ABOVE: An unshielded turbo means you’re leaving a lot of horsepower and turbo efficiency on the table. Increased turbo lag, lower max boost and increased underhood heat are all negative effects of an unshielded turbocharger.
You’ll see us talking up using Heatshield Products exhaust wrap and/or insulation to keep more heat in your exhaust system for multiple reasons. First is to cut down on the amount of heat the exhaust system radiates, which can increase underhood temperatures and interior heat; the exhaust pipes running under the floor will heat the floor and transmit that heat into the passenger cabin. Second, keeping more heat in the exhaust system helps increase performance, especially in turbocharged applications. You may be wondering, how does it increase performance?
With a gas or diesel engine, exhaust gas temperature (EGT) has a direct correlation to engine performance and health. Understanding EGT can be a tuning tool (especially for turbocharged applications) and assist in wrapping your headers and exhaust with an effective thermal barrier or insulation for solid performance benefits. EGT directly relates to exhaust gas velocity, in that as the temperature rises, the exhaust gas moves at a higher velocity. With an internal combustion engine (gas or diesel) the EGT will rise as the engine makes more power or as the air/fuel mixture leans out. In the case of a lean condition with the engine, an EGT that is too high can lead to major detonation and cause severe engine damage. Back in the 1970s and the era of carburetion and tightening emissions standards, the factory would tune engines to run as lean as possible to heat up the catalytic converters faster so that they could quickly perform their intended purpose and also to burn up as much as possible in the combustion chamber to reduce the amount of fluorocarbons and other pollutants left form the combustion process.
What does a safe higher EGT (meaning the air/fuel ratio is within optimal parameters) mean in a normally aspirated engine when it comes to better performance? As the EGT climbs and raises exhaust gas velocity for each cylinder, exhaust gas scavenging increases. More spent gases get sucked out of the combustion chamber while the exhaust valve is open. The more spent gasses that can be removed before the exhaust valve closes, the better the next combustion cycle will be as a fresh fuel/air charge is brought into the cylinder.
With a turbocharged engine, increased EGT helps on multiple fronts. The first is the same as with the naturally aspirated engine: getting all the exhaust gasses out of the combustion chamber for a better burn when combustion takes place. Second, with increased EGT, the turbocharger spools up to create boost much faster and also cuts down on turbo lag. This is from the increased velocity of the exhaust gasses, thanks to the higher EGT. The third benefit of the higher EGT is that with increased exhaust gas velocity, the turbo can spool higher and create more boost, leading to an increase of horsepower once the wastegate and blow-off valve are tuned accordingly for the increased boost.
It’s easy to keep more heat in the exhaust system to help boost the EGT. Ridiculously easy. Start with the turbo itself. A proper turbo heatshield on the exhaust side will help insulate the turbo housing to keep more heat in and boost the EGT. There’s also the added benefit of cutting down on the amount of heat the turbo radiates underhood, which lowers underhood temps and the negative affects of things getting hot under the bonnet. There are multiple options from Heatshield Products when it comes to turbo heat shields, including a DIY turbo shield kit for odd sized/shaped turbochargers.
ABOVE: Adding a turbo heat sheet like the Lava Turbo Shield pictured above helps keep significantly more heat inside the turbo housing to increase EGT and exhaust gas velocity that decreases the time it takes the turbo to spool up and start making boost, along with reducing the amount of heat the turbo radiates underhood or under the vehicle (if the turbo is remote mounted). You can also see where the exhaust pipes feeding the turbo have been insulated with Heatshield Armor for the same reasons. This particular Lava Turbo Shield is mounted on Heavy D’s BroDozer monster truck. A true testament to Lava Turbo Shield’s ruggedness, this one has survived some serious beatings and looks pretty good for something that has been installed since June of last year. It is constantly exposed to the elements like dirt, mud and heat including an engine fire. Adding an exhaust wrap or exhaust insulation like Heatshield Armor to the feed pipe (on remote mounted turbos) and the downpipe helps to shield the turbo and to keep the EGT up to help keep EGTs up before and after the turbo, which helps sustain increased exhaust gas velocity longer for better performance and turbo consistency.