What are the advantages of rear-mount engine?

[Al Weyman]

Also years ago there were many rear engined cars, Imps, Fiats, Vw's, Renaults, Skoda's etc etc and they have all gone to Front Wheel drive. A rear engined car must have been easier to manufacture than FWD so why did the manufacturers all bar Porsche do that?

[bludvl_x19]

Originally Posted by Al Weyman

Also years ago there were many rear engined cars, Imps, Fiats, Vw's, Renaults, Skoda's etc etc and they have all gone to Front Wheel drive. A rear engined car must have been easier to manufacture than FWD so why did the manufacturers all bar Porsche do that?

Packaging maybe? Having the engine up front means that you can have a decent sized boot (in theory) and if the engine is in the front, FWD makes sense.

Just my opinion though

[Al Weyman]

Ever see the boot in the front of one of those VW saloons (Type 9??) that was massive, no I dont think it was that personally I think more to do with wanting a car that would understeer not oversteer if pushed. and of coure Ralph Nader put the nail in to the coffin of the Corvair on safety grounds, snap oversteer, nothing up front to protect the driver etc.

[Jeff 8]

Originally Posted by Al Weyman

...nothing up front to protect the driver etc.

How does an engine protect the driver? I have seen engines in peoples lap after a large front ender, perhaps in a Porsche they would have less injuries.

Jeff

[Al Weyman]

Dunno ask Ralph Nader as it was one of the arguments that buried the Corvair. Seriously surely the mass bulk of the unit bolted to the chassis then further held in place by the propshaft to rear axle would be more sustantial in crash than an empty void but I dont really know is the answer.

I think the only real advantage of a pure rear engined car is they are better on snowey roads which is why they probably were so popular in Eastern European countries.

[neiltb]

as long as your snowy roads are straight

[Al Weyman]

True!

[R59]

Originally Posted by Al Weyman

Dunno ask Ralph Nader as it was one of the arguments that buried the Corvair. Seriously surely the mass bulk of the unit bolted to the chassis then further held in place by the propshaft to rear axle would be more sustantial in crash than an empty void but I dont really know is the answer.

I think the only real advantage of a pure rear engined car is they are better on snowey roads which is why they probably were so popular in Eastern European countries.

The Corvair was declared "Unsafe at any speed", it was unstable, and evil in factory trim.

However, fit some anti-roll bars a bit of tweaking on geometry, and they are much much much better.

My cousin had one, and he'd fitted antiroll bars, and tweeked bits here and there, and yes, it was miles better, and he reckoned it wasn't bad.

It was a bit of a whim, since he had VW Variants, and this came up as a silly cheap bargain..

Long since scrapped though.

[Al Weyman]

I had one, a rare turbo version but never got that running right either, I say I had one it passed through my hands as I used to do a bit of trading. One thing I found seriously dangerous was the heater, it was like a mini parrafin/LPG garage blow heater complete with spark plug and timer, only problem was this thing ran on petrol from the fuel tank!!!!!!!

[phoenix]

In 1967 Vic Elford managed to win the European Rally Championship and the British Touring Car Championship in a 911. At the beginning of the same year, on February 4th 1967, he won the first ever Rallycross event a Lydden - always a slippery event at that time of year. In 1968 he won the Monte Carlo Rally - renound for it's ice and snow.

Maybe you have to be a good driver to drive a Porsche on the limit - but the layout of the car itself is demonstrably high in rear end grip.

Other rear engined cars that have also faired well on the loose and slippery stuff over the years are Alpine Renaults, Imps, Skodas and Davrians. I'm sure ther must be others.

I have rallied rear engined Davrians and Porsches. Rear engined cars can be set up to understeer, oversteer or be entirely neutral. The one thing they all have is amazing traction because of the weight over the driven wheels. I never had an accident in rallying until I went mid-engined. Direction changes happen a lot quicker in a mid-engined car due to their low polar inertia, so spinning became a bit of difficult habit to give up.

In that respect, driving a rear engined car with the tail hanging out is a lot easier to manage safely than it is in a mid-engined car, particulary on wet tarmac, loose surfaces or snow. In that respect, a rear engined car is more stable than a mid engined car. In the dry or wet, with of course the correct rubber, 935s in the 70's were able to put massive torque and BHP down onto the track. They are still doing so today, with people like Richard Chamberlain at the wheel.

[buterworth]

Originally Posted by phoenix

In 1967 Vic Elford managed to win the European Rally Championship and the British Touring Car Championship in a 911. At the beginning of the same year, on February 4th 1967, he won the first ever Rallycross event a Lydden - always a slippery event at that time of year. In 1968 he won the Monte Carlo Rally - renound for it's ice and snow.

Maybe you have to be a good driver to drive a Porsche on the limit - but the layout of the car itself is demonstrably high in rear end grip.

Other rear engined cars that have also faired well on the loose and slippery stuff over the years are Alpine Renaults, Imps, Skodas and Davrians. I'm sure ther must be others.

I have rallied rear engined Davrians and Porsches. Rear engined cars can be set up to understeer, oversteer or be entirely neutral. The one thing they all have is amazing traction because of the weight over the driven wheels. I never had an accident in rallying until I went mid-engined. Direction changes happen a lot quicker in a mid-engined car due to their low polar inertia, so spinning became a bit of difficult habit to give up.

In that respect, driving a rear engined car with the tail hanging out is a lot easier to manage safely than it is in a mid-engined car, particulary on wet tarmac, loose surfaces or snow. In that respect, a rear engined car is more stable than a mid engined car. In the dry or wet, with of course the correct rubber, 935s in the 70's were able to put massive torque and BHP down onto the track. They are still doing so today, with people like Richard Chamberlain at the wheel.

The main problem of powerfull RWD cars is the traction limit in exiting a tight corner.
Could in be said that rear-engine have more advantages in powerfull(up from 500BHP) RWD cars?

[Al Weyman]

A rear engine car will also lift a front wheel so neither situation ideal. I loose a lot of time exiting corners in my IROC-Z as it lights up the inside back wheel especially against cars that have IRS like the Supra Turbo which is in my class.

[phoenix]

Originally Posted by Al Weyman

A rear engine car will also lift a front wheel so neither situation ideal. I loose a lot of time exiting corners in my IROC-Z as it lights up the inside back wheel especially against cars that have IRS like the Supra Turbo which is in my class.

Most well-sorted cars will three-wheel as they approach the maximum cornering G the tyres can achieve.

For obvious reasons, in front wheel drive it is preferable to un-load the inside rear wheel, and in rear-wheel drive cars it is preferable to un-load the inside front wheel. Even F1 cars can be seen to do this. It has nothing to do with where the engine located.

[buterworth]

Originally Posted by phoenix

Most well-sorted cars will three-wheel as they approach the maximum cornering G the tyres can achieve.

For obvious reasons, in front wheel drive it is preferable to un-load the inside rear wheel, and in rear-wheel drive cars it is preferable to un-load the inside front wheel. Even F1 cars can be seen to do this. It has nothing to do with where the engine located.

You'er right,most well-tuned race car may lift one wheel during a corner.

But the quetion is:lifting a wheel easily, or not so easily?And rear engined car will lift a front wheel more easily than mid,or front engine car.

IMO,a RWD car often lifts its inside front wheel during corner,cause the car has higher roll stiffness in the front axle.Nobody want to lift a wheel during a corner,but they'er force to tune the suspension that way to obtain enough rear wheel grip.

[Al Weyman]

Well I do agree that you dont want too much roll stiffness on a RWD car and its taken me a while to come to that conclusion after many spins especially in the wet which culminated in a lot of damage last year. I have softened the rear up now and also attempted to address why it was understeering in the first place and at the same track last weekend where I had the shunt and although I only did a few brief laps it felt substantially better.

[phoenix]

Originally Posted by buterworth

You'er right,most well-tuned race car may lift one wheel during a corner.

But the quetion is:lifting a wheel easily, or not so easily?And rear engined car will lift a front wheel more easily than mid,or front engine car.

IMO,a RWD car often lifts its inside front wheel during corner,cause the car has higher roll stiffness in the front axle.Nobody want to lift a wheel during a corner,but they'er force to tune the suspension that way to obtain enough rear wheel grip.

With a properly designed chassis (i.e. the wheel is not being lifted from the track because there is not enough rebound suspension travel), a car will only lift a wheel if there is no load on it. If there is no load on it, then even if it was in contact with the road, it would give no grip.

In response to your second point: "And rear engined car will lift a front wheel more easily than mid,or front engine car" that simply isn't true. If you believe it is, please explain why?

In respone to your third point "Nobody want to lift a wheel during a corner,but they'er force to tune the suspension that way to obtain enough rear wheel grip" do you understand why being on all four wheels would not be better, or that being on two wheels, if you had sufficinet tyre grip, would be worse still?

[Al Weyman]

In response to your second point: "And rear engined car will lift a front wheel more easily than mid,or front engine car" that simply isn't true. If you believe it is, please explain why?

I would assume because the weight behind the rear axle would have more of a lifting effect on the the front end of the car, no?

[phoenix]

Originally Posted by Al Weyman

I would assume because the weight behind the rear axle would have more of a lifting effect on the the front end of the car, no?

No.

[Al Weyman]

Well explain why not? Surely the rear axle will act as a fulcrum. If its such a good set up why has it been dropped by all other manufacturers other than Porche?

[phoenix]

Originally Posted by Al Weyman

Well explain why not? Surely the rear axle will act as a fulcrum. If its such a good set up why has it been dropped by all other manufacturers other than Porche?

1) Obviously, Jim Clark asked Ford to move the engine behind the rear axle so his Cortina would be quicker....:

http://www.lotustalk.com/forums/atta...3-cortina2.jpg

Or was it just for effect? 'Cos if the engine wasn't behind the rear axle, it would never lift an inside front and look so spectacular...... would it?

2) No, the rear axle doesn't act like a fulcrum in roll; the roll axis does. The centre of mass is inside the wheelbase, otherwise the car would run around with both front wheels off the ground all the time.

3) 'Cos they are pretty rubbish for shopping and taking the kids to school, but if you are a good driver, they are a handy tool if you want to get from A to B pretty fast (if a little expensive)

[Al Weyman]

3) 'Cos they are pretty rubbish for shopping and taking the kids to school, but if you are a good driver, they are a handy tool if you want to get from A to B pretty fast (if a little expensive)

Why? They must be as easy to build as a front wheel drive car that also has to cope with the steering and the front boot could be just as big as a rear boot take the VW Variant for example.

Anyhow I installed this Chevy V8 in the rear of my Chevy Blazer at the weekend but I was not at all impressed with the handling!

[phoenix]

Originally Posted by Al Weyman

Anyhow I installed this Chevy V8 in the rear of my Chevy Blazer at the weekend but I was not at all impressed with the handling!

Maybe the resultant CofG height, coupled with appalling suspension, might contribute to the poor handling...........

[Al Weyman]

Ha ha, aint that a fact, even without the weight of the engine in the boot she corners like a pig, tows well though! :-)