I remember reading somewhere here at PriusChat that the Prius engine, the ICE, will not overheat like a conventional engine, but I forget the details as to if this is true, and why. TIA
Any ICE can overheat however the Prius engine is less likely to overheat since it does not run when the car is stopped. Most overheating in an ordinary car occurs during hot weather when in stop and go traffic. In this instance the Prius ICE will only run enough to keep the battery charged to handle the AC and other electrical components.
So does it have an engine abuse managment like the northstar engines do? loss of coolent and the engine cuts out alternating cylinders to cool it. I guess someone with a tech manual could answer this PLZ PLZ PLz
What's a "northstar engine"? . I've been through the service manuals fairly extensively, and I don't think the 1NZ-FXE has the "cut alternating cylinders" feature you mentioned. Interesting idea, though, since that would help air-cool parts of the block to some extent -- you certainly couldn't pull much in the way of power in that state, but it might help you limp to the next opportunity to top up the coolant. . The only unusual thing the manual really says is warning that the thermos tank can still contain hot coolant even when the rest of the system is cold, thus presenting a minor hazard when draining the system. As they put it, "the user should never attempt to change the engine coolant." Bah... . _H*
First off, the Ice in the prius only runs between designated speed. It actually only runs at two speed. Kinda a high and low. The high isn't high enough to heat up the engine all that much. The low is around 1280 rpms. Somehwere around there. Most of the time when an engine shuts off, it heats up. This is why radiators have electric fans. Instead of everything continuously cooling off, it's now sitting and the heat isn't being absorbed and taken away by the coolant/water. Northstart is an engine that GM uses in Cadillac. Good engines.. Sound great at full throttle.
... the Ice in the prius ... only runs at two speed. . Where do you get that idea? . The ICE spins at an appropriate RPM to match power demand, in fact, and happens to conveniently map to roughly 10 kW for every 1000 RPM added [with a fall-off near the bottom] -- thus, 2000 RPM delivers about 20 kW, etc. RPM varies smoothly all over the map, following what your foot asks for. . ... when an engine shuts off, it heats up. . Where do you get that idea, too? While coolant flow may change or stop and allow temperatures to equalize, possibly registering a tiny bit warmer near the ECT sensor, there's nothing to *add* additional heat to a shut-down engine. In fact, airflow over it will begin cooling the block immediately. Slowly, but definitely cooling. . _H*
<div class='quotetop'>QUOTE(hobbit\";p=\"109476)</div> I think the assumption here was that the engine has stopped...and so has the car. So there is no airflow past the block (or, more important, through the radiator). Under these conditions, the temperature of the engine coolant that's in the block and heads will rise, since there is no longer any circulation of it away from the combustion points and through the radiator. So there is a bit of a heat soak
having had the MiniScanner on the car for over a year now I can say that I've never noticed any latent heat effect when the ICE stops. If it's very high the cooling fans run if the car is moving or not or the ICE is stopped or running. The LH cooling fan runs if the car's climate system is in Auto mode automatically on the G2 Prius. At least on Tideland Prius's car. The normal running temp of the ICE on 75-80F days is 89-92C no noticeable difference with A/C or not. I can assume that is the opening point of the thermostat in my car. YTMV. I just wish the MiniScanner was available for the G2 so that we could have more data available.
The Prius ICE doesn't seem to increase in temperature after stopping, but according to the miniscanner the converter/inverter certainly does- I've seen the temperature go up as much as 10 degrees stopped vs. in-motion- the converter/inverter does not have much thermal mass, and the coolant capacity is tiny compared to the ICE, so the little radiator needs air flow to cool effectively.
the mg's tend to peak after you come to a stop also. Again part of the small capacity of the Hybrid side of the cooling system.
<div class='quotetop'>QUOTE(seasalsa\";p=\"109448)</div> Yup, a lot of overheats are caused when a vehicle with a large engine (V6 or V8) is stuck in traffic that's not moving on very hot days. The radiator simply can't keep up with the heat the engine is producing when there's little or no air flowing through the radiator and the ambient temperature is hot. As others have said, the Prius has a few advantages in that it can shut the engine off frequently, and the ICE is a relatively small 4-cylinder model that just doesn't produce that much heat to start with. Dave
Yes, the ICE is in no danger of overheating, but as both Frank and I have pointed out, that's not the case with the hybrid components.. the hybrid cooling system really does need the air flow to keep cool- those IGBTs in the inverter/converter are particulary sensitive to high temperatures, and they're very expensive to replace, so you definitely do not want a hybrid system overheat!! An extended period of slow speed stop-and-go probably has little to no impact on the ICE, but it could put the hybrid system at risk of overheating..
<div class='quotetop'>QUOTE(DaveG\";p=\"109890)</div> Hi Dave: I think the big problem with the large vehicle with large motor is that the engine cooling fan is still driven by the motor itself. So when you need engine cooling the most (Foot on brake, 0 MPH, A/C on max, etc) the fan is turning slowest. If anything, larger vehicles with large motors benefit far more from thermostatically-controlled electric cooling fans than smaller vehicles. I put a Flex-a-lite #282 in my 2000 GMC Sierra and noticed many benefits when stuck in traffic: A/C worked much better, engine seemed more responsive, no more pinging, etc. My Sierra supposedly had that overheat protection system, but I never put it to the test. I think almost every GM brand pickup and SUV has it now. I would think if the Prius inverter/converter is anything like an industrial VFD, there would be extensive thermal protection for both the ICE and the HSD. Jay
I guess we will be "testing " the hybrid and ICE systems when we head for the high desert of arizona/nevada/california in a week or so...i hope it can handle the air temps in the 90s-100s-110s f ...everything checks out on the vehicle and its ready to roll..if anybody has any insight on the maximum allowable temperature on the system, that would be nice to know... :wave: :wave:
there are lots of them in Phoenix AZ so with the temps running in the Hi teens there I'd have to say there probably isn't an upper limit.
I live in Palm Springs. This year the temperature range up to 118 degree. My Prius is almost a week old. I have no trouble driving to work or to grocery about 35 miles round trip with AC on all the time. --Hilore --Palm Springs, CA
