Z3 ITR questions

[Cobrar05]

i have a chance to trade for a Z3 conv race car. it is about 3/4 built and needs finishing. i am looking for some direction. all my racing experience has been in mustangs and ive been wanting an scca it/enduro car and this seems like a good opportunity.

[Z3_GoCar]

i have a chance to trade for a Z3 conv race car. it is about 3/4 built and needs finishing. i am looking for some direction. all my racing experience has been in mustangs and ive been wanting an scca it/enduro car and this seems like a good opportunity.

3/4 built, what's it already have done?

[Cobrar05]

its been stripped and caged, cut of switch. beyond that, not a lot. actually. ive got the safety gear, seat, belts, nets, fire and so forth.

from reading the it rules, it looks like the stock drivetrain has to stay. i am curious about what suspension is available.

i also see that you are running a z3 in stu. i'd like to learn something about that as well.

[Z3_GoCar]

Ok, so I kind of suspected that's where you were at.

There are several good Koni base coilover kits, Jay at Ground Control or Kayle at TC Kline can set you up. I'm running TC's Smart Design double adjustable coilovers (~$2300) with TC's camber plates. Most people like Terry Vorshlag's camber plates better (bearing noise) but TC's camber plates have a shorter stack heigh. On the rear, you'll want the harder durometer urethane subframe bushings, make sure you get z3 bushings and not e-30's. I'm using Jeff Ireland's race urethane subframe bushings, keep the differential bushing stock. Before you remove the rear subframe have an alignment done on it and record where it is now, then with it removed you'll want to weld in camber and toe adjustors. I think the toe get's ~1/4" and the camber is 2.5* adjustment. Ireland engineering is also the source for the camber and toe adjustors, I like the ecentric's but I've had them loosen on me. Once this is done you can adjust camber and toe on front and back and castor on the front.

If you've still got the stock motor computer, I've found that Randy Muller at Epic Motorsports (avalible throught Bimmerworld) has a cable that can read codes, but also program the computer througt the OBDII port. It's a good way to go given that you'll be looking to increase the rev limit, remove the top speed limiter, and possibly remove the emobilizer system. Headers for the 2.8 are easy to find on e-bay, I'm assuming this is an early single vanos motor? If it's the double vanos Josh Sirota managed to find a set that worked from e-bay also. Get a merge 2-into-1 collector, muffler and 3" tubing and some time at a muffler shop and you'll be set with an exhaust. Maybe replace the intake filter box with a custom K&N, found at Bimmerworld, or delete the traction control throttle with one of their silicone elbows. Typically, there are a few small things you can do to the motor, but nothings going to give you a large gain. This is because the single vanos intake manifold was designed to limit hp for a torque gain. Since IT now allows aftermarket motor and transmission mounts, I'd use the delrin motor mounts from Vorshlag and his 95a durrometer transmission mounts. With these changed the shift pattern won't move and cause you to put the trasmission in a lower gear while accelerating (money shift).

I went to STU partly because the intake manifold issue with the single vanos 2.8 was addressed by swapping in the older 2.5liter motor, also I left IT because at the time the oe motor mounts were required, and finally I hate (hate's not too strong a word in this situation) the oe-dual mass flywheel it's so heavy it makes the motor rev very slowly, the rubber biscuit doesn't hold up, and they're one time use can't resurface them. Some links for your surfing pleasure:

http://www.tcklineracing.com/index.cfm?Action=ViewCategory&Category=287

Ireland Engineering: http://www.bmw2002.com/

Vorshalg: http://www.vorshlag.com/

Bimmerworld: http://www.bimmerworld.com/

VAC Motorsports: http://store.vacmotorsports.com/storefront.aspx

[Cobrar05]

this car is listed as a 99 2.5L car.

what do you think i need to budget for the things that you mentioned?

[Z3_GoCar]

A 2.5liter, if I remember that's 168hp and 185ft-lbs, should be in the middle of ITS. You'll have to request it be classed as only the 2.8 liter is classed at this point.

Do you have a hard top? That'll add $1k - $1.5k, and you'll need it otherwise top speed and fuel mileage will suffer. Got a welder, can you align and corner balance it? Parts wise maybe $3k to $4k. The coil over kit with springs and camber plates is $2300 from TC. With the 2.5 it should do pretty well on fuel. I've got a friend that's done well in E3 with his JP Z3. He does have to drive smooth, but he's done a 3hr enduring on one stop even with the 14gallon tank.

[Cobrar05]

i have a crew chief attached to a grand am team. he does the setup on the mustang i race and would be doing this car too.

doesnt sound like its too bad. its? hadnt thought about that.

e3? what is that?

[Z3_GoCar]

i have a crew chief attached to a grand am team. he does the setup on the mustang i race and would be doing this car too.

doesnt sound like its too bad. its? hadnt thought about that.

e3? what is that?


The chassis is an e36 but varient 7. varients 5 (ti), 7 (Z3/M roady), and 8 (Z3/M coupe) all use the semi-trailing arm rear suspension, so when you go to order the coilover kit make sure to specify Z3 not just e-36 (which is the sedan/coupe, 325, 328, 323, and M3) fronts are the same rear is different. Here's the spec's on the M52TU B25 (M52 family, TU-technical update for the double vanos, and B25 for the 2.5 liter)

http://en.wikipedia.org/wiki/BMW_M52

165hp at 5500rpm and 181ft-lbs at 3500rpm. I wanted to have this classed and had discussed this with Josh, but since I wasn't going to run it I let it go back burner.