Has anyone discussed/done a 2.7t swap into a 4.2 widebody?
12-21-2009, 12:26 AM
#1
AudiWorld Senior Member
Thread Starter
Join Date: Aug 2006
Location: UT
Posts: 1,013
Likes: 0
Received 0 Likes
on
0 Posts
Has anyone discussed/done a 2.7t swap into a 4.2 widebody?
I did some searching around and didn't even find it discussed in the past, has anyone swapped a 2.7t into the 4.2 widebody A6? I would also swap in an 01E 6-speed with it, and I'm aware of what's involved with that swap, but I've seen nothing about the motor swap. I assume the subframes are different? Any thoughts on what's involved?
12-21-2009, 10:54 AM
#4
AudiWorld Senior Member
Thread Starter
Join Date: Aug 2006
Location: UT
Posts: 1,013
Likes: 0
Received 0 Likes
on
0 Posts
My man, questions for you...
-Rear diff (I heard that some of the 4.2's actually already use the same code rear diff as the 2.7's, with the 4.11 final drive)?
-Driveline
-Halfshafts
Actually, since you did a tip, all of those would be different than what I'm doing anywho. What did you do for the wiring harness? Did you need to swap in the entire 2.7t subframe (how did you work the motor mounts?)? Do you by chance have any pics of the engine bay from the top? Is there noticably more room between the rear of the engine and the firewall? Was there any issue with the shorter 2.7t motor not fitting the snub mount in the front carrier or anything like that? Looking forward to your input!
12-21-2009, 12:13 PM
#5
Audiworld Junior Member
Join Date: Sep 2009
Posts: 34
Likes: 0
Received 0 Likes
on
0 Posts
Happy to share my experiences. See below to the answers.
Did you use the following parts from a 2.7t car-
-Rear diff (I heard that some of the 4.2's actually already use the same code rear diff as the 2.7's, with the 4.11 final drive)?
I used the rear diff from the 2.7. Yes the parts are identical but the gearing is completely different. The front and rear must have the same ratios and the 4.2 has I think 2.73 where as the 2.7T has 3.87. This gear ratio is the same in the front and rear diff so you can't interchange them. I was thinking about removing the front and rear diffs from the 4.2 and transplating them as I wanted greated fuel efficency for long trips but though that the TCU might be coded for that specific ratios.
-Driveline
I used the entire driveline from the 2.7T including the half shafts, driveshaft and rear diff.
-Halfshafts
Actually, since you did a tip, all of those would be different than what I'm doing anywho.
You would still need to replace the full drivetrain.
What did you do for the wiring harness?
I used the original interior wiring harness from my 2000 A6 4.2. For the engine harness, my engine was from a 01 A6 and so I used that harness. The wiring still needs attention for the 5 connectors that goes into the interior. I bought a Bentley and will bee looking at what differences there are. Initially, I tried using the original ECU from the A6 which was a 4B0 907 551Q which had IMMO 3 and apparently teh 01 and up has IMMO 3 which caused a slight problem everytime I tried to start up the car. Solved that with an APR chip and some S4 Stage 2+ tuning.
Did you need to swap in the entire 2.7t subframe (how did you work the motor mounts?)?
This part I thought was going to be the biggest nightmare of all. In fact, it was the simpliest things of the whole swap. I took the motor mounts from the 2.7T and used them with the 4.2 sub frame. You have to use the 4.2 because the way the subframe bolts to the body is differnt than the 2.7T The holes are wider apart on the 4.2 probably to accomodate the bigger engine. Other than that, the way teh engine and transmission sits in the frame is identical. You'll notice that the transmission mounts are larger ont he 4.2 but the subframe is recessed so the mounting point is identical to the 2.7T
Do you by chance have any pics of the engine bay from the top? Is there noticably more room between the rear of the engine and the firewall?
Because the engine sits in almost the same position in the subframe, the distance betweent he engine and the firewall is very close to the A6 2.7T. However the front is another story. There is a much larger gap betweenthe carrier and the engine. I could probably do the timing belt service without removing the carrier now!
Was there any issue with the shorter 2.7t motor not fitting the snub mount in the front carrier or anything like that?
No way will the snub mount fit. Right now I'm not using it but I will have to fab up a bracket to make it work. I may use the 4.2's front mount plate to make it work but since I will be installing a FMIC, I may have to cut that off the rail. I really don't want to so I may just end up having a custome IC pipe made to accomodate the constraints.
Some final points. Going 6 speed will run you into another issue to think about. When I was connecting the shift cable from the multi-function switch, the 2.7T cable did not bolt up as it should have. I am not 100% sure but there may have been an adapter to make up the difference that I probably lost at some point. If this is the case, then you will have no problem with the shifter linkage. However you may need to fab up something if it doesn't.
As for the carrier, I used the original 4.2 front end including radiator and carrier. You will to make a custom upper rad hose as bother upper and lower are on the passenger side on the 4.2 radiator. I much prefer to use the 4.2 radiator because its huge compared to the 2.7 one and after a hard run, its still maintains 90 degree temperatures even without the mechanical fan. (I took mine off and have an electrical fan similar to the VAST kit that I will be putting in soon)
Happy Holidays!
Looking forward to your input!
-Rear diff (I heard that some of the 4.2's actually already use the same code rear diff as the 2.7's, with the 4.11 final drive)?
I used the rear diff from the 2.7. Yes the parts are identical but the gearing is completely different. The front and rear must have the same ratios and the 4.2 has I think 2.73 where as the 2.7T has 3.87. This gear ratio is the same in the front and rear diff so you can't interchange them. I was thinking about removing the front and rear diffs from the 4.2 and transplating them as I wanted greated fuel efficency for long trips but though that the TCU might be coded for that specific ratios.
-Driveline
I used the entire driveline from the 2.7T including the half shafts, driveshaft and rear diff.
-Halfshafts
Actually, since you did a tip, all of those would be different than what I'm doing anywho.
You would still need to replace the full drivetrain.
What did you do for the wiring harness?
I used the original interior wiring harness from my 2000 A6 4.2. For the engine harness, my engine was from a 01 A6 and so I used that harness. The wiring still needs attention for the 5 connectors that goes into the interior. I bought a Bentley and will bee looking at what differences there are. Initially, I tried using the original ECU from the A6 which was a 4B0 907 551Q which had IMMO 3 and apparently teh 01 and up has IMMO 3 which caused a slight problem everytime I tried to start up the car. Solved that with an APR chip and some S4 Stage 2+ tuning.
Did you need to swap in the entire 2.7t subframe (how did you work the motor mounts?)?
This part I thought was going to be the biggest nightmare of all. In fact, it was the simpliest things of the whole swap. I took the motor mounts from the 2.7T and used them with the 4.2 sub frame. You have to use the 4.2 because the way the subframe bolts to the body is differnt than the 2.7T The holes are wider apart on the 4.2 probably to accomodate the bigger engine. Other than that, the way teh engine and transmission sits in the frame is identical. You'll notice that the transmission mounts are larger ont he 4.2 but the subframe is recessed so the mounting point is identical to the 2.7T
Do you by chance have any pics of the engine bay from the top? Is there noticably more room between the rear of the engine and the firewall?
Because the engine sits in almost the same position in the subframe, the distance betweent he engine and the firewall is very close to the A6 2.7T. However the front is another story. There is a much larger gap betweenthe carrier and the engine. I could probably do the timing belt service without removing the carrier now!
Was there any issue with the shorter 2.7t motor not fitting the snub mount in the front carrier or anything like that?
No way will the snub mount fit. Right now I'm not using it but I will have to fab up a bracket to make it work. I may use the 4.2's front mount plate to make it work but since I will be installing a FMIC, I may have to cut that off the rail. I really don't want to so I may just end up having a custome IC pipe made to accomodate the constraints.
Some final points. Going 6 speed will run you into another issue to think about. When I was connecting the shift cable from the multi-function switch, the 2.7T cable did not bolt up as it should have. I am not 100% sure but there may have been an adapter to make up the difference that I probably lost at some point. If this is the case, then you will have no problem with the shifter linkage. However you may need to fab up something if it doesn't.
As for the carrier, I used the original 4.2 front end including radiator and carrier. You will to make a custom upper rad hose as bother upper and lower are on the passenger side on the 4.2 radiator. I much prefer to use the 4.2 radiator because its huge compared to the 2.7 one and after a hard run, its still maintains 90 degree temperatures even without the mechanical fan. (I took mine off and have an electrical fan similar to the VAST kit that I will be putting in soon)
Happy Holidays!
Looking forward to your input!
Trending Topics
12-21-2009, 11:24 PM
#8
AudiWorld Senior Member
Thread Starter
Join Date: Aug 2006
Location: UT
Posts: 1,013
Likes: 0
Received 0 Likes
on
0 Posts
It would be a less involved, but it wouldn't be worth it to me, if I were you. The whole thing about the swap I'm considering is the fact that they don't have a manual transmission widebody 4.2 the US, nor a manual RS6. It would be like getting a manual tranny RS6. If I were in your situ and I really wanted a 2.7t and manual, I'd just save myself the headache and buy one already done (unless you've got crazy unique body modifications or something.) Just my opinion.
12-22-2009, 06:14 AM
#9
AudiWorld Senior Member
So why not just swap the transmission from the 2.7T into the 4.2? Order all the turbo and management parts from ebay.de and lower the engine's compression and you'll have some sort of 450hp v8 6-speed awd wide body car. I'm hoping to do something like that - the transmission, all the (probably undersized) turbo parts, and the rs6 intake manifold are either here or on the way, so I'll keep you updated as to how it pans out. Seems like the only benefit to the 2.7T is that it's already turbocharged.
12-22-2009, 06:48 AM
#10
AudiWorld Senior Member
Thread Starter
Join Date: Aug 2006
Location: UT
Posts: 1,013
Likes: 0
Received 0 Likes
on
0 Posts
Well, that would be way more expensive (and more difficult) for less power...
So why not just swap the transmission from the 2.7T into the 4.2? Order all the turbo and management parts from ebay.de and lower the engine's compression and you'll have some sort of 450hp v8 6-speed awd wide body car. I'm hoping to do something like that - the transmission, all the (probably undersized) turbo parts, and the rs6 intake manifold are either here or on the way, so I'll keep you updated as to how it pans out. Seems like the only benefit to the 2.7T is that it's already turbocharged.
I don't mean this to be a downer to you or your idea in any way; if you have the means and desire to turbo your 4.2, all the more power to you! It'll be sick!