Street Rod / Hot Rod

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Street Rod

The street rod is a production-based vehicle that is stylized and modified to increase performance. While not originally designed for sanctioned racing, the street rod was one of the original types of drag race car. Street rod owners vied for victory and glory in informal races on rural roads and city streets.

Street Rods can be characterized as production vehicles modified with artistic body alterations and performance enhancing parts. Most vehicles which have their performance increased ("Hopped up") are modified to drag race (Drive as fast as possible in a straight line).

Street Rods can have many artistic alterations, some of which include changing body panel shapes, chopping (or lowering) the rooflines, and lowering the ride height. Paint jobs that turn the vehicles into unique rolling works of art are also popular. Builders may also chrome plate components to provide a mirror like shine, and replace painted engine parts with chromed parts.

Street Rods are built and driven worldwide.

Power and Weight Stats
Horsepower (Typical Range) 125-700
Race Weight (Typical Range) 1135-1816 kg
2500-4000 lb

Design and Construction

Race Car Models of This Type

Street Rods usually start life as a collectible vehicle. Vintage (1920s-1950s), Muscle (1960s-1970s) and modern performance cars (1980s and beyond) are the base vehicles usually used.

Build Your Own Street Rod

Knowledge Level

Depending on whether your street rod goals include performance, the level of knowledge required will vary.

To restore a vintage vehicle and change its styling will require knowledge of bodywork fabrication, restoration techniques, interior upholstery techniques, and vehicle paints among others.

To modify the chassis, driveline or suspension will require design knowledge in these areas. Suspension changes are especially critical to your vehicles handling and should be well understood and well designed. If the goal is to race the car, then additional safety elements (Roll bar, roll structure) may be potentially required.

It can be useful when designing your street rod to have a working knowledge in handling, chassis, suspension, powertrain, aerodynamics and safety. These six areas of knowledge will help you to understand the customization possibilities for your project. If a particular customization is of special interest, you can learn more advanced knowledge in the areas that apply.

Design Challenges

Weight Distribution: If modifying your car for drag racing, weight transfer to the driving tires upon launch will provide the highest level of grip. The greater the weight transferred the better. However, the front tires must continue to provide steering capability. If the vehicle has a high center of gravity (CG) and light front-end, the acceleration may create enough rotational force to actually lift the front end and flip the vehicle. In that case, wheelie bars should be considered.

Suspension: If lowering your vehicle, the suspension geometry should be considered. For double-wishbone or unequal length a-arm types, the camber change created by lowering can be reduced. For Macpherson strut types, the camber change may be too negative to provide a proper contact patch from the tire.

If modifying your car for drag racing, there are some suspension components that may need to be considered. On vehicles with leaf-springs, traction bars are a useful add-on as the help prevent wind-up of the springs, and damage to U-joints.

On other types of suspensions, minimizing or eliminating tire hop/chatter when launching is vital, as the second the tire leaves the road, the forward acceleration stops. The widest tread width/largest diameter tire will give the best acceleration where the rubber compound is the same.

Chassis: Retaining chassis integrity is important. Cutting or bending structural components of the chassis may structurally weaken it leading to failure.

Powertrain: If you are interested in performance or drag racing modifications, then depending on the drive configuration and class regulations, consideration should be given to the powertrain to increase power, maximize its delivery to the tires, and optimize weight distribution.

Increasing power: Forced induction (Super/turbochargers), freer flowing intake/exhaust, removal of parasitic accessories (ie. air conditioning).

Gearing: Gearing for the engines power band will use the power the engine produces in the most efficient way.

Limited slip differentials: Putting power down to both wheels to aid traction

Drivetrain weight distribution: Moving heavy items like batteries toward the rear of a rear wheel drive drag vehicle will aid traction.

Aerodynamic: If there is an expectation of high speed cornering or dragster-type racing, the some consideration may be given to downforce, but even if not, aerodynamic components can also be used as styling components as well. Air dams, side skirts and rear fairings can add to an aggressive racing look.

Safety: Providing a substantial crash/rollover safety cell for the driver is usually a requirement where speeds and risk exceed the limits of the production car's structure. A racing seat and racing harness are also usually mandatory at that point for racing anyway. If a vehicle is to be upgraded further for drag racing use, a roll structure, racing seat and racing harness should be a first priority as it provides confidence to the driver as well. Consideration in higher power drag classes should be given to fuel safety cells and fire protection.

If you intend to race under a sanctioning body, always read and understand the regulations of your chosen racing class before designing or building any race vehicle.

Design Resources

Learn the basics about race cars and race car design from our free online knowledge series

Download our free race car design aids to assist you designing your race vehicle.

In-depth books and learning resources we recommend for street rod design.

Join our forum to ask and find answers to your street rod design/construction questions.

Construction Challenges

Having sufficient space for making modifications and fabricating custom components is important, as a cramped workshop can be difficult to work in.

Depending on the level of restoration and customization from stock production, the tool selection required to modify the car will grow.

Many customized components can be farmed out to speed shops or fabrication shops, but if you are interested in learning the skills yourself, the same money can be spent on equipment and teaching yourself.

By doing the work yourself, you not only have complete artistic and design control but you also build and gain confidence in your mechanical abilities. That's where the true sense of satisfaction and accomplishment comes from in building your own car.

Build Costs

Building a street rod vehicle can be a progressive project with the budget spread over time. Costs will depend on how much labour you provide yourself and the level of performance hop-up you intend to make.

By keeping the powertrain largely stock, but dressed up, and focusing your budget on the chassis/suspension customization, you can reduce the overall cost and have a very good looking car.

Street rod parts are widely available through aftermarket retailers so most go-fast components can be purchased off-the-shelf. These parts reduce the cost of the overall machine when compared to fabricating your own, but will still add up over time.

Build Effort

The effort required to build a street rod depends on the initial state of the donor car and the extent of chassis, suspension and powertrain changes. Restoration work can account for a large part of a street rod build if the donor vehicle is heavily rusted or not running.

If you want to race in sanctioned drag racing then the requirements of regulations also come into play.

Racing Cost

If you do go drag racing, the consumable costs will likely be on par with entry-level drag racing—Tires probably form the single largest consumable expense. Engine rebuilds will not be frequent unless drag racing is a regular activity for you and your street rod.

Transportation and Support Equipment

Vehicle is driven, but may require a support vehicle to transport equipment to a drag strip.

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