Why does the car do this?

[NeoTheOne]

I've always wondered if a car like the Mini produces max power and max torque well before the red line, why does it keep accelerating all the way to the redline?

[Back2DTM]

max. powerband does not equal redline.

[supercharged]

NeoTheOne:

The MINI's Max Torque and HP are reached before the red line. Those are just the points at which the engine produces it's maximum power. Most engines produce the peak torque before redline and most engines reach their peak HP/KW very near to redline. The redline is only there because that's the engines limit. So my point is, even when the MINI is out of it's peak power, the engine still has enough power to carry on revving to the redline.

I hope I made sense.

[NeoTheOne]

Yeh you made sense but I still dont see why after max power is reached and power begins to fall slighty, the car would continue to accelerate. Could it be to do with gearing? I don't mean to sound stupid. Any mechanics or physicists out there willing to help?

I'm not really concerned with the revs carrying on to the red line, more that for example, a MINI One produces peak power at 5500rpm but still accelerates after this to the redline where after 5500rpm power would presumably drop off slighty? Do I make sense?

[RedUn]

Quote: Originally Posted by NeoTheOne

Yeh you made sense but I still dont see why after max power is reached and power begins to fall slighty, the car would continue to accelerate. Could it be to do with gearing? I don't mean to sound stupid. Any mechanics or physicists out there willing to help?

I'm not really concerned with the revs carrying on to the red line, more that for example, a MINI One produces peak power at 5500rpm but still accelerates after this to the redline where after 5500rpm power would presumably drop off slighty? Do I make sense?

the acceleration will slow down after peak power has been reached and passed but from peak power to the redline is such a short space of time i don't think u notice mi self

[NeoTheOne]

Yeh, I guess I'll just get MTH and ask for peak power closer to the red line then!!

[Hat]

i'd be careful with that - there have been instances of chipped cars (including MTH) hitting the redline & cutting all power without warning & going into limp home mode - check some of the MTH threads. i'm not saying don't do it, just be careful going too close to the redline if you do

[obehave]

Here's a very good layman's description of the torque/ horsepower relationship.
Torque gets you going, HP keeps you going.

[NeoTheOne]

Yeh I've heard this was a problem with the One-Click system too. Does superchips have the same problem? I just don't think I could justify paying 400 pounds over MTH price for practically the same thing.

[NeoTheOne]

Quote: Originally Posted by obehave

Here's a very good layman's description of the torque/ horsepower relationship.
Torque gets you going, HP keeps you going.

Now I understand :P

It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*.

I also heard someone say, "Horsepower sells cars, but torque wins races."

[Hat]

good article but i'm still confused. given the actual output figures for the cooper of:
115bhp @6000rpm
150Nm torque @ 4500rpm

bearing in mind the only gauge we have as drivers is the rev counter & we can't see when we've acheived maximum torque, what is the optimum rpm for gear changes - 4500rpm, 6000rpm or somewhere in-between?

[obehave]

Quote: Originally Posted by Hat

good article but i'm still confused. given the actual output figures for the cooper of:
115bhp @6000rpm
150Nm torque @ 4500rpm

bearing in mind the only gauge we have as drivers is the rev counter & we can't see when we've acheived maximum torque, what is the optimum rpm for gear changes - 4500rpm, 6000rpm or somewhere in-between?

Drag racing shift at peak HP
Road racing stay at your torque peak through the twisties and run it up to HP peak on the straights.
Huge oversimplification but a starting point just the same.

[SalemMINIDriver]

Quote: Originally Posted by Hat

bearing in mind the only gauge we have as drivers is the rev counter & we can't see when we've acheived maximum torque, what is the optimum rpm for gear changes - 4500rpm, 6000rpm or somewhere in-between?

For maximum acceleration, shift at high enough revs so that you will be at or just above peak torque RPM in the higher gear. This will leave you just short of max HP RPM and redline, but it's my understanding that this characteristic of the engine has more to do with the vehicle's top speed (which is electronically limited anyway) than with acceleration.

[kapps]

The horsepower/torque debate:
Ok. Torque is what you feel when you accelerate. The higher torque numbers at lower rpm's mean you can accelerate faster sooner. If you have 155 lb ft of torque at 2000 rpm or 4000 rpm, you will feel the exact same acceleration at those respective rpm's. As for horsepower, it's a fake measurement . Howsepower is torque * rpm / 5252. This means hp is directly related to rpm so that engine with 155 lb ft at 2000 rpm would have 1/2 the hp of the engine that makes the same 155 lb ft at 4000 rpm. This is why diesels have low horsepower numbers but massive torque - their torque peak is usually well under 2000 rpm.

Which is best? You choose. More low down torque lets you get on it sooner when accelerating but you might loose the top end. In that case, you would want to be in the next gear. Also, engines that are designed for high rpm's usually have a torque peak fairly high (think Honda). An F1 car makes 800 hp at 18000 rpm so it's only got 250-ish lb ft of torque!!! The MINI benefits from the SC to lower and flatten the torque curve so when you need it, it's there.

[forevercornered]

Dont hold me on this, but I think the reason for the later than max hp/torque redline is that: Just because you dont have max hp or torque being applied to your wheels at that particular point past max, there is still a lot of power being applied that is still accelerating you. No its not the most amount of power your car can produce, but as soon as you shift to the next gear(assuming you shift at or nere redline) your rpms will be at a close to max level of output maximizing the power into your acceleration. This is why the reason high rpm cars usually have a quicker acceleration(depending on gearing), because the acceleration is sustained longer in between shifts.

Hope this makes sense.