S4 4.2 aka A8 4.2???

[308slegs]

Time for all ye wisemen to set it straight... So yesterday I ran into an Audi owner who knew about my engine problem. He said "why don't you just look for an A8 4.2? They are exactly the same engine as in the S4." I was dazed and confused. Is this true? I googled it and checked wiki. The stats are the same... But wiki can be edited by anyone I believe. So I tried searching the forum here for the answer, but came up with nothing. What do you guys know about this??

[S4orgy]

No! Smh

[S4orgy]

You can prob use some of the a8 parts but the timing is up front and belt driven if im not mistaken

[ddillenger]

I believe the A8's that had timing chains were FSI. The 04/05 allroad 4.2 however is the same, just swap the intake and accessories.

[dparm]

The 4.2L 40V V8 has many variants. They are the same basic engine but that doesn't mean they're completely interchangeable. Below is data from ETKA.


BBK: Audi B6 S4, Audi B7 S4
BHF: Audi B6 S4, Audi B7 S4
BAT: Audi A6 (04/04-05/06)
BFM: Audi A8 (11/02-05/06)
BGJ: Volkswagen Phaeton (05/03-07/03)
BGH: Volkswagen Phaeton (08/03-05/10)
AHK: Audi C4 S6 Plus (06/96-10/97)
AQJ: Audi C5 S6 (09/99-05/01)
AHC: Audi D2 S8 (09/96-12/98)
AKH: Audi D2 S8 (08/97-12/98)
AQH: Audi D2 S8 (05/99-02/01)
AVP: Audi D2 S8 (09/00-09/02)
BCS: Audi D2 S8 (09/00-02/01, Japan)
AYS: Audi D2 S8 (02/01-09/02, Japan)


The 4.2L 32V V8 FSI, which is the RS4 motor, was used on many Audis/VWs including the A8, Q7, Touareg, R8, etc. That motor is completely different from ours.

There was also the older 4.2L 32V V8 non-FSI from the D2 A8, C5 A6, C4 S6, and C4 S4.

[Slow4]

Time for all ye wisemen to set it straight... So yesterday I ran into an Audi owner who knew about my engine problem. He said "why don't you just look for an A8 4.2? They are exactly the same engine as in the S4." I was dazed and confused. Is this true? I googled it and checked wiki. The stats are the same... But wiki can be edited by anyone I believe. So I tried searching the forum here for the answer, but came up with nothing. What do you guys know about this??

It's a sturdier engine than ours, that's what I know

[SpoolBus]

I had a D2 S8 and that 4.2 was a beast with no problems..more power than the B6 S4 at 355, the tranny on the other hand..

[staubach333]

The 4.2L 40V V8 has many variants. They are the same basic engine but that doesn't mean they're completely interchangeable. Below is data from ETKA.


BBK: Audi B6 S4, Audi B7 S4
BHF: Audi B6 S4, Audi B7 S4
BAT: Audi A6 (04/04-05/06)
BFM: Audi A8 (11/02-05/06)
BGJ: Volkswagen Phaeton (05/03-07/03)
BGH: Volkswagen Phaeton (08/03-05/10)
AHK: Audi C4 S6 Plus (06/96-10/97)
AQJ: Audi C5 S6 (09/99-05/01)
AHC: Audi D2 S8 (09/96-12/98)
AKH: Audi D2 S8 (08/97-12/98)
AQH: Audi D2 S8 (05/99-02/01)
AVP: Audi D2 S8 (09/00-09/02)
BCS: Audi D2 S8 (09/00-02/01, Japan)
AYS: Audi D2 S8 (02/01-09/02, Japan)


The 4.2L 32V V8 FSI, which is the RS4 motor, was used on many Audis/VWs including the A8, Q7, Touareg, R8, etc. That motor is completely different from ours.

There was also the older 4.2L 32V V8 non-FSI from the D2 A8, C5 A6, C4 S6, and C4 S4.

What is the difference between the BBK and the BHF motors?

[Scotty@Advanced]

Time for all ye wisemen to set it straight... So yesterday I ran into an Audi owner who knew about my engine problem. He said "why don't you just look for an A8 4.2? They are exactly the same engine as in the S4." I was dazed and confused. Is this true? I googled it and checked wiki. The stats are the same... But wiki can be edited by anyone I believe. So I tried searching the forum here for the answer, but came up with nothing. What do you guys know about this??

The D3 A8 engines are nothing close to the S4 engine. From 03-06 the A8 had a belt driven engine which is closest to the C5 4.2 mills. In 07 and up the D3 A8 got FSI and was a cam chain engine. The B6/B7 S4 never had a cam belt engine and was not FSI. However the BVJ FSI D3 A8/A6 engine is a gem, but retrofitting it would be a project and a half.

[Scotty@Advanced]

The 4.2L 40V V8 has many variants. They are the same basic engine but that doesn't mean they're completely interchangeable. Below is data from ETKA.

AHK: Audi C4 S6 Plus (06/96-10/97)

AHK was a 32V V8.

The 4.2L 32V V8 FSI, which is the RS4 motor, was used on many Audis/VWs including the A8, Q7, Touareg, R8, etc. That motor is completely different from ours. There was also the older 4.2L 32V V8 non-FSI from the D2 A8, C5 A6, C4 S6, and C4 S4.

The 4.2 RS4 engine is not the same as what is in the 4.2 FSI engine in the A8, Q7 etc.

Also the C5 A6 4.2 was a 40V engine, and from 00 and up the D2 A8 was 40V as well. The 32 valve engine ceased being used in the 2000 model year.

[308slegs]

Thanks guys!! I knew you'd all be able to set it straight. I appreciate all the collective knowledge here. You guys are awesome.

[georgio3gr]

Also if i don't make a mistake, i think i've read somewhere in AZ that A8 engines have different "V" angle from S4 engine and they do not fit at B6-B7...

[Mr.Wrong]

The D3 A8 engines are nothing close to the S4 engine. From 03-06 the A8 had a belt driven engine which is closest to the C5 4.2 mills. In 07 and up the D3 A8 got FSI and was a cam chain engine. The B6/B7 S4 never had a cam belt engine and was not FSI. However the BVJ FSI D3 A8/A6 engine is a gem, but retrofitting it would be a project and a half.

Scott, could you elaborate on this a bit?

[BCsniper]

FSI motor in a non-FSI car. Same reason why swapping an RS4 motor into the S4 would be a pain.


I was under the impression that some of the A6/Allroad motors could swap over to the S4 since they were the same chain-driven 40v 4.2. I know it is technically a different engine with probably a few different parts, but I was still under the impression that they were compatible

[Das Audi]

What is the difference between the BBK and the BHF motors?

Good question.....................anyone know?

[dparm]

AHK was a 32V V8.



The 4.2 RS4 engine is not the same as what is in the 4.2 FSI engine in the A8, Q7 etc.

Also the C5 A6 4.2 was a 40V engine, and from 00 and up the D2 A8 was 40V as well. The 32 valve engine ceased being used in the 2000 model year.

Not in all countries -- that's why some of that list can be confusing.

The RS4 engine is the same one as the A8/Q7, it's just tuned differently and I suspect has different IM, etc.

[BCsniper]

eh....there's more to it than that. The V8 from the A8/Q7 is the "comfort" V8 whereas the RS motor is the "performance" V8. Supposedly the S5 V8 is a bit of a mix between the two but closer to the RS motor.

Part of the difference is in the bottom end. Apparently the RS4's have a built bottom end with a forged crank and rods. There a bit more discussion about this in the RS section here and on other forums, I'm far from an expert on the subject

[blaelock]

Good question.....................anyone know?

+1 would also like to know more about this.

eh....there's more to it than that. The V8 from the A8/Q7 is the "comfort" V8 whereas the RS motor is the "performance" V8. Supposedly the S5 V8 is a bit of a mix between the two but closer to the RS motor.t

This is the impression I was under as well, with the non FSI 4.2 as well. Aren't the cams (among other things) most aggressive in the BBK/BHF motors found in the S4 as opposed to a 4.2 in an A8 or something else?

Also, can anyone actually confirm that the timing mechanism was moved from the front of the engine to the back for the S4? From what I've read, heard and been told, they switched from timing belts or something like that to the chain to shorten the overall length of the motor, but I can't confirm that they actually moved the entire mechanism from front to back.

[JimmyBones]

Not in all countries -- that's why some of that list can be confusing.

The RS4 engine is the same one as the A8/Q7, it's just tuned differently and I suspect has different IM, etc.

Have you ever read the SSP for the 4.2 FSI engines?

It goes through most all of the changes like the crankshaft, connecting rods, pistons, timing system, cylinder head, oil supply, cooling system, intake path, exhaust system, and engine management. By the way, those awesome headers that you commented on in the RS4 section are only on the RS4s - not the Q7 version. So the two engines (Q7 and RS4) are vastly different.

[308slegs]

From what I've learned so far is that a BHF motor is for the USA and a BBK motor is for the UK. I could be completely speaking out of my ass, but I swear that someone told me that. (this coming from a guy who was also told that he was buying a PERFECT car. lol)

What is the difference between the BBK and the BHF motors?

[dparm]

Have you ever read the SSP for the 4.2 FSI engines?

It goes through most all of the changes like the crankshaft, connecting rods, pistons, timing system, cylinder head, oil supply, cooling system, intake path, exhaust system, and engine management. By the way, those awesome headers that you commented on in the RS4 section are only on the RS4s - not the Q7 version. So the two engines (Q7 and RS4) are vastly different.

Interesting. No, I haven't. Thanks for the info.

[blaelock]

From what I've learned so far is that a BHF motor is for the USA and a BBK motor is for the UK. I could be completely speaking out of my ass, but I swear that someone told me that. (this coming from a guy who was also told that he was buying a PERFECT car. lol)

Unfortunately I don't believe that's true. The receipt I have from Audi documenting my new short block says BBK if I recall correctly.

[dparm]

I believe the BBK version is for the UK, meaning that it could have slightly different fuel lines and wiring. I suspect the blocks and internals are identical, it's just all of the bolt-on parts that could be different. It's possible the mounts are different for RHD versions, too.

[ddillenger]

I have been told these interchange.

http://www.ebay.com/itm/2004-04-AUDI...598b2c&vxp=mtr

[JustMtnB44]

I was under the impression that some of the A6/Allroad motors could swap over to the S4 since they were the same chain-driven 40v 4.2. I know it is technically a different engine with probably a few different parts, but I was still under the impression that they were compatible

C5 allroad 4.2 engine (code BAS) is nearly identical to S4, but every other C5 A6/S6/RS6 used a front mounted timing belt instead of chain.

I have been told these interchange.

http://www.ebay.com/itm/2004-04-AUDI...598b2c&vxp=mtr

Physically interchangeable yes. I don't know if it's ever been confirmed what if any mechanical differences there are between the S4 and allroad 4.2 engines. Stock the allroad engine is tuned for 300hp with a 6500 rpm redline.

[onemoremile]

The v8 allroad was a chain engine? That is really weird. Did they still lengthen the nose of the car like the other c5 v8 cars?

[Scotty@Advanced]

The v8 allroad was a chain engine? That is really weird. Did they still lengthen the nose of the car like the other c5 v8 cars?

The Allroad 4.2 did use a chain engine, and no the Allroad 4.2 has the same front end as the V6 cars.

[onemoremile]

That makes sense then. They used the chain engine to avoid having the longer front end.

Sent from my DROID RAZR using Tapatalk

[mankytron]

The 4.2 from the 2005-2006 a6 4.2 is also very similar to the s4 engine as it has rear mounted chain drive timing drivetrain.

[JayTeeC]

Very interesting read; SSP on the many differences between two versions of 4.2 FSI motor for RS4 and Q7: http://www.volkspage.net/technik/ssp/ssp/SSP_377.pdf

[JayTeeC]

Unfortunately I don't believe that's true. The receipt I have from Audi documenting my new short block says BBK if I recall correctly.

Yep. Mine's a BBK. Wikipedia says BHF is "Korea only". BBK should be all B6/7 S4 motors stateside. http://en.wikipedia.org/wiki/List_of...nes#4.2_V8_40v

[MBellRacing]

So any definitive information in any SSPs about the real differences between the S4 BHF/BBK and the Allroad BAS? I have the latter, and would sure love the extra ponies and revs that you S4 boys have! It's odd, because I used to race with APR, and when I inquired about more power from my Allroad, they said blower only. The motor is apparently pretty topped out at 300hp and only gets better "throttle response". This is interesting to me considering it is a 4.2L V8 with 11:1 compression and premium-only fuel. Is the cam different between the S4 and Allroad, perhaps?

[xhackerekx]

anybody try install rs4 engine with s4 intake manifold ?

[Concavitor]

You can prob use some of the a8 parts but the timing is up front and belt driven if im not mistaken

That's correct and the reason an A8's 4.2 will not work as a swap. It won't fit!

[SewM]

That's correct and the reason an A8's 4.2 will not work as a swap. It won't fit!

Good afternoon Gentlemen, I am a female and do not know the first thing about cars. That is why I am appealing to you fellows to adivse me on what I need to do with my vehicle. I have an Audi S4 (2003) model that has recently stopped working, once at the Audi Agent it was confirmed that 8 valves were damaged due to the timing chaim tensioner that broke. I have been told that an Audi A8 4.2V V8 (2005) model engine can be installed in my vehicle. Can someone please confirm if this is possible. I have been trying to follow this thread because I saw that someone asked a similar questions, but I got lost in translation somewhere. I have searched the whole of South Africa for a second hand engine and all dealers/suppliers come back to me saying that the engine (S4) is very scarce and they cannot find one locally. Please advise.....

[B6_4.2]

Good afternoon Gentlemen, I am a female and do not know the first thing about cars. That is why I am appealing to you fellows to adivse me on what I need to do with my vehicle. I have an Audi S4 (2003) model that has recently stopped working, once at the Audi Agent it was confirmed that 8 valves were damaged due to the timing chaim tensioner that broke. I have been told that an Audi A8 4.2V V8 (2005) model engine can be installed in my vehicle. Can someone please confirm if this is possible. I have been trying to follow this thread because I saw that someone asked a similar questions, but I got lost in translation somewhere. I have searched the whole of South Africa for a second hand engine and all dealers/suppliers come back to me saying that the engine (S4) is very scarce and they cannot find one locally. Please advise.....

I believe the short answer is no. The V8 from an A8 will either be too long (timing belt) or it will require a completely different fueling system (FSI), those would be the most obvious hurdles to overcome anyway...

[DaytonCarCare]

I had a D2 S8 and that 4.2 was a beast with no problems..more power than the B6 S4 at 355, the tranny on the other hand..

Old post I know...

I was recently wondering the same thing with the engine differences. I have a 2001 S8 with the 40v 4.2 rated @ 360 HP. Though I understand the B6 S4 4.2 is a completely different engine (rated at 340 HP) with a timing chain in the rear of the engine and the S8 (and A8) has instead a belt in the front.

Is there a link somewhere with engine internal specifics with maybe a diagram or schematic?

[Bordom]

Old post I know...

I was recently wondering the same thing with the engine differences. I have a 2001 S8 with the 40v 4.2 rated @ 360 HP. Though I understand the B6 S4 4.2 is a completely different engine (rated at 340 HP) with a timing chain in the rear of the engine and the S8 (and A8) has instead a belt in the front.

Is there a link somewhere with engine internal specifics with maybe a diagram or schematic?

Google around enough and you can find them. Nothing from the S8 will transfer over to the S4.

[Jdsb6s4]

Yep. Mine's a BBK. Wikipedia says BHF is "Korea only". BBK should be all B6/7 S4 motors stateside. http://en.wikipedia.org/wiki/List_of...nes#4.2_V8_40v

I guess I have a Korean engine then. SMH. Haha. Time to slap my BHF into a Kia Soul and tear some shit up!

[DaytonCarCare]

Google around enough and you can find them. Nothing from the S8 will transfer over to the S4.

Tell me you didn't just write "Google around..." that's why I'm here asking