I've now owned the car for almost 6 years, and in that time I have tried a lot of things to make the car faster. When my car was bone stock with an automatic transmission it ran a 17.8 in the quarter mile at Firebird Raceway in Eagle, Idaho. (3200 ft ASL elv.) My first mod was cuting the muffler off. That droped me to a 17.6. Then, I put a single 2.5" cat back exhaust, high flow cat, and a cone filter and ran a 17.0. Next, I added a chip and got it to a 16.7. When moving to Nebraska the auto lost all of its forward gears (still looking for them) so I swapped the auto transmission for a 5 speed manual. I took it back to the track here in Nebraska at Scriber, Nebraska Motorplex, and ran a 15.9. Traction seemed to be an issue, so I got some Nitto 555R drag radials, and then I ran a 15.7. At the time, the car had an open 4.10 differential.
Now, I decided that I wasn't going to make the power I wanted from the motor without some help. I'm cheap. Nitrous is cheap. Nitrous it is... I bought a dry NOS kit, put in the 60 shot and ran a 14.3 @ 95, but nitrous isn't always full. It costs 35-45 bucks to fill the bottle depending on where you go. During the winter I cracked the head while spraying nitrous on a 70 shot. I bought another used head and put in a 290 cam and had the head ported and polished in hopes of making more power NA. With that setup I ran a 14.7 @ 90 mph. After a few months of that, I grew tired of the performance the car had. I wanted to be a force to be reckoned with. The cam just didnt make the power I wanted and I didn't feel like pouring 40 bucks a bottle and running nitrous anymore. I decided to make the car turbocharged.
On my first attempt at turbocharging, I made a few mistakes, but at the time there wasn't anyone to learn from. I used a t3 .42, a 2nd gen DSM BOV. a Pro Turbo® manifold adapter, Audi 5000 intercooler core, and had custom intercooler end tanks built. The intercooler charge pipe was made out of PVC, 19 lb injectors, a 2.07 mm head gasket, and an Aeromotive RRFPR. I found that the aeromotive rrfpr didn't provide enough fuel to support the boost, and the turbo would die at about 5000 rpm, because the gears were to short. I used PVC for charge pipes and they would get hot and soft then shrink under the clamps and eventualy pop off. The BOV leaked and the RRFPR didn't provide enough fuel, so I installed a vortech 12:1 fmu and went to the track and ran a 14.3 @ 98 mph.
In an effort to imporve on the setup, I moved on to a t3. 63 turbo, 2.79 diff (open), crush bent charge pipe from the turbo to the intercooler, a Mega squirt Stand alone fuel system, and a Turbo XS RFL BOV. Everything was going pretty good until I popped the head gasket on the dyno. That day I made 218 hp and 238 tq to the wheels, just before the engine puked on the floor like an out of shape kid that ran a mile for the first time.
After some research I found out that the 290 cam was too aggressive for a turbo car, and that the stock head bolts were far to weak. The 2.06 mm head gasket was to thick. It had more surface area in the combustion chamber, so it was more susceptible to being pushed. The 1.63mm stock head gasket is structurally stronger because it is slightly thinner and has less surface area in the combustion chamber. I replaced the head gasket with the stock 1.63mm and put the stock camshaft back into the head. I also got some Metric Blue grade 12.9 head bolts. (I didn't want to fork out $200 for some Race ware head studs, and i was told by IE that there crap anyway). The Metric Blue bolts are 150mm m10 1.5 pitch - torqued to 80 ft lbs.
On the above setup with 12 psi, I made 241hp and 269lb/ft at the wheel - timeslip
After about 4 months, the turbo died, so I replaced it with a newly rebuilt turbonetics t3t4 .82.60 ball barring stage 3 super V trim turbo. I also replaced the PVC upper and lower charge pipes with Mandrel bent 2.5" and 3" steel pipes. With that, I dynoed 266hp and 333lb/ft.
I replaced the 2.5" crush bent downpipe with a 3" mandrel bent downpipe, and on 12 psi I dynoed 278hp and 332lb/ft - dyno chart
Then, I found that internal wastegates suck, so I got a tial external wastegate, and on 13 psi I made 294hp and 304lb/ft - dyno chart. On that setup, I ran my first 11 second 1/4 mile. On slicks i ran a 11.99 @ 112 mph. timeslip
Since then, I've made a manual plate cutout, and I'm running about 14 psi. I'm thinking the car is puting down about 310hp, and probably 320lb/ft, but I haven't gotten back to the dyno since I ran my best time of 11.88 @ 113.7 on 14 psi.
This winter, I'm converting to a distributorless ignition, and my goal for next year is a 10 second 1/4 mile.
For more detail, check out my turbo write-up - www.bimmerjim.com
Known Performance: (as of 11/08/04 )
Power: 294.8 whp, 304.3 wtq (345 bhp 356 tq - Flywheel)
1/4 mile: 11.886 @ 113.76 mph.
0-60mph in 3.23 seconds .
Top speed: Unknown, the speedo stops at 155mph.
2.5l 2496cc turbocharged and intercooler inline 6 cylinder, Single overhead cam, 12 valve, Bosch multi port fuel injection (M20b25)