Dyno Testing the Wildcat 240RS Engine

Thanks to its 240cc and stout components, the Wildcat 240RS has immediately been a game-changing engine. What has been highly anticipated is the dyno results and how it compares to other engines previously tested. 

In the teardown video and blog about Wildcat specs, we give you a cost analysis of the individual component cost and compare the price to other brands if you had the same components to try to make those engines equal to the Wildcat 240 engine. Still, some are not convinced, or at least not without seeing the dyno results. We agree. Our work with Red Beard's Garage is about value and performance. We have added a lot of data to compare a lot of different engines.

In some cases, what we offer differs from the lowest cost or the best value. In the first Tillotson 212E vs. Wildcat 223 dyno video, the Predator 212 was the best value because the difference in power didn't outweigh the cost, even though the Wildcat had a better block and made more power and torque. The difference in cost means the Predator could get a couple of upgrades that made it more powerful than anything else tested at that level. However, the larger displacement engines offered more power over time with equal upgrades. 

In the small engine performance markets, the Wildcat 223 would have new competitors from the Predator 224(yes, the Wildcat was available about a year before the Predator) and the Ducar 224. Both are Ducar-produced and nearly identical. The Wildcat 223 was introduced because the 212cc market was over-saturated, and in Red Beard's videos, there isn't a significant difference in 212cc engines. Like the Wildcat 223, the Wildcat 240 is introduced to avoid an oversaturated market. We aimed to introduce a bigger engine that would be a big step forward in performance. 

Here are some questions we've received that we want to answer:

1. Do you offer a stock-style 240cc engine?

We don't. Stock engines will get grouped with those running the engines on power equipment outside our wheelhouse. Some people expect warranties and services we're not equipped to handle. Since we are a small engine performance company, we want to avoid selling into a market we can't support. We highly recommend the Harbor Freight Engines like the 212 or 224 because that is those engines' original intent and purpose and a setup to support that industry.

While we work to advance our brands, such as the Wildcat engines, we offer many performance parts for Predator, Tillotson, and Ducar engines. 

2. If the engine was stock, it would cost less, and it would allow better upgrades for $600

The Wildcat 240 has what we have found to be the best-selling and most commonly sold components. We tried to explain this in the previous blog. The idea is the 240 has an inherited value that is less expensive complete than it is if you bought the parts separately. For example, the Predator stock carburetor, camshaft, and flywheel have no resell value. The 265 cams, WC22, and cast aluminum flywheel can be sold, traded, or reused on milder builds. If you don't like those components or want bigger cams and carburetors, the Wildcat 240 parts can help offset the cost. In other words, your 28mm carb, 308 camshaft, and billet flywheel cost less. Remember, if you bought these parts at retail, the Wildcat 240 should cost over $800. We will eventually have kits and components if you want to build a custom 240 engine. 

Another reason for selling upgraded engines is the demand for built engines. We are not set up to handle one-off custom engines, but the Wildcat 240 closes the performance gap from engines costing a lot more for a fraction of the price. A larger displacement engine makes it much easier to produce power without compromising durability. Smaller engines have to turn more rpms and have more radical setups to make the same horsepower, but they may still not make as much torque.

Now, let's cover the reason you're here: horsepower. Again, cost is relative to performance, so we'll compare the Wildcat 240RS to other builds on Red Beard's Channel and other engines on the market.

Cost and Performance

A big concern for most is the cost of any engine or product and the performance gains. You can look at it like this: Performance / Price = Value. The Wildcat 240RS was built to offer the best value of any turnkey engine on the market, including stock or built engines. To illustrate, we compare many different engines that racers and builders consider for their mini bikes and racing go-karts. 

Wildcat 240RS- Out of the box, the Wildcat 240RS is one of the most powerful engines tested at stage 3, but the power increases tremendously with each modification. Horsepower 14.82/Torque 13.4

Wildcat 240RS with non-rev limited coil and billet rod - In our initial testing, just adding the non-rev limited coil picked up the power and torque of the engine. Still, there was no sign of improvement on Red Beard's dyno other than increased rpms where the engine turned over 7500rpms. Horsepower 14.72/Torque 13.5

Wildcat 240RS Stage 1(Coil, Billet Rod & Flywheel) – The billet flywheel moves ignition timing from 18-20° to 34° to help raise cylinder pressure. The high-strength neo-magnet improves spark energy, and the low-fin design helps to reduce drag. All of those improvements made substantial gains in performance. Not only did torque improve significantly, but it also peaked 400 rpm sooner. Horspower 15.46(.64hp gain) & Torque 14.78(1.38ft-lb gain). At this level, the Wildcat 240 makes more torque than most engines make in horsepower with similar components! 

Wildcat 240RS Stage 1 w/Porting – Porting is always a significant gain for any engine, and with the bigger valves of the WC946 cylinder head, you have a great starting foundation. The gains are incredible, considering this engine only has .265 lift, stock push rods, and 26lbs springs. 17.24hp (1.78hp over stage 1 & 2.42 over stock) 14.96ft-lbs (.18 over stage 1 & 1.56 over stock) Ignition timing has its most significant impact on torque where carburetor tuning and airflow increases horsepower as many of the stage 3 kits and similar components peak torque and peak power occur around the same rpms. The larger the engine's displacement, the sooner the power is made. 

Briggs LO206 & World Formula —Briggs has been the cornerstone of 4-cycle karting, and their two latest most popular engines are the LO206 and the World Formula. The Briggs are spec-class engines, and while the Animal is still used for modified engines, the clones are often less expensive and arguably make more power. 

Briggs LO206 – The LO206 is around the same price but slightly more expensive than the Wildcat 240RS. Most would be satisfied with the cost vs. price of the LO206 and why we wanted to compare them. The LO206 is only 8.8hp & 10ft-lbs of torque, according to Briggs. The bore is smaller at 2.6875(68.26mm) but more stroke at 2.6885(68.29mm). It has an 8.5:1 compression ratio with 29° ignition timing and a 255 lift cam with less duration than our Banzai 265 cam. The stock Wildcat 240RS makes more than 65% horsepower & 34% more torque. We haven't tested the LO206 on Red Beard's dyno, but even if we divided the gain in half, it's a massive difference in performance for an engine that costs less. 

Briggs World Formula – The World Formula will be much closer in performance but costs twice as much, around $1,150. The World Formula has an improved cylinder head, the same size and style as a 26mm carburetor, a .308 lift cam, and a dual valve spring that makes 11.5hp and 13ftlbs. The Wildcat 240RS makes more than 25% more horsepower and about .5ft-lb more torque than stock. Again, if we can cut the difference in half, the Wildcat 240RS will still make more power. If we compare our stage 1 kit to allow rpms similar to the World Formula, the difference in power is even greater. 

Red Beard's Predator 212/223—The Predator 212 is the most commonly built small engine, and for good reason: its low cost and accessibility. Most of the build's components were sold by GPS when Red Beard was working for them. His Predator 212 has had more incremental upgrades than any other build and the channel, giving the best insight into how upgrades affect an engine. 

Predator 212 with 265 Cam, 26lbs Springs, TM24 Carburetor, thin head gasket Billet Flywheel, and Billet Rod – This combination is the closest to our stage 3 kit and the Wildcat 240RS engine. The more considerable difference is the TM24 carburetor vs the Knock-Off VM22 or our WC22 carburetors. Flat slides generally make a little more power than a round slide, as tested by Red Beard, but it comes at an additional cost. As you can see in the graph, this component, even with 1.2 ratio rockers(.318 lift), is not enough to make more power or torque than the Wildcat 240RS stock. Porting the head would help it make more horsepower but not as much torque. This Predator 212 built costs around $640 vs the $600 of the Wildcat 240RS stock. The Stage 1 kit would make the Wildcat more expensive, but the Wildcat 240RS would produce more torque than the Predator could produce in horsepower unless the head was ported. The difference in power only increases if the Wildcat's head is also ported. 

Predator 212 with 308 Cam with 1.2 ratio rocker, 40lbs Dual Springs, TM24 Carburetor, thin head gasket, Billet Flywheel, and Billet Rod – The cost of this build is now over $900 with the bigger cam, dual springs, chromoly push rods and ratio rockers. Not to mention the labor to cut spring pockets and set up the springs. The Predator 212 makes 18.03hp at 7900rpms, so you really have to turn this engine to make power, but it only made 13.58ft-lbs at 5500 rpms, which is about the same torque at the same rpms as a stock Wildcat 240RS. In comparison, the Wildcat made 17.24hp at 6600rpms, more than the Predator 212 at that rpm, but the Wildcat made .79 less hp. The ported Stage 1 Wildcat made 14.96ft-lbs, 1.38ft-lbs more than the 212, and occurs 300rpms sooner. If we average the peak numbers hp+tq/2, the Predator 212 is 15.80, and the Wildcat Stage 1 with a ported head is 16.1

Predator 223: It has the same specs as the built 212 but now uses the EC Stroker Kit. The only change to the Predator 212 is adding our stroker kit to increase its displacement, stroke, and compression. As we said earlier, the added stroke/displacement and compression improve torque more than power in all these tests. The build cost is over $1100, and a reasonable amount of labor is involved, which involves clearance-ing the camshaft and crankshaft. The Predator 223 made 14.38ft torque at 5200rpms, around the same rpms as the 240, but the 240 stage 1 without porting still makes more torque and even more when ported. Horsepower didn't change much at 18.18hp, but it was made 900rpms sooner, showing the engine is much better through the mid-range. Again, if we average the peak power numbers, the Wildcat is 16.1, and the Predator 223 is 16.28. Using the Predator engine costs over $300 more for a similar performance. That extra $300 could be spent to upgrade the Wildcat 240RS further. 

Predator 224 Built– The Predator 224 became the direct competitor to our Wildcat 223 with the same bore and stroke but the main differences being the block, cam, head, and piston. Like the Predator 212, most of the build was parts sold by GPS, which includes ARC Racing and Dyno Cams. Like the Predator 212 series, there are more incremental upgrades. The engine overall is very similar to the Predator 212/223 build except for the Gage 1.2 Roller Rockers, which requires a billet valve cover and a stage 4 milled 28.5/25mm ported non-hemi head hat claims to boost compression to 12.5:1. The engine cost is around $1350 not including the billet side cover he used. The engine made 15.01ft-lbs which is only .05ft-lbs more than the Wildcat Stage 1 ported, but the Wildcat made it 300rpms sooner and made 18.75hp, which is 1.51hp more than the Wildcat 240RS Stage 1 ported. It took about $700 more for a Predator 224 to make 1.5hp more than the Wildcat. The price difference could be a billet head!

Wildcat 223 Stage 3 – The Wildcat 223 Stage 3 has arguably been the best bang for your buck, and some believe it should still be a better value than Wildcat 240RS. For the 223 engine and stage 3 kits, you are around $600, and If you swap the head for our WC946 along with the rocker assemblies, push rods, valve cover, and gasket, it's about $200, which means it's the exact cost as the Wildcat 240RS Stage 1. The Stage 3 Wildcat 223 Hemi made 13.38hp and 13.09ft-lb, and the Wildcat 240 makes 1.34hp and .31ft-lbs more stock. The ported Wildcat 223 Stage 3 made 15.48hp and 13.57ft-lbs, the Stage 1 Wildcat 240 makes .02hp less(margin of error) but made 1.21ft-lb more torque 300rpms sooner. So, if you can't port your head, the Wildcat 240RS stage 1 makes the same power and more torque. The Wildcat 240 makes 1.39ft-lbs more torque and 1.76 more horsepower if you can port.

Super Ghost 223 – The Super Ghost was a good engine except for the cost. The Tillotson 212E and Ducar 212 would be slightly less expensive but still much more due to the cost of stroking these engines to 223cc and the stainless steel valves. The overall cost is around $930. The Super Ghost made less horsepower than a stock Wildcat 240 and .55ft-lbs less torque. When the Ghost is ported, the engine produces more than .85hp than the Stage 1 Wildcat or .93hp less when compared to the ported 240. The Super Ghost makes 13.64ft-lbs, similar to a stock Wildcat 240, but it's still 1.14ft-lbs less than stage 1, which happens 600rpms sooner. 

Tillotson 225R—The Tillotson 225R produced less power than the regular Tillotson 225RS and less than most of the stage 3 engines. It's a clear difference: The stock Wildcat 240RS produces 1.2hp and .5ft-lbs more torque than the Tillotson 225R, and for around the same cost, the stage 1 produces 1.84hp and 1.9ft-lbs more torque. 

Tillotson 228R MKII – The 228R MKII has the same head as the Wildcat 240RS. The only significant difference is the stroke, which increases displacement and compression. The Tillotson 225/228/236 has a better piston design and longer rods, so there are still benefits to those engines. The Tillotson 228R made 14.82hp and 13.51ft-lbs. The engines make the same power, but the Wildcat made peak power 500rpms sooner. If we compare the performance to stage 1, making the engines around the same price, the Wildcat 240RS makes .62hp and 1.27ft-lbs more for roughly the same price. We haven't tested a ported version of the 228R yet. 

Tillotson 225R, Moflow 32/25 Billet Head, .356 cam w/1.3 ratio rockers, and 28mm slide carburetor—This is the most powerful small block engine tested by Red Beard's Garage, and it is essential to have a fully built engine with a billet cylinder head. However, a build like this will cost around $2000 or possibly more. Not only is the cost more than two stage 1 Wildcat 240RS, but the specs are much greater.

Camshaft: .265 lift vs .356 w/1.3 ratio .462

Head: 31/25 cast head vs 32/25 billet head

Carburetor: 26mm round slide vs 28mm flat slide

However, the fully built 225 made only .5ft-lbs more torque than the ported Wildcat 240, but the Wildcat made its peak torque 2000rpms sooner. That means the 240 would arguably have better acceleration and more speed until around 6500rpm. When the Wildcat makes its peak power, the Tillotson 225 will keep pulling. The Tillotson made 21.23hp but was having issues turning more than 7200rpms. Even though Tillotson made 4hp more, it's hard to argue it would be faster unless it can turn more rpms. The Wildcat 240 can turn 1000rpms more, which makes a good point.

Applying Horsepower: The real-world use of engine power.

Firstly, an engine only makes torque. Horsepower is a calculation of how much torque is relative to the work performed by a cart-horse. James Watt invented horsepower as a relative marketing term to compare steam engines to horses so farmers could understand the work that their engines could accomplish. That calculation is torque x rpm / 5252(mathematical constant) = horsepower. In many ways, looking only at the torque and rpms can simplify engine comparisons and performance.

When horsepower or torque is applied on your mini bike or go-kart, that power is transferred by either a centrifugal clutch or torque converter/continuous variable transmission(CVT). Between the clutch or torque converter and rear axles is a set of gears that make up your gear ratio. In the case of the torque converter or CVT, you also have a pull system that changes the ratio as the load and rpm change. The ratio changes the mechanical leverage between the engine and the axle. In other words, if your engine makes 10ft-lbs of torque, that torque is manipulated and increases by this ratio. Red Beard usually uses a 6:1 ratio with his torque converter setups. That means the driver or front gear/sprocket turns 6 times for every 1 rotation of the axle gear. To simplify, we can multiply the torque by the ratio, 10ft-lbs x 6, which is 60-ft-lbs, to the axle. You can use any of the peak numbers on the charts to figure out the power each engine makes to the axle. We're going to use just a few to see how much difference when the engines are used in their applications.

Predator 212 1.2 ratio rockers, 265 cam, TM24 Ported Head 13.09ft-lbs x 6 = 78.54

Wildcat 223 Stage 3 Ported Head 13.57ft-lbs x 6 = 81.42

Tillotson 225R with Billet Head 15.5ft-lbs x 6 = 93

Wildcat 240 Stage 1 Ported Head 14.96ft-lbs x 6 = 89.76

The Predator 212 vs. Wildcat 223 have about a .5ft-lbs difference, as does the Tillotson 225R vs. Wildcat 240. That difference begins to grow due to the ratio. From the Predator 212 and the Tillotson 225R, there is only a 2.41ft-lbs difference at the engine but 14.46ft-lbs when used in practice on a mini bike or go-kart. 

We were going to use another ratio that would be closer to the one used in the Briggs LO206, like a 3.7:1 

Predator 212 1.2 ratio rockers, 265 cam, TM24 Ported Head 13.09ft-lbs x 3.7 = 48.43

Wildcat 223 Stage 3 Ported Head 13.57ft-lbs x 3.7 = 50.20

Tillotson 225R with Billet Head 15.5ft-lbs x 3.7 = 57.35

Wildcat 240 Stage 1 Ported Head 14.96ft-lbs x 3.7 = 55.35

The smaller the ratio, the less difference there is between each engine. The Predator and Wildcat is now only 1.77, and the Tillotson and Wildcat 240 is 2ft-lbs. Between the Predator and Tilloson, there is 8.92, which is still a lot but much closer. Gear ratio plays a massive role in real-world performance. That is why CVT or torque converters are so useful. The variable ratio gives you either a higher ratio for acceleration or a lower ratio for more top-end simultaneously. A torque converter is the best way to improve performance for most mild builds. 

Here's another concept to consider: the power-to-weight ratio. Power is made and manipulated to move weight or a load. For example, kart classes have minimum weight restrictions to create a level playing field. 360 lbs is a normal kart class weight and similar to a Coleman mini bike and a 200 lb rider. 

If we looked at the engines straight from their torque values, it would look like this:

Predator 212: 360 / 13.09 = 27.5lbs per 1ft-lbs 

Wildcat 223: 360 / 13.57 = 26.53 per 1ft-lbs 

Tillotson 225R: 360 / 15.5 = 23.23 per 1ft-lbs 

Wildcat 240: 360 / 14.96 = 24.06 per 1ft-lbs 

If we look at a 6:1 Ratio

Predator 212: 360 / 78.54 = 4.58lbs per 1ft-lbs 

Wildcat 223: 360 / 81.42 = 4.42lbs per 1ft-lbs 

Tillotson 225R: 360 / 93 = 3.87lbs per 1ft-lbs 

Wildcat 240: 360 / 89.76 = 4.01lbs per 1ft-lbs 

As you can see more evidence, the difference in gear ratio and torque can make. 

We are showing only one aspect that helps to show the difference engine power can make. However, we must consider rpms and the entire power curve, which is impacted by the gear ratio—the bigger and broader the power, the better the performance. 

We will examine the differences between the Wildcat 240RS and the Billet Head Tillotson.

Tillotson 225R with Billet Head 15.5ft-lbs/21.23hp max 7200rpms

Wildcat 240RS Stage 1 Ported 14.96ft-lbs/17.24hp max 8500rpms

The Tillotson should be able to turn more rpms and make more power, but there seems to be a tuning problem or possible valve float. Regardless, the engine can only turn about 7200 rpms. We're going to use this as an illustration of engine power vs. rpm. 

Using our gear ratio calculator, we are using a 6:1 ratio and 19in(59.56 circumference) tires.

Tillotson 225R at 7200rpms with a 6:1 ratio will have a theoretical max mph of 67.83mph.

Wildcat 240 at 8500rpms with a 6:1 ratio will have a theoretical max mph of 80.07

That's a 12.24mph difference. You still need to overcome parasitic losses and wind resistance to reach maximum speed. 

The Tillotson 225 makes 93 ft-lbs to the axle with the 6:1 ratio. For the Wildcat to make 93 ft-lbs, you need a 6.22:1 ratio, but we will round up to 6.3:1, which makes 94.24 ft-lbs, which is 1.24 more than the Tillotson. The Wildcat 240, with a 6.3:1 ratio at 8500rpms, will have a theoretical max mph of 76.26mph. That means the Wildcat will have more torque and 8.43mph more top end. 

Another way we can look at this is the difference in peak power. We are going to figure peak power at peak rpms. The Wildcat, in this case, made its peak power sooner than the Tillotson 225, but we will see what it takes for the Wildcat to make the same torque at 6600rpms as the Tillotson at 7200rpms

Tillotson 225R: 21.23hp x 5252 / 7200rpms = 15.4ft-lb x 6:1 ratio = 92.4

Wildcat 240: 17.24hp x 5252 /6600rpms = 13.72ft-lbs x 6:1 Rratio = 82.32

For the Wildcat to make 92.4ft-lbs at 6600rpms, it would need a 6.73 ratio to equal 92.33ft-lbs. To get an easy ratio, we will bump it to 6.8, a 10-tooth to 68-tooth gear, which is 93.3ft-lbs at 6600rpms. A 6.8:1 ratio at 8500rpms and 19in tire is 70.65, which is still 2.82mph faster than the Tillotson 225. Here's another interesting point: peak torque for the Wildcat is 14.96ft-lbs, but with a 6.8:1 ratio, it's 101.73ft-bs or 8.3ft-lb more than the Tillotson 225 with a 6:1 ratio. 

The Wildcat 240 Stage 1, with a ported head and the right gear ratio, can out-accelerate and reach a higher mph than the Tillotson 225RS because it can turn more than 7200 rpms. 

Lastly, if we look at the differences in the powerband, the Wildcat will achieve its peak numbers sooner. Again, the gear ratio affects the entire power band, which means the Wildcat is accelerating harder sooner. 

Here are answers to some follow-up questions and assessments

What if you are expecting more power from these engines?

One thing we're on a mission to correct is the falsely inflated numbers advertised online. Red Beard has stated that dynos are sold with about 40% inflation, which is how these engines are advertised. It's why the Tillotson 212E was advertised as a 10hp engine when it was only 7hp on Red Beard's dyno. You can take any of the numbers from these charts and multiply them by 1.4, and it will be closer to the advertised numbers.

For example, here are the Wildcat 240RS numbers inflated by 40%

Stock - 13.4hp x 1.4 = 18.76hp

Stage 1 - 15.46hp x 1.4 = 21.64hp

Stage 1 w/Porting - 17.24hp x 1.4 = 24.14hp

To some, this makes sense: If a Tillotson 225R is 17hp, a 240cc engine with a similar cam and carburetor and a bigger valve head would make 18.76hp out of the box. The difference is the 240cc goes from doubling the power of a stock Predator 212 to nearly tripling it due to inflated dyno numbers. As we pointed out, power is being multiplied to the axle with our gear ratios, and with the inflation, that difference is more exponential. We have the most data using Red Beard's dyno to compare engine performance, whereas others lack that data and context. 

Can you make the same power as the 240RS with another engine?

Making the same horsepower is doable but usually costs more and requires porting. However, making the same torque is more complex, especially at the same low speed. The Predator 224, which costs about $1300 or upgrades, or a Tillotson 225R with a build cost of around $2000 can make the same torque numbers. It only shows the potential the Wildcat 240RS has with the same modifications. 

How do EC's stage 3 kits perform?

As much as these tests compare engines, they teach us how the combination of parts works and makes power in an engine. In all the tests of different engines, many core components are the same: Billet flywheel with 32-34° timing, 265 lift cam, and a 24mm flat slide or 26mm round slide carburetor. We find that the engine's peak torque is typically around 5500rpms or between 5100-5700; compression ratio, stroke/displacement, and ignition timing impact how much power is made in that range. Peak power is around 6500rpms between 5800-6700, and most of it is decided by the engine's displacement, carburetor tuning, and airflow. Bigger engines have more volume, which lowers where the engine is most efficient, and airflow changes where that particular engine is efficient. Our conclusions are general terms as there are other contributing factors, but they help to give an idea. Regardless of which engine you choose, you'll know where your engine should be making power, which helps determine your clutch engagement and where to set your gear ratio. 

What is holding back the Wildcat 240, and how can I get it to make more power?

Beyond the Stage 1 kit, a flat slide like our PWK24 will pick up the power slightly over the WC22. It should be good for about .300-.350 on a ported head. Anymore valve lift, then you'll want a PWK28. However, the next jump will come from a camshaft and valve train upgrade. We built the Wildcat 240 with components like the WC946 because the valvetrain is the common limitation with any cylinder head or engine. A big valve head offers more flow potential than a small one, and once you start using camshafts that require dual valve springs, a lot more work is involved. Since most don't have the means to do this work successfully, we did as much as possible to make power and torque with 26lbs springs and stock valves train. While some cams can be used to upgrade the engine with 26lbs springs, it may not be as significant as we would like. 

You must cut spring pockets to fully upgrade the Wildcat 240 beyond a stage 1 and a ported head. We also recommend using billet ratio rockers and chromoly push rods. The valves in the Wildcat 240 are stock length, which limits how much lift they can support without running into coil bind. So you may need to use longer valves, but we only have a 32mm longer valve at this time, so you will have to recut the intake valve seat.

Here's what it will cost to modify the head for the engines to support more upgrades

Chromoly Push Rods $25

Dual valve Springs $25

Titanium Retainers for Dual Springs $30

Longer Valves $50

Rocker Arms $200

Bigger Camshaft $100

Total: $430, not including labor. 

We are working on kits with the labor and setup ready for installation later this year.