Bottom Line Up Front
Some high‑performance and heavy‑duty engines use two thermostats to keep the coolant at the perfect temperature, improve power, and protect expensive components.
Why Some Engines Have 2 Thermostats – The Simple Truth
Image: Why Some Engines Have 2 Thermostats – The Simple Truth – Performance Comparison and Specifications
Design & Looks
Most engines have a single thermostat that opens at a set temperature, letting coolant flow through the radiator. When manufacturers add a second thermostat, they usually place it in a separate coolant circuit. This second valve often controls the flow to the cylinder heads or a specific hot‑spot, letting the engine stay hotter where it matters most while still cooling the rest of the block.
Why the extra part? The answer is simple: better temperature control. By isolating the hottest parts, engineers can extract more power without risking overheating.
Performance & Mileage
A dual‑thermostat setup can raise the average operating temperature by a few degrees. That sounds tiny, but combustion becomes more efficient when the engine stays warm. The result is:
- Improved torque, especially in the low‑to‑mid RPM range.
- More consistent power delivery during hard driving.
- Potentially better fuel economy because the engine doesn’t have to work as hard to stay warm.
Cars that need rapid heat‑up for turbochargers or superchargers especially benefit. The extra thermostat helps the turbo reach its optimal temperature quicker, cutting lag and boosting performance.
Price & Rivals
Adding a second thermostat isn’t cheap. It adds parts, extra plumbing, and more precise control electronics. That extra cost shows up in the price tag of vehicles that use the system. However, many buyers accept the premium because the performance gains feel noticeable.
Here’s a quick look at some models that use dual thermostats and how they compare:
| Engine | Mileage (mpg) | Price (USD) | Top Features |
|---|---|---|---|
| BMW M3 (S55) | 20 city / 30 hwy | 71,000 |
|
| Mercedes-AMG C63 (M177) | 19 city / 28 hwy | 78,500 |
|
| Nissan GT‑R (VR38DETT) | 18 city / 25 hwy | 115,735 |
|
FAQ
What does a second thermostat do?
It controls a separate coolant path, usually the heads or a turbo, allowing those hot areas to stay warmer while the rest of the engine cools.
Do dual thermostats improve fuel economy?
Yes, by keeping the engine at its optimal temperature, combustion is more efficient, which can shave a few miles per gallon off the rating.
Can I add a second thermostat to my regular car?
Retrofitting is possible but expensive and requires custom plumbing. Most owners stick with the stock setup unless they’re building a performance car.
What do you think? Share your thoughts in the comments below.
Source: Read Official News
