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Last installment was from Buttonwillow where we broke a throttle shaft. I fitted another but toook the precaution of brazing the plate to the shaft. What I didn't do was braze both sides. That, as it turns out, was a mistake. So an few events later and I'm at Calif, excuse me, AAA Speedway in Fontucky, blazing down the front straight at about 120 when the throttle once again sticks open as I shift into 6th. Instantly shut it down and coast in. I already know what's wrong with it. Turns out you can still break the shaft even when it's brazed on one side. Upon tear down I realized that once again the screw had broken in half with head stuck to the brazing but the threaded portion sucked into the engine. Crossing my fingers I pulled the top of the BP4W manifold (two piece) and very gingerly dropped a magnet wand into each runner. #3 had a tiny little camper, the 2.5m shank of the throttle plate screw. My engine was safe, or so I thought.
So I get yet another TB but this time JB weld both sides in an attempt to keep any detritus from going astray. I install, fire it up and notice some wristpin noise. Lota wristpin noise. Dammit. Maybe running 7400 down the half mile front straight at AAA all day wasn't such a hot idea. So I went back to Buttonwillow a few weeks later to finish it off, which I did at the end of the last session of the day. Seized up tight just as I wound out 5th leaving the esses. :(
Ryal Greenwood at British Car Service in Tucson has made a custom TB for he calls Throttle Zilla. He pulls the OEM 9mm shaft out, bores the TB and installs a very nicely machined 14mm shaft in there, mills one face so it has .5mm less cross section and voila! I'm testing it for him as I know now that shafts only last about two events in my motors. We're also investigating the feasibility of a single barrel type throttle body that will bolt to the stock manifold and the manifold we're working on.
So the OGK now needs a motor. I have a fresh VVT head and 01-05 bottom end in the shop I can mate for a replacement. Good time to work on adapting the VVT head and control systems into the NA6 harness. I'll be using a proprietary ECU with a custom harness. If I can come up with a reasonably priced harness that I can serial produce, I'll offer that as a kit to the public.
While the motor is out, I'll get the Miatacage installed by Drew Staveley
Yes, the same Drew Stavely from Setup. Turns out he can weld and drive, my kinda guy.
Seats going in are Momo Daytonas. 20.3 lbs, Halo, $600 ea on closeout and FIA approved. Oh and they fit. So when everything is in it should finally look something like a race car inside and be about 1000% safer.
Along way we'll be adding the Energy Suspension bushings, OS Giken limited slip and finally, the V8 Roadsters subframe. We added a dual plane APR aluminum wing for Buttonwillow and wow did it make a difference. Going 90 through Riverside in the rain was not something I would have thought possible. The event before that we added an ISC Racing front airdam and as expected the car was a tad loose with it. Adding the wing made the car tight, totally overpowering the front downforce provided by the air dam. What's crazy is even at zero angle of attack, I could feel the wing making the car stick better as low as 60mph. Amazing.
The wing is made up of parts from three different models and the minimum rake was like 10°. So I drilled new holes for the stanchions, put some nutserts in and moved the stanchions wider while I was at it. It's mounted to the body outside of the trunk. No way the flimsy FRP trunklid would withstand the pressure without a bulky support structure underneath. Not being a fan of redundant structure, I elected to mount it directly to the body to save the weight. It's now rock solid and easily supports me bouncing up and down with my entire body weight in the middle of the wing and I have zero added support structure. Perfect. The downside is I can only open the trunk about 10". Oh well, it is a racecar.
So now it needs more front downforce. We'll add a 3" splitter thats sorta squared off on the outside corners. On those corners we'll add dive plane (canards) to help keep air off the front tires. Hopefully that'll balance the car out.That's it for now. Dinner is waiting...
Vinyl body wrap
I asked Mike at All Pro Stickers in San Diego how long he would need the car to do the wrap. "A day or so. Can you leave it over night?" My answer: "What can you do in say, half a day?". He said he'd give it a shot, being his first Miata and not having complete artwork ready. Towed it down to his shop in the shadow of Qualcom stadium, we both worked on it ( I mostly got in the way I think) and this is the result.
I must say, even with some of the graphics not aligned with the body seams and a few other little things, I'm really happy with it. When I have time to leave it with him for two days he said he can redo a few panels and get it 100% dialed.
Action pic courtesy Brian at Cali Photography. He's the resident shooter at WSIR, karts, bikes vintage, drift, he covers it all.
Streets of Willow, CW -blowpass, Speedventures Oct 24
Having been too busy with other stuff to work on the car since the last event at Buttonwillow, the car was pretty much the same. I did have time to put a new steering wheel on. The cheap ebay wheel I was using was flexy so I swapped it for the rock solid Momo Monte Carlo off the turbo (280mm). I also switched the front pads from XP10's to XP12's, upgraded to steel lines and performed a long overdue flush and bleed. I love the XP12's in front but now I need more rear bite. I ended up running the proportioning valve wide open and just barely having enough rear brake. So I'll switch the rear XP8's for XP10's. Yes William, you were right.
Went out for session 2 , about 55° ambient. Being kind cool I started with fairly high cold pressures but it ended up being too much. The tires went off about halfway through the session. That's a bit of a learning curve for me. The old version of the car with stock 1.6 engine didn't put heat into the tires like this motor does. So starting pressure, way too much front brake bias, damping adjusted too soft front and way too soft in rear. Managed a 1:26.210 anyway. 3rd session I had everything dialed in but the ambient had climbed to about 85°, managed a 1:25.882. That was a bit of a surprise. As far as I can tell, that's only .5 sec off the S2K lap record for race tires on that config. Yowza.
So if I do a little supposition, CCW is usually about .5 faster for the fast cars. The wings, dyno time, finish building and tuning the suspension and a cooler 55~60° day, I could conceivably nip into the high 1:23's on NT01's.
1:22's on Hoosiers. That is 997/Z06 on race tires territory.
I'm having to rethink all my benchmarks.
OGK = Orange Giant Killa :)
Miscellaneous pics during the initial build.
I haven't posted it here so I though I'd list the current parts and mods list. The car is used for product development and testing so it'll have an ever changing list of things going on.
As of 04-22-09:Chassis prep
Safety Equipment
- TeamTech 6 point cam lock harnesses
- Momo Safari FIA containment seats, custom fixed brackets
- Hard Dog Hard Core Double Diagonal 4 pt roll bar with integral harness bar
- Momo Monte Carlo 320mm steering wheel and hub adapter
- GDL adjustable steering spacer
Motor
Drivetrain
Suspension
Brakes
Coil On Plugs that is. Just got these installed. A few guys on Miataturbo.net were building their own COPS using Corolla or GM coils. Savington there makes this Corolla coil plug and play kit fotr the Miata and doesn't charge enough. Anyway, plugged in as advertised, reduced dwell in Megatune to 3.5ms cranking, 2.5ms running and I'm done. Nice to be able to get behind the head for service now.The intake pipe is temporary. I'm going to make test different intake pipe lengths when I take it to the dyno next week. We have seen that piep length has a huge effect on power. Just switching from the short 8" pipe I ran at Buttonwillow to this nearly 25" pipe boosted midrange but killed everything over 7000. The way this things runs now untuned, I'm starting to think 155whp is possible once dyno tuned.
Oh yeah, Gordon told me my car was spitting flames on every shift when he followed me at Buttonwillow. The thing sounds really angry. It doesn't rev, it barks. Just amazes me that all this is with 100% stock internals.
The guys at V8Roadsters just sent me this trick new subframe. It's about 10 lbs lighter than stock, much stiffer, uses NB lower pick up points and is red. I could have matched the Lotus Orange a bit better if I was willing to wait for custom powder coating. I was not. So we picked the closest color they had in stock, shot it and here it is.
The NB pick up points lower the front roll center a tad and also change the camber curve a bit. So the 91 now has NB front suspension geometry. The subframe comes with shims to correct bump steer. Been holding off installing the Energy Suspension bushings until this arrived. I'll post more pics once it's in. Now you can see where the space for my battery relocation comes from.
The subframe will also allow a lot more air to flow into the wheel wells from the engine compartment. I think this potential change in air pressure will help improve radiator efficiency. What I don't know is what effect it will have on aerodynamics. On paper at least, it should slightly raise the pressure in the wheel wells. I've been toying with the idea of venting to tops of the front fenders to produce a bit of downforce and reduce drag a tiny bit. The subframe would help with the pressure differential from inside to outside the fender... I think.
Rob just uploaded a short clip of me passing on Buttonwillow 18CW last Saturday. His car is a mostly stock 95M Edition, on 205 Z214 C30's (very hard). I think he has a Goodwin intake and maybe a header, 115whp perhaps and carrying a passenger. I was right on his bumper exiting Cotton Corners, lifted a tad to make sure he wasn't tracking right, then floored it to get past. That was my out lap so I pedaled a bit through Riverside and missed the apex. That was my first time ever braking for Star Mazda on 18, very conservative so he closed on me. Exiting Star my tires are now warm enough and simply motor away like an S2K. The car feels fast but that shot exiting the esses really brought home the difference. Now I now why William was a bit bummed after I passed him. Sorry!
Second clip is from William's 99 N/A. His car is a bit faster than Rob's.
Incidentally, Rob spent quite a bit of time on the first iteration of this project car. I owe him some seat time in it so he'll be able to humble some more expensive cars soon too.
After catching up on business most of the week I finally got around to investigating the throttle shaft failure. Turns out the missing screw heads had been AWOL for a while. I see now that they were what killed the original 1.6 back in January. So I had a spare TB shaft brazed to the plate and screws. The welder put a bit too much heat into the shaft (all one side) and warped it. As a result it was binding. The return spring would bring it back closed but that kind of thing could potentially turn into a stuck throttle. Applied some careful thumps to the shaft in two planes to bring it back straight so it snapped shut like the other healthy 1.8 TB's I have in the shop.
After looking at it more, a billet 4340 shaft with a lower profile and graded set screws would be a nice modification. Much better fatigue life, better airflow and no errant screw heads to attack the pistons.
Having rushed through prep last week, I have a bunch of stuff I need to do before the next event at SOW
(Streets of Willow).
Putting an ETX9 motorcycle battery in. 7.4lbs! I'm going to try to fit it onto the subframe next to the starter. Get rid of the heavy cable running into the trunk, lower the CG & PMI, move mass from outside of the wheelbase to within it.
TheAutokonexion hood, like all Miata hoods was distorting at high speed and creating a gap to the fenders. On the drag strip of 18 Saturday I saw over a 1" gap at about 120mph! Wilson Steele, a composite engineer and Speedventures regular, suggested I bond the outer skin to the support structure underneath. As it is, it's only attached at the perimeter of the hood so the outer skin very flexible.
Engine stuff to do list before dyno next week:
1. Fab sealed airbox under RF headlight cover
2. Fit Setrab #119 oil cooler, Mocal thermostatic sandwich plate & -10 lines under RF corner
3. Install Savington's Coil on Plug set up, re-gap to about .050
4. Switch from 10-30 redline break in oil to 0-20W Amsoil
5. Siphon out the remainining 4 gal. of 100 octane Sunoco in the tank (dyno on 91 pump gas)
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