'90 Mazdaspeed Miata Rallycross Project

Yea, what he said .

Although I think that second Miata is running 14" wheels.

Cool plenty of cheap wheel options then. For rally cross the classing is pretty much solely based on tires right? like all seasons, then winter tires, then rally tires?

Not really, you can't run rally tires in stock class but you can run snows or all-seasons. In prepared and modified you can run rally tires but they are divided based on modifications to the car.

You can read about the classing in the rulebook: http://scca.cdn.racersites.com/prod/assets/2012_RallyCross_Rules.pdf

I think that some of the California clubs running rallycross events do have some classes that are very tire-based. It's a different world out there

to add to that.....in some conditions snows are better than rally tires anyhow. Here in Mid-Atlantic on the red clay, when the water truck does its passes the people on gravels tend to do alot more spinning than those on snows.

And then when it's super-hot baked hardpack clay, the people on the all-season kind of do the best.

The main advantage to the gravel tires is the super-stiff sidewall reducing the chance of debeading and allowing you to be more aggressive into turns to some extent.

IMO the only reason to not run rally tires is if the surface is abrasive enough that you would destroy a set of tires. (See: Detroit horse-track events)

The old diff came out pretty easily. No rust to deal with but a lot of dirt.

New vs. Old

Now I just have to wait for UPS to show up with the new bushings from FM and it will go in.

Are you going to throw a turn down or anything on the exhaust? So maybe you have a chance of hearing any potential funky noises from the new diff?

I'm not sure I want to hear any potential funky noises from the new diff even if they are there .

I may put a turndown on, the only problem is there isn't really anywhere to clamp it on the end of the resonator where the weld broke, I would need a welder to put anything on.

Sounds like you know what to buy next .

I've already spent all my money

And I just ran out of propane when I was going to torch the rubber off the bushing mounts/brackets.

Turns out the driveshaft I have that I thought was for a 1.8 is actually a 1.6...

Trust me, if your diff makes any funky noises, you'll hear it.

I made a quick trip to a junkyard to get the correct driveshaft, there was one only an hour away.

I just need to torque everything and put the axles in tomorrow. Hopefully there are no funky noises.

I didn't enjoy burning the rubber off the mount brackets but eventually I got it all off.

The diff is in and tested good. With one tire on gravel and one on pavement it takes off with no spinning of the tires. I do get a bit of squealing on tight turns but not too bad.

Today after class I walked out to find a puddle under my car. Turns out the CXRacing radiator with <100 miles on it just sprung a leak. It looks like it is coming from where the tubes/fins meet the end tank on the bottom. I guess that is what I get for buying the cheapest aluminum radiator.

Huh. I bought the cheapest aluminum radiator for my car...

...because it's the only one available.

Well that would make it the cheapest...

I'm thinking about putting the other aluminum radiator in along with one 300M fan, do you think that would move enough air? It has an oil cooler on one side and only room for one fan or I would do two.

Or see what it would cost to fix the cheap one that leaks.

The spare radiator is in place. Held in by hose clamps and zip-ties and only one fan but at least it doesn't leak...yet.

What seat is that? Did you take a chance on an eBay seat?

Not from ebay, but pretty much. It is a Sonic Motors VS3, "replica" of the Bride Vios 3.

http://www.sonicmotor.com/ProductDetails.asp?ProductCode=S-K109-CLR&CartID=1

I have it mounted to the floor on some brackets I made and it is very solid and comfortable, the narrow width fits well and it fits me perfectly (5'8", 180#).

The only complaint I have is that it isn't as low as I was hoping, that is mainly because I have to mount the front over the hump in the floor to have my feet in a good position for the pedals since I am short. I could probably get it a bit lower by removing the rear seat mounting things and bolting it through the floor but I have enough headroom with a helmet and hardtop so I'm not going to bother.

If you don't need a FIA certified seat I would highly recommend one if you are on a budget. Mounted on rails it is a bit "flexy" but not too bad. Mounted right to the floor it is very solid. If you are above a 32-33" waist you might want to try a different model that is wider.

Video of the event last Saturday thanks to cghstang:

http://www.youtube.com/watch?v=pccDqMiiMvA

The seat is a huge improvement, I can left foot brake much easier and I don't get carpet burns from bracing my leg on the trans tunnel in turns.

The LSD was also a great improvement.

Overall a pretty good event, I am starting to get more comfortable with the car and driving a little better (sometimes).

Driving around town a bit today, intake temps were around 200-214F

Running lean even when I dramatically change the VE table to make it richer.

Sometimes I regret going away from stock.

Could there be a leak prior to the O2 sensor causing it to seem lean? Things couldn't have been too happy while the ppf was loose.

Boost leak?

Boost leaks usually make things run rich in my experiences.

Exhaust leaks would absolutely cause what you're seeing.

The O2 sensor is right on the turbo outlet, it may need recalibrating.

At idle it is reading fine but cruising AFRs are 15.5-16.5 and they aren't going below 14 going into boost, I didn't go too far into boost.

I still can't believe the IAT is above 200...that just doesn't seem right.

I just need to let it sit for a few days so I set it on fire.