Destination SSM One Miata's Journey through Hell


Dyno Complete

Posted by David de Regt

Another hectic day at the dyno.  We laid in a base fuel tune and then went to play with the boost tune, and everything was going well until suddenly the car shut off and wouldn't start up again.  This was easier to diagnose, though.  Dead fuel pump.  80 miles or so on a Walbro 255HP and it's kaput.  Really bodes well for continuing to use that thing...

In any event, presented without further comment, 298.6rwhp, 220.7rwtq on a Dyno Dynamics:

We didn't get to playing much with the bottom end before the fuel pump gave out, so that'll have to wait for a future session.  In the interim, this is more than enough to play with for now.  The torque curve is super flat, and could probably be flattened  out even more (mostly the bottom end) with more time tuning.

Tomorrow, a new fuel pump comes in (overnighted), the car gets cornerweighted/aligned (assuming the fuel pump goes in), and we try to assemble the rest of the seatbelts, passenger seat, hood, fenders, and the front swaybar.  Then, if all goes well, I try to take it out for a first outing at Pacific Grand Prix (a local big go kart track that has car lapping days twice a month).  That should vaguely approximate an autocross experience, at least enough to get some basic setup info dialed.  Hopefully tomorrow I'll have a picture of an assembled car, finally...

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Dyno Attempt #1

Posted by David de Regt

On 3 hours of sleep, I ran down to get some 100 octane race gas, threw some more 92 into the SSM car, and we loaded it up into my dad's trailer to haul down to the dyno (the car still doesn't have a hood or fenders, and it's an unknown drivetrain, so towing seemed to be a good idea -- this proved to be a good decision).  We unloaded the car, I quickly wired up the TPS while Andre (of Pina Motorsports) started laying in a base tune and configuring anything I'd missed on the car, and then we loaded it onto the dyno.  We made it about 1/3 of the way through the base fuel map when suddenly the motor backfired lightly, cut out, and refused to even pretend to start again.

We debugged a bit and found that the cam/crank sensors weren't syncing properly, and were in fact syncing largely randomly.  We tried messing with it for a bit, but to no avail.  We did a quick compression check on #1 and found no compression, which implied something far more serious was wrong and decided to call it a day.  We loaded up the car and brought it back home, tail between our legs.

After getting some sleep (I was a zombie at this point), the next day I tore the valve cover and the timing covers off the motor and started toying around.  I quickly realized that while the cams were in sync relative to each other, and the crank pulley was correctly marking TDC (verified), they were nowhere close to correct relative to each other.  I assumed the Gates belt I'd used stretched and the belt had slipped, so I ordered a new timing belt and tensioner spring and started messing with other stuff in the car.

The next day, I figured I should tear the rest of the front of the motor off so that when the belt got there, I could just throw it on.  While I was disassembling, I realized that I could spin the crank and the cams weren't spinning.  When I got the crank pulley off, I realized the issue.  I'm using a bolt-on 6 rib pulley from Fast Forward Superchargers that mounts into the stock 4 bolts on the front of the pulley.  What I did not notice, however, is that the hole in the center is about 1mm too small for the crank bolt to pass through.  So, while everything torqued together properly, the bolt was over 1cm too far out from where it needed to be, so the woodruff key was no longer held in place.  After running long enough, it managed to vibrate its way out of the timing pulley and let it spin freely on the crank, while holding the normal crank pulley in place.  With that mystery solved, I properly reassembled everything in the correct order, and went back to finishing up some rewiring while waiting for the coil that I left at the dyno to be mailed to me.

I'm using this delay to redo some wiring in the bay that needed to happen -- moving things like the TPS, IAC, IAT, etc. around in the front harness to properly reflect where they'd moved to in the final configuration, which should clean up the engine bay quite a bit and make the car easier to work on.  I'm also installing a console-switchable fan onto the intercooler for waiting in grid.  Tomorrow the coil should arrive and I can try firing the car up again, and then take it to the dyno later this week to try again, hopefully with more success...


Finishing the Drivetrain

Posted by David de Regt

Since the day that I got the Manifold (March 9th, over a week later than it was supposed to be), I've been working pretty solid on the car every spare waking moment.  As it turns out, after taking 4 months to work on the project, Corky ignored all of my measurements and schematics that I sent to him, measured a random supercharger he had on the shelf, and designed the supercharger mount and collector based on that.  So, essentially every measurement on the manifold was wrong, not to mention that the collector output ended up being directly into the alternator bracket, as well as contacting the live post of the alternator.  So, after opening the package and a few minutes later realizing these lovely things, I've been constantly fixing the stream of problems resulting from this.

I first fabricated a new alternator bracket out of crap I had lying around to get the bracket out of the way, and tried several different slightly shorter accessory belts to try to move the alternator ever so slightly further over so that it would clear the collector output.  I then had to modify the alternator live stud to point further down so that it would clear the collector as well.  After all that, the manifold would actually bolt onto the engine.  At this point, it was time to put the stock manifold onto the car and get the car back to Doug's so that he could make the final exhaust and we could work on the rest of this fab.

Corky was also supposed to create a radiator and intercooler from cores, which, for the last 2 months straight he said he was going to ship out at the end of each week I emailed.  When I finally pressed him "now or never" last week, he said he had no idea when he was going to be able to do it.  So, that night I spent a bunch of time measuring the radiator opening and browsing the net for substitutes and ordered a 3-row (2.5" thick) 92-00 Civic radiator and RX-7 sidemount intercooler from CXRacing, which seemed to get me the best combination of what I needed at the measurements I needed to make them fit in.  I ordered them up, and they arrived just in the nick of time.  Doug had made the exhaust all afternoon Wednesday (March 14), and the parts arrived midday Thursday, aiming to make a Dyno session friday, and then autocross all weekend.  So, the race was on.  I came over at noon Thursday to Doug's and we started working.

The next step was getting the supercharger to mount to the manifold.  I had to grind away a bunch of material from around the supercharger mount so that there'd be enough room to get a wrench around some bolts, grind away a ton of material from the collector inlet and intermediate plate, so that some air could actually get from the supercharger all the way into the collector, and replace the studs with bolts, since studs wouldn't clear the SC at all.  After several hours on the floor of Chase Race with wrenches, a sharpie, and a die grinder, I finally was able to attach the supercharger to the manifold.  Not exactly a light pile of metal, all assembled.

There's a very careful order of operations to install everything.  Off the car, the supercharger and intermediate plate must be attached to the manifold.  From there, the manifold must be attached to the car, and only after that can the fuel rail squeeze around the supercharger and nestle its way into its home.  Bill Freiheit did a great job making me a quick supercharger to throttle body (I went with a 75mm Mustang 5.0 BBK throttle body, the BBK-1503) adapter, which nicely dealt with that portion of the setup.  I'll deal with the intake later on, but I'm hoping we can make something that curls down by the passenger side wheel well to pull fresh air out from under the car.

While I finished getting the manifold together, Doug had been working on making custom mounts for the intercooler and radiator and finishing up some other stuff (exhaust tweaks, etc.)  As it turns out, they work fantastically and fit great in there.  I was originally planning on getting custom ones made down the line, but it's possible I'll be happy sticking with these for quite a while now -- 100$ intercooler and 70$ radiator, can't beat that.  We finished those at about the same time, so I turned my attention to the intake piping.  Doug was new to welding aluminum, so this was a new game for him, and I'd never designed intake piping before, so I had a fun challenge of trying to fabricate legos that played nice with each other.  In the end, the assortment of stuff I got from SiliconIntakes worked great for really cheap, and we ended up with some functional piping.  Neither of us are particularly proud of our work, but it did get the job done.

The last major thing was the SC belt.  I'd managed to find the shortest belt that would go onto the setup (required forcing it over the crank pulley while turning it with a wrench), and then found a 6-rib Gates auto-tensioning pulley (usually used in mid 90s GM cars) and come up with a harebrained scheme that I figured just might work.  I did some hackneyed "measuring" with a sharpie, staring at the engine bay, and formed a plan.  We cut out a chunk of aluminum, drilled a bunch of complicated holes in it, welded on a bracket, attached it to the manifold, and, much to both of our surprises, it just worked.

Finally, there was a ton of other cleanup/finishing work -- doing some rewiring, fabricating a throttle cable bracket, running vacuum lines, etc.  Around 4 AM, we finally got the car fired up.  Remarkably, it basically fired right up without any fuss.  I spent some time futzing with the fuel map so that it'd be drivable, we identified 2 coolant leaks (one was easy, one was a total pain) and after celebrating with a quick beer I managed to finally get the car home a little after 5 AM.  It drove perfectly, and it was really hard to keep my right foot from squeezing out some more whine, even though I'd zeroed out the on-boost timing map and made the on boost fuel map super rich, just in case.  Even pushing just a couple pounds of boost on the drive home (really really light squeeze),  I could tell it was going to be fast.