# 4.2L v8 swap question



## phucking-low (Mar 29, 2010)

was wondering will the audi 4.2L v8 from 99 a8, will it bolt or do they make a bell housing adapter to fit a front wheel drive 5 speed 1.8t transmission 

and to get this straight i know a fwd v8 is a dumb swap but im just kicking around the idea


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## JamesS (Nov 18, 2008)

I'm gunna say no


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## nothing-leaves-stock (Mar 1, 2005)

why do you say no? do you know for a fact or you just guessing?

i'm going to say possibly yes. BECAUSE.... 1.8T and V6 audi trans are interchangable. and a S4 trans swap has been done on a S8 auto V8 car. so if the S4 trans bolts to the S8 motor and the S4 trans bolts to the 1.8T ...then i'd say it looks like a go.


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## MikkiJayne (Jan 1, 2007)

It will absolutely not bolt up sorry.

Interchangability of Audi motors longitudinal transmissions has no bearing on fitting Audi motors to transverse transmissions. The bellhousing on the longitudinal transmissions is deliberately designed to take the I4, I5, V6 and V8, whereas the transverse transmissions are specifically VR6 or I4 and thats it. The V-motors are a completely different pattern to the I4 and VR.

Also there isn't a stock flywheel which will fit an Audi V motor and work with the tranverse transmissions, as the Audi motors have the starter on the motor side at the back (or passenger side longitudinally), whereas the VW motors have it on the trans side at the front, ergo the ring gear is on the opposite side. The V motors have an 8-bolt flywheel too, whereas the I4 has 6 and the VR has 10.

Finally, even if you make an adapter plate and custom flywheel there is no way you'll get the passenger side axle past the block of the V8 as the oil pump is in the way. That has been tried before and it just doesn't work.

Have a beer and move on to the next great idea :beer:


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## phucking-low (Mar 29, 2010)

well i seen a swap of a 99 audi a4 quattro has a 1.8t and he had a bell housing adapter and used a 4.2L v8 in it its all over you tube.


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## antichristonwheels (Jun 14, 2001)

All over YouTube MF....


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## MikkiJayne (Jan 1, 2007)

phucking-low said:


> well i seen a swap of a 99 audi a4 quattro has a 1.8t and he had a bell housing adapter and used a 4.2L v8 in it its all over you tube.


You don't need a bellhousing adapter to put a V8 in an A4 - it will bolt straight up to the existing trans. 
That is because the A4 trans is made to fit all the different motors, not because the V8 is the same as the 1.8T 

Not a great picture, but have a look at this:










You can see all the dozens of holes in the bellhousing. There are three different patterns here - I4, I5 & V6 / V8.

Now have a look at an 02A, in this case a VR6 one:










There is only one pattern for the VR6. For an I4 version there is only the I4 pattern.

Finally have a look at the V8:










You can see where the starter is, which is in the way of the axle, and in this next pic how the alternator & oil sump are also in the way.










The bellhousing and flywheel you could possibly get round with expensive custom made parts, but you can't get round not having space for a passenger side axle. This has been tried before with the Audi V8, and failed, with the builder of that particular project swapping to a different V8 to solve the problem.

If it makes you feel any better I have all this stuff in my shed and have mocked it up myself just for laughs, and seriously - it just won't work.

:beer:


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## phucking-low (Mar 29, 2010)

Then what v8 from what audi do i need to make it fit in my a4


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## LuvToHate (Aug 10, 2005)

phucking-low said:


> Then what v8 from what audi do i need to make it fit in my a4


You need to work on your reading comprehension skills, the original poster wanted to use an Audi V8 in a FWD car such as a Jetta or something although they did not give any detail. Mikki then posted that would not happen because FWD transmissions such as 020 and the 02A because they don't have the correct bolt pattern to begin with but with the Audi transmission such as yours it would not be a problem. Then you stated that it could be done even though this thread was talking about FWD transversal applications so Mikki came back and stated once again that this swap is not a problem with the Audi because your transmission will work with the V8 but the FWD transmissions will not as shown in the pictures she posted.


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## MikkiJayne (Jan 1, 2007)

Oh dear. I'm a little embarrassed to say it might be me that needs to brush up on my reading comprehension skills sorry 

OP: Were you originally talking about an *A4 *FWD transmission? I mistakenly assumed you were talking about a mk4 1.8T transmission, such as an 02M - one of the transverse setups. If you mean a longitudinal A4 setup then I apologise for all the complete rubbish I posted earlier and suggest we start again 

Deep breath...



phucking-low said:


> was wondering will the audi 4.2L v8 from 99 a8, will it bolt or do they make a bell housing adapter to fit a front wheel drive 5 speed 1.8t transmission
> 
> and to get this straight i know a fwd v8 is a dumb swap but im just kicking around the idea


Any of the 32V or 40V V8s with belt-driven cams will bolt straight on to your A4 transmission. 

Assuming your A4 is manual then you will need to source the appropriate flywheel and clutch - talk to 034 Motorsport about this. If its auto (tiptronic) then use the A8's torque converter.

The motor mounts don't bolt straight up - you will need to fabricate brackets from the motor to join to the A4's original mounts on the body. Use V6 mounts to take the weight as the iron V6 is the same weight as the aluminium V8. You'll need to fab something to support the front snubber too as thats a different design to the A4's.

Ideally you want to find a V6 A4 as a donor, as the airbox, rad, plumbing and a few other bits will come in handy.

If your A4 is manual then you'll be best off running the motor on standalone as the OEM wiring is tricky at best, and most of the A8 ECUs don't have a coding option for a manual trans. If your A4 is an auto then you will have to run the factory ECU in order for the auto ECU to also work. In that case you'd need an immo defeat (if its a later car) and wiring diagrams (PM me the engine code).

There are a ton of little bits and bobs that will need sorting to get this to work, but it has been done in the UK both in FWD and AWD versions. Have a read of these two threads on Motorgeek:
http://www.motorgeek.com/viewtopic.php?f=6&t=27468
http://www.motorgeek.com/viewtopic.php?f=6&t=30741

Apparently the author of those threads turned out to be a scammer who took money for things he never delivered and used it to build his own projects, but he left some useful info behind.

Once again sorry for misunderstanding and have an internet :beern me!


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## phucking-low (Mar 29, 2010)

ok so to clear things up, i have a 1999 audi a4 5spd 1.8t front wheel drive. im wanting to do a v8 swap. 

1) i was told a passenger side axle wont fit because there things in the way (yes) or (no)
2) will the v8 out of a 99 a8 work (yes) or (no)


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## BARELY LEGAL (Jul 2, 2009)

NO
and 
YES


This thread was an interesting read. Good luck with the swap.


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## 35i 2000 (Jan 27, 2005)

MikkiJayne said:


> You don't need a bellhousing adapter to put a V8 in an A4 - it will bolt straight up to the existing trans.
> That is because the A4 trans is made to fit all the different motors, not because the V8 is the same as the 1.8T
> 
> Not a great picture, but have a look at this:
> ...



fantastic explanation :thumbup:

i always wondered about this, but now i know


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## MikkiJayne (Jan 1, 2007)

phucking-low said:


> ok so to clear things up, i have a 1999 audi a4 5spd 1.8t front wheel drive. im wanting to do a v8 swap.
> 
> 1) i was told a passenger side axle wont fit because there things in the way (yes) or (no)
> 2) will the v8 out of a 99 a8 work (yes) or (no)


1) No that was me misunderstanding your original Q. Your axles will fit fine, and if you use the A4 2.8 exhaust and downpipes they will only require minimal modification to for the V8 afaik.

2) Yes it will work fine, although still subject to my comments about the management. Your best bet is to use standalone for it because there is no manual coding for the factory A8 ECU.

Hopefully everything you need to know is in those two threads from Motorgeek. If you go ahead with the swap be sure to make a thread about it


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