Boxster Subaru conversion interest?

[Mike_Yi]

Damn cool man!

I'm curious though about the scoop. Is there not enough positive air pressure at the rear deck lid for a scoop there? It would be 100x cooler without the scoop. What about side scoops of some sort through the fenders ala Countach?

[Topless]

Nice update. I haven't checked in for a while and you have come a long way with the car. It is truly a work of art with great attention to detail. Bravo!

I found your dyno chart interesting as well. That nearly vertical torque curve from 3.5k-4.3K must feel like getting hit with a hammer. If you bring the car back to Fontana for the Festival of Speed in April, as a very experienced Boxster driver on the Roval I would be willing to offer my services and act as test pilot for a few sessions... Purely in the interest of gathering data of course.

[kcpaz]

Originally Posted by Mike_Yi

Damn cool man!

I'm curious though about the scoop. Is there not enough positive air pressure at the rear deck lid for a scoop there? It would be 100x cooler without the scoop. What about side scoops of some sort through the fenders ala Countach?

The next step on that front is to install some temp probes before and after the intercooler and log the air charge temps under different conditions and set-ups.

The side ducts are being used for oil coolers for the engine and trans.

[kcpaz]

Originally Posted by Topless

Nice update. I haven't checked in for a while and you have come a long way with the car. It is truly a work of art with great attention to detail. Bravo!

I found your dyno chart interesting as well. That nearly vertical torque curve from 3.5k-4.3K must feel like getting hit with a hammer. If you bring the car back to Fontana for the Festival of Speed in April, as a very experienced Boxster driver on the Roval I would be willing to offer my services and act as test pilot for a few sessions... Purely in the interest of gathering data of course.

Yeah the power delivery is completely different than the M96. In the CalSpeed video, I was experimenting with leaving the car in third gear rather than dropping down to second to see what different RMP/boost levels would do. In second gear, the car would spool instantly with any throttle input and the back end would try to come around. In third, it I would get some turbo lag but it kept the car from lighting the tires up on corner exit.

No PCA events planned right now. We are doing the NASA event at Buttonwillow April 21-22.

[The Radium King]

i wonder if anyone has ever tied an electronic boost controller into a steering wheel position sensor - less boost when turning, more boost in the straights ...

[Topless]

Originally Posted by kcpaz

Yeah the power delivery is completely different than the M96. In the CalSpeed video, I was experimenting with leaving the car in third gear rather than dropping down to second to see what different RMP/boost levels would do. In second gear, the car would spool instantly with any throttle input and the back end would try to come around. In third, it I would get some turbo lag but it kept the car from lighting the tires up on corner exit.

No PCA events planned right now. We are doing the NASA event at Buttonwillow April 21-22.

That is a very busy weekend. PCA at Fontana, POC at WSIR, and NASA at BW. It's a shame these guys couldn't coordinate their event schedules better this year. Personally I think BW and Chuckwalla are better Test-N-Tune tracks when you have unknowns to uncover. I don't really like surprises at 135 mph in turn 2 at Fontana... spook city!

Keep working out those little details with the car. I think you have a winner once everything is sorted.

[Overdrive]

Originally Posted by The Radium King

i wonder if anyone has ever tied an electronic boost controller into a steering wheel position sensor - less boost when turning, more boost in the straights ...

But what happens if you happen to have the wheel in a neutral position in the middle of a turn/slide (not likely, but could happen)? Full boost when you don't necessarily want it. Or on the flip-side, your boost gets cut when you cut the wheel to move from behind someone to make a pass.

I definitely get where you're going with the idea and see potential with it, but that was where I could see trouble with such a thing.

[The Radium King]

ok, how about interfacing it with a lateral-g sensor? reduced boost when the car is pushing sideways ...

[Topless]

Originally Posted by The Radium King

ok, how about interfacing it with a lateral-g sensor? reduced boost when the car is pushing sideways ...

I don't know. This might result in the same thing as a "lift throttle" mid corner, inducing a spin. The basic rule with a 930 or 951 is: When the car comes on boost, make sure your steering wheel is pointed straight... even if you are mid-corner make sure the wheel is pointed straight.

If it was my car being built, I would favor a wider, fatter powerband and give up some top end HP in favor of drivability. A 997TT is really pretty good here and any turbo motor could be tuned for drivability. Everything is a tradeoff.

[kcpaz]

Originally Posted by Topless

I don't know. This might result in the same thing as a "lift throttle" mid corner, inducing a spin. The basic rule with a 930 or 951 is: When the car comes on boost, make sure your steering wheel is pointed straight... even if you are mid-corner make sure the wheel is pointed straight.

If it was my car being built, I would favor a wider, fatter powerband and give up some top end HP in favor of drivability. A 997TT is really pretty good here and any turbo motor could be tuned for drivability. Everything is a tradeoff.

I am seriously toying with the idea of building a turbo capable Subaru EG33 (3.3 liter flat six cylinder) and swap it in using the same turbo as what's in there now. More torque, more linear power, and faster spool. The down side is the engine is heavier and longer and parts aren't as readily available.

[Topless]

Originally Posted by kcpaz

I am seriously toying with the idea of building a turbo capable Subaru EG33 (3.3 liter flat six cylinder) and swap it in using the same turbo as what's in there now. More torque, more linear power, and faster spool. The down side is the engine is heavier and longer and parts aren't as readily available.

Nah! Get this one sorted and see where she is. Every car has it's own personality and you just have to adapt your driving style to the car. With my car and a stock 2.5L I have to maintain corner momentum and get on the gas really early on corner exit or I am dead meat. With the Boxsubi, you can drive it more like a Viper... Easy into the corner, get the rear really settled on exit and then hit the hammer. You can afford to wait on the throttle a bit because there is so much juice available.

I gotta be honest. When I saw you were putting a STI motor in there I had visions of wiring harnesses hanging everywhere with splices and electrical tape, and two shift levers sticking out of the dash. So many projects like this end up as science experiments gone bad. I am totally impressed though. I had a hint you would put it together well because I had seen some of your Boxster Spec exhaust fabrication and I knew you were pretty handy with a TIG. Stay the course. This car will turn out great.

[Vizor]

Any update on how this project is going? I'm glad to see someone tackling it properly.

Originally Posted by kcpaz

Build a street version so I can prove that this conversion can work in an every day application. I've already got a 987 lined up.

I'm pretty excited about the prospects of your street version but am curious how you envision the electrical integration on a street vehicle. I can see stand alone engine management but am wondering if the CAN bus system for the rest of the car will freak out with the engine missing.

[kabel]

Originally Posted by The Radium King

i wonder if anyone has ever tied an electronic boost controller into a steering wheel position sensor - less boost when turning, more boost in the straights ...

Yep. My 2011 Mazdaspeed 3 has that and I have to say it is pretty annoying and wish I could disable it for track days (technically you can but it also disables the electric steering assist).

[kcpaz]

Quick update...

Based on the over cooling we experienced during testing, we decided to try out a new intercooler set-up. Without adding any serious complexity, or reconfiguring the front of the car, we were able to add an air to water intercooler system and get rid of the roof scoop. We will be utilizing the center radiator from the engine cooling system as a heat exchanger rather than using it for engine cooling, then just replace the air to air intercooler with a new intercooler, plumb a few water lines and add an electric pump. Basically the same components we will be using in the street cars, but with a slightly larger intercooler core. We will be testing the new set-up this weekend, but already, the benefits are a reduction in weight (up high and out back), reduction in aerodynamic drag, lower center of gravity, and better rearward visibility. We just got back from some dyno tuning and the car made 430whp and 380ft/lbs. The car now weighs 2651lbs with a half tank of fuel and an empty cool shirt cooler. There's another 20lbs that will be coming out over the coming weeks. Leakdown numbers are still right around 10% (cold) which is what they've been since the first test day.

[E3EJvilla]

Awesome!! Please keep updating this thread!

[kcpaz]

Well I've decided to change things up a bit. The Subaru conversion has proven to be 100% reliable in race application, so this prototype drivetrain is going to be transplanted into a street car for further testing in a more practical application. The street car will have A/C, non-electric power steering, and all of the creature compforts of a daily driver.

The race car on the other hand... it will still get an engine conversion, but something a little different. I'm actually going to pull back on the horsepower a bit and drop down a class to mix it up with some new cars. I'm going for linear power and hopefully keep the weight the same, if not slightly less. We'll see...





Yes, I realize that this has been done before, but this one will be a little different.

[insite]

Sweet; can't wait to see the build

[woodsman]

more, more, more! AUDI V8 - no waiting YIPPEE!!! Looks like a PORSCHE 5-speed? What MY is the V8? Is the tubular structure an engine cradle?

[kcpaz]

Yes, the tubular structure is the engine cradle. The transaxle is a 5 speed. The engines are only rated at around 300hp so there's no need for the extra 30-35 pounds of the 6 speed transaxle. Obviously the 5 speed bolts right on, but before you get too excited, as of right now, I don't have any plans of making a "kit" for this application. I'm not sure you will find very many people who would actually be interested in such a kit once faced with dollar figures. Horsepower for dollar, the Audi V8 is not the best option in my opinion. I can go into more detail about this if you'd like, but I'd rather start a new thread on this conversion and go into it there. The engine is the ABZ 4.2 which you can find in the 1997-1999 Audi A8. The engines are silly cheap, but the engine blocks are an "Alusil" design so most people view them as disposable and there is very little aftermarket support for them. For my application specifically though (I'm searching for a horsepower to weight ratio of no better than 8:1) it's perfect.

[woodsman]

would you start a new thread about the best V8 options for the Boxster? I would really appreciate your input KCPAZ.