In preparation for Superlap Battle, I decided to install polycarbonate windows on my 2006 Subaru STi. I had seen some pre-shaped products that supposedly seal right in, but I did not want to pay the premium. I figured I would try to make my own since I made my own splitter and had seen the savings on using raw materials (not to mention replacement cost) vs pre-made solutions. Not a knock against them, I just don’t like to pay a premium for wear items. At this point, it seems like everything is a wear item.
Step 1 Lexan
I purchased my Lexan Margard material at the Plastic Depot in Burbank. It cost me around $330. Purchasing just the rear windshield from Plastics4Performance would have run me $600+. GTA rules require the rear windshield and the rear door panels have some kind of window; so, my plan was to simply bolt the plastic where windows should go. Many folks are able to accomplish a pretty clean install of Lexan, but I had ripped all the weather stripping out of my car. This means the install would be ugly but functional just like the rest of my car. Also, we wound up doing the install 5 days before SLB; so, the cuts and aesthetics will get cleaned up later on. Most folks wind up painting the edges to hid the imperfections. I might try some oversized rubber liner.
Step 2 Measure Twice
I had the polycarbonate cut to three pieces of 5×3, 3×2 and 3×2. The 3×2 was barely enough to cover the front to back of the rear pillars, but we made it work. We removed a lot of material from the 5×3, but I don’t think it would be worth getting a smaller piece.
Step 3 Cut A Thousand Times
We wound using a jigsaw with a polycarbonate blade to trim the poly down little by little. Having an overlay would have been a lot easier, but we did not have anything handy to capture the curves. We started by tracing the inside of the top and then trimming it down to fit the curved contour along the top. There was a lot of back and forth between the car and the cutting table until we got the top to bottom to fit. Then we worked the sides out until they could bend into the grooves. We had the trunk off, which probably helped. Once we had the up/down, left/right in, we trimmed up the bottom to a reasonable fitment. You can save a lot of time by using the overlay from one side window to cut out the shape of the other side window. Be mindful of shape when bending the poly. This is really a two man job. The Lexan Margard material actually bent quite well to fit the rear window, and we were pleasantly surprised with the result — assuming it doesn’t rip out at 160 MPH.
Step 4 Drill and Rivnuts
With an eye towards replacing, removing or servicing the areas affected, I chose to use rivnuts and bolts to secure the polycarbonate. It’s a cheap and easy to use method. Drilling holes was the hardest part. For the B pillar, we wound up tapping threads into the steel underneath. We also wound up using a lock nut on a longer bolt to secure the upper rear corner of the side windows. It looks a little funny, but it beats having the window flopping around at speed. Again, be mindful of the shape when bending bolted down as you select your drill holes. I think if I add some rubber to the doors, they will actually seal up fairly well. Since my doors are gutted, I did not have to worry as much about trimming the bottoms of the side windows.
Now I just need to get my Radium Fuel Cell Surge Tank and fire suppression installed before Superlap Battle this week. If anyone wants to send me a large sheet of paper or something in the future, I’d be happy to trace my windows out for you to use as a starting point.
How much sealing do you need? Subarus are known for blowing head gaskets. Let’s accept it and move on.
So, you upgraded to ARP2000, but if you want to play on Ethanol with the big boys (400+ whp, track use, etc), you will probably want to spend the extra $450 to get the 625 studs. I learned this empirically tracking my GD and GR. I had fresh rebuilds on both of them, and they were both pushing coolant out the overflow. These cars were not crazy (430WHP, 550WHP), but I would take them out for 10 laps at a time in SoCal summer weather. Rarely saw temperature issues, but the heads would lift and push coolant out the overflow tank. We went to SEMA (2014?) and asked all the motor experts (sleeved motors, head gasket manufacturers, etc). Common response was “you need to retorque the heads,” which is a tall order for a Subaru. We tried it on both cars anyway. We did get a quarter turn out of the ARP2000, but cars still pushed coolant at the track. No signs of deformation on the headgaskets, just coolant leaking past.
This kept me off the track for a while and ultimately led me away from sleeved motors, which both cars had. I upgraded one car to 1/2″ head studs and the other to ARP 625 head studs. Based on 2 years of track abuse, I have no reason to think the 1/2″ (more expensive) upgrade is necessary. My EJ22 putting out 550WHP exclusively used on track with ARP 625 has run two seasons now without refresh (though I’m likely jinxing myself for this year).
IAG’s website hits on one very important issue. If you’re going to start playing with fasteners, you run the risk of distorting your mains. Increasing the clamping load creates all kinds of weird distortions in the block; so, spend the extra money to line hone the main journals of the case halves while bolted together with upgraded case studs. Maybe with the headstuds/heads too? I’m not sure.
Lastly, O-Rings create new issues as they tend to leak with common MLS head gaskets. I have yet to hear of a solid track build using o-rings that didn’t have a leaky gasket. Maybe spraying copper all over the head gasket would work? That copper O-Ring needs something to bite into. I simply don’t have enough empirical data to opine on the use. I do still believe sleeved motors can be used if built correctly from the ground up, but, again, extra machining is not optional. Put all your fasteners on and machine. I tried to build a sleeved motor that had seen better days last year. Machined a bunch of stuff, but didn’t do it in the proper order. The cylinders would go three thou out of round when everything was clamped together. Sadly, pistons are not egg shaped.
Just some thoughts. I’m probably 20% accurate at best, but what do I know? I was raised with girls.
Anyone else looking forward to this event? I hope it is as much fun as last year minus all the beer and electrical problems. Clever sabotage HKS. I hear Ken Kasitz will be bringing the heat in his Feal Suspension, Yimi Sport-Tuned STi this year +250 whp.
2006 Mitsubishi Evolution IX SE
- Oem 4g63 bottom end with no modification
- 1600 cc Precision injectors
- Custom RRE 4″intake (speed density)
- Kelford 272 cams
- Custom RRE lower intercooler piping
- ETS upper intercooler piping with TIAL bov
- Oem throttlebody
- Oem intake manifold
- BBK full turbo unported
- Oem exhaust manifold unported
- Buschur ported ebay 02 housing
- RRE modified skunk 2 downpipe
- Custom RRE side exit stainless exhaust with exhaust wrap
- Custom oil cooler
- Custom power steering cooler
- Nisei 4″ intercooler
- AEM ecu with custom RRE tune
- Accusump oil accumulator with auto valve
- E85 fuel — 475 hp/428 tQ
- Full 8 point custom roll cage
- DMS 50 coilovers with custom spring rates
- Cusco spherical bearings front control arm(front and rear)
- Cusco spherical bearing rear upper control arm
- Cusco spherical bearing rear trailing arm
- Whiteline rear bumpsteer bushings
- Progress 25mm rear swaybar
- Whiteline roll center adjusters
- Muellerized competition rear diff
- Oem front swaybar
- Custom brake ducts and ducting
- Stoptech ST40 front big brake kit
- Raybestos ST 43 brake pads front and rear
- Enkei 17 x 10 RPF 1 +18 rims with NT 01 275/40 17
- Schroth 6 point HANS belts
- HANS sport device
- Bell BR 1 SNELL 2010 auto racing helmet
- Sparco Profi 3 layer fire suit
- quick release fire extinghuisher
- Sparco gloves
- Alpinstars shoes
- Traqmate data system
- Gopro high def camera with external mic with remote control
- Schroth head net