NOTE: This is for reference only; I am not liable if you screw your car up. Use caution and common sense when working on your vehicle. Read the directions (like you will) use the right tools and use the appropriate safety equipment.

Tools needed

12mm socket
14mm socket
17mm socket
3/8” socket wrench
3/8” socket extension
17mm wrench
8mm Allen
Phillips screwdriver
Utility knife

Getting Started

The RX8 does come with a factory strut tower brace.  And, if you remove it, you do feel a difference.  However, the factory brace leaves much room for improvement.  For the ZWP, we decided to go with the GTSPEC Strut bar.  It is made from aircraft grade 6061 aluminum with a triple internal hollow wall.  Overall weight is about the same from the steel factory brace when you take into account all the brackets on top of the strut towers.

Factory Strut Tower Brace

Remove Factory Brace

Using a 12mm and a 14mm socket, remove the factory strut brace and additional brackets. With the factory brace removed we can really compare it to the GTSPEC.  Actually, there is no comparison, the stiffness and the build quality is drastically better than the factory brace.

Install the GT brace

Reusing the 14mm sockets, install the GTSPEC brace.  We recommend having some play in the bar mounting points to pivot the brackets for installation ease.  Once the brackets are firmly mounted, and then you can tighten the brace using a 17mm wrench and a 8mm Allen.

NOTE: We recommend that your car be on a flat even surface when tightening the bar.  Otherwise, the brace will attempt to keep the chassis in a tweaked position.

Check for clearance

I had to slightly move (Bend) the brake lines coming from the ABS controller.  I only had to move them about an 1/8 of an inch.  You do not have to create a situation where your brake lines rub against anything.

Front bar complete!

Your front bar is complete.  Of course you will not be able to fit the factory engine cover. (Unless you modify it) But for me that is 3 additional pounds that is not needed for the operation of the vehicle or needed as a comfort to the passengers.

Rear Bar installation

The rear bar is slightly more effort because you need to work around the interior pieces in the trunk.  Care must be taken to ensure you do not break the trunk interior pieces.  Let’s get started.

Remove the interior

There are several clips that must be removed to gain access to the rear strut tower mounts.  Start by removing the rear plastic piece.  There are four clips that hold the rear piece.  These clips are removed by pulling the center clip partway out.  Then tug on the center piece and the entire clip can be removed.  Once all four clips are removed, gently pull up on the panel to remove it.

The remaining side pieces are removed by removing the clips then gently pulling out the pieces.  In addition to the clips used on back piece, there is another clip that has a Phillips head in the center.  These clips are removed by gently unscrewing the center piece completely out.  Then the plug can be removed.  Apply as little pressure to the Phillips screwdriver during this process or the center pieces will not come out.  Once the panels are removed, we can proceed to the next step.

Mounting the strut tower brackets

Only the outside bolts need to be removed for this installation, the inner bolts can remain untouched.  Align the bracket for the rear strut brace and install. In order to install the other side, it will be necessary to remove the bracket from the strut bar.  This can be done with the 8mm Allen and a 17mm wrench.

Cutting the holes in the interior pieces

This is the most challenging part of the project.  You could just slit the panels to slide them over the strut bar, but that will look tacky.  Instead, we decided to cut holes for the bracket to extend through.  This is more difficult, but the results speak for themselves. Start by placing reinstalling the factory side panel.  Make sure all the mounting holes align.  Then slightly press where the strut tower bracket meets the panel.  A light tap will actually crack the panel where the bracket meets the panel.  Use this as a reference where to cut.

On the passenger side, there is more work to be done

You need to remove the strap and reinforcement piece of wood that holds the factory flat tire kit.  This can be done with a small pick took to remove the staples holding everything together.  Once this is done, repeat the same steps used on the driver side for locating the strut tower bracket. Once the holes are cut for the brackets, reinstall the interior.

Mounting the rear strut tower brace

The hard part is now complete.  Installing the rear strut tower brace requires using the 17mm wrench and 8mm Allen.  Your installation is complete.  The are several drawbacks to the rear strut tower brace.  You do lose trunk room.  Also, the mounting place for the Tire kit is taken then the strut tower mounting.  But it does look great and the rear bar does help with the chassis in corners.

What’s next?

Our first part of this project was to improve the already great handling of the RX8.  We have upgraded, the wheels and tires to light, wider wheels with more grippy tires.  We lowered the car with Tein Basic Coilovers and now we have added the GTSPEC front and rear strut tower braces.  Our next plan is to complete the suspension with upgraded sway bars and suspension links.  Then we plan to get the whole setup tuned with corner weighting and alignment.  Stay tuned.

As you can see the Enkei’s fill the wheel well quite nicely when compared to the factory wheels.  Also, the tread pattern really show the difference between an extreme summer tire versus a winter snow tire.  I know winter has only just started, but I can’t wait for spring.

First, I had to wait a couple of days to get the new ACT Clutch and lightweight flywheel.  Second, the motor to be delivered had a little problem.  You see it was shipped through Indianna.  The motor make it ok but the kit of stuff to make the transplant possible got stuck in a flooded semi-truck.  A new kit had to be shipped. So after a few days, it was time to pick up the beast.

The first thing I noticed was how different the clutch felt.  The engagement was super tight with no real play.  (This would later smooth out) Also, the motor revved so quickly, but I must honor the recommend break-in and keep the revs under 4k for 500 miles.  This will kill me.

As the project is coming together, my tires also showed up.  I decided to go with the Falken Azenis RT-615 with a non-staggered set up.  By getting the right offset wheels, I was able to fit 275/35 18″ tires on all four corners.  That is two inches more rubber per corner.   This is an extreme summer solution that has the most amazing grip.  The real beauty is that is also weighs over 5 lbs less at each corner (23 pounds total less weight) over the stock rims and tires.  Add this to the flywheel and I have a net savings of 30 pounds in rotational weight.

Here are some pictures with the new wheels and tires

The pictures taken just after a rain storm.  There was about 1/4″ of water running through the parking lot.  This created the awesome reflection seen here. What you cant see is how bad the brake rotors and calipers look.  I need to paint them real bad.  Sounds like another project.

According to the test results, from 7k and above, there was a significant loss in torque and horsepower. I had hoped the reason for this was a clogged cat. I decided to take the car to my local Kings Mazda dealer. There service has always been excellent. I explained the problem to them and showed them the dyno results. They told me that the results were not acceptable and that they would investigate to determine the problem. I wish all dealers offered this level of service.

ZWP RX8 Dyno Baseline Run from Paul Sonoda on Vimeo.

I got call late Wednesday afternoon, “Mr. Sonoda, we have ordered a new engine for your car and will get the car back to you in about a week.” WOW! This was definitely not what I expected. I was informed that the motor was diagnosed with low compression. This is probably the culprit for my less than stellar fuel economy.

Let’s see. Engine out of car. Hmmmm…….

That might be a great time to replace the clutch and flywheel. I called the Kings and asked them how much extra to install a new clutch and flywheel. Shock again! They would do it for no charge. But I would need to get the parts fast.

After doing some checking, I decided on an ACT upgraded clutch and lightweight flywheel. The flywheel weighs only 9.8 pounds. That is about a 7 pound weight savings in rotating mass. The clutch weighs about the same but increasing the holding force by about 34%. The clutch is rated to handle a maximum torque of 330 ft/lbs which is more than adequate for my vehicle.

With the change in wheels and flywheel alone, the overall weight reduction is now at 27.8 pounds. Next mod planned is a lightweight high-performance battery.

Can’t wait to get the RX back.

Here is an update on the project. As many of you know the vehicle for the project is a Mazda RX8. Nothing compares to the responsiveness and sheer toss ability of the RX8. It has a 50/50 weight distribution and comes in just under 3000 pounds. I mention this because for all its benefits, the RX8 does have one short coming: power. Compared to the Nissan 350z or WRX or EVO, the RX8 is quite slow in a straight line. My old Audi A6 2.7t would dust it. (It would also put the hurt on a 350z and WRX ) That is until you take the first turn. Many of the performance upgrades for the RX8 is less that impressive. This is really the genesis of the project. Add as much performance without adding too much weight.

The first area of upgrade I am planning is the wheel tire upgrade. This is the first step and typically most common upgrade for a vehicle. I decided not to go to a larger diameter wheel. (Too much weight increase) I decided to look for a wider wheel.

The options I found fell into two camps: heaver/cheaper and lighter/expensive. Obviously, I had no choice. After comparing the “lighter/expensive” wheels, I decided on the Enkei RP-F1. (Click on a picture to launch the gallery)

The RP-F1 is a ultra lightweight wheel from Enkei that is a whopping 9.5 inches wide (1.5 inches wider than stock) and an equally impressive 17.5 pounds per wheel versus 23 pounds for the stock 18” x 8” Mazda wheel. With an offset of 45mm, the wheel and tire combo will come out flush to edge of the car. The planned tire size of 275/35 R18 will give the RX8 a two inch wider tire contact patch at each corner! Special thanks to Dave at OE Wheel Works for helping me out.

Lighter Weight Wheels = More Performance

With the combined weight of the wheel and tire, the RX8 will receive over a 20 pound weight loss. (Estimated at 20.4 but not confirmed) The result is a 5 pound per wheel less rotational mass. Reducing rotational mass on the car lowers the amount of drive train loss a car experiences. Mazda thought this important enough to equip the RX8 with a lightweight carbon fiber drive shaft. Depending on the math, every pound of rotational mass eliminated is equal to 1.5 to 2 pounds of regular mass. A reduction in rotational mass is supposed to increase the acceleration and deceleration capability of the vehicle. Does this mean I will see an increase in wheel horse power? I plan to Dyno the car with the stock and new wheels to see if there is a measurable power gain. This will be interesting.

It is also important to note that this is an unsprung weight loss. Unsprung weight refers to the weight of the car that is not supported by the springs of the vehicle. This includes the wheels, tires and brakes. (Ok and half of parts of the suspension) Less unsprung weight improves the suspension speed and performance by reducing the amount of weight and hence inertia that is affected by the road surface and cornering forces. The results are better steering feel and quicker suspension response that can deliver a smoother and faster ride.

Now I have 20 pounds that I can add of Dynamat and stereo.

I am officially starting my Zero Weight Project build. The concept is quite simple. My goal is to upgrade all the different parts of my vehicle, performance, handling, quietness and stereo sound without increasing the weight of the vehicle.

This may seem like an undoable thing. Here is the plan.

1. Look for opportunities to reduce weight without sacrificing performance. In fact the goal is to increase performance and save weight at the same time.
2. To reduce the road noise levels inside the car, eliminate the existing buzzes and rattles and improve the feel of the car with a targeted Dynamat install.
3. Improve the sound quality of the vehicle by upgrading the stock stereo. Increase the SPL output, improved bass extension and drastically improve the stereo imaging and sound staging. This will be accomplished by trial and error and also by choosing products that offer a high performance to weight ratio. NO 50LB subwoofers need apply.
4. To document the upgrade with before and after performance measurements. Skidpad? Horse Power, AutoX times? Maybe even a drag run. Also, I will measure the noise floor, and sound quality improvements (SPL and RTA) at different stages of the build. Maybe I will enter the car in a sound “Q” and auto cross with the same setup.
5. Debunk myths of not being able to have a great sounding stereo and quite ride in a sports or sporty car.
6. A repeatable project. The ultimate goal is to show people that it is possible to have your cake and eat it too. Too many people think they can’t have a quiet car and great sounding stereo without severely lower performance due to added weight.

This is not going to be a “bling bling” project. There are plenty of those and that’s just fine. This is a project dedicated to the daily driver enthusiast. There will be no removing of the AC unit, no loss in creature comforts. I am to old for that… well you know.

Please let me know what you think. You advice in input is greatly appreciated.