The V8 Owners Forum -

As I have stated previously, I have extensive experience with the 32 and 40V 077 V8 engines, including swapping them into various VAG chassis. But this motor is different. The V8 from the D3 Audi A8 continues to reveal surprises, and other unexpected attributes.

As many may know, the 4.2 V8 40V from the C5 S6 is very different from the 4.2 V8 40V from the C5 A6. The same differences exist between the same V8 engines from the D2 S8 and A8.

Besides the obvious differences between the standard and S cars - bigger injectors, more aggressive camshafts in the S engines, the variable intakes were also different, 3-stage in the non-S engines, dual stage in the S engines.

Now, with the D3 V8 engines, there was no S8. Pre-2005 (FSI) the V8 engines were split into two. 3.7 and 4.2 40V. At first, the differences between the 2 engines is their capacity. This is what I also assumed. However, the differences are greater.

The D3 A8 3.7 runs a 3-stage variable intake manifold, in much the same way as the C5 A6 / D2 A8 4.2 did. The D3 A8 4.2 is different, and the variable intake plenum is the same dual-stage unit that was fitted to the C5 / D2 S engines. This effectively means the C5 / D2 S engine ECU's can be used for the D3 4.2 V8 40V, opening up more flexible tuning options.

I'm going to check the camshaft specification between the C5 / D3 S engines, and the 4.2 V8 40V from the D3 A8.

Update: 10th August, 2015.

So this weekend, the remains of my 2005 D3 4.2 Quattro Sport was picked up by the junk man, and for the first time since we acquired this property, I could actually see all the walls. Lots of storage space too.

My D3 loaded up, on it's final journey. I was surprised these guys didn't get busted by the cops when they hit the road, so much over hang, made worse by the fact their truck was NOT built for picking up cars. As the front suspension was all gone, it was a battle wrestling the shell onto the back of their truck. Uber overhang!



And my workspace:





























Assorted engine harnesses, ranging from 2000 B5 S4, 1998 D2 S8 and 2003 B6 S4:

As some of you guys may remember, I mentioned the D3 A8 BFM V8 shares cylinder block dimensions with the C5 RS6. As in it's larger at the rear, where it bolts to the transmission. Many RS6 owners who have looked into converting their cars to 01E 6-speed have also had issues when it comes to a bolt-in solution.

After examining the rear of my D2 S8 AHC motor (32V) and comparing it with my D3 A8 BFM (40V), bar the starter motor hoop, the BFM block is no larger. What the RS6, and D3 A8 engines have is an extra set of holes to mount to the much larger Tiptronic bell housing. These holes are on the outside of the ones that would usually accept an 01E. The 32V S8 motor also has these extra holes, though they are not used in an S8 with Tip.

I am going to bolt my 01E to the BFM engine, using the 5 bolts holes that DO match, then drill and tap the extra holes.

The BFM flexi plate, like the C5 RS6 is larger than the regular 30/40V items, so the starter motor will not work on an S4 B5 / 40V flywheel. I have ordered an S6 C5 starter motor. I am going to make a template from my 32V block, then drill / machine the starter motor area on my D3 4.2 V8.

Starter motor should be here sometime this week.

The three holes in the upper oil pan do not mate to the 01E either, so I am constructing an adapting bracket, not to be confused with an adapter plate that is commonly used for manual swaps in the C5 RS6, but also has the added disadvantage of pushing the big V8 further forward than I'd like.

I will take pictures of the process.

I spoke to a shop that has made me one-off Carbon Fibre parts in the past. I would like to get the front and rear top engine covers made out of the good stuff.



Just waiting on pricing.

Update: 27th August, 2015.

My apologies for my lack of regular updates, been super busy with work and even more exams.

I placed an order for a single-mass steel flywheel. I could have saved myself a stack of dough, and used my original 2.8 30V flywheel, with an OEM 2.8 clutch, but I opted not to do so for a number of reasons.

Being a dual-mass unit, the original flywheel is designed for smoothness and comfort, absorbing vibration. Unfortunately, this design is not built for high-torque application, and it can't be resurfaced - at least not by many shops. It is also insanely heavy for what it is. Worse of all, using the 2.8 30V flywheel will limit me to running a 2.4/2.8 30V clutch, which I would rather not do.

The steel flywheel I have ordered is specific to the 4.2 V8 40V, and designed to run a B5 S4 / RS4 clutch. Unlike the B5 S4 / RS4 though, it does NOT require the S4's engine-to-transmission spacer to provide clearance between the clutch pressure plate and bell housing, being dome 11mm slimmer. This should be with me by Saturday.

My D2 S8 ECU also arrived on the 24th August, I'll be sending it off to get the immobiliser defeated.

I know the 2.8 V6 30V twin catalytic converters and combined downpipes are a direct bolt-on fitment to the 4.2 V8 40V motor. But they will strangle performance, due to their bore size and the surface area the catalysts provide. I'm contemplating purchasing a pair of stainless 200 cell race catalysts from Germany. I can then have the rest of the exhaust system built from the CATS rearwards.

I'll post pictures soon.

Update: 29th August, 2015.

I have been considering different exhaust options for B5 420-R. My original V6 30V exhaust system WILL bolt up to the V8 40V. But...it will be restrictive, as the bore size of 2.25" is undersized for a V engine above 3.0L. It will also not sound as good, a flat-sounding V8 is not cool!

So I ended up purchasing a B5 S4 stainless 2.5" system with twin 3" tips. This is a CAT-back system, so I also purchased B6 S4 stainless steel downpipes. These are CAT-deletes, but I have the option of purchasing a pair of 200 CPSI sport CAT's to weld in, if I so choose. The downpipes are coming in from Germany.

Some pictures. Note, these are the original advert pictures.

B6 S4 stainless steel downpipes:



B5 S4 stainless steel CAT-back system:

Update: 03rd September, 2015.

So my exhaust system turned up today.

Quite a well-made system. As I mentioned previously, the downpipes are for the B6/7 S4. Trying to test fit one to my BFM manifold highlighted another difference.

The BFM manifolds have the studs slightly wider apart. This could be resolved by slotting the holes on the B6 S4 downpipe collars, but there was a more obvious difference.

The D3 4.2 V8 manifolds have conventional stainless steel laminate gaskets. The B6 S4 manifolds have integral domed fire rings, and of course the downpipes have flared ends to match. It will be easy enough to weld in a pair 2.8 30V downpipe ends to the B6 pipes, but I can't really be bothered to do this, when an easier solution lies within reach.

Buy a pair of B6/7 exhaust manifolds. Which is what I'm doing. I did consider pulling the trigger on a set of tubular headers, but I don't want to run into fitment issues on a street car. I might go the tubular route though on my DTM car.

Pictures!

Update: 04th September, 2015.

My C5 RS6 aluminium subframe turned up a couple of days ago, encrusted with baked-on oil and dirt. I marvel at how some sellers will ship items out in such a state.

Now I know the C5 S6/RS6 aluminium subframe is dimensionally different to that fitted to I4 and V6 models, including the B5. The front mounting bushes will bolt up to a B5, the rear bushes are however slightly further back, and slightly further apart. I will address that discrepancy one way or the other.

To this effect, I am purchasing a stock B5 V6 subframe. I will use this as a mini-jig to modify the C5 S6/RS6 aluminium item to fit the B5. Some may question my decision to purchase a B5 V6 subframe, when I could use mine as a jig. My reasoning here is DOWNTIME. I would rather get everything ready to fit, rather than waste time with R&d with my car in bits. Besides, B5 subframes are so cheap to buy used, and there are tons of them on eBay.

Some pictures.

The original eBay photograph. Absolutely filthy, really oily and crusty:



After a session with my local car wash, it looked like this:







I then ran a selection of rotary brass wire brushes over it to remove some staining the dilute acids used at the car wash couldn't shift, used a bunch of panel wipes to remove dust, then laid down a coat of primer, followed by 3 coats of Audi Aluminium Silver:









Much easier working with a clean subframe. I am looking at offset corrective rear subframe bushes.

Update: 05th September 2015.

Pair of Motorsport mounts ordered. I may well do the same for the transmission mounts.

My previous V8 swaps utilised stock engine mounts, and a custom front mount to replace the usual snub mount. It's possible the Motorsport mounts will be stiff enough NOT to require the front torque mount, but we'll soon find out. These Motorsport mounts are adjustable, and can be rebuilt as required.

There are lots of options for the transmission mounts without spending big bucks, if you know what you're looking for, and where to look. I'm not talking lumps of Delrin and studding either.

My C5 RS6 combined oil cooler / filter housing and right hand engine bracket also turned up this morning, so this takes care of physically bolting the engine in place.

While I'm waiting for my Motorsport engine mounts, and flywheel to turn up, there's not much I can do.

So I decided to clean up my RS6 lower brackets, and give them a couple of coats of Audi Aluminium silver.

As received post purchase:





After a session with a selection of rotary brass wire brushes, and a wash with boiling hot water, and dish washer liquid:





After a coat of primer, and 2 coats of Audi Aluminium Silver:

I also have this:



C5 S6 / RS6 oil cooler and filter housing. Which some of you may know also incorporates the right hand upper engine bracket. I have swapped the D3 V8 left hand upper engine bracket for a C5 RS6 item, though the engine mount hole appears to be identical to that of the original D3 A8 one.

The D3 right hand upper bracketMAY well fit the lower bracket, meaning there MAY be no need to replace it with the C5 RS6 bracket / oil cooler / filter housing. The only way to know for sure will be by way of trial mounting.

Once my Motorsport mounts and flywheel arrive, and I've completed the machining to all ALL the D3 V8 engine mounting holes to bolt up to my 01E, I will mount the C5 RS6 subframe on a jig, then lower the engine and 01E transaxle onto it, bolting the gearbox mounts and the left hand engine mount in place. I will then see where I am with the right hand engine mount. If the discrepancy is minor, I'll do what needs to be done to get it to line up. If it's massive, then I'll simply swap the assembly with the C5 RS6 one.

My B5 30V subframe has been despatched, so that will be with me sometime this week. It will then be used as a jig to modify the C5 RS6 aluminium one to fit a B5.

I've got another busy weekend ahead of me.

Update: 09th September, 2015,

I got home from work, and found some packages waiting.

My Motorsport mounts, V8 40V flywheel, aluminium coolant pipe are here. The steel B5 30V subframe I intend to use as a jig, to modify the aluminium C5 RS6 one, has also arrived, though I haven't ripped open the odd-shaped package yet.

I'm still expecting my B6 S4 exhaust manifolds, they should be with me sometime this week.

All I need to order now is a B5 S4 or B5 2.6 Quattro rear differential, and a B5 RS4 clutch. The Motorsport mounts and steel lightweight flywheel are so well made, it's kind of a shame they won't be visible once fitted, haha. This flywheel was worth the wait, as it does NOT require a spacer, and is super light. Much lighter than the B5 S4 item, or the 30V.

Pictures:

Update: 10th September, 2015.

My B6 S4 exhaust manifolds turned up today.

As I stated previously, the D3 V8 headers don't match the B6 stainless steel de-cat pipes I purchased. Slightly wider stud spacing, and different method of sealing.

D3 A8 BFM V8 header-to-downpipe sealing flange. Note the conventional metal laminate gasket:



B6 S4 BBK V8 sealing flange. Note the integral domed end, to match the flared ends of the B6 stainless de-cats:

Though the B6 S4 headers are very similar in construction to those fitted to the D3 A8 V8, they are different internally. The D3 headers are geared more towards comfort, and quieter operation. The B6 S4 headers are sportier, which is one of the reasons the B6 S4 has a gruffer V8 rumble, the D3 4.2 V8 is almost silent in comparison.

B6 headers were in good shape, just needed some of the "treatment" to get the stainless steel gleaming. Damn A1 A2 German! Now everything on this engine's got to be either polished, or painted, haha.

B6 headers, as delivered. A bit discoloured, but at least being stainless, they polish up good:





I clamped the first header in my bench vice, and got to work with a selection of rotary brass wire wheels / cups:













The partially finished result of one header versus the untouched one. I say partially finished, as I'm picking up some stainless steel polish, to get them to the same mirror-like finish as my B5 S4 stainless exhaust system:

















A close-up:

I have been looking at clutch options for my B5 420-R.

Whilst I don't want to install a clutch that will slip when driven in anger, I don't want a clutch combination that will make the car nasty and anarchy to drive, especially in traffic. Remember, this is a street car, at full weight. The heavier a car is, and the greater the torque the engine generates, the less compatible a race-style, or paddle clutch will be.

Paddle 6/8 PUK friction discs are grippy, but they're not kind to flywheels, it's not unusual to find a flywheel chewed up pretty bad after 30,000 miles of driving.

Heavy cars are not nice to drive either with lightened flywheels, or crankshaft pulleys, which is why though my flywheel is lighter than that of the B5 S4/RS4 or 30V, it still has a decent weight to it. Aluminium flywheels are bad news - not only due to the extreme light weight, but the very construction.

A steel insert against aluminium, secured with rivets. We're talking 2 different metals against each other, with different expansion rates. There have been quite a few cases with B5 RS4's, S4's and big-power 1.8T's, where there has been slight slip, enough to generate heat, causing the steel insert to warp, pulling the rivets out of the steel.

I have ordered a genuine B5 RS4 clutch from my local dealership. Like most modern Audi models, the clutch is NOT available from Audi as a kit, you purchase the parts individually. So pressure plate, friction disc and throw-out bearing.

The B5 RS4 runs the same components as the B5 S4, with the only difference being the pressure plate. Same construction in both cars, same profile. However, the B5 RS4's pressure plate has a stiffer diaphragm, meaning the clamping load is significantly higher. I'll have the lot with me by Tuesday. I can then complete the necessary modifications to allow the 01E transmission to mate properly to the D3 BFM V8 motor.

Just in case anyone's interested, the part number for the B5 RS4 clutch pressure plate is 078 141 123 G.