Difference between A6 and S6 4.2 V8
11-18-2015, 10:41 PM
#1
AudiWorld Newcomer
Thread Starter
Join Date: Sep 2014
Location: Brisbane, Australia
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Difference between A6 and S6 4.2 V8
Hi all,
Wondering if someone might be able to clarify something for me? I have an C5 S6 with a dead transmission. I have since bought a wrecked C5 A6 for the 5HP24A transmission. It has the 4.2 V8 in it and I am aware of some differences being 1) Intake Manifold, 2) Extra idler pully, 3) Lower compression, 4) Lower revs which means 5) Lower power output...
I would like to swap the complete engine and trans from the A6 into my S6 and use the S6 manifold and computer if it will work as the A6 has lower K's and I know how much work it was to join the engine and trans back together last time I took the transmission out...
My thoughts are if the only real mechanical change is the intake I can swap that and if compression ratio and revs are controlled by the ECU, I shouldnt have a problem?
Is there anything that would be stopping me from doing this? Eg; pistons, idler pulley makes a difference, etc?
Any input would be appreciated!
Thanks in advance.
Regards
Scott
Wondering if someone might be able to clarify something for me? I have an C5 S6 with a dead transmission. I have since bought a wrecked C5 A6 for the 5HP24A transmission. It has the 4.2 V8 in it and I am aware of some differences being 1) Intake Manifold, 2) Extra idler pully, 3) Lower compression, 4) Lower revs which means 5) Lower power output...
I would like to swap the complete engine and trans from the A6 into my S6 and use the S6 manifold and computer if it will work as the A6 has lower K's and I know how much work it was to join the engine and trans back together last time I took the transmission out...
My thoughts are if the only real mechanical change is the intake I can swap that and if compression ratio and revs are controlled by the ECU, I shouldnt have a problem?
Is there anything that would be stopping me from doing this? Eg; pistons, idler pulley makes a difference, etc?
Any input would be appreciated!
Thanks in advance.
Regards
Scott
11-23-2015, 03:34 PM
#3
Compression ratio is mechanical and equals volume of a compression chamber at bottom of stroke divided by volume of chamber at top of stroke, e.g. if the volume of the chamber is 0.525 liters at the bottom and 0.05 liters at the top, the ratio is ratio is 10.5:1.
This ratio might be coded into the ECU(buried in the weeds), but why not just use the ECU from the donor. OP did not specify that donor car was Avant, so maybe not an S6. Hunch that manifold might be fine, but I think a lot to monkey with on the S6 ECU to match it. Fuel and spark curve map is probably not a match for the non-S6 engine. Can nefmoto do this?
FYI I have a 2.7, so my experience with 4.2's is limited to Touareg.
How come the cork valve cover seal on my mother's 59 Borgward never leaked, but today it seems all VAG valve cover gaskets all leak? If they can screw with the emissions protocol, why can't they stop oil leaks?
This ratio might be coded into the ECU(buried in the weeds), but why not just use the ECU from the donor. OP did not specify that donor car was Avant, so maybe not an S6. Hunch that manifold might be fine, but I think a lot to monkey with on the S6 ECU to match it. Fuel and spark curve map is probably not a match for the non-S6 engine. Can nefmoto do this?
FYI I have a 2.7, so my experience with 4.2's is limited to Touareg.
How come the cork valve cover seal on my mother's 59 Borgward never leaked, but today it seems all VAG valve cover gaskets all leak? If they can screw with the emissions protocol, why can't they stop oil leaks?
11-23-2015, 04:40 PM
#4
AudiWorld Super User
My 2k4.2 A6Q never had cam cover leak in 190K miles.
Compression ratio is mechanical and equals volume of a compression chamber at bottom of stroke divided by volume of chamber at top of stroke, e.g. if the volume of the chamber is 0.525 liters at the bottom and 0.05 liters at the top, the ratio is ratio is 10.5:1.
This ratio might be coded into the ECU(buried in the weeds), but why not just use the ECU from the donor. OP did not specify that donor car was Avant, so maybe not an S6. Hunch that manifold might be fine, but I think a lot to monkey with on the S6 ECU to match it. Fuel and spark curve map is probably not a match for the non-S6 engine. Can nefmoto do this?
FYI I have a 2.7, so my experience with 4.2's is limited to Touareg.
How come the cork valve cover seal on my mother's 59 Borgward never leaked, but today it seems all VAG valve cover gaskets all leak? If they can screw with the emissions protocol, why can't they stop oil leaks?
This ratio might be coded into the ECU(buried in the weeds), but why not just use the ECU from the donor. OP did not specify that donor car was Avant, so maybe not an S6. Hunch that manifold might be fine, but I think a lot to monkey with on the S6 ECU to match it. Fuel and spark curve map is probably not a match for the non-S6 engine. Can nefmoto do this?
FYI I have a 2.7, so my experience with 4.2's is limited to Touareg.
How come the cork valve cover seal on my mother's 59 Borgward never leaked, but today it seems all VAG valve cover gaskets all leak? If they can screw with the emissions protocol, why can't they stop oil leaks?
I've never had the cam covers off on either car as well..
Sold the A6 a year ago.
Used synthetic oil on all of them.
I've come to the conclusion that cam cover leaks are a function of overheat (if the covers get warped), poor/incorrect installation or inferior aftermarket material, or restricted/plugged PCV systems.
11-24-2015, 06:45 AM
#5
No A6 2.7 leaks for 218k miles, but 4.2 leaking again
Also, neither does my 02S6 in 135K miles.
I've never had the cam covers off on either car as well..
Sold the A6 a year ago.
Used synthetic oil on all of them.
I've come to the conclusion that cam cover leaks are a function of overheat (if the covers get warped), poor/incorrect installation or inferior aftermarket material, or restricted/plugged PCV systems.
I've never had the cam covers off on either car as well..
Sold the A6 a year ago.
Used synthetic oil on all of them.
I've come to the conclusion that cam cover leaks are a function of overheat (if the covers get warped), poor/incorrect installation or inferior aftermarket material, or restricted/plugged PCV systems.
I put new valve gaskets and cam seals on 2.7a6 when I did all 3 timing belt, waterpump, etc. services. It has never leaked, before or after. DFWAB perhaps.
Dealer did valve cover and cam seals on wife's 4.2 Treg at about 90k to stop minor leak that was getting worse. Before that, tried DIY cleaning on PCV when first leak started. Broke tabs, so put on a new one. Old one was in good shape.
Bank 1 rear starting to weep again at 115k. Never overheated and synth oil for all changes. Thought tech at dealer was pretty good. Maybe DIY this time and check cover for warp.
Thread
Thread Starter
Forum
Replies
Last Post
kenyel
A6 / S6 (C5 Platform) Discussion
13
12-12-2010 07:32 AM
DrewT55
A6 / S6 (C6 Platform) Discussion
3
10-31-2005 05:53 PM
zoomee
A6 / S6 (C5 Platform) Discussion
7
09-15-2003 06:42 AM