Two 1990 Miatas - STS Autocross, CSP Hillclimb, PR Rallycross

So we tried RivalS1.5's

The general consensus of 'people', vastly simplified, is that RivalS are the most difficult 200TW tire to get heat into but *should* be faster on a good hot day on concrete than the Nexens we run now or the Bridgestones we ran previously.  So when the opportunity arose, I wanted to give them a try. 

Turns out I am not fond of them.  At all.  Hell no.  Something about them doesn't mesh with my setup and/or driving preferences and I never felt confident on them.

Over the course of 8 runs, we varied tire pressure across a 10 psi range, along with rebound and compression changes across a wide range.  No luck getting the front of the car to bite consistently nor the rear of the car to stick in transition as desired.

The weather was sunny, dry and 75*.   Two drivers.  That ought to be good enough to get heat into any tire I want to use, as March-June and Sept-Nov are typically cooler than that anyway.  Only a 45 minute lunch break between sessions, in the middle of the day - course and temps were the same for both tires.

Nexens:  48.274       48.022        47.204        46.618+1  (3rd run was FTD, 4th run if clean would have won PAX.)

RivalS:  48.302+2    47.672+2    47.498+2    47.880

Codriver RivalS times:  52.310    50.376    49.960+2    49.336+2

We won't be running the car on concrete until Nats 2018.  Showing up with a well developed car on Nexens has got to be a better decision than struggling all season to get enough heat into RivalS to trust them, nevermind build a setup around them.  Screw that.  I'll put Rivals on the car as soon as it loses to an STS Miata that has them.   Hasn't happened yet.

This amuses me.  There's a MS hiding in there!

Megasquirt + wideband installed in the STS car.  Well, occasionally.  Have been swapping back and forth between stock (chipped) ecu and MS to work on the tune. 

So far I've got them dead even in acceleration runs from 30-55 and 30-80 mph with the MS conservatively 'too rich' and the timing not really optimized yet.  Some struggle getting the half-throttle map to richen up for casual driving without simultaneously killing idle.  (this is set up to use the AFM flappy door voltage input as a rough approximation of a TPS - 3 positions, 0 half and full) Here's how the TPS signal is - that's all the ECU will ever see, that green line in the top plot.

 Have been doing this in blocks of about 30-60 minutes at a time so really I've got about 3 hours in this so far and it's promising.  Helps that this MS was running on another STS car previously, albeit at a much higher altitude.

The Nexens are holding up well, 92 runs on them and I flipped them last week to even out the wear from 'only' 2.5* of camber.  Took the car out to a corvette club event this weekend just to make sure the tires were scrubbed in well before the local season finale on the 8th.  A neat side effect of that was winning an event, on raw time alone, by multiple seconds.  Silly corvettes.

The SC'd car has been leaking a fair amount of oil out the front main, which started as soon as I fixed the valve cover gasket leak.  I assumed this was due to blowby/bad rings, after all the car has 212,000 miles and sat outdoors for 1.5 years.  Mentioned this to a friend who goes "you know a bad PCV will do that".  Well, yeah, but this one is brand new and I checked that it flowed.  "Yeah but if it wasn't designed for boost..."

D'oh!  $%^&*.  I never considered it failing open and allowing boost from the intake manifold directly into the crankcase.  Not enough experience with boost for it to even cross my mind. 

So later I go open up the other brand new PCV I have.  Yep, you can blow the 'wrong way' through it.  Tried another one intended for my NB2 engine - it does prevent flow into the crankcase.  So for now I fully plugged the intake manifold side, and installed the PCV venting to atmosphere.  The PCV that i took off the car does also allow reverse flow, and also has a visible failed spring inside it.

Drove to work this morning and of course the car still smells like a refinery fire but it might be dripping less.  After ~1500 miles of pressurized crankcase I am sure that front main is not happy even if the source of pressure is removed.  Oh well.  

Coolant hose behind the head took a dump on the way to work, on the NB.  Rather than try to fix stuff in the parking lot I just had AAA drag it 8 miles home during lunch.  On the plus side the tow truck driver has an autocross...Blazer.   Interesting.

The drive down to Sunday's autocross was wet.  Very wet.  Apparently enough so that the rapid cooling/splashing finished off the catback:

To be fair, this pipe was bought used - because the car it was on was wrapped around a tree and then abandoned in a field.  It's been on my car for 20,000 miles and north of 600 clutch-drop launches.

Once we determined that the exhaust wasn't going to fall off, we ran the event anyway.  We both had 'meh' runs for the event as rain moved in partway through 3rd runs.  In PAX codriver was 4th, I was 8th.  Final results for the season were 3rd in STS for me, 1st in STS for my codriver.  And for season-long pax points (Driver of the Year) competition, it came down to a tie in points with the championship determined by who had more pax wins during the season - and my codriver won that.  So although I was back in 6th overall my car won the season championship at least :D

Since the BMR winter rallycross series is effectively cancelled, AHR and NY are a bit far for me to want to deal with (3+ hours each way), it's possible the only rallyx event for me this season will be in Harrisburg on November 18.

That's a problem because currently the NB marks its territory rather aggressively.  This is the result of about 10 minutes of idling to burp the coolant system after fixing the broken heater hose:

Plus the 2000 mile old valve cover is leaking again.  Some combination of the bad PCV situation and an $8 generic gasket.  So I ordered the revised fel-pro gasket and a front main seal.

Last night I finally got a chance to take the front of the engine apart.  Cam seals seem OK, the leak is definitely from above the oil pan, so that leaves the front main.  Yeah, that looks like a nice gap opened up at the top of the seal there:

(The dot that looks like something IN the sealing surface is just a small piece of gunk that caught the flash)

The working theory is that this poor thing was 212,000 miles and 18 years old...when subjected to whatever amount of boost the bad PCV let into the crankcase, pressure on the inner lip of the seal caused it to invert which, looking at the design of the new seal, would indeed cause the outer lip of the seal to lift like it has in the photo.

The attempt to pull the seal with an improvised tool from harbor freight (that I have used successfully on cam seals and diff seals) went rather...poorly. 

The tool slipped, gouged the hell out of my other hand and might have punched a hole in the a/c condensor.  Not my brightest moment.  Looks like the crank is unscathed though, so there's that.

Two proper seal pullers are on their way from amazon, they're relatively cheap and something I should have anyway.

I pried against the crank trigger wheel slightly during dampener removal, and cleaned a ton of junk from around the crank position sensor.  Hopefully that combination still works upon reassembly.

Ok, so the NB has been mostly fixed.

-actual tools meant to pull seals arrived and were used with success.

-New seal installed partway with some huge impact socket (28mm?) until it ran out of depth.  Finished with a plastic hammer and carpenter's pencil.  Shhh.

-Timing belt wasn't too oil covered and I didn't want to bother removing the t-stat bypass hoses that capture the timing belt as I had no spares on hand for when they break.  So I reinstalled the old belt.  Don't tell anyone.

-The plastic timing covers...I've never seen them this beat up and filthy, bosses cracked, gaskets swollen from oil bath, worn through from the crank pulley, etc.  I crammed them back in place, mostly, with some bolts that old them on, more or less.  

-'Good' Valve Cover Gasket installed.

-It runs!

-The crank is dry!  Clean wood is happy wood.

-It now leaks somewhere new.  Like...like....well, like something that leaks a TON.  Turns out that although this is my 8th or 9th valve cover gasket on a Miata, I botched this one and ripped the gasket near the coil.  The amount of oil that came out was truly impressive.  Steady flow anytime the engine was running.

-So I threw away the ruined $18 'good' gasket and installed the $7 'emergency' one that was bought long ago and wasn't worth returning.  It will leak in 2000 miles based on past experience.  At least it's sealed for now.

-My scangauge was away in my wife's car when I needed to bleed the cooling system so I used my bluetooth OBD2 thingy for the first time along with the Torq app.  Pretty cool setup.  Although it seems whatever the OEM sensor for vacuum is, reads ~1 full psi higher than my mechanical gauge, with occasional fun spikes:

-Know what I didn't do?  Wash it.

Also threw the NB wheels on the STS car briefly because the NB was in hover mode anyway and I let a friend borrow the STS race tires for an event I couldn't attend.  I kinda like it!

It seems I've run up against the limit of stock injectors and piggyback type engine management in the SC car.  Once intake air temps drop below about 25 degrees,  the fuel cards are maxed out.  Above 6,000 RPM at full throttle it starts going lean, hitting 14.5 AFR if I keep my foot in it until redline.

Ultimately that's not an issue I don't think.  I can keep it below 6 grand in winter, even rallycrossing.  And the event this weekend looks to be about 50 degrees.  All good. 

Picked up a set of used mounted snow tires yesterday.  It's looking wet so I'll also bring my cut 'mud' tires.

Before the rallyx on Saturday I need to install the hardtop including frankenstein bolts and cutting up interior trim, install the front undertray, and probably do something about the gauges and cards STILL hanging from the center AC vents.  They're not going anywhere but I don't imagine rallycross tech will be happy about it.

Also my class is stacked and this will be a competition for DFL.

No results yet but I am sure I was last, having about 14 cones and a few missed gates. Conditions were absurdly sloppy and I am way out of practice driving in this kind of crap.

To update this:

-Local rallycross is still hit or miss.  Summit point is back, yay!  Summit point is over 3 hours away, boo!

-I sold the supercharged NB and all related parts for $3500.  It was a ton of fun as a daily but I owned three vehicles I could daily and without rallycross I couldn't really rationalize a second Miata any longer.  Sooooo...

-I replaced the NB with a tow vehicle so we can more seriously tackle national autocross with the STS car. 

2003 Dakota 2door/2wd/short bed/5spd/4.7liter/3.91 rear.  It's a damned hoot to drive, and also gets north of 15mpg moving the Miata through the hills of western PA.  We were going to drive two cars to the Pittsburgh Match Tour, the Miata and a mazdaspeed3 support vehicle - both cars do about 30 mpg on premium.  The truck does 15 mpg on premium and costs LESS in tolls with the trailer than it costs for two separate cars.  Uh...awesome.  Towing is saving money.  This is great.

Between the Pitt Match Tour (finished 1st & 2nd) and the New Jersey ProSolo (finished 1st & 5th), we have won almost enough contingency to cover the truck purchase   Thanks Mazda/Nexen!

Sitting in the #1 grid position in NJ: 

Unfortunately my codriver got us there, not me.  I was around a second back from 1st, finishing in the last trophy spot which is still my best ProSolo showing to date.  Even better, IMO, I matched or beat my codriver's winning pace for 90% of each course but could not get one corner right, to the tune of a half second loss per side.  That's an improvement over being 'a little slow everywhere', I think.  Pros are historically my worst events, the two mirrored courses really mess with me but they are just so dang fun I keep attending them.

So from here on, this is just an STS Miata (and truck!) thread.  Upcoming STS stuff includes fitting a super lightweight exhaust and making it not sound like crap, street tuning a 1st gen megasquirt to try to make more power than the stock ECU (so far they are dead even.  Meh.) and corner balancing the car since I took about 20 pounds out of the right rear corner recently with everyone's favorite tiny battery:

So... what weighs more? The battery or the hold-down? 

Congrats on the wins and contingency! 

The hold down does weigh more than the battery! I left it oversize so I could chuck the old one back in if the little one failed. Now that it's working fine I need to cut down the threaded rod.

I may have datalogged the truck a bit this week...

No discernible difference in the acceleration rate (slope of the line) on these two runs from 25 to 45 mph in 2nd gear, 93 tune vs 87 tune.  93 gas in the tank for both.  About an hour apart, so given that the air was better and fuel load lighter for the 87 pull, the 93 appears to make a little bit more power but not by an earth shattering amount.

I tried a hard 0-60 run, something i do on each vehicle once. For science!  9.3 seconds 0-60, with THE slowest shifts of my life.  If I cheat the numbers by knocking the time spent shifting down to Miata shift times, the 0-60 run would be 7.1 seconds.  The power/weight/gearing is there but the poor trans just can't be convinced to shift any quicker at 6000 rpm at this stage in its life.  Yes, all these numbers are substantially faster than the STS car.

NA Steering wheel installed.  Much more comfortable grip.  It's STS legal at the moment but there's some speculation that for 2019 or 2020 we'll have to revert to the original wheel.  

Fancy exhaust finally installed for good, and quiet enough to enjoy in the car.  Outside the car it sounds good and passes sound easily as well.

Ok, I guess that's not going to work.  How about this?

Still no?  Fine we'll trim it down.  Final result:

Video from the first event with it:

Boy have i neglected this thread.

-We ran the Finger Lakes national tour and finished 1st and 3rd.

-The Dakota is down for a clutch swap overcome by stuck pilot bearings, apathy, and lack of time.  it's been apart since July.

-Took the STS car to SCCA Solo Nationals (with borrowed truck) on the wrong tires (Nexens), neither me nor my codriver were happy with our driving.  Finished 8th (him) and 21st (me) out of 45.  Codriver had the pace for ~3rd place if you ignore mistakes, so that was promising for the car.  I had the pace for berkeley-all, just did not adapt to the scale and grip of the site very well at all.  However we discovered that you don't have to pay for food at nationals.  The hotel feeds you breakfast.  If you're racing a Mazda, they feed you lunch.  SCCA/GRM/others feed you dinner.  GRM feeds you a lot of beer too.  Thanks guys!

-Since taking the truck apart, I have broken and fixed a bunch of stuff on the Miata, Mazda3, my wife's Fiesta, and the $1000 E46 I bought in October.  And packed and unpacked the truck/trailer for nationals.  All in the driveway.  Two rubbermaid bins of stuff, a shopvac , a stack of tires and a jack are STILL in the driveway because...because.  Enough.  Time to get back to work on the stupid truck that I love too much to sell or part out.