Does flooring it often hurt it?


#1

Does running an automotive engine at its redline, often & hard, hurt the engine? Will, it lead to engine failure?



Does it make a difference for a new engine versus an older one.



At first, I thought it was a no brainer yes to both questions. And, that it would do more damage faster to an older engine. But, then a few people tried to tell me otherwise.



Does anyone have any helpful thoughts on the matter? And, yes… I am being intentional vague because I don’t want to taint the any answers.



Thanks


#2

Are you simply running at the line or just hammering it? Of course nailing it constantly isn’t GREAT for the engine.

But put it this way…

I once heard a figure that if you ran an engine constantly at full throttle, it would be dead in a week.

So figuring 168 hours in a week. 168 hours of WOT operation and then she’s dead. Probably less.

Now think of how many hours of operation you put on a car. If you AVERAGE 40mph, and you make 200,000 miles, that’s 5,000 hours of operation. Just driving “normally.”

And even if you average much faster because you’re a big interstate driver, remember that highway driving is cakework for an engine. It’d probably go much longer.

So 150ish hours v.s. 5,000 hours.
Big difference.

-Matt


#3

The higher the RPM the shorter the engines life, it’s as simple as that. Reciprocating mass increases with the CUBE of the RPM. So does engine stress and wear. The parts most effected are the rod bearings, pistons and rings…


#4

Thanks guys… now the whole story.

I?m studying from my Private Pilot License. And, well that poor air-cooled engine. It gets it ever time we take-off… full power. And, I was just having a very hard time gunning it (in lessons), because I know the damage it can cause over time in an automotive engine. For many reason we have to take-off full throttle in a light aircraft. However and aircraft engine does get overhauled frequently.

When I told this to my pilot comrades, why this was such a hard thing for me to learn/do… They just laughed at me and told me how this type of behavior doesn?t lead to engine damage and that automotive engines can take. Basically called me batty.

Thank you for basically backing me on this one.


#5

While I agree with you conclusion, the mass of the rotating parts does not increase. It’s the force resulting from that mass accelerating at a higher rate that puts more strain on critical parts. Also, I would not say that the force increases with the cube of the rpm for all parts, each would have to be evaluated separately. Sorry for being geeky.


#6

I understand the need to use full power for takeoff in a small aircraft, but you do have to consider the maintenance interval for aircraft engines. How many hours do you run an aircraft engine before it is due for an overhaul? There’s a reason it doesn’t cost $100 per hour to operate your car.


#7

Okay. What is it? A Cessna? These engines operate in the 2-3 grand range max. These engines are built bigger and more rugged than a car engine, with minimized mass all over the engine. Not only to reduce engine stress and wear, but to lighten the aircraft. I too will be starting piloting soon, and persuing ATP cert. for a career. I’ll also be picking up an A&P, plus a BS in Aircraft Ops. and Aerospace Maintenance. Trust me, that engine is built for it.

And if it’s ever crossed your mind WHY they only operate a few thousand revs, that’s the answer. So they can be reliably operated at WOT.

-Matt


#8

A car engine is a different animal. Be nicer to it. At 6-9 grand redline, those engines get beat up at high RPM. Just drive how you drive and don’t worry about it. Change the oil on interval, and keep up with all the maintenance.

As for the bird, let the maintenance guys take care of it. (I’ll be one of those guys at some point in my life, wouldn’tcha know it.)

-Matt


#9

Oh, I noted that… it is overhauled often and well looked after. It was just the idea, that no one thinks about that is going on inside the engine when they push the throttle, that part seemed weird to me. It made me question myself. Like, no one takes a moment to go wow, that wears an engine fast. They just think it will give forgiver…

Thanks!


#10

Matt,

That’s so weird… You would answer my post without even know what is was about. I could keep an Ace like you. Do you have an E-mail on profile, could reach you at. THANKS!


#11

I wonder about these blanket statements.

I had a 1988 VW Jetta GLI 16V that spent much of its life on the highway hovering at 4000RPM(also my shift point) at 80MPH. It redlined at 6500RPM. The car was sold running without a mechanical problem at 200,000 miles/10 years old. The next owner(sister) made it to 50k before wrecking the car without an issue.


#12

I will make a blanket statment. Very few cars are junked due to a worn out motor. They are junked due to a failure in transmission, accident, overheating, lubrication failure or emmissions problem.


#13

Forgot a major one in my parts, RUST.


#14

Well it does tend to lead to additional engine wear. However your situation is a little different than that of us poor earthbound morals.

That engine is designed for the kind of use you are talking about. It also gets far more care than most automobile engines get. Don’t worry about the engine, worry about learning to fly. Your mind needs to be on those things that enable you to become a safe pilot and nothing else.


#15

In the Ford Crown Victoria, the 4.6L V8’s redline is at 6000 rpm. In the police cars, the computer has a rev limiter set to 5700 rpm, in civilian Crown Vics, it’s 5100, both done to promote long engine life. Don’t know about other cars, but the Crown Vic is one vehicle that can be floored often and not hurting the engine. As much.


#16

Repeatedly running to red line at full throttle will wear out an engine very quickly. On the other hand, if you never run it hard, carbon deposits will build up and cause problems too.

We have two high mileage cars – a 1998 Subaru with 168k miles and a 1984 RX-7 with 185k miles. Each still has its original engine, clutch and transmission. Each gets a half mile burst of hard acceleration to 80% of red line every day. That seems to be enough to keep them clean without wearing them out.


#17

Other points. The recommended Time Between Overhaul (TBO) of an aircraft engine is about 2000 hours. The engines run at 2300-2500 rpm because the tips of the propellor blade have to be kept below the speed of sound. So for a direct drive propellor that limits the engine speed. For geared engines the crankshaft speed can be in the 3000 to 4000 rpm range. True aircraft engines run at WOT for take off and climb but are tapered off to 75 to 85 percent for cruise whereas cruise in a car is 20 to 30% of max horse power. Also air cooled engines have faster cylinder and valve wear than water cooled engines. The oil, cylinder head, and exhaust valve run hotter in an aircooled aircraft engine. It is rare for an aircraft engine to run to TBO without having a top overhaul which includes cylinder, cylinder head, valves, piston, and piston pin. The bottom end, crankshaft, rods, bearings, cam, and lifters, usually make it to TBO unless low useage causes rust issues.

So comparing aircraft engine life to auto engine life is like camparing apples to oranges.


#18

That’s not inconstant, your VW should not have any problem running at 65% of its redline for well over 200K miles. That’s a lot different than running it up to redline on a regular basis.


#19

Running an engine at WOT but with a heavy load limiting RPM is one thing…Aviation and marine engines and heavy truck engines are designed to operate under heavy load and still have a reasonably long life. It’s RPM, especially in the region above 5000 rpm, that puts destructive loads on crankshafts and pistons.Basically, it’s the STROKE of the engine that determines the upper RPM limit before piston speed becomes destructive.The shorter the stroke, the higher the RPM limit before things start to break. Remember, that piston must accelerate to top speed then come to a dead stop and reverse direction every half turn of the crankshaft. The force of the reciprocating mass increases with the cube of the RPM. That’s the drag you feel when you downshift and raise RPM, not “compression”. There is nothing to compress, the throttle is closed. What you feel is the energy required to start and stop those pistons…At some point, the energy loss exceeds the output of the engine or the engine comes unglued…