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Old 7th July 2005, 18:51   #1
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Default How to improve lower end torque..

Experts/Gurus here, need your advice, help..
Not that I am complaining about the lower end torque in my car (Petra 1.6EL)
But I really wnated to understand what contributes to the lowerend torque and top end grunt..

Are there mods, which can tweek them..
Are the techniques different for conurated engines and MPFI engines,,

All points welcome..

Thanks
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Old 7th July 2005, 19:45   #2
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hey this is my bit from what i have learned over a period of time..basic mods like the air filter and the headers and engine tuning contribute largely to low end and mid rrange torque depending on the way you design and install your setup...well as far as mpfi engines are considered the ecu plays a major role..tweaking the ecu..thee fuel curve and stuff does work miracles...then you have piggy back system's and also stand alone fuel management system's all these things when put together help in a major way to adjust your low end,mid-range and high end torque..this was my bit..please correct me if im wrong..and pm me if you ever need any more details...cheers...!!
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Old 7th July 2005, 22:20   #3
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You can get a custom header made that will improve low and mid range.....might lose some top end. Talk to Mr.Psycho
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Old 8th July 2005, 10:52   #4
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DRC, yes you can go to PSYCHO he is the man....can increase low end torque with headers...that should do...but for more phenomnal increase you need to do some serious mods
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Old 8th July 2005, 11:28   #5
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Thanks,
The intention is not to mod, but to understand technically what is responsible for Low end torque.
Thumb rule, What ever you want to do do it in ECU. But what?
Advance firing timing? Make the fuel richer? leaner?

Please prodon me If you feel I am really 1st grade boy in autos..
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Old 8th July 2005, 13:18   #6
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What is a desirable engine? that can go upto 8000RPM and still attain peak torque in the lowest RPM like less than 3000?
Experts out there, share your ideas?
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Old 8th July 2005, 15:57   #7
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Quote:
What is a desirable engine? that can go upto 8000RPM and still attain peak torque in the lowest RPM like less than 3000?
I'd seen such an engine on Best Motoring. A tuned Supra that produced 60kgm from 3000 to 6000 rpm and redlined at 7000 rpm.

Problem with such engines is that the sudden surge of torque is so intense, you hardly gain anything from it. The car would spin it's wheels at the slightest hint of throttle. It managed a time 1min 4 secs around one of the Jap tracks.

Then came a tuned Skyline which wasn't as powerful as the Supra but, the torque and power curves were such that the car was able to utilise it to accelerate and not spin it's tyres.

That Skyline was 4 secs qiucker (per lap) than the more powerful Supra.

On a track, a cars peak torque/power are the least of it's worries.

Shan2nu

Last edited by Shan2nu : 8th July 2005 at 15:58.
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Old 8th July 2005, 15:57   #8
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if it can go upto 8000rpm but reaches max torque at 3000rpm....well for this you need to understand the torque and bhp curves. a car can go upto 8000rpm but if max bhp is at 6500 after that the engine starts losing power...so the redline is not that important.
the key factors being:
a. the peak of the torque
b. the rpm at which max bhp is achieved

now if torque needs to be increased it can be done by adjusting the ignition timing, but this will lead to drop in power at higher rpm...as in car has amazing initial but becomes slower at attaining its top speed.
this is a very simple way of doing it and do not need to adjust the ecm..

ideal engine???? well any good engine can be built to meet your requirements but for the torque you need to look at bigger cc...rpm is secondary
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Old 8th July 2005, 16:04   #9
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So what you're saying is that it's best to shift just after max power is reached, rather than just before the limiter?
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Old 8th July 2005, 16:08   #10
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optimally torque should peak at around 2500 - 3500 rpm in most daily use engines since thats where most of us drive usually,,with peak power coming in at around 5500 rpm or thereabout since that relates to pick up whereas torque provides usable driveability,,to increase it u need to increase compression ratio ,,and then use higher octane say 93 octane fuel
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Old 8th July 2005, 16:31   #11
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Well, technically, it's not possible to have peak torque at 3000 and expect the engine to rev to 8000.

If you've noticed the Supra example i gave, it's peak power starts at 3000 but, carries on all the way to 6000. That is the main reason why that engine could revv to 7000 rpm.

For an engine to be able to usefully revv to 8000, it'l have to produce peak torque at high rpms too.

Examples:

1. S2000 2.2ltr
Power - 240bhp@7800rpm
Torque - 162lbft@6500rpm.
Redline - 8200rpm

2. S2000 2ltr
Power - 240bhp@8300rpm
Torque - 207nm@7500rpm
Redline - 9000rpm

3. Enzo Ferrari
Power - 650bhp@7800rpm
Torque - 657nm@5500rpm
Redline - 8200rpm

4. Ferrari F430
Power - 490bhp@8500rpm
Torque - 343lbft@5250rpm
Redline - 8500rpm

As you can see, even some of the best high revving engines cannot produce peak torque at 3000rpm. It's just not possible.

Shan2nu

Last edited by Shan2nu : 8th July 2005 at 16:33.
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Old 8th July 2005, 16:57   #12
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I kind of understand but not fully. Can explain with examples of normaly cars that we drive around?
say santro and zen.
zen has a good pickup, but santro has a better top speed (marginally better)
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Old 8th July 2005, 17:08   #13
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Quote:
zen has a good pickup, but santro has a better top speed (marginally better)
Top speeds according to OD.

Santro Xing - 142.2kmph
Zen - 145kmph

Shan2nu
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Old 8th July 2005, 18:19   #14
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saw my friend pull the santro to a bit over 150 ...speedo error i guess..

torque(in kgm) figures on the -(manufacturer website)
zen - 8@4000rpm
santro - 9.8@3000
so here can we say zen has a high revving engine ?

also, Is it true that a engine with higher low/mid range torque will have a low top end speed than a car with its peak torque at a much higher rpm ??
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Old 8th July 2005, 18:58   #15
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Quote:
torque(in kgm) figures on the -(manufacturer website)
zen - 8@4000rpm
santro - 9.8@3000
so here can we say zen has a high revving engine ?
It's not possible to tell which engine will produce max power or redline at a higher rpm by looking at it's peak torque. Max power and redline depend on how the torque is spread over the revvband.

In some cases, it's possible that an engine might produce peak torque at 4000rpm and drop drastically after that (reducing the rpm where peak power is achieved) while another engine might produce peak torque at 3000rpm and fall gradually thereafter (which will result in peak power being produced at a higher rpm).

Unless you look at an engines torque curve at various engine speeds, it's just not possible to come to any conclusion.

In this case, the Zen might revv higher but, the same can't be said about 2 other engines that produce torque at 4000 and 3000 rpm.

Shan2nu
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