The Miata experience: his and hers.

Finished up the diff install with the 4.30 Torsen.  Car is definitely a little peppier.

Also, this showed up for the NB:

It will be going on the shelf for a while...  at least until the NA gets turboed.  At that point the NB will get some hand-me-down parts.

Starting in on prepping the NB for paint by removing trim to save labor with the painter, and the first step was removing door trim.  I took the opportunity to stitch weld the seam around the door opening.  It's amazing the difference this makes in chassis stiffness on an NA/NB Miata, and I should have done it a LONG time ago, but I've been very slow getting a lot of things done with this car.

It's a pretty easy 2-3hr project if you've got a MIG welder.  I recommend using a welding blanket to protect those things that shouldn't get too hot.

Where to weld, from FM:

I didn't start taking pics 'till it was time to squirt on some primer...

All of the welded area is under the trim, so the primered spots are not visible.  In my case, they'll be painting up to the seam anyway.

More disassembly work on the NB.

Stripped out the cowl and removed the windshield header trim and rubber.

Also stripped out the passenger door and removed the mirror and door handle.

I'm thinking I might tint the windows while they're out... should be pretty easy that way.

Only had about 1/2 hour to work on the NB today, but it was enough to strip the driver's door.

Saw this and thought of your thread, here's some free CFD for you.

Thanks for posting.

I've not run the NA on track without a hardtop for at least 5 years... 

There's some CFD floating around in the Miata community, mostly dealing with the front end.  The effect of removing the hardtop has long been known, though this video quantifies it.

Returned yesterday from trip to PA to hang with the in-laws for Christmas.

Just under 4700 miles on the Grand Cherokee, which performed like a champ for the trip.

Only had one issue... I replaced the windshield wipers in PA, with Rain-X brand.  In the middle of a downpour somewhere in Indiana, the driver's side wiper decided to hit the 'eject' button!  Fortunately, traffic was light, and water was beading off well enough to get to the next exit with a truck stop and I was able to buy a replacement....

I've never had problems with wipers until the last few years, but this is the second time I've had a wiper fly off the arm when in use.  Both were the 'J' hook type of arm, and the last time was on my work car, in the middle of a snow storm and both wipers departed.  Fortunately, that time, one came to rest at the bottom of the windshield and I recovered it and kept going 'till I could get a replacement.

So, now I'm paranoid, and have decided to keep spare blades in the GC since my wife drives it.

Other than that, not much excitement driving across the land.  I did see this hauler full of C8s, which apparently survived the tornado.  The were westbound on I40 when I saw them in a rest area in East Texas.  We also saw them underway the next day, on I40 in New Mexico.  Looks like some lucky folks may be receiving their C8 orders...

Now it's time to get back to work stripping out the NB for paint.  Hoping to get it to the shop next week...

More progress.

Got the rear stripped out today.

That pretty much wraps up the disassembly.  Just a few little details to deal with.

I brought the new bumper cover and headlights home from the storage unit.  Here's a little preview:

Thank you Mazda for making so many things interchange on these cars over the years.  Almost all of the support structure for the '99 bumper cover works with the '01-05 part... here's the top support from the earlier bumper in the new one.

Starting to get excited about this. 

Still have some little parts and weather seals to order...  it's staggering how much all of the ancillary stuff adds up to on a job like this.

Dropped the NB at the paint shop today.

I forgot to take a couple things with me, and had to run back after dropping it off.  I figured the NA could use some electrons in the battery, and these guys (who painted the trunk lid for me) had never seen the NA in person, so I drove it down for the second trip.

With the NB out of the garage, the NA was in.  Time for a couple of minor fixes, and some routine checkups.

First up was a compression test.

For reference, I went deep into the archives, back to January of 2016 when I brought the engine home.

Today's numbers:

Those are the raw numbers, before correcting for our 5000ft of altitude.  Corrected numbers:

1 - 156

2 - 150

3 - 160

4 - 162

Still on the low side.  I'm using a 40 year old Craftsman gauge, and I have no idea how accurate it might be, nor do I have any verification of the 'pre' numbers, which were provided by the vendor from whom I bought the engine.  Good news is only 7.5% high to low, so things are fairly consistent.

At least the plugs look nice after 5 years of track use! 

After 5 seasons of track use, I'm really not surprised to see the low numbers, and the engine will be coming out soon anyway.  I had originally considered just throwing the turbo on this engine, since my goal had been ~220hp.  I'm glad I didn't.  In addition to the compression being a bit low, NASA changed the rules for ST4 for 2022, so I now need ~240hp which is right on the cusp of needing rods.  So it's time to drag out the spare 1.8 and start an engine build in preparation for the turbo install.

Also did a restoration on the NB2 headlights today.  Even though they were pretty good (driver's side was excellent), I wanted to start from a known quantity.

Before:

After:

Passenger light still has a slight haze, which is disappointing.  I've had really good results from these Sylvania kits in the past, so I'm thinking the inside is the issue.  Both lights will be getting Lamin-X when they go back in the car after paint.

Today I dropped off the NB windows to be tinted while the car is getting painted.  

Also had a little fun with vinyl.  My wife likes the white top, but I thought it needed something if we were going to keep it white.  We agreed on a design, and today was implementation day.

First up was cutting a bunch of pieces, so I made a template, and cut, and cut, and cut...

A few hours later...

I know checkers have been done forever.  But I still like them on a racer, and I did add a little 'twist'.  

If I change my mind down the road, it's only vinyl... easily removed.

Nice job!

Thanks!

The NA got some new plug wires to go with the new plugs.  Kind of boring on an NB2 engine, as there are only 2 wires.  LOL.

Also put in a new O2 sensor for the AEM Uego.  Manual says free air calibration is unnecessary, but I decided it couldn't hurt.

I've had some trouble with the car killing O2 sensors (this is the third in 4 years).   I think it's partly because of the less than ideal positioning in the header (not something I can easily change).  I'm trying a new strategy with this one, if it works, I'll post about it.

The other project to get done before our first event for 2022 is some lingering fuel system issues.  After the roll cage installation, the 30 year old filler tube hose was too hard to seal properly after being reinstalled, so I swapped that out.  We were still getting gas fumes, and I determined that fuel was coming down the overflow into the trunk.  1st step was to replace the gas cap, whose rubber seal was equally as fossilized as the fill tube hose.  That should prevent fuel from getting into the overflow on right corners.

If for some reason fuel does escape, I added a bulkhead fitting to replace the original snap in plastic fitting, so any fluid will go overboard instead of leaking into the trunk.

The last piece of the puzzle is fuel tank venting.  When I removed the original charcoal cannister during the engine swap, I did a quick and dirty jerry rig of the tank vent.  Lately, I've been getting a lot of pressure in the tank that's not venting, especially in hot weather.  I pulled out the check valve on the tank vent, and it was indeed not working properly.

The plan is to replace the check valve with a straight connector.  The fitting in the tank is the rollover valve, so it shouldn't create any issues with fuell passing through.

I'll plumb the vent line to a new charcoal cannister at the rear of the car... parts incoming.  Hopefully, all of this will put an end to gas fumes.

Got the fitting to bypass the check valve in the vent line...

Also picked up a cheapo catch can to use as a charcoal cannister.

I tapped the mounting holes to use M6 screws, which should make it much easier to deal with than screws/nuts.

Next up is fabbing a bracket and running the vent line.  Also have some charcoal pellets on the way.

Drove by the paint shop late last night, and saw the NB sitting in the front window.  Pardon the terrible pic... cell phone @100 yards!  Looks like they're making progress... door jambs, windshield header and around the trunk and hood openings were painted. 

Drove by the paint shop last night, and the bumper covers and hood were where the car was the other night, and had color on them.  Progress! 

Today, I finished up the fuel tank vent/ charcoal cannister.

First issue was the fitting for the cannister was 10mm, and I needed a 6mm barb.  I couldn't readily find an M16 to 6mm barbed fitting, so I got a 10mm to 6mm barbed, and went to work.

First, cut off the 10mm barb

Drill to fit the brass fitting

And JB weld.

Next up was building a bracket for the cannister.  I started with my rapid prototyping cardboard.

Then translated that to sheet metal, and welded it to the frame rail.

Finally, I filled the catch cannister with charcoal pellets, and mounted it up.

A quick test drive developed no residual pressure in the tank, and no leaks or other issues.  The true test will be on track in a week.

Finally got around to getting some video from INDE Motorsports in November uploaded.

This is a couple of laps chasing one of the PCA instructors (in the LS3 powered 928) doing lead/follow with a driver in a 911 Speedster.  Once the Speedster points me by, the instructor takes off...  I used to be able to (almost) keep up with him when he still had the 928 engine, but had no chance here! 

Tried to apply Lamin-X to one of the NB headlights today.  Working with the Lamin-X film pulled up the UV protectant layer from restoring the lights.  Guess I get to do that one again...

The only good news is I started with the headlight that came out hazy.  Bad news is I don't think 'restoring' it again is going to fix  the haze.  Debating baking it to pull the lens and re-do the inside, or just trying to find a better headlight...

No pics, but I stopped by the paint shop yesterday.  NB should be finished Friday, and is looking really nice.

Unfortunately, we have a track event Saturday, so the trailer will be full of race car on Friday.  Looks like I won't be able to pick it up until Tuesday.  After I take the trailer to MVD for its "un-salvage" inspection appointment that's been over two months in the waiting.

Trailer is loaded for tomorrow.

Picked up the NB's windows from the tint shop this morning, so they're ready to go in when the car comes home.

Also got the NB some new wheels and tires to go with the new paint.  Kosei K1s in 15x7...  I think I got the last set of black K1s with a 30mm offset, as they're showing NLA on Tire Rack's site now.

These will be getting Yokohama Advan Fleva V701s (who the hell comes up with these tire names??) in 205/50-15.  Should be in at the local DT this afternoon.  

Just for grins, I mounted a wheel up on the NA, and they clear (barely) the big Wilwoods front and rear with the same 3mm spacer I use for the Advanti Storms.

Just a couple other minor items to get ready for tomorrow.  Looking forward to being back at AMP, as the car has yet to run there with the full aero... 

Great day at the track today! 

Lots to unpack - photos, video and data.  

Dawn at the track

SWMBO on track

Kona in the trailer

More to come...

OK... track download.

First...  fuel fume problems solved!  The new gas cap, overflow line and vent/charcoal cannister worked.  No more fumes, and no more spillage under hard cornering.

Next... weight.

This was my first chance to weigh the car since the cage was installed, and it's kind of a head scratcher.  The last time the car was weighed was December 2020, and it was on the exact same set of scales.  My weight hasn't changed (~210).  The car is 68 pounds lighter after the cage install...

12/2020

1/2022

That really surprised me, so I went back to figure exactly what had changed:

Swap race hardtop for street hard top -15lbs

Remove pass seat, brackets and harness -30lbs

Swap fiberglass trunk lid for stock -10lbs

Remove seat belt towers -10lbs

Remove door cards and trim door sheet metal -15lbs

Replace battery bracket with aluminum -2lbs

So that's ~82lbs removed...  now add:

Wing +10lbs

Fire system +10lbs

Cutoff switches/wiring +5lbs

Cage...  I figured (measured cage tubes x weight of tube/ft) that the cage was roughly an 80lb gain over removing the 40lb roll bar, so +80lbs

That's +105 lbs total added.  Which leaves me with a net gain of 23lbs.  I figured there might have been about 3 gallons less fuel, but that's only another 20lbs... which is a break-even.

How the hell did the car lose 68lbs???  I guess my estimates were that much off in total, 'cause the only other option is that the scales were whacked...