120 KM/h Suzuki PKDM Alto 660cc RPMs at Cruising on Motorway

[umerkhanmkt]

Hi Fellow PakWheelers....

I recently bought Alto VXR 660cc and I am very satisfied with its overall performance within the city, however, I have tried it on Motorway but was not as impressive as the bigger engine car would do so I won't put it to that expectation as it will be unfair to this alto 660cc.

Since you guys know that it does not have the RPM meter so I want to know if anyone has tested it with the OBD meter or with the car scanner tool engaged, what is the RPM of this car if you are cruising it at the speed of 120 km/h on motorway, remember guys I am talking about cruising...

If anyone got any knowledge of it please share here for everyone's sake.

Thanks,

[Massive_One]

a 1300 cc engine cruises at 3100 rpm at 120 speed, so my guess is , a 660 cc would be cruising at 120 km/h speed at somewhere around 4500- 4800 rpm

[htb456]

its not about the engine but the gearing ratio at play. I calculated the engine rpm to be around 5000 for new alto vxr if it cruises at 140 kmph

[Massive_One]

I calculated the engine rpm to be around 5000 for new alto vxr if it cruises at 140 kmph

how did you calculate ?

[sleeper]

1300 cc 02-08 corolla
1300 cc 09-14 corolla
1300cc 14-current corolla
1300 cc 08-eternity City
1000cc efi cultus old
1000cc WagonR

These as per my drive experience always are at 3000-3100Rpm at 100kph

I would assume similar gear ratio for 5 speed alto also and it would be same 3k\3.1k at 100kph and a round 3800-4000rpm at 120kph...

I dont think there would be some reason to have much shorter ratios than what other higher cc cars have, because that ratio seem to be most optimum.

[umerkhanmkt]

Nice to know these figures, I had Baleno 99 1.3 and it used to stay at 3000 rpm at the speed of 120 kmh.

Bodyweight and HP should count in as well for this I guess.

[ZainMahdi]

Assuming it has a ring and pinion ratio of 4.71, a 5th gear ratio of 0.9 and a stock tire height (diameter) of 22.1", its slightly above 4800 rpm at 120 km/h.

Assuming the same 5th gear, but a ring and pinion ratio of 4.064, its just under 4200 rpm.

Btw, Mehran, with its 4.350 ring and pinion ratio, and a 0.9 4th gear, and 21.1 inch tires, cruises at almost 4700 rpm at the same speed.

I'm inclined to believe that the Alto is at 4800 RPM; it makes sense considering that the most common complaint about this car is the engine noise inside the cabin.

There is a reason that this is called a city car; I wouldn't buy it if most of my traveling consists of motorways.

[pwuser15860915546]

what is ring / piston ratio ? how u converted it into rpm ? with tire dia and gear ratio ? whats got rack and oinion to do with it ?

[ZainMahdi]

For simplicity's sake, I used this calculator.

RPM calculator
Use the calculator at the end of the page.The values for specific cars are available in user manuals, and online.

[pwuser15860915546]

i already know that but what is ring piston ratio ?

[pwuser15860915546]

and what has rack and pinion got to do with it,
rpm is simply tire dia and gear ratio as far as i know

[ZainMahdi]

*ring and pinion, not piston.

For understanding purposes, you can think of them as the 'input' and 'output'. The input takes rotational input from the crankshaft, the transmission/gearbox further modifies it, and the output delivers the final rotation to the wheels.

[pwuser15860915546]

ok.
sorry my mistake, read as ring and piston

[umerkhanmkt]

Very informative.

Where did you find the ring and pinion ratio of 4.71 for alto 660cc to be exact?

[ZainMahdi]

Sources:
4.71
4.064

In the paksuzuki owner's manual for the Khyber, the individual ratios and the final ratio are actually written. Stuff like this is left out of modern owner's manuals because the average consumer gets a headache if he so much as looks at anything with numbers.

Same reason that modern cars don't have temperate gauges, just a stupid red light telling you that your headgasket has shifted.

[sleeper]

So, my assumptions were incorrect for alto having similar gear ratios as that for bigger engines.. Looks like it has much shorter ones like Zain mahdi bhai said.

I dug the net a bit but couldn't find the technical specs of our alto on a website "automobile-catalog.com" (mod, delete if not allowed to tell about the website).... However, it also came under Mazda Carol badge (7th gen HB36S) with same engine and gearbox, and for it the details were there... Which are quite close to what Zain mahdi said above.... I believe the 5th gear has same ratio as that of Mehran 4th gear.... So as per the ratios below and the graph also, our alto would be at high 4500Rpm at 120kph.... Pretty sure it won't be fuel efficient at high speeds, hence a city car.

[sleeper]

[sleeper]

[scholar.center]

Agree.. it is not fuel effucient at high speed like 120kmph... driving in varying range of 85 to 100kmph is fuel efficient for this car...
Car gear ratio is mentioned in owner manual and broucher at ps website.

[ZainMahdi]

Nice catch. Its rare to find gear ratios in owner's manuals anymore.

According to these ratios, the RPM are 4468 and 4490 at 120 km/h, for manual and AGS respectively. Less than Mehran, but still way too much.