How to avoid blowing up your car after you turbocharge it
Congratulations, Chachi! You've read through THIS STORY and have now successfully strapped Spooly McBoostington to the exhaust ports of your naturally aspirated engine. You're ready to choo-choo your mad machine all over the street but, how do you avoid accidentally sending Rodney into a low orbit while driving over your own crankshaft?
While there is a fair bit of science to making your turbocharged Chachi-mobile live, it ultimately this comes down to cylinder pressure, heat management and maintenance.Tuners will try to manage cylinder pressure and temperature around your set-up, but you need to make sure you have all the hardware on your car to give the tuner the best shot at giving you a good result.
First up, let's look at cylinder pressures. Withi this I'm saying that trying to force too much boost into a cylinder never designed for it can do catastrophic damage, Chachi.
Boost is maaad, but too much boost can squeeze your cylinders into oval shapes, push your conrols into S-bends, and send your piston rings into your oil pan. Our favourite turbo engines tend to have thick-walled iron blocks to prevent the cylinders and blocks from deforming, wihile heavy forged internals with upgraded fastening hardware (con rod bolts, six-bolt mains over two-bolt, etc) resist the strain of high cylinder pressures from boost - and many NA engines simply aren't equipped with this hardware from the factory.
This is why we have boost controllers and boost gauges, mates.
Our mates at GFB have been making both electronic (below) and manual (above) boost controllers for donkey's years (that's a long time, Chachi). A manual controller (also known as a "bleed valve", or "boost tee") is a very cheap and super-simple plug in way to run more boost than stock, but not a reckless amount.
You simply plug the bleed valve into the vacuum line for the wastegate actuator, and it intercepts the air trying to open the wastegate, bleeding off air to keep the wastegate shut a little longer and bring boost levels higher. However, you really need to keep a close eye on your boost gauge to make sure you're not over-boosting the engine, particularly in cold weather when the air is more dense and you're more likely to see boost spikes.
An electronic boost controller (like the above) is a more expensive way to control your boost but it is also going to do a far better job of it. These brain boxes aren't required with most modern aftermarket ECUs but for you Chachis running a factory ECU this is a way to completely remap your turbo's performance - this includes the rate at which boost is brought into the motor.
Jamming too much boost too quickly into an engine that wasn't designed for it places incredible stress on all the internal components. Ramping in your boost as a gradual curve reduces that strain but still gives you the thrill of mad boosty choo-choo performance.
While too much boost can be bad, not paying attention to the temperature of the air entering the engine or the cylinder temperatures can also kill an engine in two shakes of a lamb's tail... this is wny intercooling and fuelling is very, very important.
The science says that when you compress air with Spooly McBoostington (known as "charge air") it heats it up as all those molecules of atmosphere being jammed together creates heat. This is why intercoolers are a beaut idea as they cool that charge air and get it to the best density possible, and cool, dense air is ultimately what you want when making power.
Broadly speaking, the standard air-to-air intercooler is going to be the cheapest to set-up and will work great when there is plenty of airflow through the intercooler core. Packaging these intercoolers can sometimes be an issue, as is going too large with your piping (which can cause boost lag).
You can also look at water-to-air intercooling, which involves using coolant in a radiator-style core to pull heat from the charge air. The coolant is circulated by a water pump through a front-mounted heat-exchanger, knocking the liquid's temperature down, before running back through the core to chill the intake charge. Obviously this is a more complex and expensive system to set-up, but can work exceptionally well when sized correctly.
Finally, "liquid intercooling" is a fancy term for alcohol or methanol injection. Basically you mist air-cooling methanol into the air intake, using a microswitch on the throttle (activating when you go foot-to-the-floor), or setting it up in your ECU when it sees a particular throttle or boost figure. This requires manually filling a whole separate fuel system to ensure you've always got the boost-friendly topping ready to go.
Speaking of alcohol fuels, this brings us to the wonders of E85 and where your fuel system comes in...
As you add more air to your Chachi-mobile's engine (thanks to Spooly McBoostington, your loyal and faithful turbocharger) you need to also increase the amount of fuel so the air and fuel mixture in your combustion chamber stays at the right ratio. Too much fuel means the mix is "rich" or "wet", while too little fuel means the mix is "lean" or "hot" - in very simple terms lean means the cylinder temperatures rise too high, leading to detonation.
Increasing the performance of your fuel system (pump, lines, injectors, fuel rails, and a boost-referenced fuel pressure regulator) means you'll be getting enough fuel into the combustion chambers. If you want to live the spicy E85 life then you'll need at least 35% more fuel system headroom or capacity over what you need for regular pump premium unleaded.
Detonation (also called "pinging", "pinking", "knocking" among other terms) is essentially your cylinders being too hot and the air/fuel mixture igniting at the wrong time. This will hammer engine bearings, pistons, con rods and more. This is why people often over-size their fuel system on a turbo car, so there is always a little bit of headroom to act as a safety barrier on extremely hot days, or if something goes wrong and your engine starts leaning out.
A wideband sensor (like the below kit from our mates at Haltech) reads the air/fuel mixture and can display on a gauge or dash, letting you know when you're in danger of blowing up your engine. This is one mad feature of good quality aftermarket ECUs, as having this support means you can get home with the car still driving.
How you drive and maintain your Chachi-mobile will likely have the largest effect on how long your engine lasts. By adding old mate Spooly McBoostington to your NA engine you've massively increased the stresses on it that the designers never intended, so you need to take some extra steps to ensure Spooly doesn't wreck the party.
You also need to be aware that you're not going to get hundreds of thousands of maintenance-free kilometres out of your engine. As you start driving the car harder and feeding more boost into it (anyone who says they won't is a naughty, naughty fibber, Chachi) the engine will be on a timeline, which is why people generally don't strap turbos to rare engines that aren't easily replaced - because you're probably going to have to replace it at some point.
Your Chachi-mobile will grenade double-quick if you try and maintain the same service intervals as a stock standard model. And a popular mantra among wise hands is, "oil is cheaper than an engine".
Regular (5000-7000km) oil and oil filter changes with high-quality CASTROL oils, and giving it some time to warm up when driving from dead cold, can massively improve an engine's longevity. Adding an external large capacity oil cooler can also help strip heat out of the engine, improving its lifespan.
It can also pay to give the engine a compression test once a year just to make sure none of the pistons are getting ready to leave and visit the sump. Prevention of the explosion is better than the mop-up after a blow-up!
Good luck and happy boosting, Chachis!