How to build a sprint car engine? Latest Guide

This has been a busy year for our sprint car. The car has toured the country with the National Sprint Car Hall of Fame after we finished assembling it as a roller with a mock-up motor. But because the engine is the heart of a sprint car, we enlisted the expertise of Zach Woods of Speedway Motors Racing Engines.

Zach can work on any engine, but he specializes in circle track and sprint car engines. As a result, he leaped at the opportunity to create a cutting-edge 410 to power our sprint car so here is detailed information about How to build a sprint car engine? If you sit in the crowd during a 410 race, you can hear nearly 900 power output spinning at 8000 rpm lap after lap. To do this, substantial hardware and attentive assembly are required. This is a once-in-a-lifetime opportunity to see what it takes to construct a competitive, dependable 410 sprint car engine.

how to build a sprint car engine

Perhaps you’ll work for a local engine reseller that specializes in high-performance accounts. You might also enjoy working on race engines. Some of you may have a family member who is active in superior efficiency and racing, and you’d like to follow in their footsteps. If that’s the case, this post is for you, as we take a look at the sprint car motor construction market.

To begin with, the structure of sprint car engines is indeed not the same as it was 10-15 years ago when anyone could construct an engine and expect it to function properly. If you’ve never constructed a sprint car engine before, expect a steep learning curve as you spend a lot of R&D effort finding the perfect mix. Sure, you can buy a spinning assembly and assemble a sprint car motor…but so can everyone else. So, who would have the upper hand in this situation?

If you want to develop sprint internal combustion engines, you’ll need a rulebook for each association or circuit you’ll be dealing with. Keep in mind that sprint car racing is usually a considerably higher level of competition than the street stocks, bombers, or even modified ones you’ll see at many tracks, and if it’s one of the 50+ traveling organizations, the teams will all be top-notch. Drivers in sprint car racing at the highest levels are full-time professionals. Many people who race with different groups across the country are in the same boat.

Because their income is directly proportional to their finish position, these drivers and owners are constantly on the lookout for a competitive advantage – and yesterday’s technology will not suffice. On the racetrack, the winners are those who have something different (better) than their opponents. To have racers blazing a path to your door, you must offer them an advantage; you must invest time and money in research and development.

If you create an engine that constantly outperforms the competition, not only will the majority of your competitors become your clients, but you’ll also have all the work you can manage. On the racetrack, the winners are those who have something different (better) than their opponents. To have racers blazing a path to your door, you must offer them an advantage; you must invest time and money in research and development.

If you create an engine that constantly outperforms the competition, not only will the majority of your competitors become your clients, but you’ll also have all the work you can manage. Although this is not true on every occasion, practically all sprint car competitors have excellent equipment.

One explanation for this is that the engine rules have remained rather stable over the last decade or so. This permits the full-time “professionals” to trickle down to the one-night-a-week racer. The best in each organization construct new motors every year, while others compete with the same engine for numerous years.

Engine cycle:

It’s not uncommon for the World of Outlaws circuit to hold more than 100 events every year. With six motors, that works out to about 16 races per engine. During the campaign, each engine will be repaired at least once. New pistons, bearings, rings, valve springs, and gaskets are usually included in most rebuilds.

The rods and crankshaft are both magnufluxed and, if necessary, replaced. The fuel pump will be flow-checked, and the heads will be thoroughly examined. Most of the parts, including the chassis and motors, are often sold by the best racers at the end of the season. When the new season begins, they will have all new equipment.

The local racers have benefited greatly from this cycle. They can get top-of-the-line equipment for a very low price, even if it is a year old. For many Saturday night racers, that equipment will endure multiple seasons, and if they have a skilled engine builder, that engine will be kept up-to-date in most situations.

Sprinting car engine:

So, you’ve never constructed a sprint car motor before and are wondering, “Where do I begin?” ” A rulebook is the best place to start. That is exactly what it is: a start; nevertheless, you must also travel to the racecourse. Find out what the racers require or what has proven to be successful for them. Let’s take a look at how the industry’s leading engine builders approach new engine development, keeping in mind that they, too, had to start somewhere.

Famous shops got to prominence because, like any other successful business, they residential a product that generated results. All of the top builders have at least one dyno cell, and many have multiples. The dyno is mostly used for research and development, but most top builders run every engine they create on it before it leaves the shop.

The advantage of a dyno is that if you dyno each engine and keep a file of the dyno charts, you can compare engine to engine (assuming you’re only manufacturing one or two types). Some NASCAR engine teams have a rule known as the “one percent rule,” which states that each engine must dyno to within one percent of the standard for that engine.

So, on an 800 horsepower engine, that’s just 8 horsepower. You won’t need to be as precise, but you’ll get a sense of where the engines should have been on the dyno. If you dyno an engine after it’s been built and it’s not up to par, you know you’ve got an issue, and you don’t want that engine going to a customer if it’s not up to par.

The Engine Build:

The first step in building an ASCS 360 engine is to order pistons and connecting rods, then a bob weight, and then a crankshaft. The availability of crankshafts varies according to the time of year and might be as long as eight weeks.

We also order our fuel injection system at the same time because it is custom manufactured to our exact requirements and can take up to seven weeks to arrive. Changing the personal skill bore for piston wrists pin oiler jets is the first in-house manufacturing operation.

We brush the mains in our line hone after performing this change to guarantee there are no burs from the oiler alterations. The block is then torque plate honed to the necessary clearance to the piston skirts. On each block, we use our profilometer to ensure the correct piston finish for ring seal and durability.

Prior to resurfacing the block, we model up the complete rotating assembly to check for any rotating assembly clearance difficulties as well as to measure the piston deck height. The block is then surfaced to allow the piston to be positioned properly below the bore in order to achieve the optimum quench.

All oil passageways are checked for correct galley plug engagement, and numerous other places, including the mechanical fuel pump boss, are tapped for plugs. To link our injections center valley plate to our injection manifold, we drilled and tapped two 10-24 threads on the block common wall. After cleaning the block, we use Total Seal quick seat and Total Seal assembly lube to prepare the cylinders.

After the manufacturer performs rough balancing, the crankshaft balance is tested in-house. We verify our rod and main bearing clearance after balancing. 2.448 main journals and 2.00-rod journals are used in this configuration.

We check bearing clearance on every build and have a range that we deem acceptable. After that, we’ll concentrate on the cylinder heads. Every ASCS engine undergoes some special changes to help with cooling and water movement. The valve guide clearance is also checked.

We are often on the higher end of what most shops consider appropriate, but we have found that a little more space does not cause any visible issues, reducing the risk of valve stem galling. We check the concentricity of each valve job once they are completed. On recently CNC’d heads, we usually have the valve job done according to the porting company’s specifications.

We start putting up our rocker arm geometry for our valve train once the cylinder head is clean. As a starting point, we use the stand height setting tools, but the final height is dictated by the sweep pattern.

When spring pressure is low, we set up our valve train so that the majority of the sweep across the tip occurs early in the life cycle when spring level is reduced, and when intensity is increased, the rocker arm presses more straight down on the tip of the valve instead of across it. With the right geometry in place, we use clay to assess piston-to-dome clearance.

On most shelf pistons, such as the one used in this engine, we find that some material reduction is required around the spark plug location. A little section of the combustion chamber is ground to accomplish this. After we’ve confirmed dome clearance, we’ll verify piston to valve clearance. The first thing we’ll do is double-check the radial clearance.

On the intake side, we allow a minimum of.060, and on the exhaust side, we allow a minimum of.080. In terms of vertical clearance, we find that similar values are acceptable, but we can usually get a good combustion chamber capacity without running the clearance that closes.

To be at the power level we consider acceptable, these 360 Sprint Car engines require a minimum of 14.5:1 compression. They can withstand more since they are fueled by methanol, but we appear to discover a diminishing return if we go too much past this point. We’re now preparing our heads for the final assembly. On this application, we usually use a standard dual spring with a dampener.

We’ve tried a few different types and found that dampener style springs on Sprint Car engines had the longest durability and the fewest cosmetic difficulties. Custom titanium intake valves and tiny stem stainless steel exhaust valves are used in our standard package constructions. The exhausts’ weight is roughly the same as the titanium intakes thanks to the smaller stem diameter. This guarantees that the valve train can keep the exhaust section of the system under control.

We cover the retainers in cmd paste and lightly oil the valve locks before installing the springs. After putting the cylinder heads together, we measured the length of the pushrods. We order pushrods based on this length, and this is usually the last item we order before taking the engine to the dyno.

We then attach the front cover. A direct feed oil pump from the camshaft and a direct drive water pump from the crankshaft is used in most Sprint Car applications. As a result, our cover contains facilities for both pumps to be mounted.

We employ a three-stage dry sump pump in our basic kit. We’ve discovered that the two scavenge stages are sufficient for maintaining a suitable level of oil in the dry-sump tank while also lowering the overall cost of the system. We start plumbing our cooling and oiling system after installing the water pump and oil pump, as well as the oil pan.

On these builds, we employ convoluted hose and crimp-style hose ends. To be able to complete the plumbing from start to finish in-house, we have a hose crimper and store an inventory of fittings.

The IR runner manifold is one of the final elements in our project. To perform successfully on the racetrack, these are incredibly intricate elements that demand a great level of attention to detail. We employ a three-piece system with two runners bolted to the cylinder heads and a valley plate bolted in between the runners.

The butterflies and linkage are given a lot of attention once the manifold is in place. The association should be timed to open both sides uniformly, and the insects must be set to the same height on both sides. At idle, if one side of the manifold is open more than the other, the motor will make a sluggish sound because one side is over-fueled compared to the other.

In addition, if the linkage opens one side of the manifold faster than the other, that bank of the motor will accelerate or stop at a different rate. This is usually noticeable during starts and restarts since the motor will not accelerate smoothly.

When the driver lifts the throttle to proceed into the turn, flames may appear from the headers on one side of the motor or the other, indicating unevenness. Our IR system is also in charge of ensuring fuel flow to the engine, in addition to controlling the butterflies.

Constant flow injection is used in Sprint Car engines, and it relies on a metered spool known as a barrel valve to provide the correct amount of gasoline to the engine depends on the position of the butterfly in respect to the spool. A leak-down gauge is used to establish this relationship.

We’ve found that between 18 and 24 percent works well for most engines. The fuel is then delivered to the nozzles via the barrel valve, which is precision drilled to specific sizes in order to maintain fuel lbs./hr. a cylinder for each

We put a modest amount of air pressure in the crankcase and checked for leaks with soapy water after the engine was entirely assembled and before our dyno test. We’ve found that between 2 and 4 psi is more than enough to discover any problems.

We then add oil and prime the engine with an old, dry-sump pump hooked to our oil pan. We next proceed to our dyno to complete the engine. On Sprint Car engines, we always install a sight tube on the oil tank. This enables us to ensure that the scavenge sections keep the oil level in the tank at a safe level while the engine is running.

We’ve discovered that some older pumps have trouble maintaining an acceptable quantity of oil in the tank. We also use an airflow meter pressed into each runner at various throttle positions to make sure our injection side-to-side is calibrated correctly.


If you’ve learned everything you need to know about how to build a sprint car engine, go ahead and build your own and race in the market!

Frequently Asked Questions

What kind of engine does a sprint car have?

They’re usually driven by a turbocharged engine, a methanol-injected overhead valve V8 engine with a capacity of 410 cubic inches (6.7L) and a top speed of 9000 rpm.

How fast do sprint cars go dependent on the mechanical setup?

Sprint cars compete with and without a massive 25-foot top wing. Winged sprint cars generate a lot of downforces, which allows them to attain speeds of about 150 miles per hour. Non-winged racing karts have far less downward force and traction, allowing them to ‘slide’ through curves.

Why don’t sprint cars have starters?

Sprint cars lack a transmission in favor of an in-and-out gearbox with quick-change rear differentials for quick throttle response. As a result, they lack electric starters (or any electrical systems other than magneto/ignition) and must be started manually. Methanol is used in sprint cars for a variety of reasons.

Why do race car drivers enjoy it so much?

The majority of race car drivers prefer methanol or ethanol-based fuel for a simple reason. Alcohol-based fuel has a high octane rating, which improves fuel economy. Methanol burns cleaner and cooler than gasoline is less flammable, and is less expensive.

Leave a Comment