Miata Turbo Forum - Boost cars, acquire cats.

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Well finally a day to get some work done on the car after the Runoffs. I pulled the car out of the trailer this last Sunday with a small window in my day. I had a quick list of things to go thru that have been bugging me since that long and annoying race week.

The brake system at Sonoma wasn't very ideal. We initially thought it was the balance bar being bound up in the Tilton pedal assembly. The problem was in any braking event it would always start the braking phase at 40-45% front brake bias, then eventually get to the mid 50% range, or what ever I was targeting. In a straight line braking zone this isn't to much of a deal. Its the slightly lateral loaded braking zones that end up being crazy with more rear bias on the initial pedal hit. So Ian from Pagid was hanging out there and we took the pedal assembly apart and hot rod lubed the thing up with some dry graphite lube. No biding any more and perfect brake bias operations. Now fixing this problem and getting more confidence with the car brings another problem along. New problem is that mainly in turn 10 braking there is a long pedal. It did not happen every time and I do perform confidence taps here and there to make sure there is no knock back. Potentially this was caused by StopTech sending the brake rotors I ordered with the street bobbin washers. There is no float in the rotors and with the loads we can see with this car it does not take much to get some knock back. I have ordered the regular flat washers to get rid of the belleville washers installed.

Next is the engine.

We had a rough time with the engine that week. The head gasket didn't want to stay sealed up. (potentially the 30psi at the low end and 26psi at the high end) I am running the standard ARP 8740 studs which will be replaced with the CA 625+ studs when ever they show up. They are rated for an extra 60,000psi tensile strength. Everything else looks good. I rolled the valve cover gasket near the DI pump on the 8th time removing the valve cover. So that's where the "smoke" came from and yes it did leak a good amount of oil...Oh well.
https://cimg5.ibsrv.net/gimg/www.mia...6056c0158e.jpg
https://cimg6.ibsrv.net/gimg/www.mia...5324c30c76.jpg

Plans to come after the 25 Hour:
RHR Dual Element wing. Has a small main foil for T1 spec. It should help balance the small splitter better than what I had.
Big splitter to compliment the dual element wing.
Fixing the front rotors
Find a 3.9 R&P
Change the head studs
Map the engine without the 37mm restrictor. (hope for 450+whp on the 6258)
Design the front upper/lower control arm spherical bearing cups
Go get some fast laps at Sonoma, Thunderhill, and maybe even Buttonwillow to stir the pot.

This was a cool shot because its all I got.

https://cimg5.ibsrv.net/gimg/www.mia...8fd7ce3a30.jpg

The NC peaking out there with it's smiley face.

Caught a little break to get back on this project as it was left in a crappy state. I have received some cool gifts recently and figured I would start getting them worked into the schedule. I got a early IMSA GTD spec Audi R8 LMS Ultra Diffuser from the mezzanine storage at work. It fits with very little modification and should be able to mount quite easily. Makes the rear look a lot more proper and aggressive. It is pretty long is just about to the front of the rear subframe when held up there.. Going to compliment it with a flat bottom to connect the dots from the front to the rear... If it does nothing for performance it looks cool and is worth more than most peoples cars when it was new... :)

https://cimg7.ibsrv.net/gimg/www.mia...e9a104883f.jpg

Next up we have some new valve springs... I kind of shot at the hip with the rate by getting the stiffest off the shelf option from Supertech. We rated them and ran them thru the valve spring software with my cam plots, software says we are safe up to 36psi and about 9500rpm. Will not see the RPM with this engine but the boost pressure is there on the low end already...So I am a happy camper. Engine block is chased for the head studs, gasket is coated, and everything else is ready to go back together this week.

https://cimg0.ibsrv.net/gimg/www.mia...78425d2f7b.jpg
https://cimg6.ibsrv.net/gimg/www.mia...1474efd423.jpg

My favorite thing I have done recently is used my friend and our lead engineer at Flying Lizard Motorsport to help me with some suspension design. Today I had him plot all the points so we can construct a model of the suspension to get a better idea on what we need to make the car work better. He has been engineering cars since they had wooden wheels so I appreciate being able to get his brain involved with my project. Hope to have some ideas on what to do in the future.

https://cimg8.ibsrv.net/gimg/www.mia...eb975dae7f.jpg
https://cimg9.ibsrv.net/gimg/www.mia...e6a5430d0e.jpg

That project is getting better with every update, great work. Very nice to see some real motorsport engineering going into a somewhat everyday road car.

Looking forward to seeing the suspension nuggets that you'll come across

That is pretty fucking cool. Definitely relevant to my interests since the RX-8 suspension is nearly identical.

not sure how I haven't seen this thread until now. will be neat to see where suspension development goes

Are you aware of any broken diff mounts on the n/a 2.5L World Challenge cars, or is that a problem that only exists on big power boosted builds like yours and Jensen's?