informed so you know what you are getting into. http://****************.com/smile/emthup.gif

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_Modified by Snowhere at 9:28 PM 3-12-2009_


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## MikkiJayne (Jan 1, 2007)

*FV-QR*

I hate to say it, but if you have to ask how you probably shouldn't be doing a swap of this magnitude.
I have no fear of taking on seemingly impossible projects, but even I would draw the line at this one since you can already buy a car of the spec you are wanting to make. The potential for complications later down the line (mostly electronic) is huge given the complexity and sheer volume of what you would have to swap and/or fiddle with.
I'm a big fan of not re-inventing the wheel, and unless the 2.8 you have has some kind of sentimental value, or unique bodywork or something I would just buy a factory 2.7T 6-speed - rare as they may be.
But, as Snowhere said - if you do try it then I will offer help where I can and enjoy looking at the pics as the chaos ensues http://****************.com/smile/emthup.gif








Mikki x


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## s4logic (Sep 9, 2007)

*Re: c5 2.7 swap advice needed (s4logic)*

thanks alot guys but ill take the risk and oppertunity of trial and error .... i have an idear but still need a lil more info .. pics and all info will be posted again thanks.....


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## Snowhere (Jul 27, 2007)

*Re: c5 2.7 swap advice needed (s4logic)*

By all means, go for it if you are determined. I just wanted you to know what you are getting into. Do you have a complete donor car?


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## s4logic (Sep 9, 2007)

*Re: c5 2.7 swap advice needed (Snowhere)*

yes i do an s4


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## MikkiJayne (Jan 1, 2007)

*FV-QR*

Now the project just took on a whole new level of scariness








How close is a B5 A4 to a C5 A6? I would say vaguely, but probably not a straight swap....?
Do you have both Bentleys for the wiring diagrams? I'd start there and see if they are the same (or similar). Engine mounts, axles, plumbing (water, air, engine & trans oil) will likely be different.


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## s4logic (Sep 9, 2007)

*Re: FV-QR (MikkiJayne)*

ats a good idea , but in all s4/a6 b5/c5 is the same software


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## GLS-S4 (Jun 6, 2005)

*Re: FV-QR (s4logic)*


_Quote, originally posted by *s4logic* »_ats a good idea , but in all s4/a6 b5/c5 is the same software

Which software?
IIRC B5 C5 ECU software is different.


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## MikkiJayne (Jan 1, 2007)

*FV-QR*

I don't thing the software really makes much difference - it's the wiring harnesses that would concern me. I know for one thing that although the clusters in the two cars are physically the same shape and size the electrical connections are different. I checked today in the junkyard while I was stripping the dash from a B5 1.8T and compared it to a C5 1.8T. Assuming that your models got immobilisers then you'll have to swap clusters to match the S4 ecu. You'd have to swap the transponder in the key too, but then you'll have to reprogram the convenience module in the C5 to match the new key.
Maybe worth checking if any of the chip tuners can do an immo defeat on the S4? If so then you might be able to keep and reprogram the C5 cluster. 
Given the way these things are built I would be spending some considerable time with the wiring diagrams side by side comparing that little bunch of connectors in the rain tray where the ECU sits. You might get lucky and find that the connections are the same, so you could just swap the motor harness right over.
I wouldn't bet any of my own money on it, but I'll keep my internet fingers crossed for you















Mikki x


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## Snowhere (Jul 27, 2007)

*Re: FV-QR (MikkiJayne)*








We never got C5s with the 1.8T. I am assuming the 2.8 is different,

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so a COMPLETE wiring harness swap will be necessary no mater what. I would love to be proven wrong, but I would be willing to bet money on it.
With the size difference from an A4 to a A6, I am assuming that swapping the dashes would take some fabrication. It will be easier to swap clusters and doing a little fabrication to make it fit right. Have you compared them side to side MikkiJayne? I am just wondering if they are truly the same size or slightly different?


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## MikkiJayne (Jan 1, 2007)

*Re: FV-QR (Snowhere)*

No I was just using the 1.8T as an example. If thats different between B5 and C5 I bet all the other variants will be too.
The dash is definitely different, and will not swap over. The basic layout is the same, but the C5 is larger and is mounted and constructed differently. The cluster will physically swap over, but the wiring connections are different. I wouldn't like to even think about swapping an B5 harness in to a C5. The B5 doesn't have a convenience module for starters!
If I were being _paid _to do this (ie running away screaming







wasn't an option), I would definitely be looking to only go as far as the rain-tray connections with the 2.7 wiring, and grafting or adapting from there. There's no way I would try and swap the whole lot over. It just wouldn't work. IMO.


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## TheBurninator (Jan 7, 2009)

*FV-QR*


_Quote, originally posted by *Snowhere* »_







We never got C5s with the 1.8T. I am assuming the 2.8 is different,

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Image uploading. Refresh page to view








so a COMPLETE wiring harness swap will be necessary no mater what. I would love to be proven wrong, but I would be willing to bet money on it.
With the size difference from an A4 to a A6, I am assuming that swapping the dashes would take some fabrication. It will be easier to swap clusters and doing a little fabrication to make it fit right. Have you compared them side to side MikkiJayne? I am just wondering if they are truly the same size or slightly different? 



The wiring harness between the 2.8 and the 2.7 are completely different. There are many more sensors on the 2.7


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## s4logic (Sep 9, 2007)

*Re: FV-QR (TheBurninator)*

its different because one is n/a and the other is boosted.. the base of the both motors are the same ,internals are different . the 2.8 heads can be uesd on the 2.7 block for better flow ,as of the rs4 is basically the same , but inn all am asking arround some tinning shops to seee whats their input on this ! but you all know am gonna do it. what i'v noticed , the c4 and b5 has the same front subframe! nothing big though


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