I find though, when taking it past 4k the next gear change is instantly going over 3.5k and has no pull compared to around 3k. I'm still fairly new to dielsels though to be honest so practice and an accurate RR should settle it.
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I find though, when taking it past 4k the next gear change is instantly going over 3.5k and has no pull compared to around 3k. I'm still fairly new to dielsels though to be honest so practice and an accurate RR should settle it.
how can torque be largly irrelevant??
one way i've always thought of it was bhp is generally the eagerness of the car and the rate that it does it, torque is the productivity whilst its doing whatever it does??
the more torque the larger the gains whilst its in gear, bhp would only raise the rate it produces the torque, correct??
Trappy
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BHP=(Torque/5252)*rpms
There are countless websites that will explain the relationship between the two in great detail, but torque is a static twisting Force. Without revs, you have no power. Power is therefore essentially a measurement of torque over time.
If you have twice the torque at half the rpm, then you'll be making the same power. Gearing can therefore allow a low revving torque monster to accelerate as quickly as a low torque rev monster like a Vtech.
This is why you'll find a Civic Type R has approximately the same performance as a remapped Ibiza Cupra TDi; they will have remarkably similar bhp/mph curves going through the gears, even though the Ibiza is likely making twice the torque at half the rpms.
Although torque and rpms together create bhp, it is the only force you need to be concerned with when calculating performance, in'gear or 'through the gears'.
There are countless websites that will explain the relationship between the two in great detail, but torque is a static twisting Force. Without revs, you have no power. Power is therefore essentially a measurement of torque over time.
If you have twice the torque at half the rpm, then you'll be making the same power. Gearing can therefore allow a low revving torque monster to accelerate as quickly as a low torque rev monster like a Vtech.
This is why you'll find a Civic Type R has approximately the same performance as a remapped Ibiza Cupra TDi; they will have remarkably similar bhp/mph curves going through the gears, even though the Ibiza is likely making twice the torque at half the rpms.
Although torque and rpms together create bhp, it is the only force you need to be concerned with when calculating performance, in'gear or 'through the gears'.
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That's how I always think about torque / BHP on graphs - You will see the peak torque of a petrol engine is somewhere around 3-4k (generally) but the BHP keeps climbing until the red line. People forgot that BHP is work done over a time so as the RPM goes higher it can do more work in less time so unless the torque really falls off the BHP will keep on increasing and the engine will generate more power.
Obviously the torque vs BHP discussion doesn't stop there, there are lots of other considerations. More torque is always better to have than not but if you generate the power at higher RPM you can get more work done and produce more power.
Trappy
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Exactly.
More torque at lower rpms will obviously result in more drivability (you are still making more bhp aferall), even if the car is no faster than a 'peakier' engine. 300lbs/ft of Torque at 1,800rpms is 114bhp. 200lbs/ft at the same rpm is still 76bhp. That's 38 less.
At 7,200rpm, just 200lbs/ft will make 274bhp. If you could make that 300lbs/ft here, you'd be pushing out 411bhp! Now this is a considerable 137bhp difference.
It is nice to have lot of low-down torque and it makes a car feel very 'grunty', but don't get it confused with outright performance. It's only the power you're making when chasing through gears that gives performance.
Trappy
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It's just down to calculations, though the losses are sometimes measured on the coast down. I believe they measure the torque at wheels while accelerating, calculate the bhp@ wheels using the formula I posted above, and then calculate the flywheel losses, by measuring the resistance from the car by letting it decelerate naturally.
The losses are then added to the wheels figures for an estimated flywheel figure.
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