Driver Aids

[scathing]

Yeah and why were they banned? Answer is safety.

That's right. They were banned because they made the car too fast, to a point where if an accident occurred the chassis would be less likely to save the driver. So, reduce the speed and reduce the kinetic energy the chassis needs to dissipate in a crash.

Anyone who's talked to someone who races knows that they don't need electronic aids to be overly confident. Even without traction control and active aero etc, F1 drivers push it to the limit of the car's cornering speed. You can't say that all those things made the drivers confident of pushing their limits more - it just made the limits that they were pushing occur at a higher speed.

Hence why, like I said, if quickness is the point then you have those things. I'm not talking about survivability or fun, just travelling a distance in the shortest possible time in the absence of f**k-ups.

However, for your average Joe who isn't out there pushing the envelope every day or 100% focused on how their vehicle is travelling, those higher limits means that at the pace they do (which isn't meant to change as technology progresses) they have more handling / braking capacity left over. If they do find themselves in an emergency situation, without driver aids their actions may push the car past the limit. With those driver aids they might stay under the limit.

Edited September 24, 2009 by scathing

[Tony de Wonderful]

then you need to learn more about how power is made and tuning.

take a stock ecu powered skyline and look at the air/fuel ratios. they will be down around 10:1. plug in an aftermarket ecu, copy across the maps, leave the timing the way it is but remove some of the fuel to get an AFR of around 12:1 and you will make more power.

a very basic way to look at it is like this:

if you light a fire then dump 10L of fuel on the fire, the fire will probably go out because it has been smothered before it could burn all the fuel. take the same fire and tip on half a litre of the same fuel and you will get a fireball.

of course with all the advances of technology the newer engines have better designed heads, etc so they flow air better so can make more power for the same amount of airflow and fuel as there is less restriction.

You're conflating efficiency with absolute fuel consumption.

Take than 3.0 L super efficient engine, now make it 2.0 L but otherwise the same. Which one now uses less absolute fuel to say drive 10 miles in the same car (don't forget the 2.0 L powered car is slightly lighter)?

[scathing]

You're conflating efficiency with absolute fuel consumption.

Take than 3.0 L super efficient engine, now make it 2.0 L but otherwise the same. Which one now uses less absolute fuel to say drive 10 miles in the same car (don't forget the 2.0 L powered car is slightly lighter)?

Its still impossible to say. Now that you've brought in a caveat that the smaller displacement engine is lighter, not "all other things are equal" (as you originally stated).

The 2.0L engine might be lighter, but the 3.0L engine will make more torque naturally due to displacement. This allows the 3.0L car to run taller gearing (for the same number of gears), bringing the RPM down, while giving the two vehicles similar acceleration values (to keep the performance as close to each other as possible, for comparative purposes).

The gearing can't be kept constant if you want to keep your "super efficient" pre-requisite on both powerplants. A gear ratio that a 2.0L engine to hold a certain speed will be too short for a 3.0L engine, and so it'll be overrevving. At that point, the 3.0L is outside of its efficiency band and your comparison becomes void.

Where the 2.0L engine might need 3000RPM to hold 100km/hr, a 3.0L of the same bore & stroke ratio might only need 2500RPM.

If that extra litre of displacement is made up by stroke only, then there's even more low down torque and that will give the engineers even more scope for gearing the car for efficiency rather than acceleration. a 3.0L long-stroke variant of the engine might only need 2000RPM to pull said car at the same speeds.

All of a sudden, your two engines making just enough power to overcome wind resistance (which is the biggest force to overcome on a car travelling at speed, not mass) at the same speeds are pumping an equal amount of air (and therefore fuel) over a unit of time.

Dynamically smaller engined car, while lighter, needs to be revved harder to match the acceleration of the bigger engined car, and the more constant gearchanges also takes an economy toll compared to being able to hold one gear.

[Duncan]

I was reading about Peter Wheeler's (former owner of TVR) design philopshy which was to reject ABS, traction control, air-bags etc being incorporated into TVR design. He believed these made drivers overconfident and so led to more accidents.

I liked how he thought, until he sold out to the russian mafia. in fact a tamora is the only car i would sell the z for.

but his issue was losing repeat customers when the killed themselves. that and I have a sneaking suspicion that they were so vocal against driver aids because they couldn't get headlight wiring reliable, let alone traction control.

but their 4l straight 6 motor is a monster.

[scathing]

but his issue was losing repeat customers when the killed themselves. that and I have a sneaking suspicion that they were so vocal against driver aids because they couldn't get headlight wiring reliable, let alone traction control.

Customers, in TVR land, are better referred to as test pilots. They seem to have the same accident rate. There's a great video of Martin Brundle trying, and failing, to drive one on a wet test track.

I remember mentioning how much I wanted a Tuscan or Cerbera to some British colleagues, who advised me against it. Aside from the convenience of not needing sat-nav to get home because you could just follow the trail of parts, Hansel & Gretel stylem that have fallen off the car from the moment you leave your garage they mentioned that TVRs have overheating in the UK.

In Australia, you'd be f**ked.

but their 4l straight 6 motor is a monster.

A P-plate legal (in NSW) to boot.

[Nic_A31]

My 1994 Maxima (3.0 V6) does 100kmp/h @ 2000rpm, give or take 50rpm on air temprature. I can squeeze 700km from a 65l tank in that, so power can mean economy. But keeping in mind that the O/D gear in that Maxima is f**king tall, gear ratio's will affect RPMs more than anything.

IMO Driving aids desensitize driver's to bad situations. Its not like ABS, ESP, TC, etc cant fail, they do.

I got breif lessons on what to do in brake locks up, loss of traction, if the back end comes out, if the front end starts sliding away, etc. My first car (1988 Astra) had nothing but lazy power steering, and I survived just fine, yet I've seen someone with a brand new car from their parents with all the fruit manage to crash it (female). Its like the auto/manual arguement, I think driving a manual is much more interactive and makes you actually think about how cars work, how you're in control, etc.

[Tony de Wonderful]

Its still impossible to say. Now that you've brought in a caveat that the smaller displacement engine is lighter, not "all other things are equal" (as you originally stated).

The 2.0L engine might be lighter, but the 3.0L engine will make more torque naturally due to displacement. This allows the 3.0L car to run taller gearing (for the same number of gears), bringing the RPM down, while giving the two vehicles similar acceleration values (to keep the performance as close to each other as possible, for comparative purposes).

The gearing can't be kept constant if you want to keep your "super efficient" pre-requisite on both powerplants. A gear ratio that a 2.0L engine to hold a certain speed will be too short for a 3.0L engine, and so it'll be overrevving. At that point, the 3.0L is outside of its efficiency band and your comparison becomes void.

Where the 2.0L engine might need 3000RPM to hold 100km/hr, a 3.0L of the same bore & stroke ratio might only need 2500RPM.

If that extra litre of displacement is made up by stroke only, then there's even more low down torque and that will give the engineers even more scope for gearing the car for efficiency rather than acceleration. a 3.0L long-stroke variant of the engine might only need 2000RPM to pull said car at the same speeds.

All of a sudden, your two engines making just enough power to overcome wind resistance (which is the biggest force to overcome on a car travelling at speed, not mass) at the same speeds are pumping an equal amount of air (and therefore fuel) over a unit of time.

Dynamically smaller engined car, while lighter, needs to be revved harder to match the acceleration of the bigger engined car, and the more constant gearchanges also takes an economy toll compared to being able to hold one gear.

I think the smaller engine being lighter is implicit in the caveat; all (other) things being equal.

That makes a vehicle lighter and also the internal moving parts (quite important).

You know as well as I do that most driving is stop/start in traffic, so yes the more powerful car (being heavier) is going to require more fuel/energy to travel x amount of distance stopping and starting x amount of time.

Also Drivers of more powerful vehicles tend to accelerate quicker than Drivers of underpowered vehicles...that uses more fuel.

[Nic_A31]

Thats a bit of a contrast. Thats comparing 4 cylinders to soccer mums with tanks.

Engine wieght doesnt mean vehicle weight, but I do agree on bigger vehicle driver's having bad acceleration habbits.

[scathing]

You know as well as I do that most driving is stop/start in traffic, so yes the more powerful car (being heavier) is going to require more fuel/energy to travel x amount of distance stopping and starting x amount of time.

That still doesn't negate the fact that the torquier engine also requires fewer RPM to achieve a given rate of acceleration (since you're trying to keep all else equal), meaning there's less combustion cycles going on while travelling.

Since you're giving an inherent caveat to a smaller engine being lighter, its also an inherent caveat that car manufacturers gear bigger engined variants of their models differently.

Whether those two factors offset the displacement disadvantage is still unprovable from what little criteria you're basing it on.

Most big engined cars still drink more fuel than their small engined counterparts since the gearing, while taller, is still set up so that the bigger engined, more expensive, model out-accelerates the povo pack entry model car with the pissweak engine.

If a manufacturer were to gear their 2.0L car and 3.0L cars to achieve the same 0-100km/hr and quarter mile times (to keep all else equal aside from displacement) their economy values would be a lot closer.

Also Drivers of more powerful vehicles tend to accelerate quicker than Drivers of underpowered vehicles...that uses more fuel.

That's an issue with the driver, not the engine. I thought we were comparing the technical differences of two mechanical devices? You said that we were holding "all else equal", not "all else equal except things that don't suit me".

It's also "tend to", not "actually do". How many P platers do you see driving shitbox little Charades or Swifts and revving the tits off them, while retirees in Falcodores, Camrys take off like they're in a funeral procession?

Even in Falcodore land, its more often P platers in their shithouse entry model cars hooning around trying to race everyone at the lights. The older blokes who can legally drive, and afford to buy, the V8s tend to have outgrown that shit.