Track car build, NASA ST5, SCCA STL
 

After looking at several different rwd platform, from E36 to BRZ, I decided to go with the RX8. Superior double wishbone suspension and chassis are cheap to find. My initial plan was to do k24 swap, but after doing some research, it seems that it would require modding the subframe which is not allowed in the rules. So I'm going to build the renesis and run it for now. The K24 would make enough hp for me to run ST4 and also detune to run ST5. But with the renesis, it won't make enough to max out the ST4 class.

First attempt at removing the tar with a blow torch. Did the center section first. Conclusion is it's too smelly and smoky if you burn the tar. And took too much effort. Then I tried the dry ice method. Much easier and less mess to clean up afterwards. Dry ice was about $3 per lb and I used about 15 lbs, plus 3 bottles of alcohol. Total tar removed was around 23 lbs

Was debating on whether to keep the HVAC unit or not since I wanted to drive the car street legal this year for some test and tune. But the cage builder convinced me to remove it. Also since I wasn't going to keep the radio, I would have to figure out a way to control the HVAC. I'm going to use a small electric ceramic heater for the defroster. Total weight of the HVAC was around 20 lbs.

Cage is done and painted. Trimming the dash to fit back in was pain. It was pretty heavy and after all the trimming, i probably took about a third of the weight off.

Some goodies going in the car. Sparco circuit seat. OS Giken 1.5 way LSD and 5.125 final drive.

Looking good. That seat mount certainly is robust. Did you make provisions for the crotch belts to attach somewhere?

the anti sub slot on the seat is right above the front of the seat base. i think i can mount the i-bolt just in front of the base or just a hole in the base to mount the i-bolt. the seat bottom is about 1" above the base at the front and about 1/4" above the seat base in the back. so not much room.

I like the heater idea. Wish I had bought and stored away a 5.125 R&P back when they were readily available.

You don't want it too far forward. Look at these guidelines.

https://www.schrothracing.com/docs/C...structions.pdf

yeah that's the guideline i used for my previous track car also

I have a spare. ;)

I've talked to my local TT director about this extensively, because I was told the same thing. What the TT director told me was that the critical thing NASA doesn't want changed is the suspension attachment points. He said changing the center section of the front subframe is fine.

For instance, I asked him if I could bolt or weld new mounts for an engine swap, and he said that was absolutely okay. He said a local racer had even been given the okay to make his subframe into three distinct pieces so it was easier for him to remove the engine.

Oh there out there for sure, but the obvious is if I have to ask for a price then I probably can't afford it ... :lol:

Are they worth that much? didn't pay a lot for the spare I have. I was going to put it in my grey car, but then... My new car already has one in it, so the one I bought is a spare.

i would have to check with the national TT director to confirm that modding the subframe is allowed as long as it doesn't change the suspension pickup points. it might be ok for one local region, but i run in three different nasa region.

if the concern was only about the suspension mounting points, then they wouldn't have include not allowing mod to the firewall and trans tunnel for engine swap.

I think it's possible I'm incorrectly applying what our regional TT director told me. When I asked him, he may have been speaking specifically about the lettered TT classes, not the numbered ones. I'll ask him about it.

Nick

Brought the car to CBRD last week to start working on suspension and engine stuff.

Subbed so I can learn how to mod my car like a bauce. 😉

What are you planning for ballast?

Your car is like a clone of mine. :P Red, Ohlins DFV, Sohn, same tanks, same intake...

Anyway, I'll tell you what I found with that oil tank. Because it's a gravity feed, of course, it has gaps built into the cap's gasket to allow air in. But that means it also lets oil out. If it's full, it can easily slosh enough out to get on the exhaust and smoke.

I don't have a great solution yet. I sealed mine up better and drilled a small hole in the center of the cap. I plan to glue some foam in the inside of the cap to keep the oil from sloshing out.

I've been wondering about cannibalizing a computer hard drive for the little breather filter they put near the breather hole. Drill the smallest hole possible and then use a bead of superglue around the hole to secure the filter.

Air Circulation and Air Filtration

thanks for the heads up on that.

ill probably just drill a hole on the cap and put a vacuum line filter on it. and seal up the seal on the cap.

https://us.vwr.com/store/product/361...n-line-filters

https://cimg3.ibsrv.net/gimg/www.rx8...e6bb4016de.jpg

i can't put the car on scales yet since i'm still working on the rear top hat for the ohlins. then figure out how much ballast i would need. i'm thinking i'll probably need 150-200 lbs of ballast. i was going to make a plate and mount it to the passenger seat mounting holes, then mount several different size weight to it so i can removed or add different combination of weights.

Got a new Odyssey battery from sponsorship. Will install it inside the car on passenger side.

Was going to do a custom exhaust from header back, but I saw that PowerXS had a 3" test pipe that was pretty cheap. I couldn't get pipes and flanges for less than what cost. So we are going to do custom cat back exhaust.
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got the antisub eyebolt mounted. Was worried that it might hit the frame rail, but the alignment came out pretty good.

Had to cut the front camber bolt on driver side. The passenger side came out with air hammer but driver side was stuck pretty good. Tried every for last couple days and finally decided to cut it off. And press the bolt out after the control arm is out.

Did the front wheel studs. I didn't remove the hub but you might as well, it just 4 bolts to remove the wheel bearing and hub and press out studs. The rear will have to press out the hub for sire, so I'm going to replace the wheel bearings also while the hub has to be pressed out .

Front suspension is done. Still working on the rear top hat. the hole was cut center to the cup, but as you can see the shock doesn't really line up center to the hole. so i grind open up the hole more and also align the spring to one side more. It will have spring retainer ring on the outside. CBRD had the plate water jet.
i removed the rear brake dust shield and will make some brake duct for the rear.
CBRD also finished the 3" exhaust.
got the power wire and master kill switch mounted done. battery will be mounted on the passenger seat side.

my first try at messing with 3d design and printing. had my friend printed out of abs, but i didnt like how it fit. so i just used 2.5" aluminium tube and flared it.
also picked up all the stuff i need to make cool shirt cooler. about $100 in parts, vs $350 for a FAST one.

Was the mazdaspeed version the basis of your intake? What was required to relocate entirely behind the bumper cover instead of blocking the radiator?

Yeah I didn't like how the Mazdaspeed intake blocked so much of the radiator. Just need a 3.5" 90° pipe, cut to length and green stuff filer. Teamrx8 had a custom k&n filter made and I was going to go that route but it will take too long. I'm going to Dyno test with filter on and off and see if there's any hp different to warrant a larger filer .

Got the spring perch done. Can't wait to get the rear shocks on and weight the car.

Had a few extra plates made if anyone interested in buying.

Got the rear shocks on finally and weigh car. She's more heavy then I thought. Looks like I won't need to run balast, actually need to find way to lose some weight. 2780 just the car, without driver. On oem wheels and street tires. With rpf1 and Hoosier, it will be 50 lbs lighter. I also used a bigger batter because I thought I would need balast, I guess I can go with a lithium battery now.

Seems heavy. Mine is about 2625 without driver, gear, or gas and our builds are similar. Did you gut the rear doors?

I've lost 18 pounds since 1/1/18, mainly for the racing season. It's easier than getting weight out of the car.

AC

all the plastic panels are out of the car. rear door is not gutted but it doesnt look like there's much metal there, the handle is removed.
front door still have power window and glass. stock flywheel/clutch and header. about 3/4 tank of gas. still gotta remove the rear wing and appearance package.

also gutted your head light? whats the weight of the rear door glass. ill probably find spare doors to gut out.

i'll probably leave the hand held extinguisher out also.

Rear doors weigh about 3 pound (they are aluminum) once the steel frame and windows are removed - there's lots of weight to lose there. Same with fronts but I left one of the sheet metal braces. Of course windows are heavy. I have a lexan rear but it weighs the same as OEM glass so don't bother. Removed the diagonal braces behind the rear seats (cage covers stiffness in this area). Gutted headlights only so that I could mount the oil coolers higher.

wow, 3 lbs rear door. ill look into gutting it out then. the diagonal brace behind rear seat is already removed. did you leave the rear bumper crash beam in?

what spark plug heat range are you running.

Well maybe 5 pounds. Regardless, they are very light. No reason to ever switch to the CF ones.

Rear bumper, yes. I race spec miata so bumping is in my genes.

Here are my gutted pics.

Apparently there is a lot of weight that can be cut out of the rear. I'm at 3200lbs with Driver and fuel. Which is way over weight. About to talk some chalk to the car and start marking it up and then start cutting.

RacerBowie is running a car in EP and got down to 2400lbs dry. He recommended doing a lot of cutting in the rear.

I read his comment in the weight reduction thread. It's hard for me to see where I'm leaving 200 on the table. I still have the dash bar in but that can't be more than 10. I can see a bare minimum cage that will just meet the requirements could save me 50. Rear bulkhead is required in STL but if not in EP, 15 could be cut out. I run the stock engine/engine bay harness. Could lose 20 there. Fuel tank weighs the same as a cell. That car must look like Swiss cheese.

yeah i can't imagine what the car looks like at 2400 lbs dry weight. i thought i would be around 2600 lbs before i put it on scale, and was really surprised im nearly 2800 lbs. i could probably drop another 80 fairly easy. my target competition weight is 2850. and i weigh 170 lbs with gears. so i need to get the car down to 2680. lighter flywheel when i do new engine, and lighter headers will help. maybe lighter brake calipers when i decide to upgrade brakes.

got screen done for oil cooler and radiator.
temporarily brake duct until i can make a more permanent backplate. hose doesnt rub with stock wheels at full lock but i haven't tried the rpf1 17x9 +45 yet.
also rolled the fenders. it probably doesn't need it but i'll probably try thick spacers to get more track.

Which studs did you use? I have longer studs in the rear, but not on the front. I would feel a little better if the studs stuck all the way through the lug nuts.

i used arp 100-7719 recommended by Teamrx8. they fit front and rear. i haven't driven the car yet. hope to get it out on the track this weekend for a shake down run.

the front hub is easy to remove, just 4 bolts. but it might be stuck from corrosion. i screw in some longer bolts in the back and hit it with impact hammer. spray a lot of liquid wrench in the back of the hub.

If you are a Mazda Motorsports member, and you should be, you can get the ARP studs from them at the racer's discount price.

AC

ah i didn't even think of that. thought mazda motorports only carry mazda stuff. i did get my studs at good price through my sponsor vendor

Yeah, I replace my front hubs every couple seasons. The car was unknown to me, so I replaced them over the winter. So they'll come out easily.

Oh yes I am. I will check their site. Thanks!

got the car all back together yesterday and took it out for a short drive. the power steering doesn't work. the power steering light is on the dash. I wont have time to diagnose and fix it before track event this weekend. would it hurt the anything or make it worse if the drive the car while the power steering is not working.

No harm. It's an arm workout though.

i drove crx and nsx without power steering on track before, it's no fun but manageable. big sticky tires is even worse.

so after searching through the forum, seems like the common issue with the wire harness. so unplugged the short harness and cleaned the pins. plugged everything back in but no luck, still had the code and no power steering. then drove to local shop where a guy had an rx8 parts car and picked up a used steering rack. wanted to get the control module also but he already sold it with the engine and ecu. got back to the shop and went to start the car up but the batter was kinda drained(small battery) and took awhile to start, battery was so drained it almost didnt want to turn over. i turned the ignition off for about 10 seconds, then tried to start again. it turned over and engine started and the power steering light went away and power steering worked. took the car around the block and everything worked great. woot.

got the car on the dyno yesterday after fixing the power steering. did a couple pull on the stock map then loaded the versatuner performance tune base map and did a couple pulls. didn't have much time to fine tune, just wanted to make sure it was safe enough for shake down run at the track this weekend. will fine tune it next week for official class number.


https://cimg2.ibsrv.net/gimg/www.rx8...67b9cd7bca.jpg

Great progress.
I am very interested on this build.

Did you do anything to get more camber?
On my track car I only got -2.1 in the front. Rear has more room but i find my front limited.
Tire wear shows that I could benefit from more.