Subaru powered Boxster "Street Version"
 

This is the next conversion car that I'm working on... actually it's a pair of cars. The goal is to keep them as a street cars that can be daily driven comfortably, but still perform on the track for Time Trials. The engine on the white car is the same EJ255 that is in my green car, but the turbo will be a smaller GT2871 using factory exhaust manifolds.

The silver car will be a little different in some of it's components, but the goal is the same as far as the car's intended purpose.


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GT3 front bumper
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New timing belt system, water pump, welded/ported TGV's, ID1000 injectors, and secondary air injection delete.
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Modified OEM Subaru wiring harness ready to be installed
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Engine mocked up in chassis
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Air/water intercooler in rear trunk. No goofy roof scoop needed...
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Turbo and stuff...
http://i180.photobucket.com/albums/x...z/IMG_2111.jpg

Here is the silver car. It's a bit of a mix of spare parts that I have been collecting.

The hard top was from another project that got a fiberglass top.
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Stripped the red paint off. The plan is to run the top with a brushed aluminum finish
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The silver car had a horrible "pink" colored interior...
http://i180.photobucket.com/albums/x...z/IMG_1516.jpg

So we ripped that out...
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And installed a black interior from a 2004 Boxster S. Now it has a glove-box
http://i180.photobucket.com/albums/x...z/IMG_2102.jpg
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My goodness! I wish I could do stuff like this! :)

Ahh, the good ole EJ's. That is an engine I know quite intimately. :) Been a Subaru guy for YEARS. Currently race an older Legacy in rally.

I've been wanting to do a project like this sometime soon.

What did you do with the red interior, if I may ask.?

Threw most of it away. All I really saved was the dash.

Where does the intercooler draw air?

It's what Lotus called a "charge cooler" on the Esprit Turbo where the compressed air from the turbo exchanges heat with coolant, not with outside air directly. I assume that there will be an extra radiator or that some engine coolant fresh from the radiator is diverted to the charge cooler.

Correct. An air/water intercooler doesn't require direct air flow over the intercooler itself. The cooling happens remotely via a front mount heat exchanger... or in our case, we will be using the factory third radiator as a heat exchanger. Think of it as a mini cooling system, where the intercooler is the engine, and we use an electric water pump to circulate water.

Crap, I would have loved a silver car with the red interior. Can't think of a more classy interior color for a silver porsche. Even looks good with a black exterior.

Maybe if it had actually been red and not a faded salmon pink I would have been able to live with it, but trust me when I say, in person, it looked terrible.

enough about interiors! when will the kit come to market? how is it going interfacing the subi and porsche computers/harnesses? how did the track testing go - effect on weight distribution, centre of gravity, power delivery? from your other thread it sounds like the subi motor doesn't need as much cooling as the porsche, so using the third rad for the IC sounds like an ok compromise (i always struggled when tpc did that on their turbos, given the heat issues already present with FI on the m96/97).

I have been quietly offering the "basic conversion components" for a while now, but haven't really done any marketing. I know the street version is what everyone wants to see, so I wanted to wait until I had an example finished before I start ramping up sales.

The track testing has gone amazingly well. We haven't had a single component failure or anything. Literally 100% successful. In fact, since the green car was finished, we also built another race car using the same conversion parts and a Boxster S 6 speed...

http://i180.photobucket.com/albums/x...6721476673.jpg

Also, based on the results of our testing, we decided to convert the green race car to an air/water intercooler system. Now that we know that cooling isn't a problem, and the center radiator is available for use as a heat exchanger, we can reduce weight by getting rid of the roof scoop and related ducting... and make the car less ugly. We just finished the new system and will be testing it next weekend on the track. So far, the stock engine has proven reliable too, despite the experiences that you might hear from the "import tuner kids". We have been running the car at 400whp for the past 7 test weekends and when we did a leakdown test yesterday, all 4 cylinders are still around 10% cold.

I will post up new weight figures on the green car when I do an update with the new intercooler set-up.

As far as interfacing the electronic systems, I think you will be suprised at how easy this is, especially on the early cars (1997-1999).

When you are ready to "go live" on the kits, please add me to your list of interested parties who would like to purchase one from you. I am truly impressed with the level of engineering detail and performance you are generating from this. I get perma-grin from just looking at the results and work you have done so far.

Take care...

Some pictures of the exhaust and intercooler system...



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Where are you pulling the Cold Air from?

Who does your welding? They are a perfectionist. What does the finished car weight in at?

Please post more when you get a chance. Of course, let us know what the "kit" will cost and here's a stupid question….what kind of mileage are you getting?

A 4 cyl with 400HP? The power to weight ratio must be OUTSTANDING! WoW!:eek:

What kind of a mad scientist are you anyway?

I say it again, very nice! Just a question, turbo lag much?

This look yummy. Nice work.

Not sure what the final weight is going to be yet. Since it's going to be a street/Time Trial car with A/C, stereo and carpet, I'd guess somewhere in the 2800-2850lb range.

The intercooler is an air/water configuration, so the intercooler itself doesn't need any direct air flow. A factory center radiator is used as a heat exchainger for the intercooler with an electeonic Bosch water pump.

I do all of the fabrication amd welding myself. I am a bit of a perfectionist according to my wife. ;)

Can u give me some of idea what this cost to do incl. engine, mods and labor for the street version? We might get a lower cost of running Boxster plus more power on 4 cylinders. I do admire your work. Looks very professional.

Ya Think!:cheers: Looks awesome!

Bringing this thing back up from the dead - Just wondering if the 'stock-like' car was ever finished and what a ballpark cost would be.
Obviously there are quite a few boxster that are popping up and it would be nice to resurrect them with some boost :)

Did you have to modify the inner dash structure at all to update to the 2004 glovebox version?

The entire dash bar behind the dash had to be swapped out. I don't see how this dash conversion would be logical unless you literally have access to the complete parts car and can take parts directly out of one car and put them into another. There are too many little details that to be addressed to make it work right.

It's been a while since I've updated this thread.

Oil accumulators for turbo oil return
http://i180.photobucket.com/albums/x...ps7b076bff.jpg

Modified AC lines for engine side
http://i180.photobucket.com/albums/x...psa7d92292.jpg

Heat reduction on white car engine bay
http://i180.photobucket.com/albums/x...ps99ee0f50.jpg

Modified AC lines on chassis side
http://i180.photobucket.com/albums/x...ps2a6f5150.jpg

Some of the powder coated parts
http://i180.photobucket.com/albums/x...psa72513ed.jpg

Rebuilt and re-coated calipers for both cars
http://i180.photobucket.com/albums/x...ps284a989e.jpg

Finished engine install on silver car.
http://i180.photobucket.com/albums/x...ps33c20805.jpg

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http://i180.photobucket.com/albums/x...ps32bff7ef.jpg

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Engine bay for the silver car. You'll notice the custom roll bar too.
http://i180.photobucket.com/albums/x...psf4d4d0e6.jpg

Dyno graph from silver car. This same engine/turbo package was making 430whp in our race car on 110 leaded race fuel. This graph was on Arizona's crappy 91 octane fuel. 364whp is about all the 275mm Nitto NT05 street tires can handle.
http://i180.photobucket.com/albums/x...pscd798923.jpg

Engine installed in white car. Major differences between this car and the silver car are smaller turbo GT2871 versus GT3076, single scroll versus twin scroll, and 5 speed versus 6 speed.
http://i180.photobucket.com/albums/x...psce10af62.jpg

White car again
http://i180.photobucket.com/albums/x...ps97263c7b.jpg

Trunk on the white car. The rear carpet section will install after the car is tuned. You can see the coolant expansion tank, intercooler, intercooler water pump and catch can.
http://i180.photobucket.com/albums/x...ps7dd3b907.jpg

http://i180.photobucket.com/albums/x...pscf653f3a.jpg

Engine bay on white car
http://i180.photobucket.com/albums/x...ps45046a82.jpg
http://i180.photobucket.com/albums/x...ps07466326.jpg

Trunk of the silver car
http://i180.photobucket.com/albums/x...ps1720b8a0.jpg

The specs on the silver car are as follows...

1997 chassis.
- Subaru EJ255 engine (stock internals) that was run in our race car for just over a full season
- ARP head studs (it was lifting the heads at 430whp)
- 1000cc fuel injectors
- GT3076R turbo (twin scroll T3 housing)
- Tial wastegates x2
- Tial QR BPV
- 6 speed conversion including brakes and rear suspension
- KAAZ LSD
- Stock Subaru AC compressor
- Stock Subaru power steering pump
- Air/water intercooler using Porsche center radiator as head exchainger
- Converted interior to black using 2004 dash
- Custom welded in roll bar
- Recaro Profi seats
- OEM hard top (convertible top deleted)
- GT3tek front bumper and Precision Porsche GT3 side skirts.

The specs on the white car are as follows...

- 1998 chassis
- Subaru EJ255 engine (stock)
- 1000cc injectors
- GT2871R turbo
- Tial wastegate
- Forge Motorsport BPV
- Stock 5 speed transaxle with KAAZ LSD
- Stock Subaru AC compressor
- Stock Subaru power steering pump
- Air/water intercooler using Porsche center radiator as head exchainger
- Stock roll bar and seats to retain convertible top function
- MK1 GT3 front bumper (OEM) and OEM aero side skirts
- OEM hard top

The white car is ready to be tuned as of today so I should have horsepower figures some time next week. I'll get some videos too.

Both cars are going to be getting complete exterior reshoots, but right now, they are both multi-colored :o

Thank you for the update, looks great!

Any updates? 400 hp sure sounds amazing. What cost if precision chassis works did the swap?

Both cars have been running and driving for a while and have no issues. I daily drive the 1997 car and have thousands of miles with no problems. I can tell you without a doubt that 996 twin turbo owners do NOT expect a Boxster to be this fast ;) I'll try to get some video up soon.

send me an email at precisionchassis@gmail for some pricing info.

Hey all,

I am the owner of the white car and wanted to post some pictures of the finished product. A little background. The car was in pretty rough shape when I picked it up. Clear coat was about non-existent on the hood, front fenders and top of the doors. Rear bumper had a bunch of cracks and had to be replaced. Soft top transmission was broken so I couldn't raise or lower the top. The engine was running but had some leaks that needed some attention (RMS and IMS). Wheels and tires were shot. You can see where this is going ... But I was okay with that because it was purchased solely for this conversion.

I can say that Kent and his team at Precision Chassis Works worked a miracle with the car. There were a *lot* of things done and the attention to detail is second to none. It looks and drives fantastic. Everything works as if the car came from the factory except for automatic climate control. I'm okay with turning the fans up/down when I need :) I even have A/C for those hot summer months here in Phoenix. The best part ... the power! Tony at UMS delivered 3 tunes via Cobb Accessport V3 (low - 300whp, medium - 340whp and max - 360whp). The car is running the medium tune at the moment which is more than enough for the street. The best part of the experience was seeing my 5 year old's face when I opened up the throttle for the 1st time. He loves going for rides in Daddy's rocket.

Chris and his team from Elite Automotive Finishes completed the transformation with paint and body work. I'm definitely digging the "Ruf 3400S" look of the car with the OEM MK1 GT3 bumper and OEM Aerokit 1 side skirts. The US-spec bumperettes were also tossed for a cleaner look.

Overall, I am very pleased with the conversion! With rumors of the next generation Boxster/Cayman getting Turbo-4s, I feel like I'm getting an early "preview"! I know this may not be for everyone but it works for me :) Cheers!

http://i197.photobucket.com/albums/a...r/IMG_4134.jpg

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Gorgeous! I love the look and to drive it has to be a kick in the pants! You have a very lucky 5 year old!

Thanks! The car is a hoot to drive! It's easy to lose traction in 1st to 2nd gear shifts if I'm not careful. Still getting my head wrapped around how fast the car generates momentum!

What wheels and tire size do you think you will need to keep it hooked up?

Can you shoot flame / turbo flash with it;)

How is the sound?

I'm currently running a set of Kumho Ecsta ASX All Seasons on 265/35/18s in the rear. I think I need to upgrade to an Extreme Performance Summer tire to get some grip back.

Haha, no flames that I know of at this time :)

As for how it sounds, it's definitely different from the M96 flat 6. Not as smooth. It's got lots of the typical turbo bov/compressor surge sounds. It does sound pretty mean, especially when going through a freeway underpass or through a tunnel. :eek:

Here's a video clip that Kent took while tuning the car earlier this year.

Subaru powered Boxster street car tuning - YouTube

From the inside, it sounds pretty similar to his setup, just a little subdued due to me running a full interior. You can hear it in one of his race videos too. The engine in the video is now in his street car.

PCW Subaru Powered Boxster at FIR Main march 17 2013 (Race Qualify) - YouTube

That's a pretty awesome setup. Sounds like your running in excess of 981 GTS horsepower with a lot more torque. Power to weight ratio has got to be at least the same or better than a 996T. That must be a blast. I am guessing this is a less expensive route then building a 3.6/3.8.

With the intake that low I am guessing driving the car in any rain (especially the monsoon season we had this year) could be a problem.

How do you get the car to pass smog?

Love to see/hear the car. We are almost neighbors.

Peak power seems to be closer to the 996TT. The difference is power delivery. I've been in a 996TT before and it produces quite a bit more low end grunt under 2500rpm and it builds all the way to peak power like a sledge hammer. My car doesn't really do much under 3000 rpm but once the turbo spools, that's when the magic happens. What I like about the car is its Jekyll and Hyde nature. I can take this on the freeway and if I keep it under 3K, I can get almost 26-27mpg. It is after all a 2.5l 4 cylinder motor. If I want some fun, I drop a gear and go into < 10mpg territory :) I would be curious as to how the new generation Turbo-4s will drive compared to mine. As far as costs go, I don't have any data on how much it takes to build a 3.6/3.8 but with Porsche prices, I would not be surprised if mine was a bit cheaper.

I have driven the car in light rain and it wasn't an issue. The filter is blocked by the rear fender liner. Now if its anything like the 2 big flooding rainstorms we had this past summer, I'm taking my truck. I plan for the car to be a fair weather toy so I monitor the weather patterns before venturing out.

The car is actually smog exempt. I insured the car under the Hagerty Classic Car program due to its unique pedigree. In AZ, once a classic car policy is written, DMV gets notified and puts an exemption on the car. I then went online and registered the car. No fuss. The program also offers "Guaranteed Value coverage" so there is no depreciation in the case of total loss. Now with that said, Kent was able to get his car to pass smog. The OBD2 port in the car is actually tied into the Subaru's ECU. If there is no check engine light, you're good. So if I ever wanted to go to regular insurance, I'm good too.

Sure thing! I plan on visiting Cars and Coffee (Gainey Village, Scottsdale) one of these days. Maybe we can plan on meeting there one Saturday morning? I think there's one this coming Sat.

Thanks burnrbr. At 26 to 27 mpg that's better then my 3.2. If the car can be registered and insured allowing for daily use I'm interested.

Next time you head up to Cars and Coffee let me know. When I'm ready to upgrade from my 3.2 Precision Chassis and Flat 6 Innovations will be on my list.

Nice .....can you contrast and compare torque curves? Do you feel there is a lot lost on the bottom end?

Porsche9, You can't go wrong with either of those 2 guys! I'll let you know when I do make it up to C&C.

JayKay, I did not do a before dyno with my old 2.5l M96 so won't be able to do a comparison. Honestly I'm not sure how much was lost in the bottom end, if any. Best way is to do a dyno day at the same dyno with another Boxster owner and compare the 2 under 3000 rpm :)