Castro Motorsport: Kato Racing's LS7 "E40Z06" M3 Race Car Build

WARNING - THIS IS A LONG READ! CLIFF NOTES WILL PROVIDED LATER AT THE BOTTOM FOR THOSE THAT DON'T CARE TO READ THE MINI NOVEL I'VE WRITTEN.

FOLLOW THE BUILD ON INSTAGRAM: @CASTROMOTORSPORT & @KATORACING AND ON FACEBOOK: https://www.facebook.com/castro.motorsport.ca?ref=hl & https://www.facebook.com/GoKatoRacing?ref=hl

KATO RACING WANTED TO THANK THE FOLLOWING SPONSORS FOR ALL THEIR SUPPORT IN THIS PROJECT AND MAKING IT A REALITY:

Castro Motorsport: www.castromotorsport.com

Cunningham Motorsports (CMS): http://cunningham-motorsports.com/

KW Suspension: http://www.kw-suspension.com/us/

Stoptech Brakes: www.stoptech.com

Undr8d Empire: https://www.facebook.com/Undr8dEmpireLlc

Shift S3ctor: www.shift-s3ctor.com/

Auto Talent: http://www.autotalent.com/

Forgestar Wheels: http://www.forgestar.com/v2/

Dailey Engineering: http://www.daileyengineering.com/

Whiteline Suspension: http://www.whiteline.com.au

Radium Engineering: http://www.radiumauto.com/

Mantic Clutch: http://mantic.com.au/

Before I delve into this amazing car project, I'd like to give a bit of background on the owner of the E40Z06 M3, and his team - Kato Racing. He has had a great passion for cars and motorcycles since he was a kid, like many of us. He focused on his passion over the years, as both a driver and a rider, and has become very talented at both, on and off the track. He started his life on the track with motorcycles; he even rode at the professional level for a while.

After falling in love with road racing on a bike, he turned his attention to cars. A few years back, he and a group of friends started a 24 Hours of Lemons team and built a run down E30 as their track beast.

A while after that I met him after he went and checked out my former E30 M3 before I had the chance. Following the purchase of my M3, he and I kept in contact. He told me he had and E30 Lemons car and that he needed a mechanic that wanted to join their team. I introduced him to Chris Castro and the rest is history. Over 2 seasons Castro Motorsport serviced and upgraded the former Kato Racing E30, and it placed very well in each series it competed in.

He also started taking the E30 to track days thrown by an awesome track organization called Shift S3ctor. Having much higher dollar competition at the Shift S3ctor event motivated him to step up his game as far as his track car was concerned.

And so the planning process began, and this is what we came up with.

The Objective:

The goal of this build was to create a powerful, well-balanced, car with an aggressive look, that can embarrass high dollar sports cars and their owners. This car will easily out perform cars valued at $100,000 or more, in every way, for a fraction of the price. With a talented and experienced driver like Kato Racing behind the wheel, the potential is limitless. Having competed extremely well and enjoyed his former low budget, E30 track car, which was initially built for the 24hrs of Lemons racing, he decided he wanted to stick with a BMW platform for his next build. But as always, he wanted to make it a bit unconventional. Initially we looked at the E36 M3 platform, which is one of the best BMW platforms, which would have definitely accommodated our needs. The E36 is light, nimble, and has a much better, engine, transmission, suspension and brake design then the former E30 he ran. Not to mention E36 M3s can be found cheap and have great aftermarket support. All that being said, he always preferred the E46 M3 chassis, but we weren’t sure that we could stay within our ballpark budget with such a car. Luckily for us, we knew someone selling the perfect specimen for our needs, a worn down E46 M3, with a few nice parts on it, with a healthy motor and transmission. The car wasn’t pretty, but it was exactly what we needed.

The Direction:

Once we found the car we wanted, we knew that the suspension and brake options were plentiful, and that the stock 3.2L S54 inline 6 was a great engine on and off the track. While we could have built the S54 into an impressive naturally aspirated, 400+hp motor, or gone with the forced induction route to achieve the power figures that would keep the car competitive, all of those options were going to be expensive. The NA engine build wasn’t going to have enough power for the money spent. A centrifugal supercharger didn’t provide the torque numbers we wanted, for the amount of money spent. Finally, with HPF (Horsepower Freaks) being the only available option for a reliable, off the shelf turbo kit, the price for high powered kit was going to put us over budget. Then we had a better idea, which would get under the skin of many BMW enthusiasts, especially the purists in love with the M3 platform. With the GM LS engine platform becoming such a popular choice in recent years, and with him having recently owned and loved his C6 Z06, we chose to give the Bavarian sports car an American heart.

The beauty of the LS engine, is that it’s all aluminum, starts with lots of displacement, has great aftermarket support, can makes tons of power NA, and even more with forced induction, and has a great reputation for its reliability, even when being thrashed on the track for hours at a time. While there was no readily available kit yet for the LS swap into the E46 M3 when we initially began to look, we figured this was the perfect opportunity to design and build our own replicable kit. We had already lined up a customer to create an LS swap kit for the E36 chassis, so we figured we should build two kits while we had the opportunity.

The Motor:

The initial plan was to go with a nicely built LS1, with the goal of a reliable 400-450whp and 400-450wtq. This would keep us within budget, and definitely make the car fast on the track. However, he decided to sell his C6 Z06, as the LS powered E46 M3 would be a very similar car to own in many respects. It was going to be hard for him to part with his Z06, as he loved the way that car performed, and wanted to make sure that the E46 M3 would be just as impressive and more. Another hindrance was that he had absolutely fallen in love with the LS7 motor in his Z06. While we knew we could build an impressive LS1, which would perform similarly, there were certain features of the LS7 we couldn’t accommodate, without going with a newer LS2 or LS3 motor. After searching the forums for months, he came across a great deal on the dry sump set-up from an LS7. We contacted the seller, and while asking about the dry-sump, we inquired about what other parts the seller had laying around. Turns out he had the rotating assembly from an LS7 as well that he was willing to part with! This definitely changed the direction of the motor.

After contacting Ryne Cunningham from Cunningham Motorsports, he got CMS on board as the engine builder and calibrator and LS power train component advisor for the project. Along with building blueprinting and building the motor, Cunningham will be dyno tuning the engine to make great, reliable power for the track. With his wealth of knowledge, and his connections in the LS world, Ryne has been an extremely valuable asset and a big part of the E40Z06 project. We searched for a few weeks for a suitable LS2 or LS3 block that could be used with the LS7 dry sump and internals, but came up with nothing worthwhile. Luckily for us, Ryne sourced us a Darton sleeved LS7 block, which was going to work perfectly for our goals. While the block was quite a bit more then we intended to spend, it wouldn’t limit the overall displacement of the engine, as the LS2 and LS3 blocks would’ve. This of course was great news, because more displacement equates to more power!

Once the block was acquired, he also sourced a nice set of LS7 heads to compliment the bottom end. The heads and block were then all sent to the machine shop Cunningham Motorsports uses, for the assembly process. While he went over his budget with the motor, at least he will never have to regret not going for the best that he could. Also, because the entire motor is being completely rebuilt, with the best quality parts, he wouldn’t have to worry about any potential issues with reliability of the motor on the track.

While we were having the motor rebuilt, we took a look at other potential failure points that could cause concern on the track. The first that came to mind were the sodium filled exhaust valves in the LS7 heads that he acquired for the build. Being a former C6 Z06 owner, he unfortunately experienced a failure that many LS7 owners have seen – an exhaust valve failed and ruined his motor. Luckily the Z06 was still under factory warranty, so the engine was replaced at the dealership. We wouldn’t be as fortunate if this happened to our motor if it failed on the track, as we won’t have a nice warranty to back the motor up. Consequently, he wanted to have the valves upgraded, as well as the valve guides and retainers. While he was in there, he figured why not get the heads CNC ported as well?! The ported heads will flow better and will allow the Cunningham Motorsports camshaft to really shine throughout the power band. The better flowing heads will make the engine more efficient, while also adding substantial power gains.

Along with the potential valve failure, he was concerned about the factory LS7 dry sump system keeping his high dollar motor lubricated on the track. After looking at various options and reaching out to Ryne Cunningham for advice, we decided on a Dailey Engineering roots style oil pump, pan and tank. This set-up is tried and true, so we won’t have to worry about the motor having any oiling issues, in any situation, on and off the track. The oil tank will be installed inside the car, as the engine bay space is very limited with the motor installed. The Dailey oil pump is fairly compact, and will be mounted where the factory air conditioning compressor would’ve gone. The size and placement of the pump were a large concern, but this set-up will work perfectly for our needs.

Official motor specs:

Darton sleeved, over-bored LS7 block
Factory polished and balanced LS7 crankshaft
Factory balanced titanium LS7 connecting rods
Custom LS7 over-bored Wiseco Forged Pistons
West Coast Cylinder Heads, Stage 2 CNC ported LS7 heads
New upgraded stainless steel intake & exhaust valves
New upgraded valve guides
New Dailey Engineering Stage 3 dry dump system
New LS7 double roller timing chain
All new performance bearings and hardware
All new engine gaskets
LS7 Intake manifold & drive by wire throttle body
New LS9 injectors
New LS7 coil packs
New 8.5mm MSD ignition wires
New LS7 MAF
All new factory sensors

Transmission and Drive-line:

To start we will be utilizing a factory F-body T56 6 speed tanrsmission out of a '99 Z28. This, couples with the factory M3 3.62 LSD is not ideal gearing, as it's fairly short for the power we will be putting down. The next step is to either build a custom 3.15 LSD differential, or get a custom geared Magnum Tremec 6 speed. Either way, for the road course, we want longer, usable gears. The car will have A LOT more power then stock, and it won't put down the low end torque too easily.

As for transmission and flywheel, we're going with an awesome Mantic 9000 series, twin disc clutch kit, with lightweight flywheel.

For a shifter, we went with a simple Hurst short shift kit for a '99 Z28.

Air Intake, Headers and Exhaust:

We've always been fans of the way Chevy designed the Corvette's induction system and radiator mounting, so we will be mimicking this on the M3. We plan to duct the air coming through the kidney grilles in the hood directly to the air filter, much like the C6 Z06 has with it's front vent.

The headers will of course be custom built to fit within our space constraints. After doing plenty of research, we decided to design a set of long tube headers versus shorties. The headers will have 1 7/8" primaries, along with dual 3" mandrel bent exhaust.

Finally, the exhaust will be exiting the passenger side of the car, before the rear tire, like the DTM E46 M3 had.

Suspension:

As with any car specifically built to race on a road course, suspension is key! Luckily the E46 M3 is already a great handling car in factory form, but it’s a whole different animal when set up properly. There is plenty of aftermarket support for the E46, which allowed us to pick and choose which parts we wanted to put on the car. Since comfort wasn’t a concern, our first course of action was to purchase a complete set of solid suspension bushings and mounts from AKG Motorsport, including their motor and transmission mounts. With solid bushings and mounts, the car will be extremely tight and responsive, leaving no unwanted play in the suspension.

Unfortunately the E46 has a few weak points in the chassis that need to be addressed, especially if the car is going to be driven hard. Therefore, we also purchased a set of AKG Motorsport rear sub-frame and sway bar reinforcements. Chris Castro modified reinforcements further to make them as strong as possible. The trunk floor and the rear shock towers will also be addressed on the roll cage is designed.

The car came with a used set of Bilstein PSS9 coil-overs, which while they are nice for a street car, we needed a better option to keep us competitive against the big dogs on the track. Having had plenty of experience with KW Suspension, the choice was pretty easy for him when it came time to choose the coil-overs for the E40Z06 project. His former C6 Z06 had KW V2 coils, as well as his nicely built 996 Turbo. Thankfully KW Suspension has come one as a sponsor for the Kato Racing M3 project, and is setting us up with their 3 way adjustable Club Sport set-up. Big shout out to Sam from Auto Talent that made this possible! The Club Sport set-up will keep the M3 competitive on the track and allow us to fine tune the car’s handling.

The M3 already came with Turner Motorsport adjustable rear camber arms, which was one less part to buy! Coupled with some modified AKG solid, spherical rear trailing arm bushings, there will be plenty of available camber adjustment out back. The front control arms and control arm bushings haven’t been finalized, but we’re most likely going with AKG adjustable front control arms. Since this will be a race car, we need the greatest amount of adjustment possible.

Finally, Whiteline Suspension will be supplying us with a set of adjustable sway bars for the project.

Brakes:

Since this will be a powerful car, we need to make sure that the car has great brakes, which provide greater, consistent stopping power. Since we’re basically doubling the power of the E46 M3, simply upgrading the pads, rotors, fluid and lines is not going to meet our needs on the track. The car he purchased came with an older set of Rotora big brakes for the front, but they aren’t going to be enough. Due to his great experience with Stoptech brakes in the past, he decided to go with Stoptech for the big brakes. We also aided his decision with our own personal experience with Stoptechs on a few E46 M3s, we loved the way they performed! Stoptech could also potentially sponsor the project.

Wheel & tires:

Seeing that an 18” wheel has the greatest number of options for both tire sizes, and wheel options for the E46 M3, we decided to stick with the factory wheel diameter. Due to the great selection of track wheels available for the M3, there are quite a few contenders for our wheel choice. We want them to be light and strong, which narrowed down the search considerably. He had APEX ARC* wheels on his E30 Lemons car, which were light, strong and cheap, and are also extremely popular amongst the E46 M3 crowd. That being said, he also had a custom set of Forgestar wheels on his C6 Z06 that he loved. While APEX has two wheel versions available, which have all proven themselves on the track, Forgestar is an even bigger name and could potentially sponsor the project. Also, Forgestar can custom make the wheels to our specifications. While APEX has plenty of widths and offsets to choose from, at this point we will more than likely go with Forgestar for our wheels.

We're love the way the F14s look on the E46, but we want WAY more tire then this car:

Our goal is to run either a 18x10.5 or 18x11 square wheel set for road course days, with a 305/35/18 all around. We also want a wider pair of custom made rear wheels to be made, to be able to run a staggered set-up for certain tracks, and any form of straight-line racing. Unfortunately such wide wheels and tires won’t clear the factory wheel arches, so we will be making our own set of rivet on fender flares to accommodate. The square set-up will be ideal for neutral handling, however we may have to run a staggered wheel and tire set-up to promote some under-steer. Any intentional under-steer can be easily corrected with the 500+ ft lbs of torque this car will be making at the wheels. We should be able to accommodate 18x12s out back with the flares we’re planning on, to fit 335s for a staggered set-up.

Tire compound and brand hasn’t been decided on yet, as we have so many options available. Hopefully once the public sees how impressive this car will be on and off the track, with a driver like him, we can reach out to tire companies as sponsors.

Safety:

As with any car, safety is key. We will be putting in a full roll cage designed off of the original E46 DTM car. With the help of John Mason of Mason Engineering, and his years of experience building professional cars, we will make sure that he and anyone else piloting the E40Z06 M3 is as safe as possible. Aside from the roll cage, we also have been and will be making various reinforcements to strengthen various weak points of the E46’s chassis.

Along with a proper roll cage, we will be equipping the Kato Racing M3 with a proper set of Sparco Evo 2 Plus bucket seats. He had this seat in his former E30 Lemons car and is extremely happy with the fit and weight of it. These seats are light and strong, both key to the safety of the driver, and the performance of the car on and off the track. The passenger seat will be easily removable with custom mounts we will make; no need for the extra weight when he is out on the track without a co-pilot.

To go along with the Sparco seats, we will also equip the car with Crow 6 point harnesses to keep him in his seat! While there are numerous options for harnesses, we got a great deal on the Crow units through Sam at Auto Talent and they're quality products.

Finally, to ensure the safety of our driver, we will install a proper fire suppression system inside the car, and an appropriate kill switch for power, to prepare for the worst.

Chassis, Exterior, Aesthetics and Aero:

While aesthetics don’t win, we do want to make the Kato Racing E40Z06 M3 look as cool as we can. That being said, any modification we will make to the car we want to be beneficial to the car’s performance. The first area we have and will need to address on the car is its weight. While the E46 M3 isn’t astronomically heavy, it’s been criticized for being heavier than its 2 ancestors – the E30 and the E36. Weighing in from the factory at 3,415, the E46 definitely feels heavier than the 3,219 lb E36 and 2,865 lb E30. That being said the suspension and brake improvements on the newer chassis, along with the award winning motor made it a very impressive M3. Well, we’ve removed everything we could to drop the overall weight of the car, and luckily the car already had some lightweight aftermarket parts on it when purchased. Some of the parts already on the car included – Vorsteiner carbon fiber roof, GTR hood and CSL trunk. Unfortunately we didn’t get the car weighed before tearing it apart but we will calculate the actual weight savings in comparison to the factory weight before building the roll cage. While the roll cage will add a decent amount of weight back, it will stiffen the chassis, which will not only improve safety, but also the handling of the car and its ability to put down the power.

The plans for the exterior of the car are both purposeful and aesthetically appealing. The major change needed is wider fenders to accommodate the wheels and tires we pland to run. While the E46 M3 can fit fairly wide tires all around, we need tire widths similar to a Z06 in order to effectively put the power to the ground. While widebody kits are out there, the quality ones are very expensive. We've decided to work together with our friends at Bare Bones Autobody & Paint to create a stylish and effective set of rivet-on fender flares for the car. With the flares we will clear direct fit 18x11s all around with 305/35/18. We will also leave enough room to run up to 18x12 rears, with 345/35/18 tires. We're hoping that with the right compound tire that the 305s will be enough, but we will have the room to go up in size just in case.

For aero, we will be making a custom front adjustable splitter for the factory front bumper, with tie downs. We also plan to incorporate 1 to 2 canards on each side of the front bumper for added down force. A custom under-tray is also in order, along with an aggressive custom rear diffuser. Finally a large adjustable rear wing will also be added to plant the car in the turns.

UPDATES AND PICS COMING LATER TODAY THROUGH THE REST OF THE WEEKEND, WE'VE GOTTEN QUITE A BIT DONE SO FAR!

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Castro Motorsport: Kato Racing's LS7 "E40Z06" M3 Race Car Build

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Castro Motorsport: Kato Racing's LS7 "E40Z06" M3 Race Car Build