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Writer's pictureRoger Maeda

How to Develop a Honda Prelude Racecar - Part 8

Photos by Sam Draiss Media and Denise Conner. Cover photo by Sam Draiss Media


Setting Up for High-Speed Tracks



The penultimate race of the 2023 season would be held at Watkins Glen, one of the fastest and most famous high-speed tracks on the East Coast. This weekend would be the toughest one yet for our Honda touring car.


Watkins Glen's Long Course layout is a full 3.45 miles, all paved with an exceptionally grippy blend of tarmac over heavily banked corners. High horsepower, low weight, and wide tyres rule the roost at The Glen. Due to the ruleset of the USTCC SP class, however, none of these things are available to us.


Instead, we made setup changes to help our existing car work as well as it could through the Glenn's banked turns and high-speed hills. In an effort to reduce rolling resistance as much as possible, we reset the front toe to 0 degrees and set the rear to 0.2 degrees of toe out. Front toe tends to have a greater impact on rolling resistance than rear toe on FWD cars, so this would net us a few extra mph down the long straights at the Glen. We took a full 1.5 degrees of angle out of our rear wing to make the flat center section level with the ground. And we lowered the front splitter slightly so it sat about 3 inches off the ground at rest, with driver and fuel.


In order to maximize our cornering speeds through the banked turns, we increased the amount of negative camber on the front wheels to the upper limit of what Hankook recommends for its F200s: 4 degrees negative camber on the Left Front and 3.8 degrees of negative camber on the Right Front.


These changes allowed our Prelude to reach a top speed of 126 mph on the entry to the Inner Loop, the bus stop chicane at the end of the back straight. It isn't quite enough to hold off the 400+hp American Sedan and 650hp Trans AM TA2 cars, but it would be enough for us to not become a rolling chicane for the higher horsepower cars in our Big Bore group.


The Price of Success - REWARDS weight



Our team had something else to contend with at this race - handicap weight. The USTCC's long-standing REWARDS weight system had been vastly simplified for the 2023 season - After two class wins, the team would receive a 100 lb weight penalty. Thanks to our class wins at Summit Point and NJMP, this meant that our minimum weight was now 2685 lbs instead of the 2585 lbs that we started the season with.


The higher minimum weight would do our 218 hp Prelude no favors. With modern racing slicks, increasing the chassis weight affects acceleration and braking performance more than cornering performance. The weight penalty would hurt our straight line speed more than anything else.



The silver lining is that the USTCC rules give us the flexibility to ballast the cars however we like. So we used the extra weight to balance out our front-heavy, left heavy 90s Honda. The featherweight Shorai Lithium Ion battery came out, and in went a 26 lb Optima Yellow Top battery in a sturdy Artec Industries mounting box. We filled the reservoir for the Cool shirt with water bottles to load up the right side and brimmed the fuel tank with 93 octane Sunoco fuel to move as much weight as we could rearwards. The resulting changes moved the left and rear weights of our cars a percentage or two closer to the ideal 50% mark, which should help the car through the Glen's tricky compound corners. 


An Explosive End to the Glen Weekend


To the team's delight, the setup changes worked. Despite the weight handicap, our green Prelude managed to stay firmly with the pack through the Saturday race. By the time we reached the checkered flag, we had managed to finish ahead of the leader in the more powerful USTCC Super Touring class. So far so good.


Sunday's Feature race on the NASCAR Short Course was a different story. A sudden mechanical issue (as well as a tap from behind) for Monza GT driver Robert Benson resulted in a chaotic Turn 1 kerfuffle that sent multiple cars diving for the runoff on the outside of Turn 1. The StudioVRM Prelude emerged unharmed, but only after giving up a handful of positions. A promising fightback ensued, only for it to be cut short when a big cloud of oil smoke escaped from the back of our Honda and the clutch gave up shortly after.



At first, we thought the failure might have been due to a rear main seal failure that coated the clutch disc in engine oil. But we soon found out that it was something much more serious. One of the metal fingers in the clutch pressure plate had broken off and had punched a huge hole in the transmission casing. The big cloud of oil smoke wasn't engine oil. It was all 2 liters of oil escaping from our racing gearbox.



Thanks to some timely help from GFAB's talented Grant Labay, we were able to replace our damaged transmission with the M2S4 gearbox from our H23 powertrain swapped in. The slightly longer gearing in this transmission would have a negative impact on our acceleration. But our old gearbox also had newer synchros which should allow for faster and more precise shifting. At minimum, it would carry us through the last round at NJ Motorsports Park. 


Staggering for Rotation



We wanted to try something different for the NJMP finale, so we pulled out one last trick out of the back of our shop - Staggered wheels and tyres. We had previously experimented with pairing our 8 inch wide front wheels with 7.5 inch rears but had yet to run them in a USTCC race. What better opportunity to try them at than at our home track?


We mounted a set of fresh Hankook F200 racing slicks on our spare wheels, opting for the narrower (and slightly cheaper) 215/615R17 size for the rear wheels. We then bolted them onto the Prelude and immediately realized that there was a problem.



The spokes on our KeiOffice KS-CE wheels were so flat that they would hit the Acura RL calipers on our FFC front brakes. We would need a set of spacers to ensure that they would clear. Because our old H&R hubcentric spacers wouldn't fit over the centering rings for the FFC brake kit, we decided to make our own. We ordered a set of forged aluminum wheel spacers and combined them with some Circuit Performance centering rings to give our wheels, spacers, and hubs a perfectly centered fit.



The budget-friendly wheel spacers worked perfectly. The extra corner-entry rotation offered by the new wheel, tyre, and spacer setup helped us get the Hankooks up to temperature through the cold autumn temperatures that awaited us at NJMP.



The new gearbox, however, posed some unique challenges at our home track. The longer 4th gear ratio meant that the 4th-5th upshift was no longer necessary on Lightning circuit's shorter main straight. It also meant that the engine would fall below the minimum RPM required for VTEC engagement through the twisty Turn 2 - Turn 5 complex. The latter necessitated an awkward downshift under cornering, which we only became comfortable with on Sunday afternoon.


Even though the awkward shift points and frigid track temperatures kept us from setting any track records, we still managed to run the fastest lap of all of the USTCC cars all weekend - a 1:16.092. In the process, Team StudioVRM.Racing became SP Class champions of the 2023 USTCC East Series.

 

The Winning Combination



Despite retaining a similar exterior, the StudioVRM.Racing Prelude has come a long way in two seasons of racing. Compare these specs now to those from when we started at the beginning of last year:


Max Engine Output:

218 hp @ 7811 rpm / 162 lb-ft of torque @ 6467 rpm (rev limited to 8200 rpm)


Weight

2625 lbs with driver


Spring Rates

Front - 14 kg-f/mmRear - 18 kg-f/mm


Alignment

Front

 

Toe

0.0 deg Toe

Camber

-4 deg LF


-3.8 deg RF

Caster

+1.5 deg

 

 

Rear

 

Toe

0.1 deg Toe out

Camber

-3.2 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 Front, 17x7.5 +35 offset Rear

  • 6mm spacers in front

  • Hankook F200:

  • 235/620R17 Front

  • 215/615R17 Rear


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 as measured from top of rocker

  • 4" flexible side skirt extensions

  • Foam-reinforced composite rear wing


Baseline Lap Times:

  • NJ Motorsports Park Lighting - 1:16.094

  • Summit Point Main Course - 1:24.534

  • Watkins Glen Long Course - 2:18.357

  • Watkins Glen NASCAR Course - 1:29.839

 

Of course, there is more speed yet to come. We plan to return to the US Touring Car Championship next season with the new suspension and aero kit we had planned for late 2023. It will be a long winter of upgrades and development work for us at StudioVRM.


After that, we'll see you at the track.

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