HOW TO DO AN ENGINE SWAP

If you've been following the progress of Marty's Gemini project you might have seen he's got the built G-series in its home, replete with a lovely high-mounted turbocharger for glorious CHOO CHOO. While Marty's engine install was simple, we thought it was a good time to go over some basics of what to look for when changing the engine in your ride to something it never came with. 

Test, test, test fit

This is important, even if you're fitting an engine that came in your model of car but with spicy additions. You'll need to test-fit it so you can check all the tips set out below. This will require moving the engine around by hand, including tilting it fore/aft and side-to-side, and generally swinging it around in your engine bay. 

You'll want to secure the engine so it can't slip, and it is a great idea to wrap the engine in some protective coverings (like old towels). A few moving blankets on the guards and firewall will also stop any errant engines from scratching your car. Make sure the engine crane (or engine-lifting device) can roll freely and cleanly in the area, with no rubbish, tools, rocks or gravel, and away from lips/gutters/concrete joins.   

Get it low and central

It doesn't take a rocket scientist to realise you want your drivetrain weight as low as possible in the chassis, and as close to centrally-mounted as possible. If you're fitting an engine in using stock mounts this might not be possible, but if you're making your own mounts it would be a good idea to have the engine as low as possible, with it towards the middle of the wheelbase. 

Check for clearance 

You need the engine to have space to clear the under side of the bonnet, radiator (remember to allow for fans and drive accessories), but also your suspension at compression and droop, and the steering rack. When you're positioning the engine to check for clearance, it can be handy to find out if things like sumps (oil pans) come in different formats to suit front/mid/rear-hump layouts, as this may save a lot of work custom-fitting your new donk.

You will want at least 50mm of clearance around the engine to allow for it rocking under full-throttle, and to provide an air gap aorund hot parts like your headers. Sometimes the headers need to be hammered for clearance, which isn't a deal-breaker, but still not ideal.

Set the drivetrain angle

Not all engines will be the same with this, but the engine needs to sit at a particular angle in the chassis so it lines up properly with the rest of the drivetrain. The centre-line through the engine's crankshaft and transmission should be parallel with the centre-line of the pinion in the diff - they don't have to be perfectly in line (they can be above, beside or below each other).  

Most rear-drive engines will be mounted with the rear set down three-degrees while the car is set at ride height. This would leave the intake manifold level, and it is important to have the car at ride height so the angle of the chassis is taken into consideration.

Plumb it up

When you're positioning the engine you should take into account plumbing any fluid lines (fuel, intercooler, coolant/heater) as well as fitting wiring around the motor. There's no point having it millimetre-perfect in the bay if you can't fit the wiring loom behind it, or the water:air intercooler outlets hit the firewall.