Bullitt73
After completing both GT4 and EPR one of the big differences I have noticed when it comes to physics is how the games handles the mass of the cars differently. If you go to Nurburgring in both games and take the Lotus Elise and the Aston Martin Vanquish V12 you really notice a difference in the two games.
In GT4 I find the Lotus which is a light car very "jumpy" and unstable compared to the the Aston Martin V12 which is a very heavy car very stable and easy to drive. This off course is mostly noticed in the high speed corners. Since I played GT4 before EPR I taught this made sense. The Ring is bumby, so a heavy car like the Vanquish V12 has more mass which makes it more stable because gravity makes it "stick" more to the ground.
Now if we go to EPR I find the opposite. The Lotus Elise is a beauty to drive on the Ring. Very stable. The Vanuish feels more heavy and unstable.
If we think about real life, the Elise is famous for it's handling and road grip. Lotus is famous for making light cars, and we all know the advantages with a light car when it comes to acceleration and top speed. Another good reason for a car with less weight is you have less mass to move around when cornering, which I would assume gives you a more stable car?
Atleast for me I think there is a big difference in the games, and only one of them has got it right. I think EPR makes more sense??
- Bullitt73
Some of what you say is true (in the real world) some of it is not.
You seem to be addressing the effect weight has on a car and how it performs, so lets have a look at a few of them.
Acceleration
Of two equally powered cars the lighter one will generally accelerate quicker due to having a better power to weight ratio. However when you get two cars with an identical power-to weight ratio but different weights, its not quite so simple.
Top Speed
The top speed of a car has nothing to do with its weight; top speed is all about power, size (frontal area of the car), its drag co-efficient and rolling resistance.
Handling
One of the best advantages of a light car can be its ability to change direction. Generally a lighter car will have a lower
Polar moment of inertia, the lower this value the easier it is for an object to change direction when moving. However like all things in life it is not always that simple, low weight on its own does not simply equal good handling; just potentially good handling. How this weight is distributed in the car, determines the centre of gravity, which is also important in determining PMI.
Remember that a low PMI (which comes from weight and how it is distributed) just determines how easily the car wants to change direction, unless the rest of the components; suspension, tyres, chassis, etc are up to the job then its still not going to handle well.
Smoothness
Generally a heavier car will be more stable at speed than a lighter car and a lighter car will be more effected by bumps and surface irregularities than a heavier one. Suspension can however change all of this, I would rather drive a light car with well set up suspension at speed that a heavy car with poor suspension.
Grip
This is the really complex one, so I will try and keep it quite straightforward.
As a general rule grip will increase as the download on a tyre increases, however this is made up of two factors.
The first is how download affects the tyres co-efficient of friction, now this will reduce as the download increases, its also not linear, so the more download the quicker the CF reduces. Now before anyone starts saying that I have contradicted myself, we need to look at how the tyres CF translates to tractive forces.
If a tyre generates a CF of 1.7 at 200lbs of download it is generating 340lbs of tractive force (1.7 * 200). If at 400lbs of download the same tyre has a CF of 1.35 it is now generating 540lbs of tractive force (1.35 * 400). So while the CF has reduced the overall tractive force has increased. However remember that the rate of increase declines as loading gets higher.
Now download on a car is never static when a car is in motion and the download will vary when you brake, accelerate and turn. It could then be said that the actual weight of a car is less important to grip that how the car transfers that weight. Certainly this is true under braking.
Now I hope that all the above make sense and just for the record its have been taken from the Physics of racing series (Link in the GT4 & Brakes thread in my sig) and the book 'Going Faster' which is the manual of the Skip Barber racing school.
As a sidenote I have driven an Elise on a number of occasions and at speed the front end is very light and bumps do affect it in quite a major way. Remember its a light MR car with F/R weight distribution of 38/62, at speed the weight is going to shift to the back reducing the grip offered by the front tyres. However get the car balanced and set-up for a corner and it will corner like very few other road cars.
The Elise does have a reputation for extremely good handling, but it should also be noted that it is not an easy car to drive quickly. It demands a lot of the driver, one UK jurno said that the original Elise had lift-off oversteer as bad as a 1970's Porsche 911. Too many people equate good handling to easy to drive, they are not the same thing.
So how does this translate to Enthusia Vs GT4
Well in my opinion its not a fair comparison, the reason is that the 'ring in GT4 and Enthusia are very different. GT4's version has many, many bumps (which I feel is accurate - certainly from my visits) which would favour the Aston in terms of stability). Enthusia's 'ring is far to smooth (but has represented a couple of the corners better than GT4) which would favour the Lotus.
In the balance neither GT4 nor Enthusia has got the physics of driving 100%; Enthusia is much better at low speed physics, but GT4 represents high-speed physics more accurately (all in my opinion of course).
Personally I have and love both.
Regards
Scaff
But I have never driven one in real life so thanks for your input.
). So I agree with you that Enthusia has it just about right.
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