Quote:
Originally Posted by Trev
I've been thinking about this hard this past year. Yes I think a Z4M could be competitive with a good driver. However it won't do it in stock trim. Your biggest competition is in the Porsche's & RX7.
You'd have to at minimum get the right wheel tire package (18x8 & 18x9 within 6mm from stock offset. Preferably 6mm Wider Front. Maybe 6mm narrower Rear Or stock to combat understeer)
Tires if in AS & not street tire really have to be Hoosier A6's. Figure 2 set for a full season. You can play with widths & profiles. Figure 245/275 with as low a profile as possible in rear to decrease rolling radius thereby shortening gearing (better acceleration)
Adjustable suspension & its setup is the biggest step to tame the roll / pitch of stock suspension. There's nothing stopping you from having coilovers in AS. You just have to mount lower perch in "same" position as stock & use stock springs. Traditionally that "same" measurement is taken from tire to perch. If you reduce the profile of front tire the lower perch can come down.
IMHO forget Koni's at least not the sport or modified sport sets. If you can find their higher end units they are significantly better.
Again IMHO consider Bilstein PSS10's, they do have clunking issues & potentials for blowing seals. But the single adjustment makes for an easy repeatable setup.
If your more suspension savy consider Penske, Moton Or Quantum.
All that being said, even though a Z4 could be competitive in AS, it'll cost more to build a competitive car and it'll be slower than stepping into BSP.
BSP allows for camber plates, Seat swap, sway bars at both ends plus adjustable end links, Whatever springs you want. etc..
If you want to do nationals, then dive in with both feet now. If you wait a year the rules will change which nulls the playing field. DO it now.
On the RTR class, yeah its fun. But without mods as above you'll be 3-4 seconds off top SS cars. Closest i got this year was 1.5 seconds from a national level driver in a Lotus Elise. For ref I needed to be 0.7 sec off his raw time to beat him in PAX.
Lastly i've been lucky enough to run with a co-driver that competes nationally in her Boxster. It's a base 2.7L with suspension & tire outlined above, that car is 1-2 seconds faster than the z4.
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IMO the car to beat is the Vette. The Porsche is up on that list too. IMO the RX7 is the least of my concern.
Ideally, I'd have to run APEX Wheels. As of now I'm running 5mm spacers on all 4 corners to eliminate rubbing in the rear and clearance on the shock tower up front.
For AS I'd have to get massive tire up front, 255 at least. I don't know how that's going to happen.
Trying to get a coilover to accept a OEM spring would be hard IMO. I've been in contact with TCK Racing and for a DA shocks it will be around $2k. They have a coilover kit for our cars that is $2500, but that is with linear springs and different dia. I was able to run a STU E36 M3 (well almost STU, had flywheel) but it was fitted with TCK DA Coilovers. The car is so neutral, and just a couple clicks on suspension completely made the car throttle oversteer happy and no understeer...So sweet. SA shocks are out of the option...they won't do squat.
I don't understand how stepping into AS will cost more than BSP. The level of modifications to become a BSP car is mind blowing. Swaybar is done on my car, I need shocks, and some tires. Ideally, I need to shed weight from the exhaust but it isn't needed.
BSP requires new seats, removal of AC/Heating Cores, cut fenders...etc, etc. It's too much prep for me.
I think the route for me to take is RTR. Some minor alignment changes with DA Shocks will make it a sweet car. If SCCA gets their head together and gets a set PAX multiplier for RT, it will be a competitive class. This year, I was undefeated in RTR in Ohio (Cleveland, Toledo, Columbus). With that, I don't think people know what the RTR car is yet, so it's all experiments.
Thanks for your opinions though, they do help