Megane Mk3 1.9 Dci 130 Revs

[defrostphone]

Just changed from a Megane Mk2 1.9 Dci 120 to a Mk3 1.9 Dci 130. The engine is revs high then my old 1.9 dci at 70mph and above. The mk2 1.9 was 1700 revs at 70mph and 2100 revs at 80mph in 6 gear, but the mk3 1.9 is 2000 revs at 70mph and 2500 revs at 80mph in 6 gear. Is this normal for the 1.9Dci 130 or not?

Thanks

[AlexB]

No, it's about 2000rpm at 70mph...

...The mk2 1.9 was 1700 revs at 70mph...

[ChrisM]

depends on what it is doing at the time really, if on a light decline my Mk2 1.9Dci will show around 17/1800 rpm at 70mph on the flat it reads around 2000rpm at 70, it is possible with a tail wind to lift off a little and get around 18/19000 rpm at 70mph , never had it as low as 1700rpm on the flat, I supose it may be possible if you are on a motorway which is quite empty, I did Cornwal last year and got something stupid like 62/5mpg out of it down the M5 at around 70mph, must say though there was hardly ny traffic on the road and we managed a constant crusing speed of 70 in fact my foot was at a guess just touching the throttle deffinatly no more than quater on weight and momentum just kept it going, don't remember the RPM didn't pay much attention but noticed the MPG as we had not long had the car so where taking note and comparing it to my wife Meg1 petrol we used for the same trip year before, but I supose that could have well been as low as 1700rpm, on an average day though 60mile round trip to work on an expressway I pull around 18/2000 rpm at 70mph and winter time around 43mpg and summer around 49mpg.

[AlexB]

No, it does not. In manual transmissions the gear ratio is fixed in each gear and the clutch is not supposed to slip when driving.

depends on what it is doing at the time really...

[davelowe]

No, it does not. In manual transmissions the gear ratio is fixed in each gear and the clutch is not supposed to slip when driving.

depends on what it is doing at the time really...

[ChrisM]

MMMMmm so what both Davelowe and Alexb are saying that when I travel along the expressway on a slight downhill gradiant with my foot hardly on the gas at around 1900 rpm I am slipping my clutch?
Have I got that right!
Intersting theory, considering my foot is not on the clutch pedal but on the foot rest, on a downhill gradiant it is possible, providing you don't have to slow down on the brakes or use engine braking, momentum takes over and you can use your throtle not to power the car but just keep it moving, your revs show the drop in engine RPM used to keep the vehicle moving, truck drivers use to use a slimilar process called slipstreaming where the truck in front "sucks" you along providing you are close enough they saved fuel in relitavley the same way by little use of the throtle.
Doesn't work on a flat road, stops working if you don't keep momentum going, taking foot completly off throtle will do this touching brake is leathal for momentum scrubs it off way to much, it is a balance between motion and throtle.
fixed torque is correct but remember where these figures come from, rolling roads and noe cad programmes in the same way that MPG is worked out, never in real land always virtual, the CC is a very heavy car and picks up a lot of momentum, simplest thing to do with it is use it in your favour when ever possible. You have to remember this car may have had a run of around 2100/300 rpm coming to this down hill section so it is storing a lot of energy, my point if you know your car well you can harness this energy and drop your revs a bit but keep the speed, the CC in one way is good at this due to its weight, but also quite poor due to its sanitised feedback to the driver
And if you both actually knew a manual transmission then you would also know clutch slip would not show up with a slight foot on throtle on a down hill, it shows up as lots of throttle, high revs and slow movement in the vehicle, usually shows up in gear changes when the car is labouring, for example out of junctions or up hills. clutch slip does not show up in crusing, and if you ment foot resting on clutch whilst crusing/driving why on earth would some idot ride with their foot perminatly resting on the clutch, Renault have even provided a foot rest for us not to do that.
Don't understand why you to are having a peck at me for something your own cars will do, apart from you obviously haven't untilised it, if the both of you are over 40 then you should be well ofay with it, in the days when driving instructors taught you how to drive a car not just pass a test....
That is when I was first introduced to momentum!
In days gone by that is what crusing actually ment, you picked up speed until you reached your "crusing speed" and sat on it, nither accelerating nor decellerating, this is how cruise control came to be, that does the same thing keeps your car at a certain speed, just more refined than your foot, you should also remember torque is basically what the car will pull (twisting motion), on a down hill gradiant the car is not pulling it is usally draging unless you are on the throttle, if you can equalise your throttle and speed then the car is almost in a neautral state (but not in Neautral), where the vehicle is neither slowing down through engine/gearbox drag, nor speeding up through torque pull, you can also change gear on a manual car by equalising the engine speed and gearbox speed with out using the clutch, I have never been very good at this but my friend can do it with ease in his Alfa, not a grind to be heard.

[davelowe]

my point if you know your car well you can harness this energy and drop your revs a bit but keep the speed

I've read this several times, and to be polite, it's plain wrong.
In a manual transmission vehicle in good order, the wheels will rotate at a ratio directly proportional to engine RPM in any given gear right from 0 to the top speed. If you are travelling at 70 miles per hour, the engine RPM will be, say, 2000rpm in 6th and will remain so going uphill, downhill, on the flat and even upside down (supposing you drive around a helical road). What it will not do is vary. Ever. The diameter of the wheel might change slightly with speed but that isn't the point. If your car does not follow the laws of physics, it is in some way faulty.

I have a masters degree in engineering, and Alex has I believe a doctorate (Ph.D) in some discipline. We are not idiots.

[ChrisM]

Momentum must be a thing of the past then used on old vehicles, either that or most vehicles cars and vans I have driven which just happen to be on the hefty side must defy the laws of physics then, wow a marvel in my own time, next I will be going back to the future!
If we are throwing degrees around I have one as well, don't most people these days, IT and Communications for me as well as a CCNA,CCNP and now CCIE, MCSE and MCITP, does not make me all knowing! it makes me good in my area, am I an idiot, possibly in many areas I am not "into to" to coin a phrase if that is how you think people see lack of knowledge.
If you do profuse to know eveything becasue you have a degree, and I feel as if I should perhaps be bowing a scraping because you felt the need to mention it, then that dose make you a pompus idiot, sorry to say!
I did notice you make no mention of the slipping clutch remark, for a person with a nengineering degree you should know all about clutch slipping, so why make this type of comment, I am also 90% sure I have had a debate with you over engine oil as well where you had said engine oil get thicker as it warms up?
I work with a lad whom has a PhD in motor engineering, nice lad, ask him any question about motor vehicle engineering and he can quote figures and stats till you are asleep, as for doing the job and actually understanding it on site away from the sterile uni classrooms he has no idea, no common sense .
You made the statment: I have a degree so I am not an idiot.
That totally depends on how people see you and more to the point how you have developed your understanding of you disapline based on your degree, if you break it down to a base level you are taught a lesson, you are tested on that knowledge, does that make you a super brain! no, it is how you develope that knowledge outside of uni, based on real time problem solving.
Sorry but I don't feel the need to pontificate about my qualifications and try and belittle others because I have a fist full of em, I would have thought with an engineering degree wasn't it you would have heard of momentum and once this has been established to a resaonable point the force necassery to move the object and be reduced slightly as the object itself is porpelling itself through its own energy taking friction into consideration of course, and that is about as far as my engineering knowledge goes these days I only got a HND in that when I was sweet 18 many years ago, to many to remember.
I know what I can make my car do, granted it is only for very short periods of time and weather dependant and only in certain places, this is not something it does all the time, and after a brake service I could not do it at all for a month or two and als oseems to be more of a front wheel drive thing as well never been able to do with a rear wheel drive car must be to much friction through the prop and diff (diff oil use to be really thick) I don't belive the origonal post at all, I can get a slightly reduced RPM, which last at most minutes (with a good tail wind) before the road levels off flat again, which 99.9% of the time is not worth talking about.
I do not need to attacked by a what seems qute a pompus man waving his degree about, talking of which it must of come from the same place as the chap in motorworld who sold me a set of alloys for my Fiat and tried to tell me it wont change the torque of the car, when I mentioned it has he also had a rant, and had to inform me of his engineering degree and how I was wrong as the overall diameter of the wheel is near enough the same, yet car did physically drive differantly same thing has happend to the wifes coupe bottom end torque has changed now we are both wrong acording to our man with the degree who is now boring people in Halfrauds.
Am I in awe of your degree with honers - NO it just enables you to get a better job it does not make you any better than the man next to you just more employable in some cases, and if you do think it makes you better than others, which I get the impresion you do then well ........
You are sadly wrong!
it is a sheet of paper you where coached into getting, simple as that.

[davelowe]

I will concede that I did make an error over the engine oil. It was a typo - a quick experiment with a viscometer and a blowlamp would fix that. As for the rest of your message, no comment, I'll let it stand on its own merit, or lack thereof. Someone else can have the last word on it.

[ChrisM]

Thought so!

Not as impressed or maybe even humble as I should have been!

Sorry, but can not abide people who brag about qualifications, simple as that.

There are far better people than both you and I out there that do a far better job than both of us could even contemplate doing and never say a word, I feel ashamed as I have actually done what I hate about a lot of people with degrees and other high profile qualifications, pontificated about what I have, It is actually none of your business what I carry and I am annoyed at myself for allowing you to needle me enough into using my qualifications in the same manner you have.

That makes me no better than you!

As for a typo? Just be a man and admit you got it wrong, being wrong sometimes is not actually that bad you know, I get things wrong at times simple things, thats life none of us are perfect.

However, I am sorry for throwing my qualifications at you, this is not the type of person I am, and as I said I am totally ashamed of stooping that low to do such a self indulgent thing, even in retaliation it was bad form. And that I must apologise for!

As for AlexB, with the PhD, well you put us both to shame by not getting involved in this stupid qualification "I'm better than you" mud sling, all power goes to you for being a true gent, I wish I could have shown the same restraint as yourself, on this occasion I let myself down terribly.

I hope you all have a Merry Christmas.

[pw981]

No, it does not. In manual transmissions the gear ratio is fixed in each gear and the clutch is not supposed to slip when driving.

depends on what it is doing at the time really...

[rjacko]

Maybe the gearbox ratio's been changed to suit the new engine? Try check renault website to see speed/gearing stats for both 120/130 dci or check your manual and compare it to someone with a 120 dci.

[Paddy]

No, it does not. In manual transmissions the gear ratio is fixed in each gear and the clutch is not supposed to slip when driving.

depends on what it is doing at the time really...

The school teacher to the pupil...

Although an award to ChrisM for the longest post of the year and fighting his corner. Even though 95% of it was tripe.... I guess we all have to learn.

Although I spared my self reading half of it, surely it stands plain as day that on a manual, in gear the mechanics work to a ratio. Maybe its just the engineer in me but thats like 'ABC'.

P

[ChrisM]

Yes you are right paddy; we do all have to learn! I have learnt that there is another ill mannered know it all on here.

Obviously the image taken this morning on my phone is the 5% that you mightiness declares as not "tripe"

And as you are twittering on about the length of the post I see you still needed to add your tuppence to it just add length I suppose and impress every one. I love the way people cut little bits out to quote to add impact.

Well you now have an image to squeak about.

Don't even bother about photo packages as an excuse, if you really think I have time to mess around with a phone image for the likes of you, you are seriously mistaken, sorry but you hold no importance in my life what so ever and never will.

So squeak on.

Will I care? NO!

[funkyg]

Hi Chris,
I've been reading this, and I think there is some misunderstanding on the points people are making.
(BTW, I don't have a degree of any kind so feel free to ignore any/all of what I say!)

I don't think anyone is doubting that your engine does 68mph @ 1750rpm as your picture proves.

What the guys were trying to get across is that your when in gear your engine will do a given speed at a certain number of revs. This is physically locked in through the gear ratios. If your engine speed changes your actual speed will change, unless there are other things in play such as wheel spin or slipping clutch.

To prove this I did an experiment last night on my way home. Went on the motorway and set my cruise control to 60MPH, which my car does at exactly 2000rpm.
I did 60 mph all the way down the motorway, and regardless of the climbs and descents the revs stayed EXACTLY on 2000rpm.
Even drafting behind a truck or clear road made no difference. Without my cruise control I could have maintained the speed but would have had to adjust the accelerator, giving it more going uphill etc.

I understand what you say about truck drivers, and slipstreaming/drafting. This does work and is a valid technique for saving fuel, but the revs don't change. You may need to give it some more gas to maintain 60mph/2000rpm when going uphill and less going downhill but the fact remains that the revs won't change.
It's all due the amount of energy required to maintain the speed under certain circumstances, due gravitational forces (going up or downhill) or additional/reduced wind resistance (slipstreaming a truck).

Let's all play nice!