Rev Limits

antodeco

Just a quick question! Revometer goes red after 7500 revs. Is it damaging to your car to be driving at 5k or 6k revs? Reason I ask, sometimes if im over taking to get a good run i let the car run up to around 6k, and I want to make sure im not f**king the car up!

Thanks

Anan1

It's fine.

crosstownk

Once you keep within the rev limit you should be OK. Most engines have a rev limiter.

But, why do you need to drive the car that hard?

unkel

Just out of interest - what car is is, antodeco? A red line of 7500RPM is a good bit higher than the average car

All cars have rev limiters afaik so it's not possible to do direct damage to the engine by revving it as far as you can. Best not attempt it when the engine is cold though!

crosstownk wrote:

why do you need to drive the car that hard?

OP is overtaking and the safest way to overtake is generally the fastest way to overtake

Guy:Incognito

unkel wrote:

OP is overtaking and the safest way to overtake is generally the fastest way to overtake

Its fairly hogh revs though, ive never gotten near 6k revs when overtaking. The op may be needlessly overtaking in too low a gear.

SouperComputer

Regardless of the engine, the wear rate increcases exponentially as you get closer to the redline. Rough example: the wear/load on an engine is about 35% less at 5000 than at 6000. If it redlines at 7500, 6K should be OK. In any case, if you dont have to rev the balls off it, then dont

Also, keep in mind, that on average, the best time to change up is 500-700RPM before the redline. YMMV though, so consult the documentation for your car on this

Also keep in mind that a revimiter wont do $hit if you overrev on a downchange!

Biro

Very true there. The more frequently you use excessive revs, the more the wear you cause on your engine. If you have a car that needs a lot of revs to get the best from it, keep the oil changes frequent, use the oil that is recommended by the manufacturer, and never rev hard on a cold engine.
It's not damaging the car by reving high, it's just wearing it a lot quicker than at normal revs (ie below 2,500).

kluivert

Thats nuts, remind me not to buy your car

It depends on the type of car you have.

My Astra has a max torque at 4000 rpms and max bhp at 5600rpm, so when am over taking theres no point in going past 4000rpm as the car runs out of steam (pull) at this stage, instead I change up gear and boot off down the road.

Personally it sounds like you either need to use the gear more effectively or need a big engined car.

Wear and tear also increases by having a heavy foot as well. Theres a difference between reaching 6k slowly than compared to flooring it to 6k.

If that is your driving style then make sure to change the oil regular, the harder you drive the quicker the oil dilutes.

cpoh1

kluivert wrote:

It depends on the type of car you have.

My Astra has a max torque at 4000 rpms and max bhp at 5600rpm, so when am over taking theres no point in going past 4000rpm as the car runs out of steam (pull) at this stage, instead I change up gear and boot off down the road.

Personally it sounds like you either need to use the gear more effectively or need a big engined car.

Wear and tear also increases by having a heavy foot as well. Theres a difference between reaching 6k slowly than compared to flooring it to 6k.

If that is your driving style then make sure to change the oil regular, the harder you drive the quicker the oil dilutes.

What exactly does the oil dilute with???? Cordial, coke, water maybe???

You would "boot off down the road" with much more progress if you revved your car to its maximum bhp rpm and then changed up gears. Thar way you keep the car in its power band instead of dropping it to well below its maximum torque value. You are in essence not driving the car to anywhere near its potential, you need to use the gearing of the car more effectively yourself!

Can any of the internet mechanics out there tell me what you are wearing on the engine when you rev it to its redline? Cars that have a redline at say 8000rpm have the running gear to tolerate the car being revved to that limit. Valve springs and retainers, Lma's, reinforced sleeves on the block, etc etc. Whether the car is in 5th or 2nd gear it doesnt matter the engine will be spinning at the same revolutions per second regardless.

I had an old mk2 crx wityh 200,000 miles on the clock that saw its 8200rpm redline daily and was still perfect. Compression was very close to stock and it burned only a little oil.

Wear and tear increases on an engine when you drive the car from cold (best to let it warm up in the drive so the oil is above at least 50 degrees if its a performance car for minimum engine wear) and when you dont change the oil regularily enough. Revving the car is not a direct cause for engine wear.

Mojito

The 2ZZ-GE engine in the Celica T-Sport redlines at 8200RPM with lift only being activating at 6000RMP. If the engine is cold the ECU reduces the redline to 7000RPM so not to engage lift while the engine is cold.

The motor will happily run at ~4000 RPM for extended periods of time, and during stress testing the motor will run at the 8200RPM redline for extended periods without issue.

jon_95

thats some nice copy and paste from google man, well done.

the corrolla fx 1.6 20v hits the red line ay 10000 rpm and limits at 11500,
generally if you intermittently bring revs to within 500 rpm of the redline its fine, limiting in a gear will dammage your gearbox and put undue strain on the timing belt potentially snapping it,
driving for hours about 4000 revs in any car will damage it, rev limits vary in every car, usually follows how many valves per cylinder though. 2 per cylinder low revving, 5 percylinder high revving, turbos will also effect the rev range of a car.

Biro

cpoh1 wrote:

Can any of the internet mechanics out there tell me what you are wearing on the engine when you rev it to its redline? Cars that have a redline at say 8000rpm have the running gear to tolerate the car being revved to that limit. Valve springs and retainers, Lma's, reinforced sleeves on the block, etc etc. Whether the car is in 5th or 2nd gear it doesnt matter the engine will be spinning at the same revolutions per second regardless.

Well, no disrespect, but I'll take Honda or Toyotas word over yours regarding the treatment of high reving engines. If it's in the manual, I'll believe it. They built the engines, they must know the long term effects.

Mojito

Mojito wrote:

The 2ZZ-GE engine in the Celica T-Sport redlines at 8200RPM with lift only being activating at 6000RMP. If the engine is cold the ECU reduces the redline to 7000RPM so not to engage lift while the engine is cold.

The motor will happily run at ~4000 RPM for extended periods of time, and during stress testing the motor will run at the 8200RPM redline for extended periods without issue.

Agreed. This video on youtube

https://www.youtube.com/watch?v=nS1I_pz_Hd8

(at about 1:30) shows them testing the focus ST engine by running it at maximum revs for days continously. This simulates the lifetime of the engine.

cpoh1

Biro wrote:

Well, no disrespect, but I'll take Honda or Toyotas word over yours regarding the treatment of high reving engines. If it's in the manual, I'll believe it. They built the engines, they must know the long term effects.

And what exactly does the manual say that contradicts what ive written earlier? What parts of the engine are you wearing when you rev a vtec engine to its redline? Considering the b16 from my mk2 and mk3 crx only peaked power wise at 7800rpm I would say thats exactly what honda designed the car to do. All my hondas from the past were high milers and loved to hit the redline.

Gerry

cpoh1 wrote:

What exactly does the oil dilute with???? Cordial, coke, water maybe???

You would "boot off down the road" with much more progress if you revved your car to its maximum bhp rpm and then changed up gears. Thar way you keep the car in its power band instead of dropping it to well below its maximum torque value. You are in essence not driving the car to anywhere near its potential, you need to use the gearing of the car more effectively yourself!

Can any of the internet mechanics out there tell me what you are wearing on the engine when you rev it to its redline? Cars that have a redline at say 8000rpm have the running gear to tolerate the car being revved to that limit. Valve springs and retainers, Lma's, reinforced sleeves on the block, etc etc. Whether the car is in 5th or 2nd gear it doesnt matter the engine will be spinning at the same revolutions per second regardless.

I had an old mk2 crx wityh 200,000 miles on the clock that saw its 8200rpm redline daily and was still perfect. Compression was very close to stock and it burned only a little oil.

Wear and tear increases on an engine when you drive the car from cold (best to let it warm up in the drive so the oil is above at least 50 degrees if its a performance car for minimum engine wear) and when you dont change the oil regularily enough. Revving the car is not a direct cause for engine wear.

The oil will gradually dilute with unburned fuel, but this varies between cars, on most its negligble.

On the rest of the points, I agree with you.
Driving from max torque to max power will give you the best acceleration, gear ratios permitting.

SouperComputer, I'd like to know where this figure for exponential engine wear comes from. Its widely acknowledged that most engine wear happens on startup, I've not read any warnings about not revving the engine a bit.

Biro, what does it say in the manual about revving the engine? Do you want to share it with us?
The manual for my car says that you can briefly bring it into the hatched red zone ( the zone between normal and the red ), but not to go into the solid red. Guess what, that means I can rev it to 5500 rpm without worrying, and its a really low revving car.
What the hell are all you idiots going on about.. this kind of attitude is the same stuff that leads to people labouring the hell out of petrol cars by changing gears at 1800 rpm, and then wondering why the car has to go into the garage again.
It makes me laugh to think of all the cars with VVTI and VTEC that has never been called into service. Oh no, the engine is making some noise, that has to be bad.

The OP's car can rev to 7500 rpm. If it wasn't safe to rev it past 5 or 6k rpm, the manufacturer would have placed the limiter at that point, wouldn't they? Listen to cpoh1 and jon_95, they know what they are talking about.
<edit>spelling and grammar</edit>

SouperComputer

SouperComputer, I'd like to know where this figure for exponential engine wear comes from. Its widely acknowledged that most engine wear happens on startup, I've not read any warnings about not revving the engine a bit.

It comes from conversations ive had over the years with different engineers and engine builders ive worked with. The figure of 30% was an off the cuff figure. My point point was that as revs increase, load increases expenionally. Weather its a pushrod V8, a BMW VANOS or a B16, this is a consequence of physics. How the engine deals with that load is another discusion. I also made this point from the perspective that the engine is fully warmed up.

I dont think anyone could argue that a most damage is done when cold and oil is not up to temp. That why the NASCAR cars I worked on last week have heat probes in the oil tank tank. Before you start them, you pull teh belt off the oil pump and spin it. The oil tank is about 5.5Gal so the whole process of heating takes ablut 30 mins!

I agree with you about labouring, it can be espcially hard on bearings and is not good either.

So what am I saying? Dont rev to high or too low

cpoh1

SouperComputer wrote:

It comes from conversations ive had over the years with different engineers and engine builders ive worked with. The figure of 30% was an off the cuff figure. My point point was that as revs increase, load increases expenionally. Weather its a pushrod V8, a BMW VANOS or a B16, this is a consequence of physics. How the engine deals with that load is another discusion. I also made this point from the perspective that the engine is fully warmed up.

I dont think anyone could argue that a most damage is done when cold and oil is not up to temp. That why the NASCAR cars I worked on last week have heat probes in the oil tank tank. Before you start them, you pull teh belt off the oil pump and spin it. The oil tank is about 5.5Gal so the whole process of heating takes ablut 30 mins!

I agree with you about labouring, it can be espcially hard on bearings and is not good either.

So what am I saying? Dont rev to high or too low

An engine under full load will not increase wear either, as I mentioned earlier the internals of the engine are designed to withstand this kind of movement of he pistons, cams valves and has been built accordingly.

The only reason continued high revs (and I mean 6000-7000rpm for a few hours) can damage an engine is that the oil temperatures rise to above their designed limits of lubrication and the ploymers in the oil begin to break down (anything over 120 degrees can be dangerous to an engine. When this happens and the oil stops doing its job the friction elements in the engine will begin to wear. This is why 90% of people change their oil before and after a track event. So once again it all comes down to the oil. cold oil, worn oil and cheap oil are the main contributors to engine failure such as worn piston rings. How high you rev the car wont effect the wear on the engine in the slightest once all the above is looked after.

On a side note it amazes me how many people throw any old oil in their car and how little they change it considering how cheap and easy it is to do. No matter what car ive owned ive never left my oil go more than 6000kms before changing it.

Gerry

SouperComputer wrote:

It comes from conversations ive had over the years with different engineers and engine builders ive worked with. The figure of 30% was an off the cuff figure. My point point was that as revs increase, load increases expenionally. Weather its a pushrod V8, a BMW VANOS or a B16, this is a consequence of physics. How the engine deals with that load is another discusion. I also made this point from the perspective that the engine is fully warmed up.

I dont think anyone could argue that a most damage is done when cold and oil is not up to temp. That why the NASCAR cars I worked on last week have heat probes in the oil tank tank. Before you start them, you pull teh belt off the oil pump and spin it. The oil tank is about 5.5Gal so the whole process of heating takes ablut 30 mins!

I agree with you about labouring, it can be espcially hard on bearings and is not good either.

So what am I saying? Dont rev to high or too low

I agree about the loads increasing with revs. Its just that I think the manufacturers build this into their calculations when they are building the engine, and specifying rev limits. If, as you suggest, you change 500-700 rpm before the redline, you will be fine. If you watch that focus video, it states that they run the engine for 4 weeks at max revs, and that this is the equivalent of 150,000 miles. It also shows a torque reading of 250 nm, so its obviously under load during this test also.
I couldn't agree more about warming up the oil before driving hard. Its worth remembering that the oil warms up much slower than the coolant, so even if the temp guage is up to half way, the oil may still not be up to temp. An oil temp guage is really handy to have.

Whats the point of toyota, honda etc putting in variable valve timing/lift systems that only activate at 5000 - 6000 rpm if they are then going to frown on you revving the car that high?

The point was made about it not being safe to drive at 4k rpm for hours, this is also ridiculous. Think about it, many smaller cars have short gearing to allow them make the most of their limited power. Now, if you are driving one of them in a country that has decent roads, and trying to make decent progress (without breaking the law), you may well end up driving at 4k rpm for hours. Any modern car should be able to stand up to this no problem.
It explicitly states in the manual for my car that sustained cruising at high rpm is not a problem, and my car was made in 1991.

SouperComputer

An engine under full load will not increase wear either, as I mentioned earlier the internals of the engine are designed to withstand this kind of movement of he pistons, cams valves and has been built accordingly.

Built accordingly (you hope!) with built in obsolecence. I dont need to elaborate on my point about mechanical load with respect of revs, the laws of physics do that for me.

The only reason continued high revs (and I mean 6000-7000rpm for a few hours) can damage an engine is that the oil temperatures rise to above their designed limits of lubrication and the ploymers in the oil begin to break down (anything over 120 degrees can be dangerous to an engine. When this happens and the oil stops doing its job the friction elements in the engine will begin to wear.

Are you kidding me? The ONLY reason? So if you cool the oil, the engine will run forever? Structural failures never happen (or dont happen sooner) due to the laws of physics in relation to higher revs I mentioned earlier? Conrods and cranks never snap? Pistons never shatter?

I'll reiterate my point again before I depart, no matter how you build an engine the loads on its internals increase exponentially with respect to rotational speed.

Some engines deal with this better than others and withstand the internal loads better, however even these engines will last longer if you avoid revving the nuts off them when you can.

Biro

SouperComputer wrote:

Built accordingly (you hope!) with built in obsolecence. I dont need to elaborate on my point about mechanical load with respect of revs, the laws of physics do that for me.





Are you kidding me? The ONLY reason? So if you cool the oil, the engine will run forever? Structural failures never happen (or dont happen sooner) due to the laws of physics in relation to higher revs I mentioned earlier? Conrods and cranks never snap? Pistons never shatter?

I'll reiterate my point again before I depart, no matter how you build an engine the loads on its internals increase exponentially with respect to rotational speed.

Some engines deal with this better than others and withstand the internal loads better, however even these engines will last longer if you avoid revving the nuts off them when you can.

I 100% agree with your posts. I can't fathom how anyone could think that an engine running at 6000 rpm is having exactly the same effect as that engine idling at 700rpm provided you keep the oil at the same temp in both. Thats like saying that if you oiled your ass then it wouldn't matter if I towed you along a carpet with the pants down at 40mph or 100mph, you wouldn't get carpet burn till the oil heated up? I'm not saying that reving a v-tec at 7000rpm is going to break it, I'm saying that someone who drives nice and handy 70% of the time and stretches the engine the odd time for overtaking or whatever, is a lot better than someone who gets up in the morning and turns on the car, waits till the oil is at operating temp then keeps the engine on the boil just 500rpm short of the limiter all day every day. After 300,000 miles we'll see which engine is in better condition, given that the oil changes are performed in each according to the way they're driven.

Anyway, Gary, here's a scan of a manual from a T-sport celica. Toyota must have just put this in for the craic, if ye boys are to be believed.

jon_95

SouperComputer wrote:

Are you kidding me? The ONLY reason? So if you cool the oil, the engine will run forever? Structural failures never happen (or dont happen sooner) due to the laws of physics in relation to higher revs I mentioned earlier? Conrods and cranks never snap? Pistons never shatter?

I'll reiterate my point again before I depart, no matter how you build an engine the loads on its internals increase exponentially with respect to rotational speed.

Some engines deal with this better than others and withstand the internal loads better, however even these engines will last longer if you avoid revving the nuts off them when you can.

Conrods and cranks snap as a result of torque while accelerating, totally different laws of physics, an engine will withstand the centrifugal forces of its own internals at any rpm, crank bearings and conrod sleeves are designed to withstand ridiculous mileage, ive done work on engined with 100k+ hours and the sleves on the conrods are perfect, the only area of the engine where the wear will increase due to higher revs is on the piston sleeves (if has them) and rings, and to put this in perspective the mk2 golf gti piston rings only seated in after 60k miles, so they will also last...

rotational speed is not a factor in engine wear,

fletch

kluivert wrote:

Thats nuts, remind me not to buy your car

It depends on the type of car you have.

My Astra has a max torque at 4000 rpms and max bhp at 5600rpm, so when am over taking theres no point in going past 4000rpm as the car runs out of steam (pull) at this stage, instead I change up gear and boot off down the road.

Shouldn't you be changing at 5,600rpm then? Your car is just starting to accelerate and you up-shift
Have you learned from this thread?
Personally I red line my car once a day, gives it the engine a good clean out I think.
In that youtube video, they run the car at max revs for 4 weeks :eek: so I don't think a few short blasts to overtake is going to be a problem.

Biro

If high revs doesn't cause excessive engine wear, how come Ford run the engine at max revs for 4 weeks to simulate 150,000 miles?

Mojito

jon_95 wrote:

thats some nice copy and paste from google man, well done.

This is a copy and past!

PS: It's not from google...

The 2ZZ-GE is a 1.8 L (1796 cc) version built in Japan. Bore is 82 mm and stroke is 85 mm. Output is 180 hp (134 kW) at 7600 RPM with 130 ft·lbf (176 N·m) of torque at 6800 RPM. It uses MFI fuel injection, has VVTL-i, and features forged steel connecting rods. Compression ratio is 11.5:1. Unlike others in the ZZ family, the 2ZZ-GE requires "premium" gasoline - 91 octane or above in the USA. Power output for this engine varies depending on the application and tuning, with the Lotus Elise and Lotus Exige offering 190 hp but the Pontiac Vibe, Toyota Corolla and Toyota Matrix versions only developing 180 hp (+2005: 170 hp). The Australian variant (Corolla Sportivo and Celica GTS) is 141kw@7600 and 181N·m Torque due to noise regulations. (Toyota recalled them for a flash of the ECU to up their output to put them into the more lenient "sports car" noise category). The Corolla Compressor and Lotus Exige S add a supercharger to achieve 225 hp, while the Exige 240R's supercharger increases output to 240 hp.

The 2ZZ-GE utilizes a dual camshaft profile system (the "L" in VVTL-i, known by enthusiasts as "lift"), to produce the added power without an increase in displacement or forced induction compared to the lesser engines in the ZZ series. This is similar in concept to Honda's i-VTEC, but the two systems are very different in design and execution.
Disintegrated oil pump
Disintegrated oil pump

Toyota commissioned Yamaha to design the 2ZZ-GE, and it shares several similarities with street bike engines, the most notable being the relatively high RPM design. The high-output cam profile is not activated until above 6000 RPM (the exact point of engagement is different depending on the vehicle, year, and ECU involved). On all of the Toyota-built vehicles, redline begins at 8200 RPM while the tachometer is typically numbered to 9000, giving an incredibly small "unusable" range. The Toyota ECU electronically limits RPM to about 8200 (through fuel and/or spark cut). It is impossible to "over-rev" the engine with the throttle alone; a downshift from a higher gear is required. But if you manage to do it, the oil pump commonly disintegrates the lobe ring.

The motor will happily run at ~4000 RPM for extended periods of time, and during stress testing the motor will run at the 8200RPM redline for extended periods without issue. For the first few years of production, the engines were notorious for breaking off the "lift bolts" inside the engine. This didn't do any damage, but did hamper performance, as the high output cam profile would not engage properly. Toyota fixed the problem in late 2002, and there is a TSB for dealers showing what bolt to replace and the redesigned bolt.

JHMEG

How to drive to the shops:

http://youtube.com/watch?v=KIx3s2AHlpQ

200ps from a 1.8L engine without turbos etc. (Can't beat that sound either)

Lovely

Rowley Birkin QC

antodeco wrote:

Revometer goes red after 7500 revs.

antodeco

bigkev49 wrote:

easier then going technical! At least everyone knew what I mean!

jayok

kluivert wrote:

My Astra has a max torque at 4000 rpms and max bhp at 5600rpm, so when am over taking theres no point in going past 4000rpm as the car runs out of steam (pull) at this stage, instead I change up gear and boot off down the road.

You need to figure out the difference between power and torque if you're upshifting at 4k.

Drive a Honda (actually you did, the 1.8 Civic!) to see the correct upshift point if you need to accelerate hard.