4 ms·

What you say makes sense, but if it is true, why aren't all cars built with the engine in the rear, then?

bagels 4y ago
Fwd is cheaper and easier to provide interior and storage space.
stephenhuey 4y ago
> Automakers began to abandon the rear-engined layout in the 1970s, with only a handful of cars still available in the 1980s. This was due to the fact that rear-engined, rear-wheel-drive cars were prone to oversteer, which caused vehicle instability. https://www.topspeed.com/cars/car-news/10-rear-engined-cars-that-aren-t-a-porsche-911/ https://www.topspeed.com/cars/car-news/10-rear-engined-cars-...
- kalupa 4y ago
  not to mention how awful they are in slippery (ice/snow) conditions, which is related to exactly what you mentioned with oversteer
- pifm_guy 4y ago
  Engines are only ~100kg usually. And a full fuel tank is also about 100kg. So the fuel tank and engine could be swapped without affecting weight distribution.
  - acchow 4y ago
    What about everything else around the engine? You wouldn’t just move the engine to the rear but keep the transmission and the alternator and etc in the front.
  - userbinator 4y ago
    Engines are only ~100kg usually 220lbs? Only the lightest ones. Let's also not forget the transmission/transaxle too. https://www.gomog.com/allmorgan/engineweights.html https://www.gomog.com/allmorgan/engineweights.html
  - BucketsMcG 4y ago
    Sorry, you're way off there. My ancient car has a gigantic 90 litre fuel tank. At 720g / litre, that's 64.8kg. And that really is a huge tank - most cars are more like 40-60 litres. The engine, meanwhile, well it depends what you count as "the engine". If we take it to mean "everything in the engine bay" - radiators, filters, pumps, etc. - you're going to be looking at several times that. Hell, even a battery is like 20kg.
  - pvaldes 4y ago
    The fuel tank is partially empty most of the time when we drive, and many drivers never refill to the top of the tank, or don't put more fuel until the tank is almost empty. Those 100Kg could be on average 30 or 40Kg.
mhb 4y ago
Does it make sense? I thought there was a survival advantage to having a giant chunk of metal absorbing the impact of a head-on collision. Assuming that it is routed under you instead of into you - which it is.
- bdamm 4y ago
  Depending on the crash, the engine being pushed under can launch the car into the air, where it is more likely to roll over. Contrast this with EVs where the battery is basically a giant puck that the occupants are sitting on top of; the deformation of the crumple zone and the low center of gravity cause the vehicle to rotate away instead of being launched.
  - mhb 4y ago
    The comparison is between identical cars except that one has an engine between you and what you're hitting and one with empty space there and the engine behind you. Also, I'm more than a little skeptical about the frequency of accidents in which a vehicle is launched into the air and rolls over due to the engine being pushed under the passengers. And even if that scenario is common, I'm skeptical that the risk of that happening offsets the benefit of having an engine between you and a colliding object.
BucketsMcG 4y ago
All sorts of reasons, but it's got a lot to do with packaging and handling. Generally you want the weight distribution of the car to be 50:50 front:rear for optimal handling. A car will handle great if you can put the engine and transmission somewhere towards the middle, but obviously that isn't great news for passengers. Mid-engined cars exist, of course, but they're usually two-seater sports cars where space and comfort are lower down the list of priorities. So you're left with putting the engine somewhere towards the front, or somewhere towards the back. Some manufacturers, like BMW, achieve ideal weight distribution by mounting the engine relatively far back in the front of the car, and putting the transmission and some other heavy bits at the back. This is elegant, but too complex and expensive for your average runabout. With a front-engined car, you can safely put some of the engine forward of the front axle. Doing so means more space in the passenger cabin, but hanging the weight out front makes the car nose-heavy. In an average front-wheel-drive family car, this isn't necessarily a bad thing, and might even be desirable, as it means good traction and a tendency towards boring, predictable understeer. Sling the weight out back, like a Porsche 911, and you get the opposite problem: the car naturally tends to want to swap ends in corners. Some drivers find this fun, right up until it kills them. If a 911 is a safe car today, it's because Porsche has spent decades pigheadedly perfecting a layout everybody else abandoned long ago for its tendency to send you backwards through hedges.
- spindle 4y ago
  I like this reply very much except that I wonder why people say that sports cars are uncomfortable. I find all the ones I've driven, including two mid-engined ones, super comfortable. Maybe it's just me. (In any case, your point that they're not space-efficient stands.)
  - sliken 4y ago
    Super comfortable mid engine ... Cayman? If you give up the rear seats it does help quite a bit, but does limit your market.
    - spindle 4y ago
lambdasquirrel 4y ago
It's more than just that. The skateboard design for dedicated EV platforms makes for a better-protected passenger cell. Whereas before you had to dedicate all this steel into keeping the car rigid while mounting this heavy 250kg engine all the way up front, usually in front of the wheels (and plus all the attendant powertrain stuff), now instead a lot of that steel is dedicated to maintaining the integrity of the passenger cell, concomitant to maintaining integrity of the battery skateboard. As for why few companies put the ICE engine in the back, whereas front-engine layouts tend towards understeer, rear-engine layouts tend toward oversteer, which is a safety and usability issue for the 99th percentile of drivers (and that's after you put in the engineering to make it work). Porsche spent a lot of effort making rear-engine safe. The design also results in less room for storage.
sliken 4y ago
Expense. Much of engine design is getting rid of heat, which is much harder in the wind shadow of the car. It also makes it harder to have a good weight balance, and you end up adding significant engineering to keep the rear heavy car from having undesirable handling characteristics ... which is something the Porsche 911 has been battling for decades.

Fwd is cheaper and easier to provide interior and storage space.

> Automakers began to abandon the rear-engined layout in the 1970s, with only a handful of cars still available in the 1980s. This was due to the fact that rear-engined, rear-wheel-drive cars were prone to oversteer, which caused vehicle instability. https://www.topspeed.com/cars/car-news/10-rear-engined-cars-that-aren-t-a-porsche-911/ https://www.topspeed.com/cars/car-news/10-rear-engined-cars-...

kalupa 4y ago
not to mention how awful they are in slippery (ice/snow) conditions, which is related to exactly what you mentioned with oversteer
pifm_guy 4y ago
Engines are only ~100kg usually. And a full fuel tank is also about 100kg. So the fuel tank and engine could be swapped without affecting weight distribution.
- acchow 4y ago
  What about everything else around the engine? You wouldn’t just move the engine to the rear but keep the transmission and the alternator and etc in the front.
- userbinator 4y ago
  Engines are only ~100kg usually 220lbs? Only the lightest ones. Let's also not forget the transmission/transaxle too. https://www.gomog.com/allmorgan/engineweights.html https://www.gomog.com/allmorgan/engineweights.html
- BucketsMcG 4y ago
  Sorry, you're way off there. My ancient car has a gigantic 90 litre fuel tank. At 720g / litre, that's 64.8kg. And that really is a huge tank - most cars are more like 40-60 litres. The engine, meanwhile, well it depends what you count as "the engine". If we take it to mean "everything in the engine bay" - radiators, filters, pumps, etc. - you're going to be looking at several times that. Hell, even a battery is like 20kg.
- pvaldes 4y ago
  The fuel tank is partially empty most of the time when we drive, and many drivers never refill to the top of the tank, or don't put more fuel until the tank is almost empty. Those 100Kg could be on average 30 or 40Kg.

mhb 4y ago

Does it make sense? I thought there was a survival advantage to having a giant chunk of metal absorbing the impact of a head-on collision. Assuming that it is routed under you instead of into you - which it is.

bdamm 4y ago
Depending on the crash, the engine being pushed under can launch the car into the air, where it is more likely to roll over. Contrast this with EVs where the battery is basically a giant puck that the occupants are sitting on top of; the deformation of the crumple zone and the low center of gravity cause the vehicle to rotate away instead of being launched.
- mhb 4y ago
  The comparison is between identical cars except that one has an engine between you and what you're hitting and one with empty space there and the engine behind you. Also, I'm more than a little skeptical about the frequency of accidents in which a vehicle is launched into the air and rolls over due to the engine being pushed under the passengers. And even if that scenario is common, I'm skeptical that the risk of that happening offsets the benefit of having an engine between you and a colliding object.

BucketsMcG 4y ago

All sorts of reasons, but it's got a lot to do with packaging and handling. Generally you want the weight distribution of the car to be 50:50 front:rear for optimal handling. A car will handle great if you can put the engine and transmission somewhere towards the middle, but obviously that isn't great news for passengers. Mid-engined cars exist, of course, but they're usually two-seater sports cars where space and comfort are lower down the list of priorities. So you're left with putting the engine somewhere towards the front, or somewhere towards the back. Some manufacturers, like BMW, achieve ideal weight distribution by mounting the engine relatively far back in the front of the car, and putting the transmission and some other heavy bits at the back. This is elegant, but too complex and expensive for your average runabout. With a front-engined car, you can safely put some of the engine forward of the front axle. Doing so means more space in the passenger cabin, but hanging the weight out front makes the car nose-heavy. In an average front-wheel-drive family car, this isn't necessarily a bad thing, and might even be desirable, as it means good traction and a tendency towards boring, predictable understeer. Sling the weight out back, like a Porsche 911, and you get the opposite problem: the car naturally tends to want to swap ends in corners. Some drivers find this fun, right up until it kills them. If a 911 is a safe car today, it's because Porsche has spent decades pigheadedly perfecting a layout everybody else abandoned long ago for its tendency to send you backwards through hedges.

spindle 4y ago
I like this reply very much except that I wonder why people say that sports cars are uncomfortable. I find all the ones I've driven, including two mid-engined ones, super comfortable. Maybe it's just me. (In any case, your point that they're not space-efficient stands.)
- sliken 4y ago
  Super comfortable mid engine ... Cayman? If you give up the rear seats it does help quite a bit, but does limit your market.
  - spindle 4y ago

lambdasquirrel 4y ago

It's more than just that. The skateboard design for dedicated EV platforms makes for a better-protected passenger cell. Whereas before you had to dedicate all this steel into keeping the car rigid while mounting this heavy 250kg engine all the way up front, usually in front of the wheels (and plus all the attendant powertrain stuff), now instead a lot of that steel is dedicated to maintaining the integrity of the passenger cell, concomitant to maintaining integrity of the battery skateboard. As for why few companies put the ICE engine in the back, whereas front-engine layouts tend towards understeer, rear-engine layouts tend toward oversteer, which is a safety and usability issue for the 99th percentile of drivers (and that's after you put in the engineering to make it work). Porsche spent a lot of effort making rear-engine safe. The design also results in less room for storage.

sliken 4y ago

Expense. Much of engine design is getting rid of heat, which is much harder in the wind shadow of the car. It also makes it harder to have a good weight balance, and you end up adding significant engineering to keep the rear heavy car from having undesirable handling characteristics ... which is something the Porsche 911 has been battling for decades.