Josh’s Rantings

I have seen plenty of EVO X hard pipes done that have shown the upper charge pipe as well as the BOV pipe, but we decided to do the whole kit. I missed getting pictures of the lower kit, but I have some of the upper kit. Keep in mind that the brace in between the upper charge pipe and the BOV pipe will be different. We did the dimple die one because…….well……..we like using the dimple dies we have.

The stock piping is ~2.3” outer diameter. We went with 2.5” for some more flow potential. The bare minimum amount of silicone pieces are used so there are only couplers at the turbo, intercooler, and BOV pipe connections. We tried to shorten things up as much as possible, but in all reality it is close to the stock length. Our goals were mostly to be technically correct, remove all of the reductions/restrictions, and remove as much soft tubing as possible with the side goals of being easy to fit, modular, and visually appealing.

I wanted to add that although it is not in the pictures, you can reinstall the factory radiator shroud with no modifications. It also uses the factory gromets/spacers to hold the upper pipe to the radiator support.

Sorry only two pictures, but the production pieces should be up before too long.

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We have been working on the cat-back for the EVO X the past few days. It presents us with a challenge we have only taken up before with the 2008 STi being a car that has a single inlet muffler and two outlets with corresponding cut-outs in the bumper skin. We did a poll on our forum as well as the EVOM forum to see what tip styles people liked for the EVO X. We always are an opinionated bunch here and border on fanaticism/lunacy when it come to how we like things. The choices were dual oval tips that were almost EXACTLY like stock, dual 4.5” dual wall round tips, and double dual (quad) single wall tips. Between the COBB staff, EVO M, and our forum the consensus was about 50/50 between the dual rounds and the quads. It came down to the idea that we believe that everyone will be doing dual round tips so thee executive decision was given to the quads.

Since the mufflers are still in the the production phase we used a hollow dummy muffler for the prototype. There is a HUGE amount of work that goes into prototyping a dual sided exhaust and don’t get me started on how hard it is to line-up systems that have two mufflers and tips. There is a lot of measuring, cutting, welding, cutting it back apart, welding, measuring, welding, cutting it back apart, etc, etc, etc, etc, etc, etc, etc, etc, etc, etc, etc, etc, etc, etc, etc, etc. But in the end you get a super nice exhaust so it is all worth it. The EVO X has an odd mounting system for the muffler, but it wouldn’t be an EVO if it wasn’t odd.

I think it came out really good and I am glad I took the time to pay attention to the little details. As soon as we have the first article of the STi (similar quads) I wil do another blog as he went through the same pains.

Without further adieu, here are the pictures of the prototype.

Kinda hard to see in these two pictures, but look hard.

Just one side. You can see how well it works with the curve of the bumper skin.

Here are a couple of side shots. I worked hard to get the tips to match the vertical elements of the faux diffuser.  I think it came out well and really matches the aggressiveness of the rear bumper skin.

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My most recent project has been the EXO X Downpipe, Hight Flow Cat pipe, and the Cat-back. Without giving away some of the short-cuts for prototyping products here is a little peak into making the prototypes and fixtures to make the Downpipe and High Flow Cat pipes. Since these are fairly simple products we will be doing the final production in-house as we already do on some of our other products. We will be doing the same sections for the X as we did for the VIII/IX, meaning that we will have a down-pipe, cat-pipe, and a cat-back.

The EVO X is a bit of a different beast technically than the VIII/IX. The X head is flipped around in the car compared to the VIII/IX. The VIII/IX had the turbo in front of the motor and the intake manifold behind. The X is the other way with the turbo in the back and the intake manifold in the front. This is the way that most modern I-4 motors are. This significantly shortens the downpipe which is a cool side effect. However where the VIII/IX cat-pipe was straight and short, the X cat-pipe is longer and has two bends in it.

Here is the prototype in the fixture. You can see the parts that locate the flanges, piping, hanger bung, and the O2 sensor bung.

 

 

 

 

The fixture has to be a sturdy piece to be able to be used a long time as well as staying accurate with the forces that welding exerts. As the stainless heats up during welding, it expands. As it cools it contracts and can end up shorter as a result. I use a spacer or two so that I can make the fixture off of the stock part, but later mill the spacer down so that the part that comes out of the fixture is exactly like stock. There are also pins that get inserted in the pipe cradles to make sure that the piping does not go too high since the cradle captures it on the bottom and both sides.

Compared to the stock cat-pipe we have less aggressive bends and we re-locate the O2 sensor. The less aggressive bends will result in less restriction. I relocated the O2 sensor bung in order to get it after the cat and keep the wiring protected by getting it to a cover that is on the car where the O2 sensor wire comes out of the chassis. We are also retaining the factory style bung for the hanger. This is due mostly to since constraints at the piping has to be close to the hanger.

Downpipe, cat-back, and hard-pipe kits to come.

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It is time I posted about the 2008 STi. I have been one of the naysayers about the love it or hate it 2008 body style, but when has Subaru ever had a body style that was not really easy to like? The “classic” body style, me favorite, was like that, the bug eye was a bit more mainstream so the classic body style lovers didn’t like it. The peanut eye was a bit more aggressive, the hawkeye was even more aggressive. I think we all got used to the more aggressive styling. Now they are going mainstream in my opinion. When Sean first got his 2008 WRX I hated it more than I hate mayonnaise (for those that don’t know me, that is a LOT). But we added the sport body pieces, got our springs on it, the gold wheels, painted the chrome bar in between the tail lights, and de-uglied the tail lights themselves, and I began to actually like it. I will only hit on what I think is cool or things you may not get to see in the brochures/info from Subaru.

I will start with the comment that the 2008 STi (I will always spell it with the little “i” to be old school) looks better in person. The one in the pictures is dirty, but the different body panels, stance, wheels, and other changes are more to my taste than the standard WRX.

Again sorry for the pictures of a dirty car, but it is winter in Utah. I really dig how the fender vents are functional. They actually help vent air from the engine bay. This is especially good on a car with a hood scoop.

Air goes from the engine bay into the fenders through the gap in between the fender skin and the chassis………

………and out of the fender vents. Nice touch!

The rear strip in between the tail lights is painted body color. You’re half way to having a decent looking rear end Subaru. Don’t stop there. Now fix the tail lights too………….this is an order!

The vents in the front bumper skirt do actually vent and the air can come from the engine bay, but most likely from in front of the radiator. Cool but not quite as functional as the fender vents I suspect. I base that upon speculation only though. It may help reduce the coefficient of drag. I am not aerodynamic guru.

 

The interior is more upscale than before. Pretty good for a daily driver, but it does not feel “performance” to me. The coolest thing is that everything actually matches. All of the gages and controls are all the same color. Something never before seen on an Impreza. Eric is stoked the the STi in the center console lights up. I say it is pretty cheezy, but a nice touch I guess. The hazard light button is red. Sorry guys you can’t replace it with a JDM version just to be cool.

The DCCD controls are pretty clean looking now. Also the controls for the SI-Drive System look good although a tab bulky feeling in my opinion.

Now on to the engine bay. Pretty standard fair if you crossed the 2007 STi with a Legacy GT/2008 WRX……..and then changed lots of stuff. The main bits resemble the older STi’s, the intake, battery, and other ancilliaries are from the LGT, and there is some new stuff. The TMIC is LARGE and is more previous STi than current LGT and is wider than any of the previous STi’s by a good margin. They had to brace the left side on the valve cover due to the extra length. The boost control solenoids are now under a metal cover on top of the intake manifold. I suspect that this is to make room at the side for the power steering and ABS equipment and perhaps to simplify the packaging in some ways. The addition of variable cam timing on the exhaust is a bonus and you can see the extra room in the passenger’s side timing belt cover.

Now on to the underside. The exhaust has the beginnings of the standard WRX, but then it all changes at the rear. Subaru has chosen a quad tip lay-out. It looks pretty agressive, but I am not a fan of the weight added or the complexity of the system. It will make a muffler that reduces sound and flows well complicated to make. We could go with a chambered approach, but that typically does not flow well in forced induction applications. they also use a smaller middle resonator. The dual tip splitter is a kind cheezy looking stamped clamshell design.

The drivetrain in the STi has been lowered half an inch and you can really see it in the tranny mount.

The rear suspension looks like standard 2008 WRX equipment with a few minor changes. The springs and struts, and sway bars are STi specific. Subaru also has chosen aluminum to mount the front of the rear diff.

The front suspension also looks like a carry-over from the LGT/2008 WRX with the same minor changes and the use of aluminum for the lower control arms.

that about wraps it up for a quick and dirty list of some of teh major changes. Although not happy with the added weight, softer suspension, and increased complexity, it has steps in the right direction. It is super cool to see that the STi is now substantially different from a standard WRX. That makes it a bit more special in my book……..now if they can just offer a stripped down version that weighs 300lbs less.

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From time-to time we get to do special projects. One that we have been working on for a while is a supercharger kit on a 2007 Eclipse GT for Cusco/Nukabe and Mitsubishi. We went with a supercharger to make something that had a chance of being considered emissions legal and it fits in the constraints of the engine bay much better than a twin turbo set-up as we were going to initially do.

The first step was selecting the supercharger. Some of the nice kits on the market use or have used the Rotrex supercharger. It is a nice, small package capable of quite a bit of power. The compressor section is basically a Holset turbocharger compressor section that is bolted to the compressor wheel drive mechanism. Inside the drive mechanism is a gear reduction section as well as an oil pump. It uses it’s own oil supply that is separate from the engine so we do not need to worry about tapping the engine’s oil supply.

With that as a base we had to figure out where to install the supercharger. The only place to really put it was on the opposite side of the motor from the belt system………..problem. The resolution was to use a shaft system to carry the rotation from the belts to where the supercharger was to be mounted on the other side of the engine bay. After lots of measuring, CAD design, rapid prototyping, changing, moving, and whatnot here is the design we settled upon as a 3D CAD rendering:

Dave did a nice job of making it rigid and looking pretty friggin mean. As I write it is sounds simple, but there is a lot of work to it. I would say Dave definitely had the hardest job and it took a while mixed in with his many duties. You have to find bearings to support the shaft, design the parts that support the bearings, the method to attach the supercharger to the shaft, the method to hold the supercharger to the shaft support system, and the pulley so that it rotates the supercharger at the correct speed. Kudos to Dave.

Now that it is mounted in the car it is time to get all the ancillaries done. Not a small task either. Cusco/Nukabe want to Time Attack this car so we had to do some work to make sure the supercharger system was up to the task of track driving. This mandated an intercooler and suggested cooling the oil that the supercharger uses. We looked at a lot of routes for intercooling and settled on an air-to-air system that is actually a little on the large side. We selected a top-to-bottom core from Bell with a 2” inlet (matching the outlet of the compressor) and a 2.5” outlet (well sized for the power levels). In order to fit and mount the large core we fabricated an aluminum replacement bumper beam. Piping was fabricated to be as short as possible with thick silicone an t-bolt clamps attaching it all. We used a Bosch BOV and re-routed it back into the intake tract for proper MAF functionality.

Since it is scheduled for track use we also installed a small oil cooler for the supercharger’s oil supply as an additional precaution.

The supercharger is good for around 400 h.p. at the crank, so we will have to see what it is capable of after tuning.

Some pictures of the set-up:

         

 

         

 

         

 

 

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At SEMA one of the things we brought that everyone thought was the bee’s knees was the carbon intercooler piping. I thought I would show everyone how we have been doing prototypes and one-offs. It is a pretty involved process that requires some of the cool stuff as well as the talents of those here.

Step one is designing the part. A rapid prototype is made to check the dimensions. These are done during the design process for the actual part if it is ultimately to be a production part. In this case it was done by Billy, one of our dashing young engineers.

Once the part is verified to be correct it go several ways. In the case of the 350Z intake we are looking at, it was sent to our silicone production company to be made in silicone. Also, in this example we want to see how it works in carbon. So we have to make another CAD file to rapid prototype that is made to be the correct dimensions for the inside of the pipe. This is done so that the carbon sleeve can be laid out over the rapid prototype. We generally have to do them in multiple pieces due to the size constraints of our rapid prototype machine.

Here are a couple of pics of the CAD files.

 

 

A few pics of the rapid prototype inner mold.

 

The x braces are there to keep the tube from collapsing when the carbon is laid over and the shrink applied. The epoxy and heat can make the gypsom and bonding material flexible and ruin the part. Also some extra straight is needed at the ends so that they can be trimmed correctly and not mess up the carbon weave during the fabrication process. The pictures here are of Eric and myself’s first attempt. The inner mold broke in one part and the shrink wrap didn’t go very well. They can’t all be winners the first time.

Since this part had to be printed in two pieces, they had to be glued together and the seam filled in. This is a hard step because any imperfection will be seen in the carbon piece so it takes time to get everything smooth. You have to basically use your hands and feel the imperfections. Very Jedi. Pics of that in process.

After the force tells you that the part is smooth it is time to get started on the process of laying the carbon up. The first step is to apply mold release……aka wax. This takes a couple of layers and is done so that the carbon will release from the mold.

After the mold release sits for an hour or so you can begin to lay up the carbon. Your start by spreading out the carbon sleeves and sliding them over the inner mandrel. You have to be careful to avoid messing up the weave. On most of the tubes we do 2-5 layers of carbon sleeve are used depending on if it holds vacuum, boost, or lots of boost. You have to slide each layer on with no epoxy on anything so you either have to slide all the layers you want to do at once then epoxy, or do it one layer at a time. Laying one layer down, wetting it, then trying to immediately do the next would result in the sleeve you are adding getting stuck to the wet one and messing up the weave, making a mess, or the wet layer not allowing you to properly place the next. Here is the sleeve dry over the inner mold.

Once the sleeves are in position it is time to wet the sleeve(s) with epoxy. Now is the time to actually mix the epoxy and hardener so that you have the most time to work with it before it cures. This is where it gets messy, and the gloves come out. Spread on a liberal amount of epoxy making sure that you wet down every square inch of carbon and give it a little extra to make sure it gets to all of the layers. You can use a lot as the excess will later be squeezed out. A second person is very helpful as they can hold the work and move it about while you go nuts with the epoxy. In some cases I have pre-squeezed out a bit of the epoxy with my hands working from the middle out to help spread and remove epoxy as well as get the carbon sleeve to lay flatter before adding the shrink wrap. Sorry no pics here……we were in a hurry to get the heat shrink on before the epoxy cured.

Up next is the careful addition of the heat shrink tubing. You have to manage to slide on the heat shrink, again, without messing up the weave of the carbon. The second person is also helpful here to help get the shrink wrap over as well as position the tube while you apply the heat. Generally you start in the middle and work your way out to the ends. However sometimes you have to start at a spot that is in the bend or someplace other than the middle to help the shrink wrap shrink properly. As you shrink the wrap the excess epoxy will start pouring out of the end of the tube, so we generally do it over a plastic drop cloth as can really rain out of the end if you used a lot of epoxy.

Now it is time to let the epoxy cure. The time it takes depends on the epoxy, temperature, and size of the part but we generally let them sit overnight. You can speed it up a little with the addition of some heat. We have to be careful in this case so that the inner mold does not get too flexible and also not to over heat the shrink wrap. Some parts you can use an oven or autoclave, and in some cases it might be required depending on the epoxy used. The epoxies we generally use can cure at room temperature.

Now comes getting to see the end results. You cut off the shrink wrap and remove the inner mandrel. Remove is a bit of an understatement sometimes as you may really have to beat the pipe to get the gypsom inner mold out. It is a bit like sandstone, so it is fairly brittle and will break out. If all goes well you have only a slight amount of the gypsom left and you can wash out the remainder. This is where you add additional layers if required as we generally do not like to lay more than a couple of layers at a time.

Production pieces are generally done quite differently. I will try to go into that at a later time.

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One off the many tests we do on exhausts is related to sound. I feel that showing the sound testing process we go through will give people a window into part of the subtlety that is one of the trademarks of our exhausts. It does not make for the lightest or cheapest exhaust, but we feel the benefits of sound quality make for a more enjoyable driving experience for the majority of people.

Under the SAE standard, a sound meter is placed 20 inches from the exhaust outlet at a 45-degree angle and the engine is revved to three quarters of maximum rated horsepower. The highest decibel reading is then recorded with an established noise limit of 95-decibels (SAE J1169). We do this out in the open to get a more real-life sound reading of the car in it’s natural habitat so to speak. We also test an entire system or as complete of a system as we offer, such as a full turbo-back, with our high flow cats to ensure that even with a fairly modified system you can pass the sound tests.

Here are the sound levels of some of our systems.

2005 STi, Stock Turbo, COBB catted turbo-back

• Idle – 80db
• SAE J1169 – 91db
• Ambient – 65db

2006 EVO, Stock turbo, COBB catted turbo-back

• Idle – 80db
• SAE J1169 – 94db
• Ambient – 61db

2007 MazdaSpeed3, Stock turbo, COBB catless turbo-back

• Idle – 64db
• SAE J1169 – 87db
• Ambient – 58db

Not only this but we like to make sure the tone is performance oriented. This is purely subjective, but we try to land on the deeper end of the spectrum. Those frequencies tend to be less objectionable to the majority of people and seem quieter for the same decibel reading.

We currently have two muffler end caps that we can use different lengths of bodies for as well as change inlet/outlet locations/sizes and two resonator styles that we can alter the length on to get the fit right and maximize the amount of muffler that we can get in the space constraints. Combine that with many different tip styles and sizes, y-pipe splitters, flanges both flat and formed, and different styles of catalytic converters and we have the ability to make an exhaust system tailored to suit the sound, looks, and fitment of each car.

Here are some of the wide range of parts we use.

 

 

 

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Here is a little insight into the prototyping process for exhaust systems. In this case it is the turbo-back for the MazdaSpeed3. The first prototypes end up looking pretty Frankenstein’s Monster. The point is to make a prototype that may not be functional, but has all of the important information built into it that is required for making the fixtures. Things get made, cut, changed, re-welded, torn back apart, and redone many times. Particularly if you are as OCD as Eric and myself about fitment. This prototype is about a third or fourth iteration. We have gone from 3 pieces to 2 pieces. Changed some routing slightly for better clearance. Not to mention having been through combos of 3 different mufflers and 2 different resonators to get the sound where we wanted it and have room for another resonator should it be called for in the future. We have tried 3 different tips to get the proper look with the bumper cut-out.

Here is the front of the cat-back showing the connection to the downpipe (our prototype) and the large front resonator. The resonator is as large as most of what I have seen used for mufflers on the MS3. You can see one point where we deleted a flange.

Here is a view of the muffler we designed and custom produce for the MS3. Initial sound testing showed we definitely needed a larger muffler, so we went with the largest one we could find. It is a tight squeeze to say the least but we had to do it to meet the SAE sound requirements as well as our own.

 

Up and over the rear subframe. This is the part where consistency will be key in production. Not much room for error.

 

The tip in the cut-out. It is a larger tip than we have used in the past, but anything smaller looked odd in the cut-out.

 

So you can see it is a fun process. Later I will show you the fun that goes into the downpipe.

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Well, another year of SEMA has come and gone. It is always a lot of work to say the least but this year actually went pretty smooth. Other than the guys that set-up the booth mangled it a bit, the set-up and tear-down went easier than the past few years. There were some pretty cool cars and custom parts there, but I am somewhat unimpressed with the production parts that were there. On the times I was able to walk the show I found myself taking note of the awesome fabrication and machining on things like custom intake manifolds and headers, but few actual products.

Back in the shop it is the rush that is normal when a few key staff member have been gone. I have been having to split my time between working on strategy for production of hard parts and actually making some of them. We had a backorder of EVO JDM bumper fitment cat-backs that I had been pushing back getting ready for SEMA so I have been making those. They are actually pretty difficult as I have to modify some of the U.S. bumper fitment cat-backs. It is just a shortening of the tip which sounds easy, but it can be more difficult to modify something that is already supposed to be a finished product. Each muffler section takes me about an hour to modify. I have also been making the catted test pipes. They are a lot less time consuming, but take time none the less. The good side is that I get a lot more practice welding. This is always good. Here are a few pictures of a catted EVO test pipe.

                    

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Today is more set-up. We had to assemble the table for the engine display, remove the carpet plastic, clean, position the cars, and clean some more. Everything looks pretty good. A few pics………

 

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