Quote:
Originally Posted by Daox
The purpose of this thread is to use 'free' exhaust heat to speed up the warming of the engine to decrease fuel consumption.
A block heater does work, if you have 110V power. If you don't, this device can and will help.
Using 12V power from the alternator will actually increase fuel consumption, not decrease it. So that kind of defeats the purpose we are going for at least, though you would get heat quicker. VW actually does do this with their TDI engines to get them up to temperature faster.
Vman is correct. Ethlyene glycol is only supposed to be (page 16). That is certainly achievable by warming the coolant with the exhaust. I'm not sure if the water will start boiling out before that point or not, but if it does, thats not good either.
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I agree that the exhaust heat is 100% free, while a 12V heater is not. I guess I was thinking people were looking to heat the engine up quicker to reach operating temps faster.
Quote:
Originally Posted by dremd
I’d also note that the quality of 12volt energy is limited. Even with VW’s large battery and alternator the difference in warm up time isn’t noticeable to the average driver with the system disabled. The gen 3 Prius warm up time is genuinely impressive until you move to EV’s and expect heat instantly.
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With a 100A alternator, a 12V heater could put out more than 1kW of heat into the coolant, which is very little compared to an idling engine, say 5hp (3.7kW), so the engine is already putting 4x more heat into the fluids. Still, 1kw heater would add 27% more heat, but barely noticeable to a driver. Gently driving around using 100hp(75kW) would put out 75x more heat and make the 12V heater very insignificant.