New Prius owner, ICE question

Prius engineers tend to put safeguards in so that their cars don't self destruct.
Just drive it.

 

congrats and welcome!
i found the gen 4 engine noisy as well, compared to my '12. i think you'll just have to get used to it. it may be that in toyota's quest for increased mpg's, something has been lightened in the hood and firewall, or the muffler system, or the engine design.
noise is last on the prius list, although the rest of the car is supposed to be better insulated.

 

The engine sound has always been loud in any Toyota Hybrid I've had the pleasure to drive when accelerating. Even my Prime was loud when the engine activated. The main reason is the engine hits a higher rev right away because its an Atkinson and then the e-CVT has to divy up the resultant HP to drive and feeding the front motor and battery (if necessary). So there is a disconnect between the amount of power that is needed to get the car to accelerate and cruising. It goes high rev for a bit immediately before calming down when you hit a cruising speed. Does it get better over time? Not really, mostly because you are getting used to it. Lower speed acceleration seems to accentuate the engine noise, cruising not so much. That being said I've floored my Prime several times to activate the engine and have never damaged the engine and usually to merge, pass, or just get out of a potentially dangerous situation. They respond quite quickly because of the electric motors.

 

Have you tried ‘Power Mode” that tends to give more “push” for less “noise”

 

The computers controlling the car know exactly what RPMs are safe for the engine, and never exceed that. So putting it in power mode and flooring it (or just flooring it, which is the same power in all modes) will make it sound like a Prius at full power, but it won't be harmful to anything.

If I remember right, gas mowers tend to be governed to around 3000 RPM. The Prius 1.8 reaches full power at 5300 RPM (at least, that's what I remember for Gen 3, and Gen 4 is pretty much the same engine). So it'll sound not quite twice as spinny as a mower. (The exhaust note will be higher than that, because more cylinders than the mower.)

Of course the engine is mechanically safe to RPMs even a fair way above 5300, but the power graph starts going back downward past that point, so there is no advantage in using any higher RPM, and the car's computers won't.

 

Actually the Prius engine is always run close to the maximum power it can give at any RPM, ie close to full throttle. If it could provide more power at that speed the engine would be run slower to get better efficiency.

The blue curve on the BSFC graph below is the operating line used on the 3rd generation, the red the 2nd generation. The 4th generation is similar to the 3rd though it was modified somewhat. By keeping to that line efficiency is optimized.

As far as I know it always operates along that same line independent of whether the car is economy, normal or power mode. The mode alters the throttle mapping and the operation of the air conditioning but not the engine.

There is no risk of "throwing a rod", the engine will not be allowed to go above about 5500RPM under any condition.

kevin

 

Welcome and congratulations on buying what might be the most reliable car on the road, or very close to it. I noticed today that there was a new member of the Facebook Prius Prime group who was excited about having just bought a used Prius Prime with over 250,000 miles on it. There are lots of other Gen 4 Prii out there well into the six digit area.

ROFLOL!! I hope you're pulling our collective leg. I've seen several Gen 2 Prii with holes in the engine block. (I work part time in a hybrid shop.) But what oil they had in the pan was a black goo. The Prius didn't get its stellar reputation by self destructing just because the driver's foot got a little enthusiastic.

 

FWIW......I have both {Gen 3&4)......yes, the Gen 4 engine IS noisier (in/the/cabin).......again, FWIW

 

congrats!

 

Has anybody seen a plot like that for the 4th generation engine, or data from which it could be constructed?

A fundamental reason Prii engine seem noisier than those of other cars when accelerating or climbing is that engine torque along the allowed "operating line" is so low at moderate engine speed, in proportion to the weight of the car. As a result, the engine must spin faster to produce moderate power, compared even to other vehicles of similarly modest peak power/weight ratio..

 

Having come from another type of car altogether - I find PRIUS engine quite quiet. I did notice that generally, Gen 3 was a noisier car - with Gen 4 seeming quieter. My suspicion is that, with a quieter overall car, the engine is more obvious than old model PRIUS'.