+ 1

but the two tanks seem to be made of aluminum (thick welds) I may be wrong however, very impressive attention to details none the less.

.

Your comment proves you know your way around the Boxster chassis and are familiar with the space limitations you run into once you start adding components all over the chassis. Keeping all of the plumbing and wiring systems modular and serviceable is definitely a challenge in these mid-engine cars.

The two tanks are aluminum. The rear tank is a coolant expansion tank and the front tank is an oil/vapor catch can. This is probably the same configuration I will use in the street version only instead of the front tank being a catch can, it will probably be a reservoir for the air-to-water intercooler system.

awesome stuff.....please let us know if you are thinking of a "street" car conversion kit or something down the road

I would be interested in this set-up once you get it done...!

kcpaz -

i like that truss you've used to replace the shear plate at the rear subframe. will you be selling these?

the oem plate was specifically designed to direct airflow over the transmission, no? also, the oem plate ties back to the brace (the one used as the subi engine mount). is not the oem a bit better as a result?

actually, the OEM shear plate is designed as a stress member. a side effect may be airflow directed at the transmission.

the part shown in the subi conversion improves upon this. a shear plate is a good choice in tensile applications. in this case, though, cornering forces will apply both tensile and compressive forces to the shear plate. a shear plate does nothing to fix subframe component locations when resultant forces attempt to move subframe components closer together (i.e. toward the center of the car).

the result is flex under cornering loads. this causes two primary concerns:

the first is at the lower control arms. without another structural component, cornering forces would push the lower control arm subframe mounts to move toward the car's center. this would result in loss of camber, particularly over bumps. porsche combats this with a boxed steel crossmember that bolts to the subframes, fixing their outward locations. kzpaz's component further improves upon this by placing the lower control arms BETWEEN two structural members.

the second concern is at the toe arms. in this case, porsche provided NO structure to support compression loads at these subframe components. the result is toe change in corners, especially over bumps. this can result in severe instability and snap oversteer. aftermarket 'lower stress bars' were designed to jack these points & keep them fixed under load. kcpaz's solution addresses this.

ultimately, porsche's shear plate would have been better designed as a trussed component, as kcpaz has developed here. it fixes these suspension subframe components for tensile and compressive forces in both longitudinal and lateral directions. the result will be a truly fixed set of locating points for all control arms & the inherent stability that comes with it. porsche's shear plate is a nice, cushy, CHEAP solution that works fine for a road car. on r-comps at speed, it doesn't measure up.

Couldn't have said it better myself. You just saved me a bunch of time :cheers:

As far as transaxle cooling, because I'm running an external oil cooler and spray-bar set-up above the gear stack, I'm not at all worried about transaxle cooling.

kcpaz -wrote:

i like that truss you've used to replace the shear plate at the rear subframe. will you be selling these?

[/QUOTE]

kcpaz, + 1 your bar...!

I believe that your truss bar will be a nice compliment to the Mantis Sport rear stress bar that I installed a couple of years back :)

.

kcpaz, + 1 your bar...!

I believe that your truss bar will be a nice compliment to the Mantis Sport rear stress bar that I installed a couple of years back :)

.[/QUOTE]

I could probably be persuaded to build some more. I just never pursued it because most of the Boxsters that are being raced are Spec cars and it's not legal in that application.

sorry if i was misunderstood. i understand the structural role the oem plate plays. i just noted that it also has air scoops build into it to direct air over the transmission, and that the boxster transmission needs all the cooling it can get. so , his system may work for a built transmission, but for the rest of us track rats we may miss the additional cooling. also, if you look, his truss system doesn't hit all the tie-in points that the oem plate does, so there may actually be some lost rigidity in some directions.

The only part it misses is the two bolts that go into the factory steel crossmember in the front and that part doesn't exist anymore. Instead, I integrated the engine cradle into those parts of the sub-frame so it's actually stronger than it ever was. Now the question is how strong are the 4 sub-frame bolts and their attachment points in chassis? I am planning on keeping a close watch on these and if I see any sort of deflection or cracking, I will be integrating the roll cage into those points.

hard to say whether the old plate increases airflow or whether there is more airflow with the transaxle completely exposed.

as to the tie-ins? i missed it before, but it looks like the boxed steel crossmember that connects the lower control arm sub-frame mounts has been removed in this application in order to make room for the exhaust and engine carrier. in its place are two provisions: the first is the lateral bar that ties the lower control arm subframes together. the second is the engine carrier itself.

in a boxster engined configuration, this truss could tie in with the boxed crossmember, as the OEM shear plate does, although i'm not sure if anything is lost by simply removing the shear plate & installing the truss as pictured on the subie car.....

regardless, i am awestruck by the amount of work that's gone into this. simply amazing.

how much caysh has gone into this car so far (including labor) and when is Excellence coming to shoot?

I haven't been tracking labor because it's not a customer's project, but we are talking hundreds of hours. As far as cash, it's just a bit more that a Boxster Spec car, but a lot cheaper than a used Cup Car. :p

I seriously doubt Excellence would be interested in a car that doesn't have a Porsche engine. It's my understanding that a lot of people were peeved off when they did the story about the Subie powered 914. Maybe I'm wrong though. I haven't had anybody mention anything about wanting to do any articles, but that could be because it's not finished yet...

Can I bug you again for any new sound clips, kcpaz? :D Whatcha got?

What's a turn-key all bells and whistles Boxster Spec going for?

Excellence would definitely be interested as long as the donor car wasn't an IMS victim. :dance:
bad P.R. for the factory...

PM Sent...

What has been happening with the build? I haven't seen anything written or pictures posted in a while.

Any news?

Wow, what a car...

I hope you do not mind me asking what is probably a stupid question?

I am going to install some wider rear arches on my Boxster racing car and to do this I will have to cut the outer and inner arches - as I will assume you had to do on this car?

Could you please give some details on how you attached the inner arch to the outer one again after having cut it, and possibly some pictures?

Did you just fold the outer up to the inner and weld them back together?

So we took the car to UMS Tuning to take care of the tuning. Tony worked his magic and the car made 416whp at 17.75lbs of boost. Considering the application of the car (road racing) we pulled a bit timing just to play it safe and ended up at 396whp and 354 ft/lb. Should be plenty of power for a 2400lb car. Dyno video link at bottom. Sound quality questionable...

http://i180.photobucket.com/albums/x...z/IMG_0312.jpg

Subaru Powered Boxster dyno tuning - YouTube

love this thread. it's one of my favorites to follow. nice numbers. 400hp should have it honking along pretty well. thanks for the update.

Here are some pictures and an in-car video. No blazing fast lap times this time out. I'm still a bit rusty because I haven't driven on track in almost 3 years, and the car has only been completed for 12 hours at this point. There is a lot of speed potential in the car (more than my driving ability could use this past weekend) and I can't wait to see how it fairs against other cars in it's class after we get some development time under our belts.

http://i180.photobucket.com/albums/x...pmIMG_3689.jpg
http://i180.photobucket.com/albums/x...pmIMG_3628.jpg
http://i180.photobucket.com/albums/x...30IMG_2220.jpg
http://i180.photobucket.com/albums/x...30IMG_1979.jpg

VIDEO!
Precision Chassis Works Subaru Powered Boxster Shakedown at Chuckwalla Valley Raceway - YouTube

And for anyone who was wondering if the Boxster cooling system could handle the cooling needs of the Subaru turbo engine... this is what we had to do just to get the car to run at normal operating temps. This was with a restrictor plate in place of the functioning thermostat. We are going to have to go back to a thermostat. Without any tape on the front end, the water temps never got above 125 degrees while driving.

http://i180.photobucket.com/albums/x...8302871340.jpg

great progress, thanks for continuing to keep us updated :)

God I love this thread

the motor sounds great too!

That track looks fast. Much faster than the one I drive on here in Texas. Lots of long sweepers.

ah...the sound of a blow off valve in the morning :p

Amazing work! That has to be a very powerful toy!

Few question:

1/ how do you like the MR2 electric power steering ?
2/ What transmission year model do you have ?
3/ Did you figure how to hook the ABS ?
4/ does the CV axle not the same length right and left because of the R&P on the side?

Thanks

Greg

The MR2 pump works perfectly. It's a variable speed unit based on load. It feels completely natural.

The transmission in the test car is a stock G86/20 which is the stock 6 speed in the 2000 Boxster S. The adapter kit will work with all Boxster/Cayman transaxles up through 2008.

The ABS system functions exactly as is would in a stock car. Nothing had to be done to the stock ABS system to make it work with the engine conversion because the ABS system doesn't take any input from the engine management.

Porsche transaxles all use equal length axles... unlike BMW stuff.

Glad to know you have the PS working with variable speed! I only heard people using it ON or OFF which is really bad for the pump to run 100% all the time.

When I look at the 2005 Boxster S engine on the floor. I have a hard time to imagine the axle the same length...
The only way it could be possible is if the engine is offset on the right a little bit. Or maybe It's a very good illusion. I just measured with approximation 6.5" in from input shaft of gearbox to left CV flange and only 5" from the same axis to the right CV flange.

Thanks

Greg

Engine is not offset... I'm not sure what you are seeing but every Porsche I've been under uses equal length axles.

Do you have any information concerning the MR2 pump wiring?

I found few other people doing this but did not find yet somebody with variable steering yet like you are doing.

I found this person that did a great job but I'm wondering if there is a way around of not having the ECU and all the components he is listing...

http://www.dsmtuners.com/forums/articles-suspension-brakes/415129-how-install-mr2-power-steering-pump.html

Greg

bravo bravo. As with most, I love this thread.

From this past weekend...

Precision Chassis Works Subaru Powered Boxster CalSpeed - YouTube

Awesome...
 

I've followed the thread with great interest, and seeing it in action is amazing and reinforces what the Boxster can be.

Congrats on an amazing project...and I think you could have kept up with the first few cars had you really intended to, but I'd play it safe too...especially with the time invested into your Boxstaru project.

Please keep us updated...all the best!

The car is capable of a lot more than you saw in that video. I'm still VERY MUCH a novice driver and that weekend was my first time on that track. Watching the video now, I can see a bunch of places where I'm giving up time... including slowing down WAY too much on the NASCAR banking :o

Looks like fun! Great project. What is your expected life of that engine before a rebuild?

Dang .. just went through the entire 12 pages .. my car feel so inadequate now .. *bow down*

Aha!
 

SOOOOOO kcpaz we finally find something that you haven't mastered ... (yet)!!

I knew there had to be a skeleton in your closet! :D

If you take to racing like you did to building the car, everyone needs to watch out!

Great stuff as always, I'm betting one or two more races is all you need to be a pro, then what will you do??

Cheers.

J T

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. ;)

As far as life expectancy on the current engine... The plan is to run it at it's current power level and after the first season, if it's still alive and kicking, I'll pull the engine apart, put it back together with a Cosworth shortblock and turn the boost up and see how long the transaxle lasts at 450 whp. :cheers: