[Shan2nu]

mine viva petrol on stock engine and the same noida express highway......

Hey what gear was that in?

Shan2nu

[rks]

Originally Posted by rks

I am wondering how much your K&N filter had to do with your observed increase in speed. Top speed depends on a number of factors -- some of these might be:

(1) Downward slope/tail wind (upto 20 kmph increase is possible).
(2) Load in your car (including fuel tank -- full vs less than 1/2?-- not too sure about how much difference this makes).
(3) Tyre pressures -- helps if tyres are over-inflated by 2-3 psi.
(4) State of the tyres - upgraded vs stock, bald vs lots of tread -- I think less tread may help to a certain extent -- not too sure of this -- check with race drivers.
(4) Road conditions -- smooth roads help -- less friction.
(5) Engine tuning, wheel alignment/balancing -- all these would matter.

Probably you can add to the list too. So the quesiton is whether you found the increase in speed under almost the same conditions as you did 155 kmph? Was it at least the same stretch of road?

I did my 160 kmph (see my avatar) in my unmodified 1-lit Santro with stock tyres on the long, mildly sloping downward stretch just after the Kamshet tunnels on Mumbai-Pune Expressway (towards Pune). I was not always able to hit 160 kmph in this stretch -- sometimes only 155. In fact from the Kamshet tunnels all the way to the end of the Expressway near Dehu Road, the concrete road is very smooth and my Santro hits 150 kmph even on level road in this stretch, with fuel tank near 1/2, no load and tyres over-inflated to 33 psi (alignment and balancing are very good in my car, and my stock tyres have done 33000 kms - still reasonable amt. of tread left). My mileage is about 11-12 kmpl in city conditions and 13-15 kmpl on highway depending on driving style -- flooring the pedal gives abt. 13, 90-100 kmph top speed gives 15. So probably my engine is tuned more for pick-up than for mileage.

To put it in a nutshell -- If on the *same stretch of road* under almost identical conditions, your top speed remains, say at 150-155 kmph; but after fitting K&N filter, it *consistently* exceeds 160 kmph; *then* you can be reasonably certain that the speed increase was due to K&N. But maybe a slight re-tuning of the engine without K&N filter would also have achieved the same result, probably at the cost of a little mileage.

In my case if I were to add K&N filter to my Santro and find that the top speed consistently exceeds 160 kmph on the above quoted Expressway stretch, I can be reasonably certain that the speed increase is due to the K&N -- because on several dozen trips on that stretch, my top speed varied from 155-160 kmph, but never exceeded 160.

By the way, removing the thick rubber mat on the carpet below the driver's feet will give some additional scope for throttling. I always remove this rubber mat on long drives as it keeps moving under my feet. I suspect even this factor can affect top speed by 5 kimph -- not too sure about this either.

[suman]

Originally Posted by low_bass_makker

I dont know either.... many be there is some problem with the car system they lit when i cross 150-160 mark ..... and it has not happen once every time i cross the 150 mark the lights come....also when I bring back the car to stand still they dont go till i switch off the car and start it again...both the corner lights are of brake , the left one is for the brake oil and the right side was of the abs.... the fuel one lits because i was low on fuel... see the fuel gauge.....

Man, even your temperature gauge is showing really steady temperature, I would think it would have been closer to the H mark rather than in the center with 200 kmph on the speedo! Amazing car I must admit

[rks]

Originally Posted by suman

Man, even your temperature gauge is showing really steady temperature, I would think it would have been closer to the H mark rather than in the center with 200 kmph on the speedo! Amazing car I must admit

I don't think that is true. The engine will not heat up as long as the vehicle is in top gear. The rpm indication is only 5500, way below red line.

[suman]

Originally Posted by rks

I don't think that is true. The engine will not heat up as long as the vehicle is in top gear....

Is that correct, I didn't know that. I would think that 200 kmph is way past the touted top speed of an Accent Viva. In my experience, overheating is not caused by redlining alone but also by sustained overflogging of the engine - also, 5.5k rpm is not exactly a city cruise kind of a situation either. Don't you think the coolant would have heated up slightly by now?

[rks]

Originally Posted by suman

Is that correct, I didn't know that. I would think that 200 kmph is way past the touted top speed of an Accent Viva. In my experience, overheating is not caused by redlining alone but also by sustained overflogging of the engine - also, 5.5k rpm is not exactly a city cruise kind of a situation either. Don't you think the coolant would have heated up slightly by now?

I don't know much about Accent Viva -- you probably have to check with owners regarding their experience. As far as my Santro is concerned, I have flogged it to full speed (mostly in 5th gear) continuously for 50 minutes on the Mumbai-Pune Expressway and don't ever recollect the temperature indication even reaching the half-way mark. My top speed was something like 150-160 kmph and avg. speed for the 94 km Expressway was about 113 kmph. But then again my Santro's 1-lit engine produces top speed in 5th gear at a relatively low rpm (maybe 2800?). Maybe the Xing engine will tend to heat up a little more. It depends on the car, cooling system design, etc.

[low_bass_makker]

people this was achived on the nodia experss high way with downhill add also..i dont think the engine will heat up in 5-10 of this trashing.....if any one doubts on this get a viva run it at 150-160 and see the lights come up.......

[rks]

Originally Posted by Shan2nu

Hey what gear was that in?

Shan2nu

Is the rpm reading consistent with this speed at 5th gear? (assuming the Viva does have a 5th gear). Or maybe it was 4th gear?

[suman]

Originally Posted by rks

It depends on the car, cooling system design, etc.

Exactly....just because a car is in top gear doesn't necessarily mean it will not heat up. And remember, I'm talking about "CLOSER" to H, not H or past H which is overheating

Originally Posted by rks

I have flogged it to full speed (mostly in 5th gear).

RKS, if you see the speedo, it is calibrated up to 200 kmph which (to me) signifies that the declared top speed of the vehicle is way below that.....what is your Santro speedo calibrated up to?

[BUSA]

Santro speed is calibrated upto 180

[rks]

Originally Posted by suman

RKS, if you see the speedo, it is calibrated up to 200 kmph which (to me) signifies that the declared top speed of the vehicle is way below that.....what is your Santro speedo calibrated up to?

My Santro speedo is calibrated up to 180 kmph. The true top speed of my ZipDrive model is supposed to be 136 kmph -- the top speedo reading I have experienced is 160 kmph (see my avatar) on a slightly downward slope. With speedo error and taking into account downward slope this is OK.

[suman]

Originally Posted by BUSA

Santro speed is calibrated upto 180

Right, speedo calibrated upto 180 & RKS hitting top speed of 160 as he says - sounds OK, but I'm confused with the speedo calibrated upto 200 and someone doing as much or more on a stock car.....must have happened of course since the photo says so

[1100D]

Originally Posted by low_bass_makker

people this was achived on the nodia experss high way with downhill add also..i dont think the engine will heat up in 5-10 of this trashing.....if any one doubts on this get a viva run it at 150-160 and see the lights come up.......

What color is your Viva? Red?

[low_bass_makker]

Originally Posted by 1100D

What color is your Viva? Red?

what does color gonna do with this any ways it was white....

[Shan2nu]

Right, speedo calibrated upto 180 & RKS hitting top speed of 160 as he says - sounds OK, but I'm confused with the speedo calibrated upto 200 and someone doing as much or more on a stock car.....must have happened of course since the photo says so

Most cars have their top speed limited by their aerodynamics. So you will not get the same fig every time you test for top speed.

For that reason, top speed runs are usually done twice (in opposite directions)and the average of those 2 runs is taken as the final fig.

Maybe his car did touch 200kmph. But if he was to run the car in the opposite direction, things might have been diff. And the average of these 2 runs would have resulted in something close to 170-180kmph.

Shan2nu