What happens when you put a more powerful engine into a different set of chassis or smaller car? Sometimes magic happens and you’ve Frankenstein’d your way to a real muscle or supercar. An engine swap is the process of removing a car’s original engine and replacing it with another. This is usually done either because of failure, or to install a different engine, usually one that is bigger and better to make your car more powerful and or economical. Sometimes older engines may have a shortage of spare parts and so a modern replacement may be more easily and cheaply maintained.
Swapping to a diesel engine for improved fuel economy is a long established practice, with modern high efficiency and torque diesel engines this does not necessarily mean a reduction in performance associated with older diesel engine swaps. For the particular application of off-road vehicles the high torque at low speed of turbo diesels combined with good fuel economy makes these conversions particularly effective. Here on shoptalk we wouldn’t promote swapping you engine since it is an easy way to void your coverage but if you are a hobbyist extending the life of your car beyond 10+ years we have compiled a guide to 10 of the top 10 things people commonly forget or underestimate when doing a late-model engine swap.
10 Things to Consider Before Swapping an Engine:
Wiring is always a constant problem for people, no matter what size project they are taking on, but especially in modern engine swaps. Wiring can be very complex and it requires a lot of understanding about amperage, wire gauge, relays, and overall circuits. A perfect example is the electric fan circuit. A lot of people run two wires (power and ground), but the circuit needs to be tied into the cooling system, air conditioning system and the system needs one or two relays.
Cooling systems aren’t tricky, but many people just underestimate the volume of work that goes into it. Mechanical fans will work OK with older engines, but today’s engines run hotter and require a lot more cooling. Most people just don’t think about specific functionality of the modern engine they are installing and reinstall the mechanical fan or they hook-up a cheap electric fan that doesn’t have enough flow.
Most people know or have a good idea that the exhaust manifolds are going to need to be modified. However, it isn’t until the engine is sitting in the engine compartment that they realize how complex the issue can be and people can quickly get in over their heads. Steering linkage, spark plugs and wires can really cause some headache when fabricating a header. By the time most people have a good mental image of how the headers need to lay out, they come to the realization that the tubing is going to hit the frame or body, and have to start from scratch again—a common and costly mistake.
Oil Pans and Pick-Up Tubes
Since most chassis and cross-members are in different locations, oil pan clearances are often a problem. Luckily, with the wide variety of aftermarket oil pans out there, people usually don’t have to build custom pans and pick-up tubes. It takes a little more effort to find exactly the right fit.
Steering linkage can get tricky when trying to figure out how to navigate past the headers and around everything. In addition to that, many people upgrade their suspension and steering systems at the same time as the engine. With the wide variety of aftermarket components available, sometimes the combination of parts used can require an odd combination of steering linkage.
Late-model engines usually have mounting brackets or bosses for air conditioning compressors. While this can make it convenient, the compressors are usually mounted on the lower sections of the engine. This can create problems when trying to get an engine between the frame rails. So, mounting the compressor in a different location is often necessary. In addition to the compressor, a lot of people have problems laying out the system and figuring out where the accumulator/dryer or fixed orifices go.
One commonly overlooked modification is that in general all of the reservoirs need to be changed. The cooling system isn’t a big deal, but the power steering reservoir can be tricky. Packaging gets really tight and sometimes a remote mount reservoir is needed.
While a driveshaft doesn’t seem like a big deal, people will sometimes run into problems either measuring the driveshaft or selecting the right yoke or flange. Once in a while, we run into a problem where people don’t tell the drive shaft shop that they put a blower on the car and it has 800 hp. So, they will bend the driveshaft or kick it out the side of the car when they hammer it.
Most people know they need larger and higher-quality fuel lines and better filtration. Where they run into problems is selecting the right fuel pump. We usually recommend people try and use a factory-style in-tank pump for their daily driver,” says Meyers. “Frame-mounted high-volume pumps vibrate, run hot and usually aren’t designed for extended driving cycles. So, failure, and cabin noise can be a problem.
If the rest of the driveline is staying the same (designed for an early-model engine), sometimes getting a converter with the right flywheel pattern and transmission spline count can be tricky. There are aftermarket “hybrid” converters to solve this problem.
Most of the issues mentioned above can be solved ahead of time with extensive research and forethought for system layouts. An engineering education isn’t required but practice makes perfect and it helps for novices to seek out help from experienced professionals. Today, there is a wealth of information available online, through magazines and at car shows. Odds are, you won’t be the first person to do that particular swap. Finally, don’t be afraid to go to an expert for help when it’s needed. It will save you a lot of time, money and headaches in the long run.
So, Dr Frankenstein, what monster do you wish to make?