Cosworth Supercharger Owners Thread

[sly]

Some initial impressions. The power feels perfectly linear. I'm used to my wife's WRX where the turbo feels peaky. This does not. It comes on all the time, and except for the slight supercharger whine (which I love), it just feels like a bigger engine.

There is no torque dip at 4000 rpm. I find myself revving a little higher before gear shifts. In the past I would shift before 4000 or rev it well above to get it out of the dip. I tried to stay out of 4000 rpms as much as possible. Now I don't even think about it. I have the entire rev range to play with.

The A/C compressor "clunks" a little harder now. I think it's because the engine rpms don't dip anymore when the compressor kicks in. I used to get a couple hundred drop in rpm when the compressor kicked in, but with the supercharger producing a stronger engine, coupled with the higher 850 rpm idle speed, there is no engine lag with the compressor. So now it seems to click with some authority. The only time I get a drop in rpm is when the cooling fans kick off. It drops a little more than I thought it should but so far has not stalled on me.

I now have two tunings for throttle sensitivity. 2 and 3 on the cruise control map selection... I think 3 is what I've been used to. With the stage one system, the throttle was tuned more like 3. I've played around with the lower sensitivity on 2 and so far haven't found a use for it. Maybe it would be better on the highway so there is less jerking from the engine every time my foot bounces from a bump in the road...

I like the sound of the Bosch circulation pump running. However, I haven't found a good place for the relay switch. Right now I have the coil of wires tucked down next to the battery with the relay. It seems like it could be mounted somewhere but I haven't found it.

It took a little while to purge the intercooler. I opened the bleed screws and barely got a trickle with the pump running. Squeezing the hoses helped work out some of the air. Basically what I ended up doing is I kept a bottle of antifreeze in the trunk and would pull over every few miles and top off the reservoir if needed. It was real foamy for about 20 miles and then cleared up completely and the level stopped dropping. What surprises me is how WELL the intercooler works. I drove it for an hour yesterday and when I got home I checked the coolant in the reservoir it was COLD. With all that driving in 90 degree heat in stop and go traffic there was no heat build up in the cooling circuit. This kit is definitely cooled well...

I have the stock Prius tires and was concerned that it would be dangerous to drive. Not at all... It still feels completely predictable. Sure, if you wanted to you could break it loose easily. But, the power band is so linear and smooth I think you won't break it free unless you really mean to. Haven't driven it on wet road yet, though.

My biggest problem with the install was routing hoses and wires properly. It took a lot of trial and error to get it right. I also recommend removing the 3 bolts from the A/C compressor and setting the compressor aside. That will give you a lot more room to fit the intake manifold without grabbing and will give your hands room under the supercharge to move and relocate wires if needed once it is in place. With the compressor removed to the side, I would comfortably access everything underneath the supercharger for routing purposes.

One last trick for the install is to torque everything correctly. Go even on the intake manifold. Start with something like 5 ft/lbs and tighten all the bolts. Then increase to 10, 15 and then 20 until it's all evenly snug.

If you don't know the torque values on something, don't spend an hour trying to look them all up. Instead, take a marker and draw a line on the nut and the mounting surface. Then loosen the nut. Now take a torque wrench and measure how much torque it takes to return the nut to it's initial position. This is the torque to use. I torqued everything that way including the torque on the nut for the shock tower. You don't even need calibrated torque wrenches. If your torque wrench says it took 20 ft/lbs to retighten that bolt, then just retorque until you get to 20 ft/lbs. The number is not important, it's that you torque it until the marks on the nut and mounting surface line up. The torque wrench will be accurate to itself...

That's about it. The supercharger really didn't change the characteristics of the BRZ. It just eliminated all the imperfections. It still feels like the same car but with some serious passing power on the highway and an even power band with no laggy torque dip. It feels like the same car but only better. It's the car Toyota/Subaru should have made in the first place.

[sly]

I just wanted to add that I got my supercharger from RallySport Direct. Even though they didn't mention it in the write-up, it came with an extra air filter and low temperature thermostat. It also came with the aluminum Cosworth badge. It's not quite as good as the acrylic badge that came with the stage 1.0 kit, but looks just as professional. I put mine on the front air dam at the bumper.

[secho]

Originally Posted by sly

I just wanted to add that I got my supercharger from RallySport Direct. Even though they didn't mention it in the write-up, it came with an extra air filter and low temperature thermostat. It also came with the aluminum Cosworth badge. It's not quite as good as the acrylic badge that came with the stage 1.0 kit, but looks just as professional. I put mine on the front air dam at the bumper.

Drop-in filter and Thermostat is also included in the kit ordered directly from Cosworth. Thx for your mounting insights, I feel it exactly the same. The hardest part was to route IC hoses so they are not squeezed. But it is fun anyway.

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[Seba]

I cant wait to have my kit installed. It is still in a box in my garage.

[Matt@Cosworth]

Just to add that there is a mounting point for the relay, if you look at the back page of the instructions there's an exploded diagram for the bracket assy
and there are 2 small tapped holes in the bracket to go with the two small m3 screws in the kit so you can bolt the relay to the bracket plate

and the air filter is a cosworth free flow item that should be fitted if you haven't already

and glad you like the kit a nice write up

[sly]

Update: Been driving it a week now. Just got back from a 150 mile trip to Grandfather Mountain. The car is awesome. It drives and idles so smoothly. There is no idle dip anymore. It took a few days to learn the idle strategy (as was mentioned in the install manual). My mileage is virtually unchanged. This surprised me. I'm only going by the in car gague and I know it's not accurate, but it's accurate to itself... I was getting around 36mpg before and now 35mpg after the supercharger. This is all highway driving. CIty I get about 31-32 on the dummy gauge.

It rips through the mountain roads perfectly. I don't have to struggle to find the right gear or rev up to pass anybody. Just punch it and go. Oh, and I smoked a 2007 WRX STI at a stop light. No, I don't condone drag racing. Just a little occasional spirited driving... I pulled off once we hit the speed limit but it was awesome. I think he was a little shocked that his STI got beat by a BRZ... So in short, it's fast. smooth, predictable, reliable (so far) and efficient. Definitely the best kit in terms of overall system balance. It's OEM quality. Looks way better than the stock plastic manifold.

[sly]

The previous picture was before the install was finished. It took almost all day to get it done. Worked slowly and took my time routing all the cables and hoses. A lot of trial and error to get it just right. I wanted to mention that I have the OEM Forester Oil Cooler. The Cosworth kit does fit fine with the cooler installed, but I had to disconnect the wiring harness and all the sensors on that side of the engine to route them underneath the fuel rail. Normally you need to move a wiring harness underneath the fuel rail to make room for the larger intake manifold, but the oil cooler was right in the way. It almost touches the fuel rail and so there was no way the wires would wrap underneath. So I had to disconnect everything on that wiring harness and then pull all the wires back and route them underneath and then plug everything back in. The hardest part was getting a sensor to plug in under the engine near the thermostat. It was hard to get to it without taking off the skid plate, but it can be done...

So YES, you can use the Cosworth kit with the Forester cooler. But if you haven't installed the oil cooler yet, it would be better to install the supercharger first and then the cooler second so you don't have to pull the wiring harness.

[J1Avs]

Originally Posted by botbs

Just ordered and will get it install few weeks from now.

Ever get it up and running on the tS???

[botbs]

Originally Posted by J1Avs

Ever get it up and running on the tS???

In the shop now getting it install should be done by Sat. I told them to take their time to do.

[J1Avs]

Originally Posted by botbs

In the shop now getting it install should be done by Sat. I told them to take their time to do.

Awesome!! Let’s me know how it turns out. I’m still debating between this kit at the JSRC C30, but I’m really leaning towards this. Did you just do the base kit or did you do the smaller pulley/anything else??

[botbs]

Originally Posted by J1Avs

Awesome!! Let’s me know how it turns out. I’m still debating between this kit at the JSRC C30, but I’m really leaning towards this. Did you just do the base kit or did you do the smaller pulley/anything else??

I did the base kit only. No other modifucations as I am looking for long term reliability and as OEM as possible.

I just want the small bump to fix the power or torque that the car lacks of. HOwever, I am looking at a lightweight exhaust and a pair of carbon bride seats.

[sly]

Got my first CEL today. I don't think it's related to the supercharger but I'll keep an eye on it. I got C1201 which is a generic communications error with the ABS/Traction control. And I got P0441 which is related to evaporative purge. This can be caused by a loose gas cap or some other problem with the evap system. Code C1201 can be benign or a problem with the ABS computer. Sometimes whenever there is a code thrown, it can also trigger C1201. If C1201 were the only code then I would be more concerned. Chances are it was triggered by the evap code.

I looked at the purge solenoid and found the hose had pulled forward some. It's really tight and could stand to be about 1/2" longer. It may have pulled loose and started leaking triggering P0441. I may have to get a hose clamp for it. I did have a hard time getting it to reach to the throttle body. That and the brake vacuum booster hose were tight during the install.

[ajc209]

I reused the stock spring clamps on my EVAP lines.

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[Matt@Cosworth]

C1201 crops up all the time, I think it just means the traction control has been triggered
so I wouldn't worry about it