It’s Wednesday night, and this update is late. Car #86 has spent the week getting ready for Summit Point, and the publish button has had to wait its turn behind the brake bleeder.
When we collected the car from Haas Auto Service Center in Manassas, it drove onto the trailer under its own power. After the way it left Kentucky, that earned a polite round of applause. It went in with its oil and coolant sharing accommodations. It came home with new pistons and rings, freshly honed bores, coated rod bearings, new valve seals, and a cylinder head that has rediscovered the joy of being flat. Same block, same head, fresh everything inside, and the throttle pedal has noticed.
It Went In for a Gasket
Sunday morning at NCM, the oil and the coolant were considerably better acquainted than the service manual recommends. The head gasket was the obvious suspect, and the Accord’s Kentucky weekend ended on the trailer, headed home and then to Haas with one line on the ticket.
Saturday had already involved high temperatures and low oil, which gives an engine builder reasons to keep looking once the head comes off. A new gasket would have addressed the symptom. The job grew to include fresh internals and the machining needed to give that gasket a sound surface to seal against. “While we’re in there” remains one of the most expensive phrases in motorsport. It’s also, annoyingly, one of the most correct.
Bill Haas and the team at Haas Auto Service Center deserve a proper thank-you. They took an engine that had been through a punishing weekend and put in the machining, parts, and careful assembly to make it healthy again. The result feels stronger and sharper than the day we first brought it home from Springfield. We’re glad to have their work under the hood at Summit Point.
A Little More Squeeze
The new pistons are specified at 11.5:1, against the TSX engine’s factory 10.5:1. That’s a full point before the head work, and the head work counts. Haas took 0.020 inch off the head face, which is 0.508 millimeter if you prefer. Overheating distorts aluminum heads, and a new gasket needs a flat face to seal against, so the cut restores the mating surface. It also removes a little volume from above the piston. Less room, more squeeze. The number on the piston box is only the beginning.
A higher compression ratio squeezes the mixture harder before ignition, which means more efficiency and torque, provided the fuel and calibration support it. The napkin math: at the stock 87-millimeter bore and 99-millimeter stroke, each cylinder displaces about 588.5 cc, and at 11.5:1 that leaves roughly 56.0 cc above the piston at top dead center. A 0.508-millimeter cut across the full bore removes about 3.0 cc; the chamber opening is smaller than the bore, so call it 2.0 to 3.0 cc, which lands between 11.9:1 and 12.1:1. Our working guess is 12.0:1. The real number depends on measured chamber volume, piston crown, deck height, and gasket thickness, and we’ve resisted the urge to submit the napkin as a dyno sheet.
Two consequences: fuel stays at 93 octane, no exceptions; and the KTuner map that was conservative for the old combination has to earn that description on the new one. Fueling, timing, and knock all get checked under load before we lean on it at race pace.
For anyone reading from the BS inspection tent at Summit Point: yeah, the pistons were part of the repair… we’re just very pleased with the repair.
The Parts You Never See
The pistons ride on the original connecting rods, which Haas inspected and kept, so the napkin math’s geometry is stock. Between the rods and the crank sit new ceramic-coated performance rod bearings. A bearing lives on a film of pressurized oil, and the coating adds protection for the moments when that film gets marginal. The bearings still require a continuous supply of oil or you end up with problems…
That last point has history. The first engine died at NOLA of oil starvation under cornering load, and the replacement spent its Saturday at NCM shedding Accusump lines. So chasing leaks has been the priority this week, however good the bearings look on the invoice. Call the coating an insurance policy for the bottom end. Nobody hopes to need it, but combined with the Accusump, we think we are in a pretty good spot if we need it.
The cylinder bores were honed for the fresh pistons and rings. Honing leaves a controlled crosshatch that holds an oil film while the rings establish their seal, which keeps combustion pressure in the cylinder and oil out of the chamber. After Kentucky, the engine’s experiment with open-plan living is over.
Upstairs, new valve-stem seals address the oil that used to slip down the guides overnight and announce itself as a blue puff at startup. The car now starts without that little confession and can look innocent on a cold morning again.
Breaking It In
Fresh rings need a proper introduction to freshly honed cylinders, and “be gentle” leaves out the important part of the instructions. Seating rings takes real cylinder pressure, with speed and load varied per the builder’s procedure; prolonged idling and light-load running make it harder, not easier. The engine reaches operating temperature before it’s asked to work, and the early oil and filter change matters because the first miles leave wear debris in circulation. Like most new relationships, it benefits from warming up before anyone asks for full commitment.
Our break-in miles are complete. The engine starts cleanly, runs well, and the fluids are staying where they belong. The next examination involves a helmet and considerably more sustained throttle.
The Right Foot Review
We don’t have a dyno number. We have a seat-of-the-pants assessment, and the pants are unanimous: it’s stronger.
We started the season with a K24A8 rated at 166 hp when new, though after 205,000 miles we suspect a few of those horses had found a gap in the fence. How many were still reporting for duty at the season opener is a question we never put to a dyno. The rebuilt RBB3 carries a TSX factory benchmark of 205 hp, and an optimistic estimate of around 210 once it’s properly tuned. If that holds, it’s roughly 44 hp more than the original had when new, about a quarter more power, and the jump from whatever herd remained at 205,000 miles is larger still. The dyno still gets to count the horses.
The extra compression alone might be worth 2 to 4 percent over a healthy stock TSX engine, fuel and tune permitting. Much of what we feel beyond that is probably fresh rings sealing and an engine that’s healthy again. Measurements will have to separate the two.
What we can feel without instruments is how readily it answers the accelerator. The old engine responded the way you answer a text from a number you don’t recognize: eventually, and with suspicion. This one is keen to get on with it, especially coming off a corner. It’s still a 2,900-pound Accord with an automatic. It has simply become a lot more enthusiastic about its job.
Now It Has to Last
As of Wednesday night, the brakes have been changed and bled, the leaks have been chased, and the tires have been rotated. The long-range antenna is installed and the Baofeng radio is hardwired, which gives the radio fewer excuses, though we can’t guarantee any improvement in the driver commentary. Inventory is complete, spares included. We look forward to hauling them to the track and bringing them home unemployed.
Thursday morning we finish the load-out and head for Summit Point to claim a paddock spot and set up for Friday’s test day. Nothing like an endurance race to make a conveniently located patch of asphalt feel like prime real estate.
Friday is the car’s first track outing since Kentucky. Two drivers share it this time, and neither of them has driven this version of it. The opening laps are for getting acquainted, bringing everything up to temperature, and hearing what the gauges and logs have to say. Enthusiasm can wait its turn. Saturday is when the fresh-engine promise has to become completed laps, through hot stints, driver changes, and the long hours that make this endurance racing.
A little head work goes a long way. We’d like that distance measured in completed laps. All the Way.
