Turbo V8 Facts of Life
Have you ever ridden in a vehicle powered by a properly engineered twin-turbo V8? No, a single-turbo V8, or heaven forbid, a single-turbo four cylinder is not the same thing, not even close.
We’ve all heard the wisdom that there’s no substitute for cubic inches, but cubic inches of what? Is it cubic inches of engine that count, or cubic inches of air in the combustion chamber? It’s obviously the latter. So consider this, 15 psi of boost effectively doubles the size of an engine. That means 15 psi of boost will make a 350-cubic-inch performance engine seem like a 700-cubic-inch performance engine!
Actually, this picture isn’t accurate. If you understand engines, you’ll immediately realize that 15-psi boost more than doubles the performance an engine. It does this for two reasons: first, the internal friction of the engine remains largely the same regardless of boost, so the extra power from turbocharging is almost totally available to power the vehicle; and second, the 15 psi of boost in the induction system actually helps push the pistons down on the intake stroke whereas the intake stroke created a pumping loss (negative torque) when the engine was normally aspirated.
Now you may be thinking that the turbochargers create exhaust backpressure that increases the pumping loss on the exhaust stroke, but let’s go back to the first sentence of this discussion — we’re talking about a “properly engineered” system. That means the exhaust restriction created by the dual turbos will be minor, and that boost pressure will always exceed exhaust system backpressure. Simply translated, in terms of performance, a good twin-turbo 350 V8 will turn your inside out!
Okay, just for fun, let’s compare our 350 twin-turbo V8 at 15-psi boost to a 120-cubic-inch compact four cylinder running 30 psi of boost — twice that of the V8. By our rule of thumb, the little four-banger will now be flowing air equivalent to a 360-cubic-inch normally aspirated engine. That’s impressive for a small engine, but it will still have only half the power potential of our twin-turbo V8 running at half the boost. If you push the V8 to 30-psi boost, you’ll have the equivalent of 1050 cubic inches and over 1500 hp, if it is done correctly.
Turbocharging is fun. It’s addictive.
Advanced Performance Tuning: Turbo V8 Facts of Life
Have you ever ridden in a vehicle powered by a properly engineered twin-turbo V8? No, a single-turbo V8, or heaven forbid, a single-turbo four cylinder is not the same thing, not even close.
We’ve all heard the wisdom that there’s no substitute for cubic inches, but cubic inches of what? Is it cubic inches of engine that count, or cubic inches of air in the combustion chamber? It’s obviously the latter. So consider this, 15 psi of boost effectively doubles the size of an engine. That means 15 psi of boost will make a 350-cubic-inch performance engine seem like a 700-cubic-inch performance engine!
Actually, this picture isn’t accurate. If you understand engines, you’ll immediately realize that 15-psi boost more than doubles the performance an engine. It does this for two reasons: first, the internal friction of the engine remains largely the same regardless of boost, so the extra power from turbocharging is almost totally available to power the vehicle; and second, the 15 psi of boost in the induction system actually helps push the pistons down on the intake stroke whereas the intake stroke created a pumping loss (negative torque) when the engine was normally aspirated.
Now you may be thinking that the turbochargers create exhaust backpressure that increases the pumping loss on the exhaust stroke, but let’s go back to the first sentence of this discussion — we’re talking about a “properly engineered” system. That means the exhaust restriction created by the dual turbos will be minor, and that boost pressure will always exceed exhaust system backpressure. Simply translated, in terms of performance, a good twin-turbo 350 V8 will turn your inside out!
Okay, just for fun, let’s compare our 350 twin-turbo V8 at 15-psi boost to a 120-cubic-inch compact four cylinder running 30 psi of boost — twice that of the V8. By our rule of thumb, the little four-banger will now be flowing air equivalent to a 360-cubic-inch normally aspirated engine. That’s impressive for a small engine, but it will still have only half the power potential of our twin-turbo V8 running at half the boost. If you push the V8 to 30-psi boost, you’ll have the equivalent of 1050 cubic inches and over 1500 hp, if it is done correctly.
Turbocharging is fun. It’s addictive.
Advanced Performance Tuning: Turbo V8 Facts of Life
