1969 TVR Vixen

 

" i think mid-engine means taking into account the weight of all drive-train components, the weight is evenly distributed over the front and rear wheels..."

remember, s2000 has 50-50 weight distribution (i think thats how you spell it). i just started to think about it being mid. it is noticably placed in the middle of the car, 50-50 weight distribution, yet we sit behind the engine

 

The Corvette has been a mid-front car since the introduction of the C4... in 1984.

 

Tox, what you need is a side profile of the car. If you know the weight distribution, you know the ratio of distances between the CG and front/rear tires. On the S2000, it's easy, it's half way between the front/rear tires. Looking at a side profile, the approximate position is around the rear view mirror, probably down below the stick shift. I don't have either the weight distribution information, or a side profile image of the Boxter, so cannot do it for you

 

Panoz has been using the Front/Mid configuration since it's inception.

 

Yup...it sure is. I would have never thought they fit that big engine that far back but I went and looked at my neighbor's '91 and they sure did.

I'll trust that the C5 is too, although it is tough to tell the way the engine bay is laid out with inner fender wells covering the upper a-arms. The only pic I could find of a rolling chassis was not very good (C5 frame)

And SRTRick is right too...amazingly the Viper has all 10 of its cylinders behind the front wheel axis.

I can't say much about the TVRs since unfortunately they stopped coming to the US. I think the last one I saw was a 3000S in the '80s.

 

[QUOTE]Originally posted by Tox
[B]

...

I can.

 

Hmm. I may have been wrong about the driver's CG in a 2-seater always being nearer the rear axle. While that's true of the S2000, for the Boxster it looks like the drivers' CG may be about midway between the axles. That more centralized mass would at least be an advantage, but it may be too little to matter.

But there must be some super-important difference between the two configurations -- after all, front-engine cars (which were all front-mid) totally disappeared from open-wheel racing about 35 years ago because they weren't competetive with the rear-mid layout. How come?

 

[QUOTE]Originally posted by Tox
[B]But there must be some super-important difference between the two configurations -- after all, front-engine cars (which were all front-mid) totally disappeared from open-wheel racing about 35 years ago because they weren't competetive with the rear-mid layout.

 

Like Mikey said, PMI depends on the axis of rotation, not on the center of gravity. Ideally the mass should be as close as possible to the axis of rotation. Clustering mass around the CG is only good if the CG is near the axis of rotation, which it is not always. At higher steering angles, when you tend to be pitching the car around and really feel the PMI more as a driver, the axis of rotation is going to be closer to the back of the car so you want the weight there. Unless your car happens to have something like a 40/60 weight distribution, that point is not going to be near the center of gravity. That's one reason why mid-engines are so popular in racing: You have a low PMI when you feel it the most. There are other advantages that you get from a rearward weight distribution, such as better acceleration and better braking that are also desirable in racing. The biggest disadvantage, a tendancy to oversteer in steady state cornering, can be fixed through suspension tuning, tire widths, aerodynamics, etc.