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Racing Secrets Revealed

Building a Honda Prelude Race Car - Part 1

by Roger

Building a Honda Prelude Race Car - Part 1

When I first started on my mission to turn a 93 Honda Prelude Si into a racecar, everyone thought I was completely off my rocker. Never mind popularity and racing heritage. For an amateur racer, building a racecar is a formulaic exercise in following the leader.
 
The sane thing to do is to establish a budget, choose a racing organization and class, then either buy an established front-running car or build a new car based on the make, model, modifications, and setup of the existing class-leader. That's why you see so many of the same car at the sharp end of most SCCA and NASA racing classes. Deviating from this formula comes at a huge expense in both time and money. And sometimes, you'll find that after hours and hours of blood, sweat, and tears, the minimum weight values, power restrictions, and regulations defined by the almighty rule makers mean that your car may be at an inherent disadvantage against the other cars in its class. It's a high dollar, high-risk investment.
 
Now that I've gone down the road of the less-than-practical and made that investment, I'd like to share the fruits of that process with all of you. This little series will walk you through all of the major steps that I took in the process of turning a street driven 4th gen Honda Prelude into a racecar.

 

Choosing a Class

 

Decisions, decisions. What class stickers will adorn the sides of your new race car?
 

The look and feel of the 4th gen (92-96) Prelude was what drew me to the car. The fact that I found a competitive racing class for it is what sealed the deal.
 
All successful racecars are built to the rules defined in its class. Class rules determine the allowed level of modification, necessary level of safety equipment, and the approximate cost of what it would take to race a specific racecar. Simply put, those rules are there to make sure that the cars are both competitive and safe. Here's are the series of questions that I asked myself when I figured out what class I wanted to run the car in:

  1. What popular SCCA and NASA classes are a 1993 Honda Prelude Si eligible to compete in?

    As it turns out, there are lots of classes where I could race a 93 Prelude Si. At the time, the list included:

    SCCA Improved Touring S
    SCCA Super Touring
    IMG Performance Index 4
    NASA Performance Touring D
    NASA Honda Challenge 1
    NASA Honda Challenge 2
    NASA Honda Challenge 3 (now defunct)

  2. Which classes allow me to do suspension and chassis modifications, while keeping the cost of engine modifications down?

    I priced out the parts and major labor costs for theoretical cars in each of the following classes, and found that they fit into my long-term budget:

    SCCA Improved Touring S
    IMG Performance Index 4
    NASA Performance Touring D
    NASA Honda Challenge 3 (now defunct)

  3. Given the wording of the rules and the car being what it is, what would be the biggest hurdle in making the car work in each class?

    SCCA Improved Touring S - Take enough weight out of the car so I could achieve the minimum competition weight of 2555 lbs

    IMG Performance Index 4 - Since the class is so new, spend lots of time and money in figuring out what makes a car competitive in the class.

    NASA Performance Touring D - Make enough power and do enough chassis modifications to offset the high minimum competition weight of 2888lbs. Or run super sticky tyres and pay the penalty points for a competition weight that is lower than the base weight.

    NASA Honda Challenge 3 - Do enough work to the engine internals so the car can produce enough power to be competitive in a field of lighter cars.

  4. Which car class has the largest race fields in the last few years?

    Of the choices above, SCCA Improved Touring S had the largest uniform field in this region. NASA Honda Challenge 3 had the smallest.

  5. If I built a car to one of these classes, could I run it in any other popular class?

    This was basically an exercise in figuring out which class had the most restrictive rules, and seeing if it could be readily adapted to fit into the rulesets of another class. Based on the four theoretical cars I priced out in step 2, I made this compatibility chart:

     Running in
    SCCA ITS
    Running in
    IMG PI-4
    Running in
    NASA PT-D
    Running in
    NASA HC3
    Built for SCCA ITSYesYesYesYes
    Built for IMG PI-4MaybeYesMaybeMaybe
    Built for NASA PTDProbably notYesYesNo
    Built for NASA HC3NoYesYesYes

    Building the car for SCCA Improved Touring S gave me maximum flexibility and options as far as where I could run the car.

SCCA Improved Touring S seemed like the clear winner. But what modifications would I need to do to make the car race ready? The rulebook is long and wordy, but the paraphrased mod list comes out quite short:
 
  • 8 point roll cage
  • Racing Seat
  • Racing Harness
  • Intake
  • Header
  • Exhaust
  • Reprogrammed ECU
  • Some very minor work on the cylinder head
  • Some very minor boring out of the cylinder walls and re-fettling of the bottom end
  • Height-adjustable coilovers without external canisters
  • Racing brake pads
  • Suspension bushings and bearings
  • Stiffer engine mounts
  • Aluminum wheels
  • R compound tyre
  • Take out as much weight as possible
That was more than enough to satisfy my appetite for mods, while keeping the overall budget in line with what I was willing to put into the car. So with that, I borrowed $2000, signed the paperwork for a used Honda Prelude Si, and the build process began.