I've run a first generation MR2 in 3 lemons races now and managed to not win every single time!
Here is what I've learned:
The MR2 very likely one of the best handling cars in history. It will certainly handle better than all but a few of your competitors on the track. You will be amazed and what you can do with it by the end of the race. Need to jam on the brakes mid corner? Just do it, you'll probabally be ok. Need to take the outside line and hold it at speed? No problem. Need sneek in to a 4' gap between the 67' buick and the inside of the track, no worries just stick stick your fender against their rear quarter panel... which brings me to-
The MR2, while very small is actually built like a tank. the radiator is set back in the car about 2'. It's mid mounted engine is forward of rear bumper about 2.5 feet. The fuel tank is in the very center of the car. Everything is pretty well protected from impact, so let your bumper car urges free to the extent you are unafraid of getting black flagged. During the oct 07 Altamont race, often referred to as a demolition derby by lemons veterans, hitting people was pretty much my SOP when passing. (In accordance with the stricter contact rules, I've repented of my contact sins since the Oct 07 Altamont race) Tie rods up front are vulnerable to impact so try to avoid driving over course marking tires and use caution when passing from grass to asphalt. Cut away wheel wells and add some structure to protect your front wheels, as part of your car prep.
Give yourself 2-3 hours to learn the capabilities of the car. At the start of our rookie race we all thought our car was slow... in fact its was one of the best cars on the track, we just didn't know how to drive it yet. As you drive ask yourself "should that '67 buick be able to pass me on a corner?" This will help you figure out if you are driving the car to its limits. After owning and driver several MR2's I thought I new how to drive. I didn't.
To pass large, high power/high torque cars: hang with them till you approach a corner, pass them as they brake for the corner.. inside is preferable but outside will probably work.
To pass lightweight front wheel drive cars: Choose medium sweeper, drift around them on the outside as these cars almost always hug the apex and generally can't drift.
To pass a medium weight rear wheel drive car (BMW): good luck.. be
persistent and little lucky.
I strongly recommend cutting away the entire sunroof "hatch" it will give you more head room in the car. If I were going to do my cage over again today I'd cut holes in the roof of the car and form the top of the cage above the roof.. more head room, I'm 6'2.
Don't worry too much about power, go for reliability. Winning won't be so much about speed ( the MR2 is fast enough) as keeping the car on the track as much as possible. If you have good compression and your engine is reliable, don't bother to open it up. If you need a head gasket, go ahead and try to find some cam timing gears while your at it. A performance header won't give you more power unless you change a bunch of other stuff in the motor also.... sum of parts kind of thing. the stock header is fine up to pry160+ hp. Just be sure to cut off the stock exaust just before the cat and put cheap, high flow, muffler to meet sound requirements.
Keep the car on the track. Keep the car on the track. Keep the car on the track. All the performance mods you can dream up are outweighed by having good pit procedures. If fueling takes you 20 minutes (which is easily possible @ t-hill) shaving 10 seconds off you lap times doesn't really matter.
Suspension is going to be one of the best performance mods on the track. Anti-sway in back I don't think came on these cars except in 1985 and on the supercharged versions. The mounting points are there so buy, steal or fabricate one. We get better handling when we increased the stiffness of our rear sway bar by bending and welding an additional bar to it. Our struts are shot. We haven't taken the time to properly cheat some new ones on to the car or find some better ones in the junk yard. We desprately need to.
Buy good tires and wheels! Have a full set of backups if you can.
Go to a track day somewhere and try to run your car for 3-6 hrs as continuously as possible. Try to sniff out a problem before race
Read & execute proper coolant changing procedures and adhere to them when draining/refilling your anti-freeze/water. The car has a great cooling system but it will overheat if you have air in it. I recommend bringing a spare ignition coil. I had one develop a heat related intermittent problem which cost us about 1hr 20min tracking it down and fixing it.
07 Altamont: worst postion: about 80th best postion: 14th place finished:18th place Bent steering rod (driver error), suspect clutch behavior, over hot inginition(toward the end).. all told pry about 2 hrs off the track poking proding and fixing shit.
07 Thunder Hill: Worst Postion 55th Best postion (4 hours later) 3rd place, finished: 13th Broken steering rod (driver error), over hot ignition, horrible fueling stops.. About 1.5 hrs off the track wrenching.
08 Altamont: Started 38th place ran to 10th place in 10 laps. spun a rod bearing=end of race. DOH!!