what is the ideal torque range for street cars?

[davidv00]

hi there,

i am referring to 1500/1600 c.c. street cars we saw... like honda city, toyota vios, toyota avanza 1.5, nissan sentra 1.6G etc... all having almost 14x n.m. / 4200rpm or higher but only one car... Gen2 is having 148 n.m./4000rpm only... the questions are:

1. why gen2 having this kinda of torque?

2. anyway to improve that?

i hope i hear some positive answer and professional views... bashing can keep for other threads... thanks :)

 

[SkYwAlKeR]

after horsepower, now torque pulak...

1) whats the difference between the 2 figure??... both is at 14X range.... or u mean the highest torque @ what rpm arr??... that one can change la, make use of adjustable compulleys....

2) tuning... increase engine performance... bla bla bla...

 

[ScoobyDoes]

For me the maximum torque should be the point in the rev band (street cars) where you need the most acceleration.

Let's say you are sitting in a queue on the highway and want to pass somebody or pull into the outside lane..... the normal thing to do in order to do this quickly is drop a gear and you your maximum torque to be at the rev of the lower gear. Best place for me is between 3000 and 3500rpm where most of the work is done. I've tuned mine to have max. torque at just 3500rpm and it's a much better drive.

 

[davidv00]

if i were adjust using the adjustable campulley to 4.2k rpm, do you think is a good idea?

 

[samuel87]

4.2k for a street car? isn't that kind of too high?

 

[TitanRev]

Eh....correct me if I'm wrong. I dont think adjusting your campulley will give you better torque. Adjustment of the cam is only to advance and retard the ignition timing.

If you want to alter the torque band and its figure. I think you have to reconfigure your gearbox ratio. A close ratio gearbox would be you choice if you are looking for more torque and acceleration rather than top speed. Close ratio gearbox has very good torque but you will lost your top speed.

If you have played PS's Gran Turismo then you should know about this gearbox configuration.

Here's some info of gear ratio
http://en.wikipedia.org/wiki/Gear_ratio

Another thing you can increase your torque reading if you have a big block or a longer stroke engine. Like those American muscle car. They have huge torque readings.

Refer to these site
http://science.howstuffworks.com/fpte4.htm
http://vmaxoutlaw.com/tech/torque_hp.htm
http://www.g-speed.com/pbh/torque-and-hp.html

Correct me if any given info is not correct

 

[SkYwAlKeR]

icic... i also not sure la... coz i heard some say by using adj campulleys, u can lower ur max torque to a lower rpm, hence u get max torque much earlier...

for street cars, better adj ur max torque at lower rpm range lor... good for pickup...

 

[ScoobyDoes]

Actually on most cars simply re-chipping or running piggie backs on the ECU can alter your tuning and both the power and torque bands. Just alter your fuelling.

You don't need to change the g/box ratios.

I simply run a piggie back to take the torque from 5k to 3.5k rpm.

 

[rollakid]

sorry titanrev but i have to disagree.

If you want to alter the torque band and its figure. I think you have to reconfigure your gearbox ratio. A close ratio gearbox would be you choice if you are looking for more torque and acceleration rather than top speed. Close ratio gearbox has very good torque but you will lost your top speed.

firstly, gearbox ratio does not alter the torque output of the engine (assuming dynoed at the flywheel). Gearbox ratio is changed to suit and take advantage of the torque band of the engine. If your engine has a narrow peak torque band (eg. highly tuned 4age, torque band from 8k-10krpm only, crappy power at all other revs) will need an extremely close ratio gearbox so that when the driver change the gear, the rpm will always stay in that 8-10k rpm, so they won't lost power.

changing torque band only gives you extra acceleration if you talk about fully make use of the narrow torque band. This is because a narrow torque band engine cannot use normal/wide gear ratio, and normal engine using close ratio gearbox is just wasting the engine's wide torque range, and making the driver have to shift often.

close gear ratio will not make you lost top speed, most close ratio gearbox do have the same ratio for the highest gear compare to stock one.


i think what you mean is the Final drive ratio, not the gearbox ratio.

 

[prozac]

1. Sometimes it's not so much about what the torque is, but where in the powerband it is. A car with less torque but at a lower rpm can have more pickup than one with torque at a higher rpm. Anyway, the Campro is known to be not very torquey at low revs.

2. There are mods, but I can say it's not going to be cheap and the effects more psychological than say, driving a car with more torque. Here's a tip if you feel the car is sluggish; jab at the accelerator if you want to move fast. The drive-by-wire system tends to be lazy if your right foot is equally lazy.

 

[rollakid]

my idea of ideal torque band for street driven car is peak torque comes at 2.5k rpm all the way to 5k rpm all flat XD.

not everyone likes to double declutch to have the rpm go into the 5k+rpm range and 2nd gear to overtake other people...

 

[davidv00]

thanks all... i agrees s4ph engine (gen2, not Campro, inside dun have CPS and VIM) does have bad low end torque, but in high end the power is there.

the problem we faced about "street cars" is we hardly rev till 4k rpm (in s4ph case), even on Klang Valley highways, at most 3k rpm for 120km/h, so for layman speed for driving, this is adequate and for any SOHC cars, the torque band is just nice for such needs and my headache now is how to make the DOHC s4ph to have what rollakid has mentioned, a flat band from 2k to 5k rpm... wow.. that would be nice if achievable.

what you say?

 

[rollakid]

thanks all... i agrees s4ph engine (gen2, not Campro, inside dun have CPS and VIM) does have bad low end torque, but in high end the power is there.

the problem we faced about "street cars" is we hardly rev till 4k rpm (in s4ph case), even on Klang Valley highways, at most 3k rpm for 120km/h, so for layman speed for driving, this is adequate and for any SOHC cars, the torque band is just nice for such needs and my headache now is how to make the DOHC s4ph to have what rollakid has mentioned, a flat band from 2k to 5k rpm... wow.. that would be nice if achievable.

what you say?

easiest way is to get used to the torque band of the engine, shift down when need extra power.

i personally have no problem with shifting down, but then the problem is with other people. Let say, there's this grandma driving at 50km/h and i'm in a rush to go to somewhere. 50km/h i'd most probably be in 3rd or 4th gear, and both of them isn't in the torque band yet. so for fast overtaking i'd have to go down to 2nd gear, which my engine will roar like hell.

i have no problem with that, but what if the poor obaasan heart attack? later me become culprit pulak XD


well, another way would be bolting on a root or screw type blower XD you'll get all the power you want low down the rpm.

 

[TitanRev]

Thanks Rollakid

Rollakid, thanks for your correction. Now I know gear ratio is to take advantege of the power band right ?

 

[davidv00]

care to explain what is this?

easiest way is to get used to the torque band of the engine, shift down when need extra power.

i personally have no problem with shifting down, but then the problem is with other people. Let say, there's this grandma driving at 50km/h and i'm in a rush to go to somewhere. 50km/h i'd most probably be in 3rd or 4th gear, and both of them isn't in the torque band yet. so for fast overtaking i'd have to go down to 2nd gear, which my engine will roar like hell.

i have no problem with that, but what if the poor obaasan heart attack? later me become culprit pulak XD


well, another way would be bolting on a root or screw type blower XD you'll get all the power you want low down the rpm.

 

[si|verfish]

It means supercharging lar. Roots and screw are different types of superchargers.

 

[davidv00]

thanks