When we last left off with this series, we had just returned from Pittsburgh International Race Complex, having endured a catastrophic failure of our Prelude’s race-prepared H23A1 engine. During the 2023 pre-season, the team disassembled the engine to figure out exactly what had happened.
What Happened
Our at-track troubleshooting efforts at Pittsburgh had shown us that the #1 piston had crumbled due to a ring land failure. And a tell-tale white band on all four spark plugs hinted that all four cylinders had been running lean at some point. But we didn’t see the full extent of the damage until we had separated the head from the block.
A completely obliterated piston #1
As expected, the ring lands on cylinder #1 had disintegrated and the cylinder walls on #1 were heavily scored. What we hadn’t expected was that there was similar damage on cylinder #2. These two cylinders were problem children from day one. Despite multiple break-in attempts, we were unable to get these two cylinders to show less than 5% leakdown, even after cylinders #3 and #4 were testing under 1%.
Damage and heavy cylinder wall scoring on Cylinder #1
Similar scoring and piston chunking on Cylinder #2
The striped markings on the spark plugs were a red herring. The real cause was clear. The FRM cylinder liners on our engine were too badly scratched for the rings to fully seal. That allowed red-hot combustion gasses to blow past the rings, washing the oil off the cylinder walls in the process. Eventually, this allowed a hot spot to develop on the edge of the piston, which caused it to break apart, resulting in this catastrophic failure.
Unfortunately, the chunks of loose piston bouncing around the combustion chambers had ripped up the head beyond reasonable repair. The resulting metal dust had also circulated throughout the bottom end of the engine, destroying the crank, bearings, and bottom end internals. Aside from the cams, gears, and a few external accessories, there was little we could save from our experimental race engine.
The root cause of the issue was something that had happened long before our engine was even assembled. The previous owner of our block had sent it to a machine shop in preparation for a rebuild. That shop had scratched the cylinder walls of our H23A block in a botched attempt to polish out some cosmetic scratches. Powertrain Wizard Robert Oliver had attempted to repair this damage using a specialized FRM honing process used by Porsche mechanics. And while he had succeeded in repairing cylinders #3 and #4, the damage to #1 and #2 were very slightly beyond repair.
The team knew that this would be a risk going into the build and accepted that this was the consequence of taking the risk. The real question was: What are we going to do?
Parts Availability - The Perpetual Challenge
The first thing we did was to look for a new H23A1 long block to replace our broken engine. Unfortunately, this is where we came up against one of the unfortunate realities of racing older cars: There is a finite number of hard parts out there. And that number is dwindling by the day.
Between COVID related import restrictions and the immutable reality that the Honda H23A1 engine was never built in the same quantities as its VTEC-enabled siblings, it was impossible to get a new core at a reasonable price. And even if we had, the Powertrain Wizard wouldn’t be able to build it in time for the start of the 2023 USTCC Season.
We would have to find another way.
Allies, Friends, and Axis Powers to the Rescue
It turns out we wouldn’t have to look far. We just needed to ask for help.
As soon as news spread of our misfortune, CMP Racing’s Ross Shull reached out and offered the perfect solution. Having long since made the decision to retire his successful ChampCar-spec 4th gen Prelude Si VTEC, Ross offered to sell the entire powertrain from his car (at well below cost) to help keep us going. This was the same engine that had recorded a 194 fwhp on Shue Tuning’s ego-bruising SuperFlow dyno with multiple 8+ hour endurance racing wins to its name. Installing this engine would make us instantly competitive in the Sportsman class of the US Touring Car Championship. We happily accepted the kind gesture from a capable ally from years ago.
In the first few weeks of the 2023 calendar year, trusted friend (and sometimes teammate) Martin Szwarc transported the new powertrain package back to the Studio on the back of his Silverado. When local shops couldn’t slot us into their busy schedules, ProjectCRX’s Andy Yoon drove 100 miles with his engine hoist and stand so that we, with Chris “Cessna” Eng’s help, could transplant the new powertrain to replace the StudioVRM Prelude’s broken heart.
It took only two days of wrenching to install a new engine, transmission, wiring harness, and ECU into our Prelude. When we went to turn the key, the whole team was rewarded with the beautiful sound of silence.
There was a problem. Something was keeping the Prelude’s new engine from firing up. With Ross’ help, the team proceeded to troubleshoot on and off for two whole weeks. To little avail. The ECU had power and the engine had fuel. But there was no spark.
CMP Racing had converted their engine to Coil on Plug using a HondaRulez-based Burton Racing COP conversion kit. Yet there was something within this very kit that was keeping our Honda’s new VTEC powered heart from ticking.
Burton Racing’s Support team thought that the problem must be with the car’s wiring. Helpful, but vague. So, we reached out to one of the best all-round Honda engine builders in the US – Our technical partner, Cole Mulvey at Bad Guys Worldwide.
Unsurprisingly, the eccentric and experienced master machinist had seen us struggling through social media and provided us with a few key pieces of advice. And in the event that those didn’t yield any results, he had the contact information for Nomis Industries, the biggest distributor of HondaRulez coil on plug boards worldwide.
As it turned out, all we needed were those few words of advice. We found the problem that night. It turned out that one of the wires in the Burton Racing COP harness had pulled out of its crimp connector under three layers of insulation. Replacing the crimp connector was all it took. The StudioVRM Prelude’s engine roared to life as we excitedly messaged everyone with the good news.
We like to think that Cole let out a sly chuckle while sitting atop his throne made of Honda D-Series Engine blocks under the Bad Guys themed flag inspired by the old Imperial Japanese banner. And that Ross, Andy, Martin, and Cessna duly celebrated a job well done from the comfort of their own homes with their favorite alcoholic beverages.
In reality, half the team was likely off at work while the other half were spending their evenings watching YouTube. Either way, we had done it. The StudioVRM Honda Prelude Si VTEC was now alive and ready to fight in the 2023 United States Touring Car Championship season.
Completing the 2023 Car
Because the new engine harness had no provisions for the factory gauges, we needed to build our own. Out came the factory gauge cluster, and in went a new custom gauge cluster that read from the car’s Hondata S300-equipped ECU.
Our tachometer, speedometer, and warning lights would now be displayed by the SDash for USB Android app, displayed on a Samsung Galaxy Tab A8 that would be bolted to the dashboard frame with a RAM mounts tablet holder. As a backup measure, we installed an oversized Autometer water temperature gauge with its sender in line with the engine’s radiator inlet hose. The mechanical oil pressure gauge and AEM Air Fuel ratio gauge remained just as they had with our previous configuration. We also replaced our temperamental Braille lithium battery with a larger but higher quality powersport battery from Shorai.
With all of these changes, a corner weighting session, and a race alignment, our Prelude was ready for battle with the following updated setup:
Max Engine Output:
194 hp @ 7700 RPM (rev limited to 7900 rpm)
Weight
2615 lbs with driver and no fuel
Spring Rates
Front - 14 kg-f/mmRear - 18 kg-f/mm
Alignment
Front |
|
Toe | 0.1 deg Toe out |
Camber | -3.75 deg |
Caster | +1 deg |
|
|
Rear |
|
Toe | 0.1 deg Toe out |
Camber | -2.75 deg |
Brakes
Raybestos ST-45 Front / ST-77 Rear
FatFour Customs Acura RL Big Brake Kit front
Stock Prelude Si VTEC calipers and rotors rear
Wheels / Tyres
17x8 +35 offset
Hankook F200 C52 Medium Compound Slicks in 235/620R17
Aero
Front splitter mounted to frame, extending 3" forward of the bumper as viewed from above
VIS Racing hood, with vent grill removed and 3/4" tall gurney installed in front of vent
4" aluminum side skirts with 4" plastic extensions to seal sides to ground
Foam-reinforced composite rear wing
How will our new VTEC powered contender fare in a fight against a field of new challengers in the 2023 season? Find out soon in Part 6 of How to Develop a Honda Prelude Racecar, coming soon.
Until then, we will see you at the track.
Disclosure:
The Bad Guys (AKA Bad Guys Worldwide) joined StudioVRM's racing arm, StudioVRM.Racing as Technical Partner in August of 2022. Neither StudioVRM nor Roger Maeda are affiliated with or sponsored by the other vendors and suppliers mentioned above.
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