How the heck do you turbo your car?
One of the most popular questions we get asked is, "why do MOOG's feet smell like lollies?" I can't answer that, but I can answer the 2nd most popular question: "how the heck do I turbo my maaad car?"
For the sake of this article I'm going to keep the theories very simple. I'm really talking about a simple street car here, not something making four-digit power or being used as a race car. We will go through that later on, and I'll do another article next week on how to size a turbocharger for your car (and different KINDS of turbocharger).
Firstly, if you have a popular car, like MOOG's former BRZ, you can potentially pick up a sick turbo kit that makes everything easy - as he found out in THIS VIDEO. However, what happens when you don't have a car that has a kit available, or you want to do something individual?
Marty worked through something like this a while back (nine years ago!), with his MX-5-Miata-Roadster. He handily made a video about it, which YOU CAN WATCH HERE, stepping through how adding a turbocharger to a naturally aspirated engine relies on handling upgrades in the three key areas of any motor: air, fuel, and spark.
For the air side of things you need a way to get the air into, and out of, your engine via the turbocharger. This means you need to sort out a pre-turbo air intake, an intercooling system up to the throttle body, plus an exhaust system, and a way of mounting the turbo to the cylinder head to scavenge the spent engine gases.
Sometimes you can be lucky and find an off-the-shelf exhaust manifold, but sometimes you'll have to make one, or have it made. Basic combos can use the tried-and-true, simple log manifolds, while spicy set-ups might work best with tube spaghetti manifolds - it all depends on the engine you're turbocharging, and how hard you'll be pushing it.
Don't get too hung up on the material used in your manifolds and piping, but remember steam pipe and thick-wall steel will deal with heat and road driving vibrations much better than thin-wall tube.
One tip we'd stress is to make sure you spend decent money on quality silicon joiners and hose clamps, because popping intercooler pipes off at the track is no fun.
When it comes to fuelling, you'll need more. This often means a bigger fuel pump, larger-capacity injectors, and a rising rate fuel pressure regulator. Big-banger set-ups can also require a new fuel rail and fuel lines, or a surge tank with extra fuel pumps.
A rising-rate fuel pressure regulator is important because your fuel pressure needs to rise as the boost rates increases, because your engine needs more fuel to go with all that extra air you're ramming into it with your choo-choo spoolyboi. It's a fairly simple concept, but one that is often overlooked in the excitement of making psshhh-pssshh noises.
Spark is the next area to look at because, with more air and fuel you need to make sure you have enough zap igniting the mix of air and fuel in the combustion chamber. Some cars will be fine with what the factory equipped them with, while others will benefit from a decent upgrade to the hardware - using off-the-shelf high-quality coils like the units found on LS1 V8s, or aftermarket upgrades, can let you have stable, high-charge spark even in the face of boosted air and gushing fuel squirters.
While LS coils are infamous for being ugly in their factory location on the rocker covers, there are plenty of sweet brackets you can buy to mount them just about anywhere. You just need to be ready to make custom ignition leads to then bridge the gap to your spark plugs - you should also read up on what spark plugs your engine will need as some engines will need new-spec spark plugs to suit your turbo!
Part of this I'll consider the ECU. All engines you strap a turbo to will need to be retuned to suit the new mods, and while some ECUs can handle being retuned to suit a turbo an aftermarket ECU really works well here. Either wired in as a standalone to run the whole car, or as a "piggyback" (which lets the stock ECU run the transmission and car functions, while the aftermarket ECU controls the engine functions).
If you use a standard ECU you'll need to think about boost control. Having lots of boost will keep The Internet happy, but it's a great way to blow up your turbo and engine. All turbos have an efficiency range where it works best, and this is based off the size of the turbo and how efficient the engine is at consuming all this compressed air.
Most modern turbochargers need their bearing cartridges cooled (which allows them to spin, making your precious choo-choo) using a mixture of engine coolant and engine oil. This means you need to hook up feed and drain lines for your turbo, and this can be a little tricky as there is some science as to where you should run your oil drain.
Coolant lines are fairly simple and should be able to be spliced into the existing coolant system. We wouldn't recommend using the radiator hoses (or the radiator overflow) for this. Instead look for smaller diameter hoses, like heater hoses, which you can throw a brass T-piece into.
Ideally your oil drain will go straight down out of the turbo and into the sump (oil pan), and that means you'll need to remove the sump off the engine. This is because you'll have to get a hole drilled in it (and you'll need to clean out the leftover pieces of metal from your oil pan) and either tap a thread into it, or have a weld-in bung fitted you can then thread a fitting or hose onto.
For the oil feed you'll also need to find an oil gallery on the motor you can unplug and put a fitting in, to then run a hose into your turbo. Where you source your oil to feed into the turbo, and where you need to return the oil out of the drain to, will depend on the type of motor you're turbocharging so do some research as how others have done it in the past.
Hopefully this gives you some idea into some of the parts you'll be needing before you start dreaming about making psssh psssh noises.