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Overrevving Limit?

  • 13-12-2009 5:17pm
    #1
    Registered Users, Registered Users 2 Posts: 167 ✭✭


    Hey guys.....
    Ive always been fairly conservative about revving my car, no matter which one im driving....
    Currently im driving a 2004 Fiat Punto 1.2, where the revs go from 0-7000...
    I usually limit myself to 3000 in 5th gear, but im wondering how much revving can you do before it damages or is dangerous to the car? I just want to keep my car in good condition, but like 3000 isnt even half way.....the car does about 65/70mph at these revs, but is that too high?
    Is there a recommened percentage of ur maximum revs or what?

    Cheers,
    Kav


Comments

  • Closed Accounts Posts: 1,149 ✭✭✭skyhighflyer


    Rev it as hard as you like, your car like pretty much every other has a rev limiter which willl stop it doing major damage... on yours it's probably around 6.2k revs.

    It's worth keeping the revs low (i.e., below 3k rpm) for the first few minutes of your journey as the warming up period is where most engine wear occurs, but asides from that I wouldn't worry about it.

    However keeping your revs low saves fuel and reduces noise, with a standard Punto there's not much to be gained from revving it hard. Your 3k rev limit does seem conservative and perhaps even dangerous; merging on to a motorway in a supermini you shouldn't be afraid to stretch her out to 5k to get up to speed :)


  • Registered Users, Registered Users 2 Posts: 4,102 ✭✭✭afatbollix


    ya listen to him^^^^^^


  • Closed Accounts Posts: 1,044 ✭✭✭AugustusMaximus


    I wouldn't be putting the revs above 5000 for very long. OK during acceleration though.

    Extra revs = extra stress on pistons and con rods and the like.


  • Closed Accounts Posts: 4,445 ✭✭✭Absurdum


    Kav1892 wrote: »
    Is there a recommened percentage of ur maximum revs or what?

    100% :D


  • Registered Users, Registered Users 2 Posts: 167 ✭✭Kav1892


    Rev it as hard as you like, your car like pretty much every other has a rev limiter which willl stop it doing major damage... on yours it's probably around 6.2k revs.

    It's worth keeping the revs low (i.e., below 3k rpm) for the first few minutes of your journey as the warming up period is where most engine wear occurs, but asides from that I wouldn't worry about it.

    However keeping your revs low saves fuel and reduces noise, with a standard Punto there's not much to be gained from revving it hard. Your 3k rev limit does seem conservative and perhaps even dangerous; merging on to a motorway in a supermini you shouldn't be afraid to stretch her out to 5k to get up to speed :)

    Haha so im being a bit ridiculous with being so conservative by the sounds of it?? I had no idea....i just presumed the faster i went the more stress i put on the car.....so for a 40 minute motorway journey at 4/5000 revs, there would be no stress on the engine as long as i let the car have its warming period?

    Thanks,

    Kav


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  • Registered Users, Registered Users 2 Posts: 167 ✭✭Kav1892


    Absurdum wrote: »
    100% :D

    Lol :o


  • Closed Accounts Posts: 1,149 ✭✭✭skyhighflyer


    Kav1892 wrote: »
    Haha so im being a bit ridiculous with being so conservative by the sounds of it?? I had no idea....i just presumed the faster i went the more stress i put on the car.....so for a 40 minute motorway journey at 4/5000 revs, there would be no stress on the engine as long as i let the car have its warming period?

    Thanks,

    Kav

    At 5k revs in fifth gear, your Punto would probably be nearing 100mph, the engine wouldn't be under undue stress but your concentration levels and eardrums might be ;)

    But cruising at 80-85mph at say 4.5k revs would in fact be less stressful for your car in terms of wear to engine / clutch / gearbox than city traffic would.

    That said when you are tipping around town or generally cruising about there's no need to have the revs high, but like I say you shouldn't be afraid to stretch it out when you need a turn of speed.


  • Registered Users, Registered Users 2 Posts: 167 ✭✭Kav1892


    At 5k revs in fifth gear, your Punto would probably be nearing 100mph, the engine wouldn't be under undue stress but your concentration levels and eardrums might be ;)

    But cruising at 80-85mph at say 4.5k revs would in fact be less stressful for your car in terms of wear to engine / clutch / gearbox than city traffic would.

    Ok thanks......i think ill branch out from 3000k so :D
    This will indeed take some time off my M7 journeys in d slow lane :rolleyes:

    Thanks again :)


  • Registered Users, Registered Users 2 Posts: 4,102 ✭✭✭afatbollix


    Keep in the most left on the M7 unless you want to over take.. Do not stay in the right hand lane if the lanes on your left are free


    * As you dident know how much you can rev your car Im guessing you dident know this


  • Registered Users, Registered Users 2 Posts: 167 ✭✭Kav1892


    afatbollix wrote: »

    * As you dident know how much you can rev your car Im guessing you dident know this

    Thanks but im actually really good with the rules of the road.....i just dont have a clue of my car's limits.....even more annoying than people who sit in the right lane of motorways are those who stop in yellow box junctions, blocking ur path when the traffic lights change for ur side!! :D

    But thanks anyways.... :)


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  • Registered Users, Registered Users 2 Posts: 3,795 ✭✭✭Neilw


    Engines are designed to be rev'd, it's good for them once the oil (not coolant ;)) is up to temp. It's better for an engine if high revs are used on a regular basis.

    Ever hear of an Italian tune up :D


  • Registered Users, Registered Users 2 Posts: 23,067 ✭✭✭✭Esel
    Not Your Ornery Onager


    It's worth keeping the revs low (i.e., below 3k rpm) for the first few minutes of your journey as the warming up period is where most engine wear occurs, but asides from that I wouldn't worry about it.
    Best not to exceed 2,000 RPM during warm-up period.
    Extra revs = extra stress on pistons and con rods and the like.
    Define 'extra revs'. :confused: Any well-maintained engine will not be damaged by high revs unless the rev limit is exceeded. Fuel consumption, however, may plummet...
    Neilw wrote: »
    Engines are designed to be rev'd, it's good for them once the oil (not coolant ;)) is up to temp.
    What he said.

    Not your ornery onager



  • Closed Accounts Posts: 1,044 ✭✭✭AugustusMaximus


    esel wrote: »

    Define 'extra revs'. :confused: Any well-maintained engine will not be damaged by high revs unless the rev limit is exceeded. Fuel consumption, however, may plummet...

    High revs. Would 5,500 revs constantly for say two hours straight be good for an engine for instance ? There would be a lot more stress on engine parts in comparison to say 3000 revs.


  • Registered Users, Registered Users 2 Posts: 1,107 ✭✭✭ytareh


    I wouldnt go near max revs until Id done at least 10-15 minutes driving and ideally almost double that .While theres no problem pushing her on a bit , say 4 or even maybe near 5k rpm for brief periods after 15 minutes ,I wouldnt be bouncing off the rev limiter until VERY well warmed up...


  • Registered Users, Registered Users 2 Posts: 23,067 ✭✭✭✭Esel
    Not Your Ornery Onager


    High revs. Would 5,500 revs constantly for say two hours straight be good for an engine for instance ? There would be a lot more stress on engine parts in comparison to say 3000 revs.
    If not above the rev limit, and engine is well-maintained and lubricated, then it wouldn't do the engine any harm whatsoever.

    Not your ornery onager



  • Registered Users, Registered Users 2 Posts: 3,795 ✭✭✭Neilw


    High revs. Would 5,500 revs constantly for say two hours straight be good for an engine for instance ?

    Less stress then trundling up a hill in 5th with the engine rattling away around 1100rpm. Rev's are there to be used ;)


  • Registered Users, Registered Users 2 Posts: 1,560 ✭✭✭Prenderb


    3000 rpm or so would be in the nice economical zone. Remember that the longer you spend at high revs, the more fuel is burnt per minute.

    There is no argument for revving the engine high, just because you can, but don't be afraid (once warmed up as the guys have said) to "stretch the legs" on your engine to build up speed for merging to the motorway, etc.


  • Registered Users, Registered Users 2 Posts: 4,663 ✭✭✭stealthyspeeder


    Some engines (Mazda's rotarys for example) need to be given some high revs every once in a while to keep them in top condition. I think I read somewhere that a V-tec needs to given a blast at the top end every now and again to keep engine depostis down? Is that true?


  • Registered Users, Registered Users 2 Posts: 3,795 ✭✭✭Neilw


    High revs. Would 5,500 revs constantly for say two hours straight be good for an engine for instance ? There would be a lot more stress on engine parts in comparison to say 3000 revs.
    betafrog wrote: »
    2,000? :eek:

    I'd be in 5th gear before I even get to 30mph if I followed that rule.. While I wouldn't go bouncing off the red line as soon as I pull out of the drive I would think 2,000 is far too conservative a limit, I would say anything around the 60% of your engines limit would be alright for the first 5-10 minutes.. Which would mean keeping it below 4,000 for me...

    4k is too high, I stick to 2.5k rpm on mine for the first 15-20 mins as it takes at least that long for the oil (not coolant) to get to operating temp.

    4k rpm in a diesel would be prob 90% or so of the engines rev limit, a sure turbo killer!


  • Registered Users, Registered Users 2 Posts: 1,917 ✭✭✭B00MSTICK


    It depends on the car I'd imagine, 2.5k for 20 mins in an S2000 would be a bit overcautious.


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  • Closed Accounts Posts: 4,091 ✭✭✭Biro


    The higher the revs, the more wear on the engine. That's not to say that reving it is bad, but prolonged use of an engine at 5,000rpm will be far more taxing to that engine than one used at 2,000rpm and stretched to 5,000 briefly for accellerating. It stands to reason really.


  • Registered Users, Registered Users 2 Posts: 8,718 ✭✭✭Matt Simis


    Biro wrote: »
    The higher the revs, the more wear on the engine. That's not to say that reving it is bad, but prolonged use of an engine at 5,000rpm will be far more taxing to that engine than one used at 2,000rpm and stretched to 5,000 briefly for accellerating. It stands to reason really.

    Yeah, Im a bit surprised people stating 4-5k RPM for 2hrs straight is ok and as designed. OP needs to get a bigger engine, I could drive at 100mph at 3k RPM.


  • Registered Users, Registered Users 2 Posts: 4,663 ✭✭✭stealthyspeeder


    I know the Ford focus ST engine is tested to run at over 5 thousand RPM for 150,000 miles constantly! (obviously a test engine, not the one they stick in your car!!)

    So I think the modern engine should be able to take the high sustained revs for a lot longer than the could back in the 80's and 90's

    Edit: saw this in 5th gear.


  • Registered Users, Registered Users 2 Posts: 22,815 ✭✭✭✭Anan1


    Matt Simis wrote: »
    Yeah, Im a bit surprised people stating 4-5k RPM for 2hrs straight is ok and as designed.
    Back when I lived in Germany, I had a Golf GTI 16v which had a top speed of 200km/h at (from memory) 6000rpm in top. I drove for hours at that speed, with no obvious ill-effects. Whilst i'm sure wear would have been reduced at lower speeds, I think most engines are designed to take it.


  • Closed Accounts Posts: 4,091 ✭✭✭Biro


    Matt Simis wrote: »
    Yeah, Im a bit surprised people stating 4-5k RPM for 2hrs straight is ok and as designed. OP needs to get a bigger engine, I could drive at 100mph at 3k RPM.

    Me too. It's simple Physics. The more rpm the engine is doing over a set distance the more wear and tear is happening to the engine. And it wouldn't be as simple as driving 100 miles at 5,000rpm is causing twice as much wear as driving 100 miles at 2,500rpm because there are many factors to consider, such as the increased inertia of the moving parts, the extra heat generated and the knock on effect, etc.


  • Closed Accounts Posts: 4,091 ✭✭✭Biro


    Anan1 wrote: »
    Back when I lived in Germany, I had a Golf GTI 16v which had a top speed of 200km/h at (from memory) 6000rpm in top. I drove for hours at that speed, with no obvious ill-effects. Whilst i'm sure wear would have been reduced at lower speeds, I think most engines are designed to take it.

    It's not that they can't take it, its that its causing excess wear and tear for no good reason. No point in sitting at 70mph in 3rd at 6000rpm just because you can and the engine is "made for it".
    Car manufacturers test their cars to destruction at engine speeds like 5,000rpm for 150,000 miles like above. If there was no difference then they'd just test them at 1500rpm for 150,000 miles.


  • Posts: 24,714 ✭✭✭✭ [Deleted User]


    Biro wrote: »
    It's not that they can't take it, its that its causing excess wear and tear for no good reason. No point in sitting at 70mph in 3rd at 6000rpm just because you can and the engine is "made for it".
    Car manufacturers test their cars to destruction at engine speeds like 5,000rpm for 150,000 miles like above. If there was no difference then they'd just test them at 1500rpm for 150,000 miles.

    But the point he is making is that in places like Germany with high speed limits/ no limits a car travelling fast for long periods will be at high revs even in top gear. I think not giving a engine the beans every so often is probably worse in the long run.


  • Registered Users, Registered Users 2 Posts: 2,755 ✭✭✭ianobrien


    Just my €0.02.

    The majority of engine wear happens when the engine is cold. I know, as I bought a car that had 40K miles on it and had to rebuild the engine. The car lived in London, and as it never heated up, the block was worn, and needed a +60" overbore (a +30" wouldn't have gotten rid of the wear on the block)

    Once the engine is up to temperature (ie water, oil, metal etc) the wear on the block and other rotating parts is minimal, once there is good clean oil in the engine. If the oil changes are neglected, the oil gets thick and sludgie, blocking oilways and as a result, some moving parts do not get adaquite lubrication. One other problem is that with modern rev limiters, people can "bounce" the cars off the limiter. This can damage the engines because as the engine "bouces" off the limiter, the engine shakes and can ruin bearings (the Nissan SR20 engine is prone to the big end bearings turning when bouncing it off the limiter)

    Every moving part has a rev limit, and the rev limit of the engine will be set below the lowest limit of any part. For example, in the Ford Crossflow (it's an engine I know a bit about having to get one rebuilt), the GT spec engine had a rev limit of 6500rpm. Above that, the con-rod bolts were liable to break (wrecking the engine). When I rebuilt the engine, I fitted stronger bolts, and now the rev limit is 7500rpm. Above that, the crankshaft and con-rods will break.

    OP, once the engine is warm (after 10/15 miles or so), rev the engine up to the red zone (but not into it) all you want. The extra power is needed for merging onto motorways etc. I do it all the time with my engines, and I've never had any engine problems (indeed, one Micra at home had 160,000 miles of very hard driving, with plenty of high revs and never missed a beat and the engine still ran as sweet as the day we bought it)


  • Posts: 0 [Deleted User]


    5k rpm constantly on an engine with a redline of say 6.5k is relatively low revs as the stress to the components increase more than in linear when the revs increase.

    Back in the day Ford Sierra owner handbook listed safe constant revs limits they were only a couple of hundred rpm less than the max permissable engine speed.

    When engine is under load, the power of explosions are transferred in each cylinder via a piston, conrod and bearings at both ends of conrod to the crankshaft. At high speed the explosions cause proportionally less and less transient loads in the bearings. Under high speed there is also high oil flow rates and the chance of bearing failure is almost nil. When the revs are increased beyond the designed max speed something (normally conrod) will give.

    Also at high revs the oil film between piston rings and bores is also easier to maintain.

    The high revs on the other hand increases the forces when slowing down the piston approaching the TDC. However, this load is way less than the force that happens during the work cycle of the engine. The difference is getting a bigger with the modern engines and e.g. in VW TDI is relatively easy to bend the conrods if too much torque is used at bottom end of the rev range.

    Overloading the engine at low revs is way more damaging to the health of the engine than constant high revs (within in the allowed range) as the loads there are hammering in nature. Luckily modern engines have very high oil pressure at idle leading to many a saved engine from bearing failures.

    All the german cars in general since first beetles are designed to be driven at top speed constantly. I once used to once have a MK2 Escord with 2 litre engine mated with the 1.6 drivetrain. This is the only car that I have ever had that could not be driven at top speed constantly as the engine would reach max allowed revs on 4th.


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  • Moderators, Business & Finance Moderators Posts: 17,852 Mod ✭✭✭✭Henry Ford III


    Meh. I've done trackdays with maximum revs under 6k.


  • Registered Users, Registered Users 2 Posts: 491 ✭✭woody33


    I'm following this with great interest as my high-milage '97 Polo 1.0L is pretty low geared. It usually spins around our 80Km local roads quite happily but a couple of days ago I went for a long drive on 100Km roads where it was at maybe 3500 revs with a light throttle. That's usually near the max I'd rev to before changing gear, so I was wondering what a safe cruising speed/rev range would be. Interesting that lowish revs/lots of throttle is more efficient that the opposite (within reason).


  • Registered Users, Registered Users 2 Posts: 23,067 ✭✭✭✭Esel
    Not Your Ornery Onager


    betafrog wrote: »
    2,000? :eek:

    I'd be in 5th gear before I even get to 30mph if I followed that rule.. While I wouldn't go bouncing off the red line as soon as I pull out of the drive I would think 2,000 is far too conservative a limit, I would say anything around the 60% of your engines limit would be alright for the first 5-10 minutes.. Which would mean keeping it below 4,000 for me...
    It's your engine, so cause it undue wear if you want....
    I know the Ford focus ST engine is tested to run at over 5 thousand RPM for 150,000 miles constantly! (obviously a test engine, not the one they stick in your car!!).
    It should be exactly the same engine they stick in your car - otherwise, what's the point?
    samih wrote: »
    5k rpm constantly on an engine with a redline of say 6.5k is relatively low revs as the stress to the components increase more than in linear when the revs increase.......

    Overloading the engine at low revs is way more damaging to the health of the engine than constant high revs (within in the allowed range) as the loads there are hammering in nature.
    Yep, lugging the engine can cause major wear to big-end and main bearings.
    woody33 wrote: »
    Interesting that lowish revs/lots of throttle is more efficient that the opposite (within reason).
    I'm afraid you've got that backwards. Lowish revs/lots of throttle can mean eventual disaster, if you are in too high a gear.....

    Not your ornery onager



  • Registered Users, Registered Users 2 Posts: 491 ✭✭woody33


    I'm afraid you've got that backwards. Lowish revs/lots of throttle can mean eventual disaster, if you are in too high a gear.....[/QUOTE]

    I was refering to this, but maybe it was in a different thread.

    http://autospeed.com/cms/A_111510/article.html

    They seem to say that you use less fuel getting up to speed in lowish revs and lots of throttle than high revs and little throttle. I'm not suggesting you should "lug" the engine though.

    What about max torque, keeping within the torque band in my case 3000 to 3600 revs. Or a bit above that so if you loose revs on a hill you are falling into a better torque range, the engine is more efficient and you might not have to give it extra throttle.


  • Closed Accounts Posts: 148 ✭✭TheElf


    I'm a firm believer that some cars, not all, need a good dogging through the revs now and then, stretch it's legs! I had an Almera a few years back, and if I gave it socks for a short while the car would feel brilliant for a while, gears nice and loose, good response, then I had a 1.4 golf, if I drove that hard all it wanted to do after was go asleep for a while, and I have a Mondeo at the moment, if i drive it slow for a few days it starts to feel sluggish and stiff, but give it a good run out the ring road and it feels brand new. Car's need exercise too! Or maybe it's all in my head!


  • Registered Users, Registered Users 2 Posts: 23,067 ✭✭✭✭Esel
    Not Your Ornery Onager


    woody33 wrote: »
    I was refering to this, but maybe it was in a different thread.

    http://autospeed.com/cms/A_111510/article.html

    They seem to say that you use less fuel getting up to speed in lowish revs and lots of throttle than high revs and little throttle. I'm not suggesting you should "lug" the engine though.
    I'm no engineer, but, to me, that article just reads like marketing gobbledegook designed to sell their product...

    Not your ornery onager



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  • Closed Accounts Posts: 7,686 ✭✭✭JHMEG


    The manufacturer set the rev limiter to a nice, safe 7k. You'd have to rev to 10k or beyond to do damage.


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