Hi all. Is it true that the lower the rpm reading, the better of the car's fc?

Currently I'm driving a b14 sentra '97(A).
RPM = 2700 @ 110km/h
The FC is around 11-13km /l

I'm interested to know others car like toyota seg 1.6, myvi 1.3, toyota vios, city idsi, hyundai getz 1.4. Both auto and manual............
others model are welcome also, thanks.

summary :

Model RPM @ 110 km/h
nissan sentra b14 1.6(A) 2.7k
sentra b14 SR16VE engine 3.3k
nissan sunny 1.3(M) 2.6k
getz 1.3 2.6k
kelisa 1.0(M) 3k
kelisa 1.0(A) 3.7k
kancil 660(M) 4.2k
kancil 850EX(M) 4.2k
myvi 1.0(M) 3.6k
myvi 1.3(A) 3k
kenari 1.0(A) 3.6k
kenari 1.0(M) 3.4k
viva 1.0 (A) 3.7k
saga blm 1.3(A) 3.1k
saga blm 1.3(M) 3.6k
waja cps (M) 3.2k
waja mitsu(M) 2.9k
savvy amt 3.6k
gen2 campro >3k
persona 3.2k
wira 1.5(M) 3.2k
wira 1.5(A) 3.8k
wira 1.6(A) 2.6k
wira 1.6 mivec(A) 2.5k
wira 1.6(M) F5M221XPXL GB 3.1k
wira 1.3(M) 3.2k
iswara 1.3(M) 3.5k
iswara 1.5(A) >3.9k
satria gti 3k
satria neo 1.6(A) 3k
satria 1.6(M) 2.8k
perdana v6 2.8k
honda civic eg 1.6(A) 3.1k
honda city idsi 2.7k
honda city vtec 2.5k
Honda City 2009 i-VTEC (5AT) 2.5k @ 120km/h
honda accord 2.0(A) 2.3k
honda accord 2.4(A) 2k
honda accord CB3 3k
civic ej8 b16a(M) 4k
civic fd2 1.8 2.35k
honda crv(3rd gen) 2.1k
vios 1.5(A) 2.5k
camry 2.4(A) 2.1k
toyota seg 1.6(A) ae111 2.5k
avanza 1.3(A) 4k
wish 2.0(A) 2k
wish 1.8(A) 2.9k
lexus rx300 3.0(A) 2.7k
suzuki swift 2.7k
Isuzu Trooper 4JG2 3k
kia carens 1.8(A) 2.9k
naza suria 1.1(A) 3k
hyundai accent 1.5(A) 2.5k
fiat punto 1.2(CVT) 2.2k
mitsubishi galant 1.8(M) 3.1k
Mitsu Lancer 2.4l (4g69) 3.1k
mazda 929 2.0(A) 2k
mazda 323 1.6(M) 3.5k
chevy optra 1.6 2.5k
chevy aveo 2.5k
bmw e90 325i 2.5(A) 2.2k
freelander td4 2.0 diesel 2k
citroen c3 1.6 (semiAuto) 2.3k
ford lynx 1.8(A) 2.75k
golf gti 2.6k
saab 9-5aero 2.1k
saab 9-3aero 1.8k
my Audi A4 2.0(A) 2.2k
Benz C200 2.9k

This post has been edited by joanalooidog: Aug 27 2009, 09:39 AM

proton waja
2.8k-3k RPM @ 110km/h

This post has been edited by jlce10: Aug 1 2008, 09:17 AM

The lower the RPM, the more efficient the engine and hence better fuel consumption. However, it cannot be used as a comparison as the engine itself would be the main factor in the calculation of fuel consumption and not the gear ratio. Furthermore, there are no aftermarket parts to change gear ratios (too much work to be cost effective) and hence it is seldom a factor in the calculation of FC.

The gear ratio is only effective in calculation if you are comparing 2 cars of the same make, same engine but different gear ratios.

erm my persona rpm 3k at 110km/h, but my 1.3 getz around 2.6k @ 110km/h...

so my getz more effective?

but when hi speed, my persona more effective

persona high rev engine mah....................

my neo 1.3 RPM 3100 @ 110km/h

How could you have a range of 2.8k to 3k for your RPM? RPM per km/h is always fixed per gear and never changes until you suffer clutch slippage.

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Added on August 1, 2008, 9:23 amActually, it's more of low power and need a shorter gear ratio to keep the car moving at high gear.

This post has been edited by sleepwalker: Aug 1 2008, 09:23 AM

maybe his car is going downhill, so at 2.8 oledi got 110km/h

nono, i not sure its either 2.8k or 3k... should be 3k bah...

Which part of 'fixed RPM per km/h' that you don't quite understand? It's a constant and not a variable as the gear ratio is fixed per gear.

I think the valve timing mechanism will also affect the RPM reading. My Sentra 1.6 MT driving at 110km/h, the rpm will increase or decrease slightly a little bit, from 2800 to 3000 rpm.

different size rim will cause your speedo meter to over or under read and will make your rpm reading @ 110 km/h not accurate anymore

senario example
13" 110@3k
15" 120@3k <-- bigger rims cause the speedo meter to over read

dei, after change rims your speedo still the same reading. it's the actual speed that is different.
speedo reading is taken from gearbox, not gps/ satellite position tracking.

IT has nothing to do with the engine. Your RPM meter is screwed if it moves while you maintain constant speed, or that your clutch is slipping. Your RPM is calculated at the engine. It is transferred to the gearbox by a big flywheel and clutch and turns the gearbox. The gearbox has fixed gears that will change the RPM of the engine to the RPM of your wheel. Each gear has a fixed ratio.

I don't care even if you jack your car up and spin the wheels. If it is 3000rpm at 110km/h on the road, it is still 3000rpm at 110km/h when the car is jacked up in the air and the wheels spinning freely.

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Added on August 1, 2008, 9:44 amWrong. Rusty nail is correct. Your RPM per KM/H on your dashboard will still remain the same. The only thing that will change is your actual speed and not speedo speed, meaning if the police shoots the laser camera at you, then you will be driving at 120km/h but speed still show 110km/h. That is how bigger wheel OD will affect you. It will not affect your speedo but affects your actual speed.

This post has been edited by sleepwalker: Aug 1 2008, 09:44 AM

Bro, you are wrong.
He mean RPM vs KMH..
It really will change when u change bigger sport rim
Police laser camera will shoot on our KMH speed. but we also see the speed is correct.
Only the RMP change lower litter bit, but laser camera is capture our KMH meter, not RPM meter.

Use math calculation..You will get when u use
KM/H = RIM round per hour VS RP/M = Gear round per min

13" 110@3k (you will feel your car powerful, pickup damn good)
15" 120@3k (you will feel still power ok)
17" 125@3k (you will feel your car no power)


**PS: when down hill, my car can reach 110kmh with 1000 RPM.. cause use free gear.

This post has been edited by LeVis_Jeans: Aug 1 2008, 10:06 AM

Waja CPS (MT) 3.2k RPM@110km/h

Depending on which gear it's on.
I get around 2.5k (4th gear) at normal and 3k (3rd gear) if I really push....well it's an auto though...

My Gen2 campro engine also same.. consume petrol so much when RPM over 3k.

Wira 1.5(M) 3.8K RPM for 110km/h ..

You are wrong. It will not change. Your speedo comes from your gearbox. It is fixed. Changing the size of the wheel will not change the readings on your speedo meter. It does not matter whether you change to 20inch. If the rpm is 3000rpm at 110km/h on the respective tacho and speedo meter, it will remain at 3000rpm at 110km/h even if you change it to 20inch (even though you are travelling at 130km/h).

You have to remember that there are always 2 speeds.

1. KM/H on speedo meter (this cannot change as it is a fixed reading from the gearbox)
2. KM/H actual speed (this will change depending on the OD of your wheel)

What we are talking here is the reading on the speedo and tacho meter. Actual speed aka real speed aka speed captured by speed camera will change but not the reading on the speedo and tacho.

We are talking about the speed reading on the speedometer. That is the only speed that we know. You will NEVER know your actual speed until you get caught by the police or go through one of those speed indicators like the one on Kerinchi link.

This post has been edited by sleepwalker: Aug 1 2008, 10:04 AM

What gear u use ?

Kelisa (M) 1.0
3000rpm @ 110km/h

I feels that there is no difference in term of FC while cruising at 110km/h and 14km/h. Several CPS user also confirmed this.

Correct. Only the actual speed will change when changing rims size. Can try to googled cars bible and use the provieded calculator to see how much the difference.

sleepwalker: can you explain a bit what is "clutch is slipping" ? Clutch want finish already, no teeth ?

i wanna ask.. i driving Kancil 850 Auto, RPM is maintain 3k when i was on 80km/h, is count normal or got problem? full tank RM60, can only go for 200+ km, count as normal??

This post has been edited by invisiblelim: Aug 1 2008, 10:11 AM

The clutch has no teeth. The clutch disc has materials similar to the brake pads. Once that wears out, it starts to slip.

Engine crankshaft -> Flywheel -> Clutch -> gearbox. IF clutch is working then..

3000rpm at crank -> 3000rpm at flywheel -> 3000rpm clutch -> 3000rpm gearbox

If clutch slipping then

3000rpm at crank -> 3000rpm at flywheel -> 2500rpm clutch (slipping, can't hold on to flywheel) -> 2500rpm gearbox.


THis is just a rough explanation. Go google for full explanation.

This post has been edited by sleepwalker: Aug 1 2008, 10:15 AM

your car engine 850cc only mah. cant get high speeds. at high speeds, u pushing the engine too far and this means higher fuel consumption

my old iswara was about 3.1k @ 110km/h.

I using campro
I also tried before...if i run over 130-160kmh (RPM stick at 3.5-4k). Only can run over 480KM per tank.
If drive slow slow 90KMH (RPM only 2.5-2.7k). I can run over 550KM per tank.

This post has been edited by LeVis_Jeans: Aug 1 2008, 10:19 AM

oh.. that means is normal de la? cause really feel like high fuel comsumption =.= i thought kancil should be save fuel de ma =.=

haha of course ler. lower rpm = lower engine power = less fuel consumtion lor

erm i'm not sure lah but coz your engine capacity is small, thus cant go higher speeds ler.
i think its efficient if u stay below 90km/h and city driving n stuff.
thats what i know.

unless the pro's here can explain better

FOr a moment there I thought you wrote 14km/h.. wait.. you did write 14km/h but you meant 140km/h right?

There would be a diffence. The other CPS users are wrong. For most road cars that is not aerodynamic in shape (like those lambo/Ferrari type), wind resistance becomes your number 1 fuel comsumption killer. For most cars, max efficiency is gain around 90-100km/h where the best rpm to speed ratio is gain and wind resistance is not an issue. Any slower and the rpm to speed ratio is no longer efficient as you take longer to reach your destination and any higher speed would encounter wind resistance that will require more fuel to keep the car running at that speed.

i thought maybe around 70-80km/h would be better?

are u sure its not?

of course driving styles play an important role too.
but comparitively, driving at 70km/h vs 90km/h, it wont save fuel to drive slower?

is't..lol..my satria using 16' rims...so how i wanna know how fast i drive then?
i'm a good citizen..dun wan to be caught by police

1.3 SAGA LMST

3k rpm @ 100km/h
3/5k rpm @ 120km/h
4k rpm @ 140km/h

IF IM NOT MISTAKEN LA

The common fuel efficiency gauge is on 90km/h at RPM 2k. That's the myth.

proton savvy that used to get in Malaysian Book Of record For MOST FC car (if not mistaken) been driven at 90KM/H

i think its more like urban legend.

haha i think for high capacity engines, its possible to have lower rpms.

for a 3.0L accord or bmw, i think the revs is around 2.5k or lower.

sleepwalker: thanks for the info

That's true. A 2.5L 325i revs around 2k rpm at 110km/h IIRC.

from my experience
i used to drive mazda 929 wif 2.0v6 engine
auto
it cruise at 110km/h wif 2k rpm if not mistaken

as now driving S/neo
also auto but 1.6
in the speed of 110km/h
i think the rpm is above 3k since 80km/h adi need 2.5k rpm adi -.-

should b looking for the power of the engine instead of juz rpm i guess

got bike only... hehe..

110km/h 6.3k rpm...

This post has been edited by popnyat: Aug 1 2008, 11:12 AM

haha i'm so clever

not bad dude. but 110km/h on a bike?
dangerous.

i think rims is not an issue (unless you take weight into account) but the tire radius.
http://swatt.j.porter.name/tech-center/tool/tire-calculator
compare your stock tire with the new ones that you are using. then you can see the difference in size.

Depends the 3.0L accord or BMW how big Gear Box.. Gear radius/diameter is main course the RPM.
If 3.0L engine go with gen2 gear box.. it will same will go thru 3k rpm, 110kmh.

This post has been edited by LeVis_Jeans: Aug 1 2008, 11:25 AM

myvi 1.0 110km/h at 3.6k rpm
matches engine peak torque at 3.6k

haha why u wanna compare this sorta things dude?

normal comparison only mah.

Dun let other ppl confuse only ma, hehe

Kenari Auto

110km/h at 3.6K RPM.

BTW, for auto user without lockup clutch, the RPM can vary. For example, when u release the trottle, ur RPM will drop faster compared to your speed.

the lolz !

i think automatic transmission will generally have higher revs for the same speed.

right?

Yes because of the gear ratio.
It's the same whereby you drag your car at 3rd gear to 110km/h and 5th gear to 110km/h would give you different RPM read.

I am not comparing auto transmission with manual transmission. What I am saying is, if your auto transmission does not have lock up clutch, your RPM to KM/h ratio will not be fixed 100% of the time, since your gearbox is always slipping against the engine, through the torque convertor.

wow, from the readings, smaller cc auto cars tends to have higher rpm readings @ 110km/h.
i feel like the fc will increase when the rpm > 3000
anyone knows for hyundai getz 1.4?

it make sense, isn't it? smaller engine needs to work harder to achieve high speed.

there are plenty of aftermarket 1-5 gear ratio and final drive. They even can custom made for you if your pocket is deep enough.

But you are right, the RPM at certain speed is all affected by the gear ratio and final drive.

No there isn't and custom made ones are not considered as plenty in the market. Plenty in the market means you can walk into BROTHERS and say.. "I'd have that ratio mixed with this one and put them all into the gearbox while I go next door mamak for a teh tarik". That I would consider as plenty in the market.

Gear cogs are not something you find on the shelf in every shop. It is good info to have about RPM per KM/H but that is all.. just nice to have. It is not something we can change easily or even make use of in our daily course of driving and modding. It takes some serious 'moolah' to get it done and not worth it if it is just for FC.

This post has been edited by sleepwalker: Aug 1 2008, 12:45 PM

Thanks..will try..

Satria Neo 1.6(A) 110km/h = 3000rpm highest gear(4th)

so if the readings of the speedo are not affected by rim size, means say if 13" rims, 110km/h real speed,110km/h speedo speed, 3000rpm.....
n then use 16" rims 130km/h real speed, 110km/h speedo speed, 3000rpm..
means use bigger rims can make your car quieter??

Quieter?.......

so lets say im using campro now n using this INVECSII (i think) gearbox from mitsu...

izzit possible to change to other gearbox? lets say from mitsu also, izzit possible?

btw, i still dun get it, in campro, got engine braking concept rite, the one which will lower ur gear when u going downhill..

will it consume petrol more? lets say i drive at 90km/h with around 2.6k rpm, n suddenly the engine braking activated when going downhill without pressing the pedal..

so should i press the pedal more lets say 110km/h at 3k rpm so the engine braking will not activated or juz let the engine braking lower the gear and make it whooping at around 4k rpm at 90km/h without pressing the pedal

which one consume less fuel?

sori if im talking crap here im no good in engrish

2700rpm @ 110kph on my suzuki swift.

My Myvi RPM is 2.9k at 110km/h...Is it normal? Or should it be lower..My dadz 4wd only 2.2kRPM at 120km/h but bigger CC lah.

Engine braking does not use fuel. At that moment, it is the wheels driving the engine and the throttle body is shut. There is no need for fuel to go into the engine until the idling control valve takes over when the RPM drops too low. So there is no waste of fuel.

Those people driving autos would appreciate the engine braking feature in the campro when they come down from Genting.

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Added on August 1, 2008, 3:19 pmMost of the time the differences is maxed out at about 5% and not as much as you have mentioned. We were over exaggerating our examples before this to emphasis the point of the discussion.

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Added on August 1, 2008, 3:22 pmHe thinks that he could oversize his tyre to the point where he gains a 20% increment in speed difference so that he could actually travel at 3k rpm @ 110km/h (meter speed) but moving at 130km/h on his actual speed.

This post has been edited by sleepwalker: Aug 1 2008, 03:22 PM

err anyone can answer me bout the gearbox? can we change to other gearbox?

No wasting petrol.. your fuel consume maintain at RPM 1100 rate

Vios/Belta 2.5krpm @ 110km/h. (2krpm @ 80km/h)

No use fuel no into engine will mati engine laa..haha

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Added on August 1, 2008, 3:29 pmYes, you can change suitable gearbox.
But i dunno which gearbox can install in only.

This post has been edited by LeVis_Jeans: Aug 1 2008, 03:29 PM

Car draging the engine, the engine is moving, how to mati - the engine is driven by external force.

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Added on August 1, 2008, 3:34 pmIt might not be a perfect fit and 'long lasting' might be an issue. eg. Fitting a K50 trans (KE70 manual) on a 4AGE (AE86) would kill the K50 faster. Hence it is better to get T50 (AE86 trans) together with 4AGE for mods.

This post has been edited by dstl1128: Aug 1 2008, 03:35 PM

so we can install gearbox diff from ours if compatible? no nid to change other things besides our gearbox only? so wat gearbox is suitable for this camtakpro engine besides wat we hav now la?

Different gearbox sure, either there is a commercially available compatible (mounting) ones, or you found a gear machinist that could machines out the cogs/gears with the ratio you like. If you have the money, even mounting can be changed.

Hmm... Possibly those from Mitsubishi or Renault ones might be possible for the Campro.


This post has been edited by dstl1128: Aug 1 2008, 03:40 PM

This shows how little you know about engines. Fuel is need to keep the engine alive when it is idle. You don't need fuel to keep the engine alive when it is driven by an external force.

On our car's ignition switch, there are 3 positions. First is OFF. Name me the other 2. If you don't know what they are, then there is no point continuing this discussion as you would not understand. Once you find out what they are, you would understand why I said that you don't need fuel to keep the engine alive.

Another hint.. Why can the car be pushed start when the battery is dead? There is no fuel in the engine and there is no battery to crank the starter but PRESTO... magically the car can start when it is pushed. If you get my hint, you would understand.

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Added on August 1, 2008, 3:44 pmThe question now is what gearbox is the campro based on? I can't remember. I've lost track of Proton Campro developments as most parts are not related to Mitsu anymore.

It's always possible to change if it fits but why do you want to? Why change when there is nothing wrong with the gearbox?

This post has been edited by sleepwalker: Aug 1 2008, 03:44 PM

so it is possible rite? juz the long lasting n compatible issue only rite?

thnx for the explanation

Aiya i know that..
It use external force to turn on your engine.. but u forget after turn on the engine, the engine also need keep using fuel to keep alive.
You say down hill.. yes, engine still alive. But it will die when at flat road when u are no fuel !

Your example is use for battery dead. But when it push and get starter the car. you also need fuel..

No fuel go engine = engine dead.
Pls.... no engine will running will alive without fuel unless u force him by your self.

hahaha... engine still need fuel le.. its in idle even dragging by external force.. its preset by the fuel injector "engine management chip" and by manual twisting fuel screw beside my beloved bike carburetor..

no fuel engine mmg mati la.. hahaha.. internal combustion engine need momentum to stay continuous explosive..

penat engineer buat flywheel tu..

This post has been edited by popnyat: Aug 1 2008, 03:54 PM

Ya la.. agree with u.
Maybe my english not good. so he confuse already.

err if lets say u guys know campro auto gear is sluggish rite? u can feel the diff with other cars like p2 or other car manufacturer.. it is not very smooth, when from idle to 'd', the car will jerk a bit, not very smooth... the car is new...

so tht thing is related to engine or gearbox?

err ok so maybe i want wrong info here, sori sifoo sleepwalker

hehe.. complicated dy.. heard of rotary? triangular shape horizontal spinning piston in rx8..

Myvi Ezi 110kmh@3000rpm.

You did not even read my reply properly. I said that there is no fuel used as you are going down hill until the idling controller takes over when the rpm is too low.

Once you hit flat road, the idling controller takes over and pumps fuel to keep the engine alive. While you are going down hill, fuel is not needed to keep the engine turning because it is being turned by the gearbox.

Abit sluggish.. because of low torque in low revving campro.. even appear in lotus website.. they remedy this by introducing variable valve in CPS engine.. valve timing and opening duration by computer calculation..

one good thing about persona auto trans its 4th gear revving lower than 5th gear manual trans..

highway driving was superb.. but takdak pickup.. because high ratio different between each gear..

ultima.. i got persona too.. H-line..

who says i got persona

oo ok, so its the engine tht makes the gear sluggish rite? okok i got it, thnx u guys

Maybe I didn't make myself clear. Only engines with ECU will cut fuel to the engine when you are going down hill. Engine will not mati because your ignition is still in ON position. The spark plugs are still firing but there is no need for fuel as the engine has not mati yet because it is being driven by your gearbox.

If you are driving a car with ECU, here is a simple test you can do to. Rev your car on idle until 5000rpm. Let go of the throttle. As the RPM falls, there is actually no fuel going into the engine as the throttle body is closed and the rpm is driven by the spinning flywheel. Just as the RPM is about to drop to ZERO, the car engine suddenly shakes and RPM goes back up to 800-1000rpm (idling rpm). This is where the idling control valve takes over and pumps fuel into your engine to keep it alive.

IF you ever rev to 5000rpm and then turn off the engine, the RPM will not suddenly drop to zero, it will just fall like normal and if you turn on the engine (turn to postion ON (position 2), not ignition position (position 3)), the engine will come back to live again (if you can do it before the rpm drop to zero). You most probably won't understand what I'm talking about here. Some other would.. they might want to explain it better. What I'm trying to say is that your engine will not mati immediately when you turn off the fuel, as long as some else is turning the engine.

haha..dont have it but asking around how to change gear box?

so if we off the engine at 5k rpm, it will make pop sound rite? like the mat rempit always do, rev hi then off engine, on it again, got pop sound

juz need a knowledge, no nid a car rite?

U say no use fuel.
But it still need use fuel to make it alive. But it auto control from valve only.

I told the guy is "fuel consume still maintain around RPM 1100 rate"

Can try this
www.safetyperformancestyle.com

They got campro transmission final drive. But got server problem today...

Hahah.. the infamous carburator POP. This works only in carb engines as they don't have fuel injectors. Fuel is sucked into the engine by the vacuum, so they rev the engine and then turn off the ignition (no more spark from the sparkplug). Since the engine is still moving, it draws fuel into the combustion chamber from the carb and out into the enhaust. The moment you turn the igniton back on, the spark plugs fires and all the unburnt fuel explodes, giving you that POP sound macam gunshot.

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Added on August 1, 2008, 4:27 pmCorrect. So when people ask if engine braking at high rpm is wasting fuel or not, the answer is NO. Remember, the original question was about whether then engine use fuel while doing engine braking. Once you hit idling rpm, it is no longer engine braking and fuel will be required to keep the engine alive.

This post has been edited by sleepwalker: Aug 1 2008, 04:27 PM

so the pop sound only on carb? if efi no sound? dmn thts boring

but izzit harmful? damaged ur engine?

No report on City at 120kph? Is it true that IDSI runs 120 kph at below 2k rpm? I think someone local wrote that online somewhere.

Only carb. EFi ECU will not pump fuel once you turn off the ignition. No fuel will collect in the combustion chamber and exhaust. With such a big uncontrolled explosion in your engine and exhaust, what do you think? Harmful or not? I believe you can answer that question yourself.

Isnt the FC is on the very high side? 100% stop-go-stop-go driving? Or is it possible the Auto is not running at top gear, somethiong wrong with the torque converter? No comments from other Kancil 880 Auto users?

em maybe it is harmful i think

but i do it on my bike only, if damaged juz small cost only

so if lets say put the turbo in ur car, the rpm still the same like normal?

i do read in certain cars, turbo can reduce ur fc, does it mean running the car in lower rpm?