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Old 7th January 2005, 17:48   #1
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Default What is run-in speed? I don't get it.

I've was reading this post on indiacar, where run-in speed was being discussed. Most said that a car should not cross 80kmph until the run-in period is over.

I personally feel, that your run-in speed is more depedant on your engine rpm rather than your vehicle speed. If i have a car with a tall 5th gear which will let me cruise at 100kmph, at 1500 rpm. I don't see why i can't cross 80kmph.

I've noticed, most new cars being ripped in the first to gear until they reach 80kmph and then stift into 5th. I don't see any point in doing so. Revving your engine in the first 2 gears will cause more damage to an engine.

So, i believe that when you run-in your new car, watch your tacho at all times and see that you don't revv the engine above 2500-3000 rpm (ir-respective of vehicle speed).

Shan2nu

Last edited by Shan2nu : 7th January 2005 at 18:38.
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Old 7th January 2005, 18:04   #2
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Shan2nu, I agree with your point. But, it is just easier to keep an eye on the speedo than on tacho. As one changes the gears, the RPM keeps on fluctuating. I guess, manufacturer expects the driver to follow appropriate speed band for each gear. You may also have heard suggestions such as only 1/2 or 1/4th throttle should be opened( especially true with bikes) Unfortunately, most newbies keep on ravving the engine in low gears causing the damage.
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Old 7th January 2005, 18:23   #3
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I compleltly Agree with you Shan2nu, I think 80 Kmph was a figure that was a result of some rough calculation when most of the cars didnot have tacho.

Right Now i think we just need to maintain the engine RPM below 3000 in the run in peroid
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Old 7th January 2005, 18:34   #4
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I agree, but, i have seen in quite a few owners manuals providing the appropriate speeds corresponding to gears,during the run-in period...... so i guess thats why t is called run-in speed, and i guess it is assumed that the car is in top ger while doing the run-in speed....... and yeah it completely depends on that car's gearing though.
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Old 7th January 2005, 18:41   #5
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Quote:
i have seen in quite a few owners manuals providing the appropriate speeds corresponding to gears,during the run-in period
That's true, but no 2 cars will have the exact gear ratios, maybe a M800 will hit around 3000 rpm at 80 in 5th, but a bigger car might do the same at 90-100.

Even in your manuals, check the speed to rpm raletion, the max allowable speeds will always see to it that the engine rpm stay well below 3500 rpm.

According to calculations, the Vtec is geared to do 104 kmph (+/- 2 %) at 3000 rpm in 5th gear. So why should i limit myself to 80kmph?

Shan2nu

Last edited by Shan2nu : 7th January 2005 at 18:45.
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Old 7th January 2005, 19:25   #6
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hey shan2nu i agree with you .
never cross 2500 rpm at the max for the first 2000 kms.
like in my merc on the way to pune i did 130 kmph at around 2000 rpm ...
say is it possible or your car to start wobbling if u rev it 80 kmph just after run in period because my brothers was .
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Old 7th January 2005, 19:27   #7
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Usually cars that dont come with an rpm meter have a sticker from the manufacturer advicing on maximum speeds in each gear.

But when you have a tacho...use it!

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Old 7th January 2005, 19:29   #8
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Guys when my dad bought the ALto VXi we cudn't find any mention of the runin in the manual, also the dealer also told us that its a thing of the past.

Further as of today not many cars come wid tacho specially the likes of zen, m800 & Alto Lx, so its easier to provide speed than rpm
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Old 7th January 2005, 19:36   #9
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It is usually advised to run in the engine. Does not depend on the speed. But actually you should be putting slight load on the engine. For e.g. try climbing up a hill which u would in 3rd but climb up in 4th gear.. Dont over load the car till it stalls but just give it some load. You shouldnt be ripping the new car. Though the engines can take it but if you want the engine life longer you should run in the engine for atleast 1000kms which is more than enough. Highway driving is not recommended but city driving with frequent gear shifts is good so that the clutch engine everything gets set in soon.
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Old 7th January 2005, 20:26   #10
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Don't ri the car, slowly give more work to do also do not drive too slowly in higher gear. Try not to drive at a constant speed. Ensure the engine gets varied loading - helps the engine bed in
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Old 8th January 2005, 02:03   #11
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I have 3 Maruti Manuals... all say 100km/h.. max... no matter what car...
they also say the most fuel efficient gear shift is 5th @ 40km/h ... again for all cars.... .. BUT u see esteem... with its long gearing 40.. in 5th is... not possible!!
So these manufacturers like maruti don't really do their homework well... thats why there is confusion!

yeah .. rpm is a much better indicator!
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Old 8th January 2005, 04:02   #12
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Hi Shan,

The most important part of the run in is the run in of the engine. However, dont forget the other parts of the car also need to be run in.

Staying below a certain engine rpm is important for the runin for the engine, but staying below a certain speed is better for the run in of other moving parts.

In the good old days cars didnt have tachos and hence they would specify a speed. Also, older manufacturing techniques were not as precise as they are today, and hence running your car in was much more important.

Taking it easy on your car in terms of rpm, speed, braking etc for the first few weeks/kms is important for a variety of reasons.

cya
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Old 8th January 2005, 10:35   #13
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Spot on Rehaan!! Tyres, Brakes, cooling systems...all need running in periods to perform well over a longer term.

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Old 8th January 2005, 13:46   #14
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Quote:
Tyres, Brakes, cooling systems
Brakes maybe. Cooling system? I mean at hundred the engine get more air to cool it, than at 80. So cooling is taken care of, and it's not as if i'll be doing 5000 rpm at 100. I'm gonna be well below 3000.

Man the Vtec tyres are rated for 190 kmph, don't tell me they'll start wearing off at 100kmph. I've done speeds of close to 100 on my car when it was new and nothing has gone wrong with it, the engine is as good as new, the tyres are showing minimal wear n tear, fuel efficiency has been great etc.

I still feel your engine rpm is more important than vehicle speed. Maybe for tacholess vehicles, they used to mention the max vehicle speed so that the engine doesn't cross 3000 rpm in 5th, at that speed. But if you're gonna do 80 in 2nd and think you're safe, you couldn't be more wrong.

Even for the Vtec, they have mentioned the max speeds you can do in each gear during normal driving. Probably for those who don't know what a tacho is.

Shan2nu
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Old 8th January 2005, 22:32   #15
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Hey Shan2nu,

There are a lot more things that happen within a cars systems than that meets the eye.

You may have done 100 on your 190 rated tires without a problem, but its always a good idea to break in slow. Tires for example may perform better after they have had a bit of time to set in, especially if the vehicle is running high camber.

Quote:
nd it's not as if i'll be doing 5000 rpm at 100. I'm gonna be well below 3000.
Dont forget that your rotational speeds of parts of your gearbox & differential will be higher with roadspeed as opposed to engine speed. along with several bearings along the way.

I agree that the engine and brakes are the two most important things to be broken in, however some people prefer to do it right till a 1000% as oppoesd to 100%.

cya
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