Project Audi V10 5.2 performance. S6 / S8

Project Audi V10 5.2 performance. S6 / S8

The V10 5.2 Audi was a car I’ve always wanted since it first came out. The usual saying is “it’s a 4 door Audi with a Lamborghini motor in it.” While we all know that’s not exactly the truth, I figured why not do what we can to make that true. I plan on really making something of my V10 5.2, what a better place than here and what better people than the people on this site to share and get ideas on whats going to work best. I’ve been lucky enough to be part of several projects many of them listed on here. If you’re interested and have several hours to burn.

This gives a quick overview of something things I was involved in.

Some of you might be familiar with this build

This was for my S4 build thread.

Here is a fun A6 project I worked on.

Here was a fun has never before done project that the customer couldn’t find anyone on earth to get the car running on the Me system

Headers on an A8

There have been several others but that is a good start.

I’ve had my S8 (I know this is the S6 section) for quite a while and I’ve done quite a few things that I think owners here might be interest in. I have plans to take the car further than where it currently is now.

Some of the exciting things I’ve done are

The JHM intake spacers
The JHM Lightweight crank pulley - almost 9lbs of weight savings.
The JHM Lightweight brake rotors front and back - weight savings you wouldn’t believe
JHM beta ECU and TCU tune.
Full custom 3" exhaust
Carbon clean
SAI removal
Fuel filter
Up-date plugs and coil packs.
Oil change and fluid assessment.
Compression test
Cylinder inspection

The list goes on but it ends right now with track testing in the 1/4 mile with what I understand to be the fastest D3 S8 all motor car if not overall fastest. Don’t get too excited it’s not as fast as I’d like it but its a lot faster than stock.

I figured with so much excitement over here in the S6 section that there would be a few guys who might enjoy the outline and work I’ve done so far. Don’t be afraid to ask questions if you have any. That’s the entire point of this thread.

So, if you’re interested, feel free to keep reading as this is my S8 journey.

Due to production numbers, there probably won’t be too many of us S8 guys. That’s not to say there isn’t performance stuff going on. To help keep the amount of conversation going I make a post in the S6 section over here.

Hmm this is very exciting. Is the age of The 11 second limo upon us??

Yes plz… bueller…?

I know I have the thread going on the other section (S6) but I thought I might bring some of the fun over here for the possible S8 surfers that might not make their way over to the S6 section.

For those of you do didn’t know this is my car.

Before I get too far into the performance part of the thread. It’s important to mention a very important thing and that’s maintenance.

We all know about how important carbon cleaning is, but what are some of the other big issues that seem to keep coming up but not talked about?

Injectors, there has been a good amount of talk about this lately and a good amount of talk about this quietly in several S6 threads, where people have mentioned they had one or more injectors replaced to help with a miss fire or some sort of other driving issues.

On my test runs at the track, I felt the car laying down after 6k. Some of that was the cars Tq limits kicking in but another component into that was some of my injectors were not flowing right and something in the upper RPM range was going on.

Turns out injectors are an issue that needs to be looked into when talking about performance and maintenance.

After realizing this might be a bigger issue than most knew about, I I took a minutes to investigate. I started by looking at some car faxes from current for sale V10 S6 cars to get a good idea on if this was common or not.

The good thing about V10 S6 and S8 owners is, the first and usually second owners of these cars generally took the cars to the dealership to get serviced. The dealerships have a good rate of reporting to car fax when work was done, so I felt like this would be a good pool to look at to see just how common this might have been.

This was pulled from just the first few carfaxes I looked at.

It shows replacement of the injectors one or more. These were on cars with less than 52,000 miles

From just looking at the carfax reports on that day. It showed about 30% of all the cars were getting some sort of injector replacement or injector service.

This is something that is right in front of our faces but seems to have been very quiet for a long time.

It might not be a bad idea to start a thread just on this issue to help make more of the community aware that this is something to look into.

It’s not all bad news, there are several big things you can do to help. One of the major things you can do is to make sure to keep the car free of carbon.

It was a common practice in the past to have the dealership use a fuel system treatment to try and help with the carbon. The fuel system treatment would help remove the carbon in the injectors but it would do nothing for the carbon on the valves and in the intake.

One of the suspected killers of the injectors is carbon. So on my way to talking about the performance of my car and its results, I think the big talk is all the steps I took to help make the car safe along the way.

We have a carbon thread started here. I’ll make sure to step into that thread sometime next week to make sure I get it updated and get this entire thread more off the ground.

Let me kick this into gear.

For those of you who don’t know. Here is a picture to show you where the HPFP’s are (High-Pressure Fuel Pumps) where your air boxes and throttle bodies are along with your air box.

Also, a big misconception was that these cars had an intake silencer. That’s not the case, the V10 has a symposer system that actually projects motor noise into the cabin.

Now with some of the pre-performance talk out of the way, I started getting to the heart of what else needed to be done before adding the JHM Tune.

We all know carbon is an issue but so are your plugs and coil packs. The number two reason for misfires on the V10 is an outdated or just worn out coil pack. Once the coil pack starts to get bad it will effect the burn in the cylinder and over time, it will kill the plug.

It’s good to pull the plugs and packs and give them a good once over.

I was told my coil packs were changed recently. Turns out on inspection, that sure maybe some of the coil packs were changed but they were changed with coil packs that were actually older than the cars build date. So, this means someone put in old used coil packs. M

My car is a 09 but here this shows you how to look at the coil packs in your car and tell when they are from.

The plugs looked original. Some of them worse than others. The fresh change of both the plugs and coils helped the car start and run better.

After the carbon cleaning and before I put in the plugs I did a quick compression test. These cars can have as high as 200 on the readings. I was happy most of my car was in the 180 to 190 range. I didn’t spend the time to do the compression test the proper way. I just wanted to get a quick idea where the compression was. The motor was cold and hadn’t been running for a few days. I had one cylinder that was lower than the others. I never went back and checked but I chalked it up to a lifter that had bled down.

Getting closer to running through the entire maintenance gauntlet.

The next steps are installing the JHM intake spacers, the new fuel filter, checking the air filters and putting it all back together getting ready to build the cat back exhaust and then the JHM ECU and TCU tune

Next in line after the carbon clean and tune up was to inspect the intake manifold. It’s been well documented that this is a big issue on the V10 cars.

After pulling my intake apart it became quickly obvious something was wrong.

With a clearly broken intake, you can expect reduced performance.

I don’t know if everyone knows exactly how the intake works and why the broken shaft can have a big impact on power. So let me show you more. Here is what the flaps look like when they are closed.

As you can see all the flaps are closed and seal off their respected port. This causes the air to be diverted into the other section of the intake runner. One of the suggestions is to just epoxy the intake flaps into this position and to epoxy the flap anchors and supports. After that just remove the link to the motor so the flap motor won’t do anything. You won’t get a code as there is no sensor there.

If you lock the flaps closed you remove the second stage of the intake. So, the overall power band will be affected but its better than having a broken section.

Here is what happens when you have the broken section and how the flaps react.

As you can see by this picture you have 8 of the runners open but 2 shut. So those two cylinders are on a different stage of the intake than the other 8. That causes uneven air flow to the cylinders and a drop in power.

These flaps are the internal flaps. They control the stages of the intake to put the car on the long runner that is good for low-end TQ and the short runner that is used for the upper RPM air flow.

There is another set of flaps that also get carbon on them and can cause issues but those are on the ends of the runners found when you look at the underside of the intake.

I had two options. Epoxy the runners shut or order a new intake manifold. I knew no matter what, I was going to put in the JHM intake spacers. They do too much good to not put them in. So, knowing that I figured I’d get a new intake while I was at it. I was quoted around $2,000 plus shipping everywhere I looked. Thankfully JHM was able to get me one directly from Audi for less than that.

But when the intake manifold came from Audi I found a few things that didn’t sit too well with me. I’ll post about them in my next post.

After my last post, I left off where my OEM intake was in need of repair or replacement. Since the JHM intake fix wasn’t ready at the time I paid the money and got a new one.

As some of you might know Audi came up with a new intake design to address the issues with the early intake manifold issues.

The only problem was

My intake already was the new updated part number. Little good that did, the new updated intake manifolds clearly didn’t fix the issue. Again I found something odd. The build date on my intake manifold was well before my actual car was built.

As if that little find wasn’t great the next thing I found was equally just as bad.

As you can see this intake was made about 6 months before I bought it. It came directly from Audi but as you can see it’s not actually new. As you can see from the marks and grime on the intake, this intake manifold is a repaired intake manifold. Still same part number as my original one but clearly not new.

This to me is a little frustrating. Here is why. You don’t really know your intake is messed up unless you pull it apart and after you do that it takes a good amount of work to put it back together. Since there are no actual sensors on the intake flaps you don’t know if one or more are broken. So, at this point, everyone could have a broken intake and unless you pulled it off and checked you wouldn’t know. As if that’s not bad enough the fixed or repaired intakes from Audi don’t appear to have anything different so, there is a very good chance that this intake will suffer the same fate as my other intake.

I do plan on taking apart this intake at the end of every season to check and see if it’s still holding up. So, that will at least be helpful and I’ll see if there is anything different on the inside of the intake vs my original one. I would have to say I don’t think there is going to be anything different. If Audi changes something they change the part number to reflect it.

oh well. Sucks about the intake but It’s not like that is going to stop me. :slight_smile:

The next parts are the JHM intake spacers and the JHM crank pulley along with my SAI removal

Let’s start getting to the good parts. The performance parts.

One of the best single parts you can put on the V10 motors. Is the JHM intake spacers. We all know the V10 heat is such a big deal. That heat is the single cause for numerous issues from pre-aging gaskets and other parts to robbing power and the overall drawbacks of just having too much heat.

The JHM spacers are a simple but well-proven part. These have been around and used not just by JHM but by actual race teams to do the same task. The spacers have been used for years in the Audi market to help drastically reduce heat and help return performance.

If you’re talking about performance or just general ownership. The spacers really are a must when you pull the intake to do a carbon clean.

There are several things I like about the spacers. An additional thing I like on top of all the performance and other gains is that the JHM spacers actually work. They help seal the intake manifold from what I have seen. So, in my opinion, I see a better seal from the intake manifold to the heads as the JHM spacers make a nice fit and seal really well. This cuts down on the dreaded V10 misfire from intake leaks.

The only real note is to make sure to remove some of the motor pull assembly brackets when you install AND DO NOT REINSTALL THEM. If you try to reinstall the motor brackets you will get interference with the motor arm once the spacers are installed.

I thought now would be a good time to give a quick how-to on getting the intake manifold off. This can be used to get to a carbon clean or better yet the install of the JHM intake spacers.

Paul F started a How - to C6 S6 and basically S8 intake manifold Removal how to. Since paul sold his S6 to get an RS6 I thought I’d take what he started and add to it for this section of my thread with some expansions.

Below is a combination of Paul F and myself on how to do the following. Paul’s original thread can be found here

First - here are the tools you will need:

3/8 or 1/2" drive ratcheting wrench
1/4" drive ratcheting wrench
1/4" Drive Torx T30 (picture later)
Long bit Torx T30 (I used 1/4" drive - picture later)
Short (normal) bit Torx T30 (I used 3/8" drive)
M8 Triple Square/12 Point
M10 Triple Square/12 Point
10mm Wrench/Spanner (stubby is better)
14mm Wrench/Spanner
17mm Wrench/Spanner
Needle Nose Pliers
Flat Screwdriver
Precision (tiny) flat screw driver (for clips)
Extendable magnet

Before you start - repeat the following 10 times: “I will not drop any screws.” I haven’t (yet), but it’s not like an old Nissan - every screw is important!

Another thing to note is that a lot of these screws are aluminium, so be sure your bit is well seated, that there’s no debris in the screw head, and use lubricant before excessive force. If you do strip one, you can hammer the next size Torx into the hole and the material is soft enough to allow a new imprint to be made.

Give yourself about 2 hours.

Step 1 - Take off engine covers. One at the front, one at the back. Remove intake pipes between the manifold and air filters.

The passenger side air intake is a little more tricky to take off and will require some time. There are two PCV attachments to the inlet pipe that are on the back side and they’re very hard to get to.

Here is the picture of the motor with the covers off. We’ll be looking at the passenger side. Egnore the yellow square box. That was in the picture for something else. Just take note of the passenger side inlet pipe comming from the air box to the throttle body.

When you look down the back side of the intake pipe you will see two PCV lines attached to the inlet. Take care pulling these off. They are prone to break and are usually brittle.

Quick Tip: If you pull these off when the motor is hot the intake will be a little softer and that helps the fittings come off a little bit easier.

Once off this is what it looks like.

Note the connections location on the intake tube after you remove them. Also, the lines are not very long at all so, you don’t have a lot of room to pull on them.

Quick Tip: keep careful note of the coolant Y located right in the path of where you’re working. Remove that from the expansion tank and move out of the way. If the car is still warm be careful of coolant pressure.

Step 2 - Unclip the wiring harness on the left side. Unclip the two clips circled in red. You don’t need to remove the ground wire circled in green. The two arrows point to clips attached to the fuel lines. Gently pull these off. Lift the wiring harness over the fuel pump to the left side and leave there.

Step 3 - Do the same on the other side. There are no fuel line clips on the right side.

Step 4 - Remove the PCV vent hose from the left-hand side (squeeze and pull). You need to remove it from the valve cover and from the oil separator. Move the hose out of the way. You can leave the right side connected. Put a rag or something to block debris from going into the opening in the valve cover.

Step 5 - Remove the valve/hose. Squeeze the clamp with the pliers and pull the hose up.

Step 6 - Remove the ‘air distribution housing.’ There are 8 Torx T30 bolts holding it to the manifold. You will also need to remove the bracket connecting the oil separator to the right-hand side throttle body. Remove the two M8 12-pt bolts on the throttle body and the Torx T30 on the oil separator.The housing should now lift away. It may be a good idea to replace the bolts onto the throttle body so you don’t lose them.

Quick Tip: most people don’t like to put back the oil separator mount to the throttle body. That is fine as it makes for easier service. Just remember to put the bolts back into the throttle body as listed above.

Step 7 - Remove the oil separator. There’s very little clearance between the firewall and the oil separator, so this is where you will need your 1/4" ratchet and 1/4" drive Torx T30. Remove the bolts (be careful not to drop the bottom one), and pull/push the oil separator towards the firewall to remove it.

Step 8 - Fuel lines. The factory service manual says to remove the fuel lines and the fuel pumps, but I found this wasn’t necessary. Nonetheless, you must remove one line and loosen the others in order to free the manifold. We’ll do this step now so you can let the fuel drain out while you do the rest. I was expecting these lines to be under high pressure, but they weren’t. Put a rag around the connection as you loosen it in order to soak the fuel. When you do the rear connection, be aware that more fuel will come from here than from the pump connection

Now loosen the two lines on the left-hand side, at the pump only.

Step 9- Now move to the front of the intake manifold. Remove this little hose and move out of the way.

Step 10- Remove the module at the front left of the manifold. sort of a vac sensor - It controls the air box flaps and ties into the SAI system. Unplug the connector, the two hoses, and then remove the bracket it is attached to. One 10mm bolt and one Torx T30 hidden underneath. To remove the 10mm nut, use the stubby wrench, rather than a socket. Using a socket will cause you to foul the hose barb sticking off towards the right, and you don’t want to break it.

10b - remove the engine lifting brackets. Otherwise, this will foul the manifold when you try to remove and cause issues once the intake spacers are installed. The engine lifting brackets are to be fully removed and not put back in. 2x Triple square/12pt M10

“You will also want to remove wiring harness bracket from the studs on the driver side head. You can secure the wires with a zip tie so they stay out of the way of the flap arms. This is because the brackets can interfere with your flap arms and give you the
following codes:

008196 - Intake Manifold Flap; Bank 1
P2004 - 002 - Stuck Open - MIL ON

008197 - Intake Manifold Flap; Bank 2
P2005 - 002 - Stuck Open - MIL ON”


Step 11. You’re going to need to remove the intake manifold bolts. You’ll need a longer neck tool for this as there is little room to get to most of the bolts. It’s also a good idea to make sure you have a magnet to help pull out the bolts once you’ve loosened them. There are 6 bolts on each side of the intake. This picture shows you their location and also the next step. That’s removal of the passenger side HPFP.

Loosen all the bolts and remove them with your extendable magnet. It will be hard to get to some with your fingers, and you may need a friend to wiggle the manifold and fuel lines to help you free a couple of them. Be careful when removing the rear screws - DO NOT DROP THEM. The rear left one has the highest danger of dropping into never-never land.

Once you have the 12 bolts removed from the intake, you’ve removed the fuel lines and HPFP out of the way the intake manifold will be able to move but will still be unable to come out.

You’ll need to unplug all the sensors and plugs on the front of the intake. Due to the reduce ability to see these plugs with the front end of the car on and overall the reduced space to even unplug these plugs, I have a picture of what the intake and the plugs look like from the front of the car with the front end off.

Quick Tip: I put the bracket bolt location in this picture to help suggest removal of these bolts. This will help in getting these sensors off the intake.

Once you’ve removed all the bolts, the brackets, plugs, fuel lines and passenger side HPFP you’ll be ready to pull out the intake manifold. The best method is to slightly pull the intake manifold forward rotate the intake clockwise as you pull up and out the intake. With the passenger side HPFP off, you’ll use that side to pull the intake to when you pull it out.

When you’re done you’ll be left with it looking like this.

Quick Tip: take notes of the cap off points for the fuel and for the HPFP location. Lots of people run into issues when they put the cars back together. They get debris in the fuel lines and that can take out an injector. Capping off the fuel lines is a good practice.

As I mentioned above. The JHM intake spacers made a huge impact on lowering the overall underhood temps along with giving better cooler intake temps.

Some of the exciting things I’ve done are

The JHM intake spacers - check we talked about those a few posts above.
Carbon clean - talked about that -
Up-date plugs and coil packs. - Did that earlier in the thread.
Compression test - Did this earlier in the thread.
Cylinder inspection - Did this earlier in the thread
Intake manifold inspection - Did this earlier in the thread

Coming soon…

The JHM Lightweight crank pulley - almost 9lbs of weight savings.
The JHM Lightweight brake rotors front and back - weight savings you wouldn’t believe
JHM beta ECU and TCU tune.
Full custom 3" exhaust
SAI removal - coming soon with the crank pulley
Fuel filter - part of the oil change and fluid assessment.
Oil change and fluid assessment.

After all, that I show the tract tested results from all the above work.

Now back to the performance parts of the build. Last time we talked about the JHM intake spacers and their ability to help keep the 5.2 V10 heat issues in check. While the spacers are helpful at keeping the motor cooler and more efficient the motor could also beit from shedding some of that unnecessary weight strapped to the front end of the crankshaft.

Installing LW parts onto the rotational assembly of the motor for performance gains are not new. This has been around since people have been hot rodding cars. Things like underdrive pulleys and lightweight pulleys have been a big part of the performance must do’s. We all know the huge gains seen with adding an LW flywheel if you have a manual car. We have a huge TQ converter strapped to the back of our motors filled with several quarts of transmission fluid and since we obviously can’t remove that we now look to the front of the motor and the crank pulley.

Why would you want to remove and replace your crank pulley? Simple, if you want to see the science behind this go cut a piece of string just over 2 feet long. Then from there tie a 10lb weight to the end of that same string and see if you can swing that 10lb weight in front of you like a propeller of an airplane. If you even can swing it, try to keep it going at a constant speed, then after a few seconds try to swing it as fast as you can. It will take a large amount of effort to get the speed of the weight to accelerate. After you did this replace the 10lb weight with a 2lb weight and repeat. The results will be drastically different. You’ll be able to speed up and control the 2lb weight and its spinning speed much easier and with more acceleration on demand.

That’s the crappy roadside simplistic explanation. The physics behind rotational weight reduction are sound and impactful. The JHM LW crank pulley allows the motor to spin up faster and with less work. It allows for much less resistance in rotational acceleration of the motor RPM. This results in a much more eager throttle response out of the motors acceleration and its simple.

You’re dropping almost 9lbs off the front of the crankshaft.

So, for those of you who don’t know where this is or what it looks like. Let me show you.

Here are all the important things I reference where they’re located and what they look like.

You’re going to have to pull the front end of the car off to replace your crank pulley. While I was in there I decided to remove the SAI system. SAI stands for Secondary Air System. It’s the system that turns on in cold weather to help your cats heat up quicker. The downside is the car tends to run rougher on cold starts when it’s activated and over time people have seen terrible carbon build up in the SAI valves. So, for me, I just removed it. Keep in mind unless you have a JHM tune doing this would result in a CEL the first time the SAI system is required to turn on.

Back to the pulley install. For me, the JHM LW crank pulley was a no brainer. It’s like doing the intake spacers when you do the carbon clean. You’re going to be in there anyway, you might as well put in the spacers while you’re there.

I was replacing my OEM belt that looked to be original and also looking to service my belt tensioner. The belt tensioners like to freeze up over time so, I would pull off the belt, take off the tensioner and lube it. While I was in there I added the LW crank pulley.

The stock crank pulley is definitely heavy. Even if you don’t have to replace the belt it might not be a bad idea on replacing the crank pulley. The B6 and B7 S4’s had issues with these failing and the B8 S4s are known to have their crank pulleys fail.

As mentioned, while I was doing the maintenance I decided to remove my SAI system.

Here is a picture of all the other hardware removed. You can clearly see what lines are the SAI lines. They tap into the front of the cylinder heads.

You can’t just pull the SAI lines off and not cap them. Or you’ll have exaust gas coming out the front of your cylinder heads. So, I quickly cut and welded the ends off the SAI lines.

If anyone wants more pictures on the SAI removal let me know. I removed the pump and the valves that were located off to the side.

After the SAI lines were off and I made the caps I started putting everything back on again. Making sure to use Locktite on the crank bolts and using a nice white lithium lube on the belt tensioner.

The crank pulleys on the 4.2 S4 and S5 are just like our crank pulley on the 5.2. They are counter weighted and that’s something serious. The money in the pulleys is in the balancing of the pulleys to make sure they have the right counter weight.

Years and years ago when this came out for the 4.2 S4 a few people would try to make the argument that putting an LW pulley on would cause issues. Well, there been no issues with the 4.2 S4 or S5 after 10 years and after several motor teardowns for built motors in the 4.2 there was no sign of any bearing issues. As a matter of fact there seemed to be less bearing wear on cars with LW crank pulleys over OEM units.

For fun, I did a crude test to show there was no change in NVH. I did the oldschool water on the intake test.



from 3200 back to idle.

There are huge offset weight tolerances in the OEM pulleys where the JHM units are balanced with precision balancing. I actually noticed a smoother idle and lower knock voltages when crusing with the JHM LW pulley.

GIVE ME A BRAKE… Next phase in the performance journey, was to replace my squeaking worn out brakes.

There are several options when it comes to just replacing the OEM rotors. For me, I’ve seen lots of guys go the cheap option and you get what you pay for. Cheap rotors tend to use cheap material that wears out quicker and doesn’t seem to offset the cost in the long run.

For me, I really want to bring out the supercar in my super car. So, the search for performance rotors started and as usual as most of you know there was nothing. So, I called the guys at JHM and asked what they could do. They have performance rotors for just about every other platform why not us. The S8 and S6 front rotors are the same on our cars so its like one big market.

I wanted a lighter more performance oriented rotor that would help drop some rotational weight while pulling out the heat and helping with pad life. Heck, if the Lambo gets performance rotors, that dissipate heat and weigh less, why don’t we right?

BOOM I saved 30lbs of not just weight but rotational weight. That’s a 15lb weight reduction EACH SIDE, while adding a huge drop in breaking temps. That’s more than some light weight rims offer and at a fraction of the cost of lightweight rims.

The added great part is way-way down the line when it comes time to replace the rotors again, you just need to order the rings. Ording the rings will save you quite a bit of money. The rotors cost a bit more due to being two piece and being that their performance rotors. Being two piece has several advantages if you really want to track the S6 you can just get an extra set of rings for the track like lots of the road race guys like to do.

I’m not a huge cosmetic guy but even these OEM rotors look underwhelming.

The other thing l didn’t like about the stock rotors was the fact that the rotor was just a little bigger than the pad surface needed to be. So, this resulted in my rotor having a huge lip on it from where the pads had worn away the material. It made getting the heavy OEM rotors out quite a chore.

Now putting on the JHM rotors. Very easy a straight forward job. The addition of the slotted feature that comes with the JHM rotors is not just great to help in braking performance, but I think it looks nice as well.

To me, it’s hard to beat adding performance while doing maintenance. Nothing is real exciting about doing a brake job, except when you know you’re dropping weight, adding performance and helping make things look just a little better at the same time. It’s a win win win.

This week we drop another 10lbs off the rolling weight of the car with the JHM rear rotors and I walk quickly through what you’re going to need to do with vag com to be able to get the rear breaks off.

Yes, you read that right. You can’t do rear breaks on these cars without the help of the computer. So, when you’re doing brakes keep that in mind. You’re in good hands here though, I post at the bottom on what you’re going to have to do to open the rear brakes.

Now on to the thread.

I did the front brakes and dropped over 30lbs between the two of them. Each side I was able to drop 15lbs with the JHM LW rotors.

With that big impact, I thought it would be time to drop a little weight from the rear rotors. Again using the JHM rear rotors.

These not only look great but they function better than the OEM units and they weigh 5lbs less each.

With the JHM rear rotors, you’re knocking off another 5lbs a side. For rear rotors, that’s a lot of weight. You normally don’t see that kind of weight reduction in rear rotors. The front brakes do the majority of the work so the rear brakes don’t need to be as big. Still, it’s a good area to shave weight when you can.

With all this weight savings I actually saved a ton of money. Usually to get these kinds of weight savings you have to get light weight rims. Since the S8 comes with 20" rims stock. It’s kinda hard to find nice light weight 20" sport rims.

Oh, and if you’ve ever wondered how much the OEM S8 rims and tires weigh.

That’s a lot of weight for rims and tires.

Now for the technical part of the post. Most of you might not know but you can’t just jump onto the rear rotors like you can the fronts. The rear rotors with the electronic parking break require the use of a computer to unlock and open the rear brake caliper.

If you’re a DIY’er 90% of the brake job is going to be the same the rear brakes come off easy without much fuss but when you need to open the caliper you’re going to need a computer. If you have a vag com I’ll show you what you have to do.


Open vag com and select the “SELECT Control Module” option


Select option #53 - Parking Brake


With the Parking Brake controller open click on the - 04 Basic Settings


In Basic Settings open the drop down menu and click on Open Rear Parking Brake


You might have to still help open the piston manually. Clicking on Open Rear Parking Brake doesn’t necessarily open the piston all the way. You might have to open it to the specific spot you need to place on the pads. Now is when you would push back the piston on the caliper as far as you need and put in the pads. After the pads are on and the caliper is back on and in its place. You’re ready for the next step


That will get you all set. Some people like to do the Parking Brake Function test. I never found a need for it. That’s there if you have an issue and you’re checking the function of the system.

This walkthrough works for most cars with rear parking brake systems.

Now with all the weight lost from the JHM Rotors, you’re car will be transformed into a lighter fighter. All in all, it’s a mod worth doing. The rear rotors don’t get changed that often so this mod should last you years and years and years before you’re going to even need to think about replcement of the rings.

Getting further along in the Performance build of project V10 5.2. The next biggest step is the exhaust.

The big thing with exhausts is that you can do it wrong lose power and still sound ok. Many people have been scammed by just buying an expensive sounding stock sized Catback exhaust. Not all exhausts are created equal. The size of the exhaust can make or break the improvement factor of the exhaust. I’ve read many fancy exhaust shops and companies post about how building an exhaust isn’t some black magic. The reality of that statement is that those companies or people who don’t know how to get more power and quality out of an exhaust system don’t know how much they’re losing. In other words, some companies and or people just don’t know what they don’t know.

When it comes to exhaust systems for the Audi 5.2 V10 most of the past offerings have been a complete rip-off. The S6 5.2 exhausts have been an adapted A6 4.2 exhaust system. The Aftermarket 5.2 V10 exhaust sizes have been a complete joke and frankly have been taking advantage of people’s lack of knowledge about their cars.

There was a company that offered an X pipe for the S8 V10. Frist off the size was too small for real performance but let’s forget about that for a second. The biggest scam here is, that the S8 V10 5.2 exhaust system already has an X pipe. What a rip off that was.

So, the next question is other than sound do we really want an exhaust system for our cars? Well, we bought V10 cars for fun and performance. A real performance exhaust doesn’t have to be loud and obnoxious. My exhaust system is 3" and I’ll put up video of the in cabin noise, you hear more road noise than exhaust tone. You’d almost not know there’s an exhaust. The truth be told 2.75" is perfect for these cars, it adds that euro tone and makes in cabin noise more controllable. It’s also good for about 200hp over what the stock exhaust system flows.

One last thing to think about before I get too far into my post. Adding things like air filters help the motor breath better on the intake side. It allows easy flow of the outside air into the intake manifold. We all know that the motor pulls in outside air when the piston is on the intake stroke where it pulls in air by creating a void. But did you know that the headers and Catback actually pull in and act in pulling in more air than the motor itself?

Now onto the actual post. Knowing how much hp can be gained I decided to do some testing and take it one step at a time to see just how much more power I would be able to pull out of the V10 by just messing with the exhaust.

Note- the S8 exhaust is where the bulk of the power gain is over the S6. The S6 will actually gain more power than the S8 as the S8 exhaust isn’t as restrictive. While the S8 exhaust is still restrictive the S6 exhaust is just terrible stock.

We have a thread dedicated to this but if you haven’t seen it before. The S6 exhaust is on the bottom. Look at how the piping isn’t smooth and its all crushed.

The other thing you’ll notice is that the S8 has a valved exhaust where you can have both tips flowing air vs just one.

So, for testing, I did what we all would have done.

I welded the exhaust valve open.

I did notice a little more noise but it was only in the higher rpm’s. A little more noise at idle but not enough to consider this a mod. Start up was obviously a little louder as the motor goes through its rev range warm up cycle.

After that modification didn’t do much I just said the heck with it. lets just take off the old system and build a new one.

Here is what the old system looked like on the car.

So, it went from this.

To this.

The difference was tremendous. Sound, performance, and throttle response all came into play and all worked much better with each other. These cars react really well to a proper exhaust as I mentioned the S6 will react even more so, While I did feel a gain it was clearer now that the ECU was now working overtime to hold back even more power.

These cars are De-tuned from the factory to hold back a lot of the V10 power. That became clearer after adding the exhaust. I kinda felt it each time I added something new to the car like rotors or intake spacers but adding the exhaust put the car over the top. I could now really tell the Audi De-tuned computers were working overtime.

Thankfully, the next modification was the best for last. The JHM tune. Stay tuned that’s coming up next.

A video would help right? Sorry, here it is.

I have some in car video if anyone is interested.