How To Find Engine Rebuilding Jobs

Why Do Rotary Engines Offer Bad Mileage?

The rotary engine has a constant crankshaft, and the corresponding cylinder block revolves around it. The engine has its plus points and some drawbacks, but the low mileage offered by the rotary engine is the matter of concern.

1. The Inefficient Engines

The thing is; the rotary engines end up producing excessive power. The engines, in turn, are not built to handle the excessive power. As a matter of fact, the more power the more fuel is burnt as the revs of the vehicle get higher. This is the simplest reasons that explain why rotary engines offer a bad mileage.

2. Seal Leakages

The temperatures of each chamber of the engine house differ. This tends to be problematic when the diverse expansion coefficients of the materials lead to faulty sealing. Furthermore, a case of seal leakages occurs that results in leakages of combustion gas into the other chambers. Such wastage of gas directly means low fuel economy.

3. Low Compression Ratio

Compression ratio is the overall ratio of the maximum and the smallest volume of the cylinder at any given point within the internal combustion engine. The best compression ratio that has been recorded on a rotary engine is 11:1, which is not okay in terms of what modern engines can offer. The best compression ratio for a petrol engine is 10:1.

4. Long Combustion Chamber

The combustion chamber of a rotary engine is designed to be very long. This may work well to some extent, but the high surface area to volume ratio makes things tricky. You may ask, ”How may it affect the fuel consumption,” to which the answer lies in the extended cooling time of the fluids. If the cooling is suffered, so is the overall fuel economy.

5. The Case Of Fixed Ports

The valves or camshafts are missing in a rotary engine. This problem with the rotary engines leads to the inability of meddling with the valve timings, i.e., the case of “no valve timing.” The port time can only be changed by machining the ports of altering the piston skirt. So, when the valves do not open and close at a synchronized timing, the engine performance deteriorates. In simple words, the rotary engine fuel economy turns out to be bad.

The most common mistake made by rotary enthusiasts intent on supercharging their engines is to supercharge a stock, unmodified non-turbo engine. 

Unless you are content to use the power gain only occasionally, and even then only briefly, you run the very serious risk of catastrophic engine failure. Sustained use generally brings failure, and the more common failures include broken apex seals and flattened apex seal springs. On occasion a stationary gear breaks, or a rotor gear moves away from the rotor and jams against a side housing, or a bearing fails due to overheating. With any of these failures, a complete engine rebuild is required.

The causes of these problems, and others, are many. Superchargers generate heat loads well in excess of what a stock engine can handle: the stock water and oil cooling systems are overwhelmed and simply cannot carry away the excess heat fast enough.

Additionally, the compression ratio commonly found in non-turbo engines is not low enough for supercharger applications. Depending on horsepower requirements, a compression ratio as low as 7.5:1 may be in order for reliable operation. The higher the boost level you desire to run, the greater the likelihood you will need to address the issue of a lowered compression ratio. In our experience, we have found that 5 psi., approximately, is the threshold above which the stock, non-turbo compression ratio is no longer appropriate.

As the above comments would suggest, we do not recommend supercharging an otherwise stock, “non-turbo-based” unmodified engine. When you weigh the anticipated power gains against the very real likelihood of a premature, and costly, engine failure it’s likely not worth the headaches.

If you are willing to build an engine that is capable of handling the increased heat loads that superchargers develop, the following tips will prove beneficial, increasing the likelihood of a long-life engine.

How It Works

A rotary engine is a barrel-shaped internal combustion engine that lacks many of the major parts you’d find in a conventional piston engine. For one thing, there are no pistons chugging up and down. Rather, rounded triangular rotors—most often two, but sometimes one or three—spin around a shaft through the hollow barrel.

Fuel and air are pumped into the spaces between the rotors’ sides and interior walls of the barrel, where they ignite. The rapid expansion of exploding gases turns the rotors, thus generating power. The rotors fulfill the same task as pistons in a piston engine, but with far fewer moving parts, making a rotary engine lighter and smaller than a piston engine of equivalent displacement.

The basic design is a century-old one. Felix Wankel himself was a German engineer who came up with his version of a rotary engine in the 1920s. Being busy with warmongering on behalf of the Nazi party, however, he didn’t get the chance to develop his vision too far until 1951, when German automaker NSU invited him to design a prototype.

Wankel Engines

Try not to get caught up in the semantics of what to call this engine. Commonly referred to as a rotary engine (even by Mazda, though often this refers to a rotating piston-cylinder-based layout), the Wankel engine was last used in production in the Mazda RX-8. There are no pistons, camshafts, or connecting rods.

Advantages

  • Simplicity: rotary engines can have as few as three main moving parts, versus more than 40+ for piston-cylinder based engines. Fewer moving parts typically leads to better reliability.
  • No reciprocating mass: this allows rotary engines to rev high, and also run very smoothly.
  • Weight: rotary engines are compact and offer great power-to-weight ratios.
  • Power delivery: because of the way a rotor rotates, power delivery lasts for more of the rotation of the crankshaft versus a piston-cylinder engine, resulting in super smooth power delivery.
  • Size: rotary engines are compact, allowing for easy packaging.

Disadvantages

  • Fuel economy: the exhaust often includes unburned fuel, on top of which Wankel engines typically have low compression ratios, resulting in poor fuel efficiency.
  • Emissions: unburned hydrocarbons leaving the exhaust makes it difficult to pass emissions regulations.
  • Rotor sealing: due to the varying temperatures throughout the combustion chamber, the apex seals expand and contract making it difficult to create a good seal, leading to inefficient power production.
  • Oil burning: by design, Mazda Wankel engines burn oil to help maintain the longevity of the apex seals. Not only does this further increase exhaust emissions, but it requires the owner to add oil periodically.

Mechanical Operation

A rotary engine uses a triangular-shaped rotor to divide the space inside the engine, enabling a standard four-stroke cycle of intake, compression, ignition and exhaust. The moving rotor transports fuel to the various engine compartments for each leg of the cycle. In this way, it resembles a reciprocating piston engine. Rotary engines can be built with any number of rotors, much like the multiple number of cylinders offered in piston engines. The rotors engage a drive shaft, which then powers the vehicle’s drive mechanism (the propeller of a plane, or wheels of a car).

Simplicity

One of the major advantages of a rotary engine is its mechanical simplicity. A rotary engine contains far fewer parts than a comparable piston engine. This may decrease the cost of design and manufacture. This also leads to decreased weight. Compared to standard reciprocating piston engines, rotary engines contain no valves, camshaft, rocker arms, timing belts or flywheel. All this means decreased weight, fewer opportunities for malfunction and easier repair. When rotary engines were first developed, they were used to power aircraft, taking advantage of the rotary engine’s high power-to-weight ratio.

The Difference Between Engine Rebuilding And Overhauling An Automobile Engine

How to Tell If It’s Time for an Engine Rebuild

Most people have heard of an engine rebuild but not as many really know what a rebuilt engine really is or what is done when an engine is rebuilt. Engines are rebuilt for a variety of reasons. In this article, we will take a look at why engines are rebuilt, what is done to rebuild an engine, and some signs that your car might benefit from a rebuild.

Reasons for a Rebuild

There are two main reasons people choose to rebuild an engine: wear to engine bearings, and poorly seating piston rings. The moving parts of the engine (such and the crankshaft, rods and pistons) are mounted on bearings that allow them to move freely. These bearings are lubricated by engine oil. Bearings are built to last many thousands of miles, but they do experience wear after time. This wear is accelerated exponentially when a vehicle is poorly maintained and is run on low oil levels or the oil change schedule isn’t properly followed.

What’s Done during an Engine Rebuild

When an engine is rebuilt, a few basic things are done to restore it to good working condition. First, the “short block” or lower half of the engine is removed and sent to an automotive machine shop. At the shop it is disassembled and cleaned so that the condition of the block can be properly assessed. Depending on the condition of the internal parts of the engine, the piston rings, bearings and sometimes the pistons themselves are replaced. The internal surfaces of the cylinders are also reconditioned to ensure that the new piston rings can form a proper seal with the cylinder walls. Finally, the engine is reassembled and installed back in the vehicle. Often the cylinder head is also reconditioned at the same time.

Signs You May Need a Rebuild

There are some frequently seen signs that a rebuild may be necessary for your engine. The most common sign is oil consumption and excessive white smoke in the exhaust, especially when the engine is cold. This is normally a sign of worn piston rings. More extreme signs could be metal shavings in the engine oil (a common sign of dangerously worn bearings) and “knocking” or “chattering” from the engine bearings.

How to Evaluate Engine Rebuild Kits

Engine rebuild kits are a subject of some controversy in the automotive repair field. They are packaged and sold both by manufacturers, such as Sealed Power, and by individual parts wholesalers. The purpose of the kits is twofold. First, is to enable the buyer to obtain all needed parts at a reduced price. Second, is to force the buyer to obtain all needed parts from the same source. This means that all of the profit will go to the seller of the kit.

A Beginner’s Guide to Engine Rebuilding

At a certain time in your life, especially if you are a car guy or gal, you may find the need to rebuild an engine, and there are many reasons why you might discover this. You may want your engine to perform like, or better than, the day it rolled out from the factory or maybe you are just curious about what actually happens inside of an engine. Whatever your reasons are for tearing apart your engine you still might wonder how you should go about disassembling your engine. If you have never torn apart an engine before, or taken apart hundreds of engines, this is the guide for you. In this instructable, I will be covering my first ever engine rebuild and the steps I took to make my engine good as new. I hope that you find this instructable helpful and I hope that your engine rebuild goes well. Now let’s get started tearing apart that engine.

Research and Planning

Before you go tearing apart an engine it is very important to research and plan out the engine rebuild. There are many questions you should ask yourself before rebuilding an engine. What kind of engine do I want to rebuild? What kind of performance do I need out of the engine? How much do I have to spend on this project? How much time do I have to rebuild the engine? For my rebuild, I chose a classic American V8 engine and I just need it to perform as a stock engine. I would like to have the rebuild completed in less than six months.

Engine & Accessory Removal/Labeling System

Alright, time to get to the disassembly of the engine. If your engine is already in a car you will need to use an engine hoist to remove it from the engine bay. Then it can be placed on an engine stand. I will not cover that here because it is different for every car. I purchased my engine outside of a car locally on Craig’s List. I used a come-along puller and the trusses of my garage to hoist my engine onto an engine stand.

After securing my engine onto my engine stand I took off all of the accessories (alternator, water pump, air conditioning compressor, and power steering pump), pulleys, and the accessory brackets. I will include pictures of my accessories being removed but refer to your Haynes manual or other resources for information on how to remove your accessories.

Top End Removal (Valve Covers, Carburetor, Intake, Distributor, & Valley Pan)

It’s time to really start the disassembly of your engine. For this section of disassembly we will remove the valve covers, carburetor, intake distributor, and valley pan, so let’s get to it. Start off by removing the two or more bolts holding on your carburetor to your intake manifold. The engine I purchased did not include a carburetor, so I skipped this step. Next, I will remove the valve covers by removing the four bolts on each valve cover. I will label and bag those bolts and remove the valve covers.

HOW TO CHOOSE AN ENGINE REBUILD KIT

An engine rebuild is a large and expensive job, and choosing the right kit can seem a daunting task. There are a lot of kits for sale, and they may all seem similar but vary greatly in price. Knowing the difference between the various engine rebuild kits will help you shop with confidence, knowing you’re getting the right parts for the job at hand

THE DIFFERENCES BETWEEN IN-FRAME, OUT-OF-FRAME, AND RE-RING ENGINE REBUILD KITS

A lot of customers that call in and want to rebuild their engine simply say they need a rebuild kit. Usually, we guess that they want a standard inframe rebuild kit, as that is the most common kit sold. However, there are several levels of rebuild kits to use, based on the state of the parts in the engine and the engine’s OEM. Another important thing to note that can confuse a lot of people, is that ”overhaul kit” is often used synonymously with “rebuild kit,” but it can also specifically mean “out-of-frame kit.” To avoid confusion with the term “overhaul,” we use “rebuild” instead. Also, please keep in mind that this article contains only the general components for these engine kits. For content lists specific to the kit you need, be sure to check the product’s page on our website, or call in to ask one of our parts techs.

RE-RING ENGINE REBUILD KITS

The re-ring kit is the smallest rebuild kit. It is one of the least time consuming ways to rebuild your engine, but it assumes that your pistons are reusable. Evaluate the condition of your other engine components before choosing to order a re-ring kit.

RE-RING KIT CONTENTS

Re-ring kits generally contain cylinder liners (if used in the application), piston rings, connecting rod bearings, main bearings, thrust washers (if used in the application), a cylinder head gasket set, and an oil pan gasket set. The big thing to pay attention to is that re-ring rebuild kits do not include pistons. Sometimes, you may see kits labeled as “pistonless” or “without pistons”—those are re-ring kits. The term re-ring comes from the fact that, even though the pistons in an engine are being reused, the rings should be replaced while you’re pulling them from the cylinder. Therefore, you need to re-ring the old piston. You can see a couple examples of re-ring kits here and here to compare how exact contents differ between engines.

CHOOSING A RE-RING KIT

A re-ring kit is for people that need to refresh their engine with a rebuild, but still have pistons that are in good condition. All of the more wearable components get replaced, such as rings, bearings, and gaskets. If the pistons are still good, they do not necessarily need to be replaced. This can save a lot of money, in both parts and labor. Labor expense is saved because this type of rebuild can be done while keeping the engine in the chassis.

Engine Rebuilding or Replacement – Which Is Right for Your Car?

When engine troubles get serious, your car is down for the count. You have only two options – you can choose to have your engine rebuilt, or you can replace it completely. Which is right for your needs? Both options offer you the ability to get back on the road, but they’re not the same. Let’s take a closer look.

Rebuilding – Rebuilding an engine is exactly what it sounds like. In this instance, your old engine is pulled out of the car, and the damaged parts are replaced. Any components that are still in operating condition are not usually replaced, but are reused once more.

Replacement – Engine replacement can involve replacing your engine with one of two different options. You can choose a used engine, or a crate engine.

Used engines are exactly what you think they are. They’re taken from donor vehicles (often wrecked, but with little to no front-end damage). They’re in operational condition, but that’s usually all you know for sure.

A crate engine is basically a remanufactured engine. This is different from a rebuilt engine in that the engine is torn down completely. All components are replaced, and the housing is machined back into OEM tolerance. It’s as close to a “new” engine as you can get on the market. Even engines marked as new are really remanufactured/crate engines.

Your warranty will play a role in what type of engine you choose. Some extended warranty companies will only cover used engines or engine rebuilding, while others will cover engine replacement with a crate engine.

The most important thing is to ensure that you’re working with a reputable Weston, Florida mechanic shop that offers engine rebuilding and replacement. Not all mechanic shops offer this service, so choose your provider with care.

Tips To Successfully Buying A Used Engine

If you’re in the market for a used or rebuilt engine, it’s fair to assume that it’s because you’ve either pushed your engine to its limits and damaged it beyond repair, or want to perform an engine swap for performance gains or another reason. Regardless of your situation, buying a used engine can be a great solution, but it is also important to not get caught with a lemon, because nobody has time (or the spare money) for that. We’ve consulted with an expert in the field and come up with 12 killer tips to ensure your engine-buying process is a success.

There isn’t a universal set of rules that govern how to inspect a used engine prior to purchase, as every mechanic or shop has their own theories and methods. Our friends at Ichiban JDM—importers of Japanese engines and transmissions— have shared some pointers that will come in handy to protect yourself from purchasing a problematic used engine. Private Sellers vs. Certified Engine SuppliersWe wondered whether there is a difference between buying an engine from a private seller on the internet or Craigslist versus purchasing one from an established supplier.“Professional engine suppliers like Ichiban JDM purchase engines first-hand so we know exactly where they come from. Our parent company, based in Nagoya, Japan, logs a vehicle’s mileage, then conducts full diagnostics on the engine prior to pulling it out. Once the engine touches down at our LA headquarters, we test the engine once more to make sure it’s ready to sell,” says Chris Ankor, general manager of Ichiban JDM

“Most professional engine shops stand behind the engines they sell with a 30-day startup warranty, as opposed to buying from a private party who insists you meet at some gas station because he or she doesn’t want you to know where they live,” says Ankor.“Nine out of ten times, these guys are selling engines pulled from some wrecking yard, or cobbled together using random pieces, with full intentions of trying to flip them for an easy profit without actually knowing their true running condition.”

At one time or another we’ve all witnessed or heard about some buyer who visually inspects an engine, then pulls an impulse buy because it looks clean, but doesn’t bother to test it because they lack the proper tools. Those are the same guys that end up getting hosed with an engine that’s only good enough to be used as a coffee table.

Ankor says, “We all like to think that people are honest but that’s not always the case. When you’re buying an engine from a stranger you’ve never met before, you’re taking a risk. You don’t know if the engine is good, if it’s going to be smoking, or even healthy enough to fire up. That’s a chance that many are willing to take, but honestly, why take the gamble? The most important thing is to protect yourself and go through the process of testing an engine before making a purchase.”