Front engine safer than rear?

[ORD]

XJ Flyer said:

There is a point where crumple zones are defeated by sheer non deformable mass.IE a tank has no 'crumple zone' whatsoever but it doesn't need it because it will just use whatever it hits,assuming it's something softer than another tank,as its crumple zone to cushion its impact against the softer target.By the same logic I think I'd prefer to be in something like an E Class or an S Class Merc ( or for that matter an old Austin Westminster or the XJ ) in a head on crash involving the 911.On the basis that that in addition to the crumple effect that they contain in the front structure,the remaining combination after that of engine and bulkhead will probably defeat what remains of the Porsche's bulkhead structure first.

Wrong. This has been done to death in actual tests. Old, heavy cars kill the occupants and tiny, modern st boxed protect them.

There are two important factors - slowing the rate of deceleration (so your organs don't tear themselves to pieces or smash onto your bones) and channelling energy away from the passenger cell. Old cars are crap at both. It's not about winning a fight with the other car. The car that looks the most damaged often has the living occupants.

[ZesPak]

ORD said:

Wrong. This has been done to death in actual tests. Old, heavy cars kill the occupants and tiny, modern st boxed protect them.

There are two important factors - slowing the rate of deceleration (so your organs don't tear themselves to pieces or smash onto your bones) and channelling energy away from the passenger cell. Old cars are crap at both. It's not about winning a fight with the other car. The car that looks the most damaged often has the living occupants.

One of my favorite vids:
https://www.youtube.com/watch?v=emtLLvXrrFs

[Monty Python]

Without an engine at the front you eliminate intrusion injuries, which account for ~40% of those sustained in frontal impacts. These also tend to be quite severe. So, a rear-engine car automatically removes this risk.

[SkinnyP]

To those specifying the 911, have you googled them for crash results? Either they all crash going very fast, or they are made from tin foil. Which is a bit worrying as I drive a cayman

[ZesPak]

SkinnyP said:

To those specifying the 911, have you googled them for crash results? Either they all crash going very fast, or they are made from tin foil. Which is a bit worrying as I drive a cayman

This is the Cayman that crashed a couple of years ago next to my door:



I know my cars, but I had to see the rear lid to know what porsche that was :S.

Not to frighten you or anything.

[SkinnyP]

ZesPak said:

This is the Cayman that crashed a couple of years ago next to my door:



I know my cars, but I had to see the rear lid to know what porsche that was :S.

Not to frighten you or anything.

Thanks for that

Even Cayennes seem to get ripped apart, either the brand attracts loonies or Porsche can't make safe monocoque chassis'.

[ORD]

Yeah. What would NCAP know? I'd rely on a few Internet photos when assessing a car's safety in a crash

There are quite a few people on the 911 pages that have had high speed accidents vicious enough to tear the engine out of the car, and they've walked away without a bruise.

You can pick between anecdotes or go with what the crash testers have concluded after smashing the things into walls under test conditions.

A mangled car might well indicate that the crash structures did their job in channelling forces away from the occupants (although that particular Cayman in those photos looks to have taken a beating all over!)

[ZesPak]

He went off at highway speeds (presumably above NSL) and hit a 30yo tree sideways, about 1m above the ground.
He died in the crash unfortunately.

I don't think any other car would have done better to be fair.

[SkinnyP]

ORD said:

Yeah. What would NCAP know? I'd rely on a few Internet photos when assessing a car's safety in a crash

There are quite a few people on the 911 pages that have had high speed accidents vicious enough to tear the engine out of the car, and they've walked away without a bruise.

You can pick between anecdotes or go with what the crash testers have concluded after smashing the things into walls under test conditions.

A mangled car might well indicate that the crash structures did their job in channelling forces away from the occupants (although that particular Cayman in those photos looks to have taken a beating all over!)

Where are the ncap tests for Porsche?

[ORD]

Fair point re Porsche not playing along and getting NCAP tests done. Weird decision in my view. I expect that they benchmark to the same stuff internally, so I don't see any good reason not to get the assessments done. Apparently Ferrari don't play ball either.

I guess they have worked out that it doesn't affect purchasing decisions, but I would be happier buying a 911 if I knew it had a 4 star rating. I doubt I am alone in that.

[JonnyVTEC]

Monty Python said:

Without an engine at the front you eliminate intrusion injuries, which account for ~40% of those sustained in frontal impacts. These also tend to be quite severe. So, a rear-engine car automatically removes this risk.

I assume wheels are part of those intrusion injuries?

[Wills2]

kambites said:

paulrussell said:

I'd say a front engine car would be safer, as with a rear engine car you've got a fuel tank in front of you.

I'd have thought most rear engined (as in with the engine behind the passengers) cars have the fuel tank in the back? Mine certainly does.

A 911's fuel tank is in front of the firewall just behind the luggage compartment, so very much in the front same with the boxster and cayman.

Edited by Wills2 on Monday 25th August 10:56

[zippyprorider]

At a guess I would imagine rear engine would be more comfortable in a normal (not life risking crash) as bumpers and bodywork would absorb the impact nicely.... Avoiding whiplash etc. In a huge head on I would think the metal engine block would be beneficial in front stopping you dieing.

[XJ Flyer]

ORD said:

XJ Flyer said:

There is a point where crumple zones are defeated by sheer non deformable mass.IE a tank has no 'crumple zone' whatsoever but it doesn't need it because it will just use whatever it hits,assuming it's something softer than another tank,as its crumple zone to cushion its impact against the softer target.By the same logic I think I'd prefer to be in something like an E Class or an S Class Merc ( or for that matter an old Austin Westminster or the XJ ) in a head on crash involving the 911.On the basis that that in addition to the crumple effect that they contain in the front structure,the remaining combination after that of engine and bulkhead will probably defeat what remains of the Porsche's bulkhead structure first.

Wrong. This has been done to death in actual tests. Old, heavy cars kill the occupants and tiny, modern st boxed protect them.

There are two important factors - slowing the rate of deceleration (so your organs don't tear themselves to pieces or smash onto your bones) and channelling energy away from the passenger cell. Old cars are crap at both. It's not about winning a fight with the other car. The car that looks the most damaged often has the living occupants.

That's only in the case whereby the big tougher tank hits something that's just as strong,if not stronger,like a tree for example.In the real world of car v car collisions the tank will use the softer target st box,( in this case Volkswagen Beetle design in terms of frontal armour protection ),to add to it's crumple zone.It's a reasonable bet that something like an E Class,or an old Westminster for example,would prove be the more survivable car than a 911 in one of those real world head on scenarios set up by Fifth Gear.But that won't fit the script of trying to make less seem like more.

Edited by XJ Flyer on Monday 25th August 14:23

[XJ Flyer]

ZesPak said:

ORD said:

Wrong. This has been done to death in actual tests. Old, heavy cars kill the occupants and tiny, modern st boxed protect them.

There are two important factors - slowing the rate of deceleration (so your organs don't tear themselves to pieces or smash onto your bones) and channelling energy away from the passenger cell. Old cars are crap at both. It's not about winning a fight with the other car. The car that looks the most damaged often has the living occupants.

One of my favorite vids:
https://www.youtube.com/watch?v=emtLLvXrrFs

What a surprise the 'test' was set up so that it used the benefit of the transverse engine layout in an offset collision rather than a head on one whereby the engine of the Volvo could play no part.IE crumple zone + engine and bulkhead of the st box v just the the front wing etc and bulkhead structure of the Volvo.Which in this case actually proves the case for having the engine there as a barrier to add to the frontal strength of the bulkhead.With the st box doing exactly as I've said in using the softer nature of the Volvo's wing structure as its crumple zone.Now try the same test in a full on head on collision between the Volvo and a 911.Or for that matter the st box in the test.

Edited by XJ Flyer on Monday 25th August 14:38

[ZesPak]

XJ Flyer said:

What a surprise the 'test' was set up so that it used the benefit of the transverse engine layout in an offset collision rather than a head on one whereby the engine of the Volvo could play no part.IE crumple zone + engine and bulkhead of the st box v just the the front wing etc structure of the Volvo.Which in this case actually proves the case for having the engine there as a barrier to add to the frontal strength of the bulkhead.Now try the same test in a full on crash between the Volvo and a 911.Or for that matter the st box in the test.

The point made was rather simple, and by no way influenced by your remark:
The "stbox" has the ability to absorb the impact with it's full front, instead of just the part where it hit. The fact that you'd have to say you have to hit the Volvo (or any older car) on the engine to make it work defies the point, doesn't it?
Anyway, I'd love for them to see them hit the two cars head on. I'm betting a fiver on the outcome to be very similar, despite the extra bulk of the older car.

[XJ Flyer]

ZesPak said:

XJ Flyer said:

What a surprise the 'test' was set up so that it used the benefit of the transverse engine layout in an offset collision rather than a head on one whereby the engine of the Volvo could play no part.IE crumple zone + engine and bulkhead of the st box v just the the front wing etc structure of the Volvo.Which in this case actually proves the case for having the engine there as a barrier to add to the frontal strength of the bulkhead.Now try the same test in a full on crash between the Volvo and a 911.Or for that matter the st box in the test.

The point made was rather simple, and by no way influenced by your remark:
The "stbox" has the ability to absorb the impact with it's full front, instead of just the part where it hit. The fact that you'd have to say you have to hit the Volvo (or any older car) on the engine to make it work defies the point, doesn't it?
Anyway, I'd love for them to see them hit the two cars head on. I'm betting a fiver on the outcome to be very similar, despite the extra bulk of the older car.

Look at the video again the fwd shopping trolley used it's tougher engine and bulkhead combination to actually penetrated the softer wing structure of the Volvo which is why they set it up as an offset collision.Just as a front engine car would in the case of hitting a rear engined car assuming the engine can play a part in guarding the bulkhead.As for shopping trolley v old school Volvo in a 'real' square on head on collision where its engine would be added to the equation.My money would be on the Volvo.

[ZesPak]

XJ Flyer said:

Look at the video again the fwd shopping trolley used it's tougher engine and bulkhead combination to actually penetrated the softer wing structure of the Volvo which is why they set it up as an offset collision.Just as a front engine car would in the case of hitting a rear engined car assuming the engine can play a part in guarding the bulkhead.As for shopping trolley v old school Volvo in a 'real' square on head on collision where its engine would be added to the equation.My money would be on the Volvo.

I think you'd be surprised by the stiffness of the cabin of a car like that, once the crumple zone stops.

[SkinnyP]

A bit off tangent, but the small overlap crash test doesnt half do some damage. Goes to show that no matter how new the car is if its not designed to pass a specific safety test in mind then it will probably perform poorly.

https://www.youtube.com/watch?v=-bdydHzCO5s

[shoehorn]

ZesPak said:

I think you'd be surprised by the stiffness of the cabin of a car like that, once the crumple zone stops.

Yes, but an engine and transmission are a bloody big hammer at 20plus mph.

I`d rather it be in front of me,hitting first and absorbing some energy and possibly spreading the load across the shell,than it be right behind my head carrying energy and quite likely some rpm still, until something stops it,usually the flimsy rear cabin bulkhead and then your head or the fuel tanks,what a choice.
At least with front engines they tend to stop immediately and you don`t have things thrapping around at 6000rpm still adding to the confused carnage.
It might not break through but it might churn its way in,nice.
I repaired a 4 cyl E36 coupe once that had hit a Gatso camera at 10-12 mph,the engine shot forwards,snapped the engine and gearbox mounts and pulled the prop out of the box,imagine that at 60-70 with the usual 8/10/12 cylinder configuration monsters and big transaxles these cars usually have.
FWIW I was a front seat passenger in a MK1 Cavalier which hit a stopped 7.5 tonner head on at about 35 to 40,the car was destroyed,the engine had gone back and sideways with the gearbox under my floor area and the rear of the head buried into the inner wing bulkhead join.

The traffic plod pointed out to us where you could see that the engine had tried to break through the front of the lorry and got wedged in between its chassis rails,
with no sign of such damage where the cars chassis inner wings had hit either side of it.
The engine had worked like a big wedge across the car diagonally and without it it looked to me that the lorries chassis,forwards of its engine and front axle was long enough to pierce the cabin and would have killed us both as the rest of the car was non existent around the engine.
We were pretty bashed and bruised,nothing broken and we lived.
In theory we should have been badly injured or worse but theory means sod all when it comes to cars hitting things,infinite variables.
As I said above though,if you are in a crash that involves the engine being displaced then chances are you will be better off with it coming in to the cabin and finishing you off anyway.