STS Systems

rufio11

I've been reading this post and I have always thought this would be the way to go for FI. One thing that I keep reading from you guys is that HEAT is needed to keep the turbos working at optimal performance, why do you think so? Its the speed of the air moving the turbo not the temperature of the air. Maybe better put would be that the exhaust moves the turbo, it doesn't matter how hot the exhaust is.

LiquidZ

Heat is thermal energy. If you keep as much of that heat contained within the exhaust, your exhaust's energy will increase. In turn, the retained heat creates an increase in temperature. Keeping heat in the exhaust is best for turbos as it increases the exhaust velocity.

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Nixlimited

This statement could not be more inaccurate. Heat = energy, which increases pressure. If you remember the equation from high school chemistry, pV = nRT i.e. increased Temperature increases pressure which is forced through the turbine blades. Heat is critically important to a turbo working correctly, which is why people wrap headers, downpipes and turbos to keep heat within the exhaust system. It's also why cars that have the turbos close to the heads spool faster.

If this were the "way to go FI," you would see car manufacturers, especially at the high end, using it. Instead, you see them placing turbos as close as practical to the heads.

KingDavid

That is not completely true.

While heat does play a factor in turbo function, it's not the most crucial dynamic. The cone effect, whereby velocity increases inside the turbo housing, is much more vital than the slight heat loss caused by moving the turbo system to the rear of the vehicle.

Turbos start producing boost only above a certain exhaust mass flow rate (depending on the size of the turbo) which is determined by the engine displacement, rpm, and throttle opening. Without an appropriate exhaust gas flow, they logically cannot force air into the engine. The point at full throttle in which the mass flow in the exhaust is strong enough to force air into the engine is known as the boost threshold rpm. Engineers have, in some cases, been able to reduce the boost threshold rpm to idle speed to allow for instant response. Both lag and threshold characteristics can be acquired through the use of a compressor map and a mathematical equation.

Outside of operating temperatures, heat is a car's worst enemy.

Oh this post was a quote, lol.