# Engine exhaust recovery: Correlation Prices it moves with, and why Source page: https://www.materialinsights.org/energy/e_engine_recovery/correlation/ Turbochargers and turbo-compounding are bought as engine parts. Costs depend on nickel superalloy turbine wheels, aluminium compressors, castings and precision machining; demand follows engine output and tighter fuel and emissions rules. No public price Engine exhaust recovery has no public monthly price series: Sold inside engines as parts; no separate public price. #### What its price moves with Energy [ICE Internal combustion engines and gensets](https://www.materialinsights.org/energy/e_engines/)Host equipment Almost every diesel engine and most new petrol engines have a turbocharger, so turbo demand follows engine production. Turbos let makers use smaller engines for the same power, saving fuel. This part has no price series, so no statistics are shown. Not enough overlapping price history to measure. Commodity [Ni Nickel](https://www.materialinsights.org/commodities/nickel/)Turbine wheel The turbine wheel sits in hot exhaust and is cast from nickel superalloys. Nickel prices therefore affect turbo costs, though machining and engineering are larger parts of the price. Lighter titanium aluminide wheels are an alternative in some designs. Not enough overlapping price history to measure. Commodity [Al Aluminium](https://www.materialinsights.org/commodities/aluminum/)Compressor wheel The compressor side of a turbocharger is usually cast or machined aluminium. Aluminium is a modest cost item, so its price matters less than volume and precision manufacturing. The housings are usually cast iron or steel. Not enough overlapping price history to measure. Energy [Oil Crude oil](https://www.materialinsights.org/energy/crude_oil/)Fuel saved Turbocharging and turbo-compounding cut fuel use, so high oil and diesel prices increase their appeal to truck and ship operators. Fuel savings are the main selling point, which links demand to oil prices. Not enough overlapping price history to measure. Energy [Shp Ship propulsion](https://www.materialinsights.org/energy/e_marine/)Major use Large marine engines rely on turbochargers, and some ships add turbo-compounding or exhaust power turbines. Shipbuilding cycles and fuel rules for ships drive a large part of heavy turbo demand. Not enough overlapping price history to measure. Energy [EV Electric and hybrid vehicles](https://www.materialinsights.org/energy/e_evs/)Shrinking market Battery electric cars need no turbocharger, so their spread reduces the market for car turbos. Hybrids still use them, so the shift is gradual, but it lowers long-term demand. Truck, ship and genset engines will keep the market alive longer. Not enough overlapping price history to measure. How to read these numbers **Correlation of monthly changes** (the number in the coloured pill) compares how much each price moved, month by month, since 2006 or the first month both series exist. It runs from −1 to +1: near +1 the two usually rise and fall in the same months, near 0 there is no link, and a negative number means they tend to move in opposite directions. Above 0.7 is strong, 0.4 to 0.7 moderate, 0.2 to 0.4 weak. **12-month changes** compare year-on-year moves, which shows whether two prices share the same cycles even when the month-to-month noise differs. **Price function** is a straight-line fit of the two prices on logarithmic scales: price ≈ k × (partner price)^β. β is how much this price moves, in per cent, for a 1% move in the partner over the whole period, and R² is the share of the variation the fit explains. Two prices that both drift up with inflation can fit well without any real link, so read it together with the monthly correlation. **Lead or lag** checks whether the monthly correlation is clearly higher when one price is shifted by 1 to 6 months. Correlation is not cause. The reasons on each card explain the economic link; the numbers show how strongly it has shown up in prices. Proxy series are US producer price indexes or related prices and can blur the real link. Data: World Bank Commodity Price Data (Pink Sheet), October 2026; US Bureau of Labor Statistics producer price indexes, IMF primary commodity prices and US EIA prices via FRED, Federal Reserve Bank of St. Louis, retrieved November 2026. Calculations by this site. ## Other sections - [Summary](https://www.materialinsights.org/energy/e_engine_recovery/index.md) - [Overview](https://www.materialinsights.org/energy/e_engine_recovery/overview/index.md) - [Science and thermodynamics](https://www.materialinsights.org/energy/e_engine_recovery/rc-sci/index.md) - [Engineering and integration](https://www.materialinsights.org/energy/e_engine_recovery/rc-eng/index.md) - [Economics and contracts](https://www.materialinsights.org/energy/e_engine_recovery/rc-econ/index.md) - [Impact and additionality](https://www.materialinsights.org/energy/e_engine_recovery/rc-impact/index.md) - [What to track](https://www.materialinsights.org/energy/e_engine_recovery/tracking/index.md) - [Relationships](https://www.materialinsights.org/energy/e_engine_recovery/links/index.md)