Is it bad to redline your car?

[itguy08]

HECK NO.

My first car was a 1986 Mustang with the 2.3L 4 and a 4 speed stick. Bought it with 58k on it. It didn't have a redline but the tach stopped at 6k and the carb wouldn't let it go past that. Being the average male I was, the car saw max revs almost daily. The blistering 88hp meant you had to ring everything out of it all the time. Going up a hill would be in 2nd or 3rd at 5k RPM and whatever speed it would go at with the pedal to the floor.

Changed the oil every 3k and when I junked it at 175k it still would start right up and run like a top. I only junked it in 2005 because the body was rusting away and it had to pass the new emissions in PA which it wouldn't as being a poor college student as the stuff would break I'd remove it.

If a 1970's era engine (designed for the Pinto) can put up with the use that car had I'd say just about any modern engine in decent shape will.

Once my cars are up to operating temperature I don't feel guilty about running them hard every once in a while.

 

[SteveSRT8]

Originally Posted By: Josh48065

Quote:

I've been redlining (and revving past Redline by 400rpm) since my 2007 Civic Si was new. It now has 110,000 and still runs like new. It has seen track time (time attack racing) and I beat on it daily (check my UOA posts) and all is well.

Enjoy your car. Keep up with maintenance and it will last a long time for you.


Though.. Do you have a manual transmission? A/t seem not to handle high rpm shifts as well


This is extremely platform dependent. Many higher powered AT cars have so much torque management software controlling every aspect of the shift event that it is nearly impossible to harm the trans. You would not believe what's going on in a couple hundred milliseconds!

So just say "some AT's" and not all.

 

[KrisZ]

My car has a small enough engine / power that it never loafs around 1500 RPMs like some big V8 do. So I never even think about "exercising" the engine. If I need to step on the gas, I do, the car is always happy to comply. I also like to use the manual mode every once in a while, whenever traffic is lighter, that always keeps the engine at higher RPMs.

 

[Josh48065]

Quote:

This is extremely platform dependent. Many higher powered AT cars have so much torque management software controlling every aspect of the shift event that it is nearly impossible to harm the trans. You would not believe what's going on in a couple hundred milliseconds!

So just say "some AT's" and not all.


Interesting..I definitely stand corrected. I never actually knew/or thought of it that way, but it really makes sense. I guess I made that statement b/c seems most high-mileage transmission that break down seem to be automatics.. But I imagine it is purely because of neglect to the fluids. I imagine a majority (not all) of auto enthusiast would lean more on buying a manual transmission and actually properly maintain their tranny.

 

[Michael_P]

At the gas station, redlining will hurt your wallet.

 

[rslifkin]

I see no issue with running an engine hard. My Jeep gets would up routinely, as in any time I get on the highway (if it's good and warmed up), and periodically at other times just for fun.

Over the summer, when I had a highway section in my commute, it saw a WOT 30 - 70 run daily. At the end of the summer, I pulled it apart for heads and cam, and the insides of the exhaust manifolds were CLEAN (no carbon on fingers after wiping, none visible, just a fine layer of white ash). The 2 week old y-pipe was spotless inside as well (clean metal).

 

[sciphi]

Not at all, not when one has VTEC and the other a turbo to keep things fun!

I broke in the Cruze by many pulls to 5500 RPM (1000 RPM before redline) and using the turbo a lot, figuring that the engine better get used to it. Since then it's seen mixed-RPM driving, with a lot of low-RPM highway cruising mixed in with daily 3500-5000 RPM blasts up the hills around me. The car falls on its face at 5500 RPM when the stock programming limits the turbo pressure, so it doesn't see much beyond that.

The Honda sees a lot of 3000-4000 RPM driving every day going up hills at 75 mph on cruise control. It doesn't burn a drop of oil at 50k miles, and has decent power for a 1.5 liter NA engine.

 

[hattaresguy]

Nah, besides if it breaks it wasn't much of a motor anyway good riddance.

 

[OVERKILL]

Originally Posted By: HTSS_TR
Originally Posted By: Nick R
Quick answer: IMO, absolutely not. Redlines are set to be very conservative.

Honda S2000 from 2000 to 2003 redlines at 9000 RPM and fuel cutoff at 9300-9400 RPM, that is not conservative at all. From 2004 redline is set at 8000 RPM and fuel cutoff at 8200-8300 RPM.


Those were different engines however. There was a displacement bump that corresponded with the drop in redline RPM.

Usually, the engine has been tested well past the value that is settled on as the "redline". However, the Redline occurs shortly after peak power in many cases.

 

[cmf]

Originally Posted By: SteveSRT8
This is extremely platform dependent. Many higher powered AT cars have so much torque management software controlling every aspect of the shift event that it is nearly impossible to harm the trans. You would not believe what's going on in a couple hundred milliseconds!

So just say "some AT's" and not all.


Absolutely correct, and it's not just high powered AT cars. Most cars have a pause between gear shifts in normal automatic mode. When you floor those cars the pause gets longer. So yeah it's shifting at high rpm but it's rev matching during the pause and when it reconnects it's very close to the same RPM.

Thanks to the fact that most people in America buy automatics, the technology has improved to the point where modern automatic transmissions are very reliable. Just have to remember to change the transmission fluid because it's an integral part of how automatic transmissions function.

 

[01rangerxl]

Originally Posted By: swirlparanoid
i had a topic similar to this a while back and it was concluded that nothing would really happen as long as oil was up to temp. but something i thought of after i made that thread was the affects of a redline shift on a transmission. it is widely said on here that an engine will outlast a car but the same thing is never said about an auto trans, would an engine redlining have a negative affect on a trans over the years? i would imagine it couldn't really help its longevity to do so....


Probably less of an issue than it used to be. Engine and transmission programming doesn't allow people as much freedom to tear up their cars.

My truck has a 5-speed automatic with adaptive shifting. It has 109K miles with a whole lot of shifts in the 5-6,000 RPM range and zero transmission problems, ever. Fluid has been changed every 30K, other than that it has never been touched. The pan has never been off.

 

[buster]

Originally Posted By: LS2JSTS
I'm of the "stretch it out" school of thought.

I firmly believe that an engine that gets stretched out early and often will outlast an engine that gets driven gingerly it's whole life.

And especially believe that holds true when changing use patterns...ie an engine thats been babied and then gets driven hard will fail sooner than an engine that gets driven hard then spends years in light service. Just my anecdotal rubbish opinion, but I've seen this scenario play out again and again.


I've kind of thought that as well. Seems to be a pattern.

 

[buster]

I have a manual.

 

[JHZR2]

Im not really sure what redlining does unless there is some amount of expansion of metal parts under those forces that helps them to reach a full motion range or something similar.

I think that WOT after full warmup is smart (within reason as it is wasteful), and that may involve higher RPM runs.

But I dont see anything sacred about hitting redline versus exercising the car controllably and carefully under the right conditions, which is likely healthy.

 

[mechtech2]

The highest cylinder pressures are at wide open throttle and mid/mid high RPM.
This is your torque peak - the most cylinder filling.
At high RPM, you have less filling, but at a higher rate.

The biggest stress from high RPM is the unloaded TDC of the exhaust stroke. The rod changes direction with high loads on it's bearing and pin.

 

[mva]

It is a bad idea to rev an engine to the redline in neutral, when cold.

Once the engine is warmed up there should be no issue reving to the redline.

My BMW's manual advises not to rev over 4,000 rpm until the oil temperature is above 60C. Some other BMW's have variable redlines that increase as the engine warms up.

 

[Scott_Tucker]

Originally Posted By: mechtech2
The highest cylinder pressures are at wide open throttle and mid/mid high RPM.
This is your torque peak - the most cylinder filling.
At high RPM, you have less filling, but at a higher rate.

The biggest stress from high RPM is the unloaded TDC of the exhaust stroke. The rod changes direction with high loads on it's bearing and pin.


^ This. The largest mechanical load on the engine is on the rod bolts at TDC on the exhaust stroke (they are in tension). On the exhaust stroke, there is no gas pressure in the cylinder to cushion the inertia of the rod and piston.

If you take your fist and put it to your chest and then punch outward as hard and far as you can, it's probably not going to hurt your arm. If you put a 10 lb dumbbell in your hand and do the same thing, your arm will probably pull out of it's socket. This is the same thing as the piston. Think of it as, the higher you rev the engine, the heavier that dumbbell becomes.

The shorter the crankshaft stroke, the higher you can safely rev the engine. Engines with higher redlines have shorter strokes than other engines. Formula 1 engines have a 4" bore and a 1.7" stroke. This ultra short stroke allows them to rev this high.

 

[Nick R]

Heck, don't even think about turbo charged engines like mine. In addition to having 16psi of boost (on the stock tune alone), it is undersquare, with a stroke that is not insignificantly longer than the bore. Redline on this engine is only 6,500RPM. GMs "High Feature" 3.0/3.6L V6s have redlines slightly above 7,000RPM, our equinox exhibits this.

 

[SteveSRT8]

Originally Posted By: mva
My BMW's manual advises not to rev over 4,000 rpm until the oil temperature is above 60C. Some other BMW's have variable redlines that increase as the engine warms up.


This is even on my 2006 Chrysler. Hardly a BMW only feature.

 

[SteveSRT8]

Originally Posted By: OVERK1LL
Usually, the engine has been tested well past the value that is settled on as the "redline". However, the Redline occurs shortly after peak power in many cases.


This! Typically the cam is what sets the redline in many cars.

FWIW, the 5.7 Hemi has a much lower redline than my car. But my car was odd in due to power peak at 6200 and shift point at the exact same rpm! Factory redline is 6400

Best thing I ever did was RAISE the redline to 6600, then allowing the shift point to occur at 6400. Makes the car noticeably quicker through the gears.