How do car manufacturers decide on engine configurations?

[JohnsonsEvilTwin]

The next generation of engines will have alot more torque.
The reasons are simple....lower revs = less use of accelerator and therefore less fuel consumption.
Small capacity turbos are the future...

Ahead of that check out Mercedes-Benz DIESOTTO technology.
S-class mercedes weighing 2 tonnes can crack 7 second 0-62, 150MPH and still get 40-45MPG in real world driving.

[RH1300S]

There just isn't a simple answer to that question, other things beyond the baisc configuration affect how the engine feels. Bore/stroke ratio and firing order are just as important in influencing the performance.

Certainly more cylinders gives the potential for more power than fewer cylinders, the power comes at a compromise of packaging & fuel consumption also heat.

If any of you are interesting in bikes you will know that firing order has been played with forever to affect the engine's response.

This video is worth watching to the end (even if it seems to peter out in the middle).

http://www.youtube.com/watch?v=UvTXMtTT ... r_embedded

[autogyro]

In 1975 there was a 2.0L V8 production engine that delivered 170HP at 7,700 rpm...

Daimler hemi, I had one in a Sunbeam Tiger.
It was a superb engine and I still recomend it for hot rods dragsters, kit cars etc. A friend and racer had one in a T bucket on methanol/nitro with a supercharger.

Correction the Tiger had a 270 ci Ford V8.
It was the daimler Dart that had the 2L daimler hemi V8.
The 270 Ford was the for runner of the 289 Mustang engine and I remembed some prefered it to the 289 because it reved better.
The V8 Daimler is still one of my favourite engines.
It was a simple matter to increase power. In those days a cast iron block would take loads of machining, not like modern ally computer designed engines with no metal to play with. If unlimited unburstable power was asked for, I would still use the Daimler as the base design even today.

[adam2007]

Adam

The mitsubishi engine is a turbo(booooooo!) and therefore is not compareable to the Honda which is of natural aspiration. Still a very impressive engine, granted.

WB, I have just found out via the S2000 forum that the F20C has the same innards as that of the Honda Accord Type R which has similar performance but tuned for more torque and slightly less Bhp(220).
These are high number production cars we are talking about.

Also another interesting fact about the F20 was that honda built the engine in total secrecy. The factory was akin to area 51 and staff were asked to sign industrial waivers so as not to spill any secrets in the way honda built these engines.

Even so a big turbo n intercooler on 2.0 making healthy 400bhp very impressive. When you have big 5.0 v10 supercars with 500bhp

The new ford engines for the focus are like 1.0 turbocharged engines lol have you seen this? still got around 110 bhp i think

[Richard]

There just isn't a simple answer to that question, other things beyond the baisc configuration affect how the engine feels. Bore/stroke ratio and firing order are just as important in influencing the performance.

Certainly more cylinders gives the potential for more power than fewer cylinders, the power comes at a compromise of packaging & fuel consumption also heat.

Are the 4 cylinder units that dominate the mass market based on manufacturing costs? Ie the average consumer wouldn't notice the difference compared to a 6, especially as the rest of the drive train is similarly designed for least cost?

Manufacturing costs presumably include the additional chassis and power train costs for a bigger engine? Hence adding fuel injection, turbos and 16v units to a standard car was affordable, but sliding in a V6 is prohibitive?

[spnx]

It was the daimler Dart that had the 2L daimler hemi V8.

Actually, the Daimler SP250 has a 2.5 litre V8.

I love the engine as well. My Dart is currently undergoing a full restoration and I look forward to having it on the road again soon.

[WhiteBlue]

http://www.usautoparts.net/bmw/engines/6cyl.htm

Some good points regarding the choice of straight six versus V6. Also a table of all straight six engines BMW did from 1933-2000

[adam2007]

IF i have 2 ford focus's and have 100bhp each

They weight 1100kg each if i took 100kg of weight off how much extra power would i get in terms of bhp, if you get how i am wording this.

for every 100kg save how much would it give you say 10bhp over the standard 1100kg car for every 100kg you remove,

Or have i confused you?

[JohnsonsEvilTwin]

A straight 6 is the desired format but is more costly to manufacture.
BMW still do it because its synonamous with the brand.
Mercedes-Benz I remember, famously dropped their straight 6's in the mid 90's during their cost saving obsession, ending their equally succesfull relationship with the engine type and moving on to the V6 2.4 2.8 3.2 litres respectivley.

When Merc replaced them, they offered the same power for in return for more MPG and also less weight over the front axle.
On closer inspection though this was only due to the engines being more modern than the straight 6 counterpart, which is why the 2.8 litre straight 6 BMW of the 90's was so brilliant...it did what mercs V6 could do, but offer more power and a crazy red line with the BMW sound.

Mercedes newer 3.5 V6 is fantastic though, a match in character for the 3.0 6 of BMW....

Hmmmm V6 or straight 6.......

[JohnsonsEvilTwin]

IF i have 2 ford focus's and have 100bhp each

They weight 1100kg each if i took 100kg of weight off how much extra power would i get in terms of bhp, if you get how i am wording this.

for every 100kg save how much would it give you say 10bhp over the standard 1100kg car for every 100kg you remove,

Or have i confused you?

Power to weight ratio.....

[Belatti]

In 1975 there was a 2.0L V8 production engine that delivered 170HP at 7,700 rpm...

Daimler hemi, I had one in a Sunbeam Tiger...

Correction the Tiger had a 270 ci Ford V8.
It was the daimler Dart that had the 2L daimler hemi V8...

Actually, the Daimler SP250 has a 2.5 litre V8.

I was talking about the engine in the Ferrari 208...

[autogyro]

I have a friend with a 308, it has a 3 liter V8, transverse mounted on top of the gearbox. I developed a 328 for the Ferrari challenge with practicaly the same engine with four valves per cylinder (the 308 and early weber carbed 328 had two valves per cylinder).
The regulations restricted us with the four valved 328 engine to Tacelmite and Jackson standard lever operated fuel injection, as opposed to the two valved early engined cars who were allowed to use the four standard downdraft twin choked webers. This gave an advantage of 120mm total air intake diameter from the carbs as apposed to 70mm on the injection intake. A big advantage.
I fitted two complete injection systems to get over this with 140mm but we had trouble getting the two inlet race camshafts we machined up to work, because the flow variations in the intakes began to make the balanced intake flow measuring flap bounce up and down at low revs throwing out the mixtures.
We got over it by leaving the inlet cam standard and machining a very clever pair of exhaust cams. The car won its class.
The Dino Ferrari of which I had two over the years had originaly a V6 2liter alloy blocked Ferrari engine and then a iron blocked 1600cc Fiat V6.
It was the 208 GTB and GTS that had a 2 liter V8.

[autogyro]

I still say the Daimler V8 (which was two liters) was a much better engine that the Ferrari engine.
It was fitted in the 2.5 Liter Daimler Jaguar (MK2) and made that car much better in handling than the 2.4 3.4 and 3.8 liter Jaguar versions.
The Daimler Dart with that engine was a fast and nimble car for the time, it was just pig ugly.
Sorry Belatti you are correct it was 2.5 liters.
I am sure I built a 2 liter Daimler dragster engine though, it must have been stroked.

[DaveKillens]

Give an engineer free rein and he will design a specific engine configuration for each requirement. But car manufacturers are run by accountants, and financial considerations can determine what engine configuration is selected.

There's a lot of cool technology such as balance shafts, which allow engineers to select a configuration and be confident it can achieve such goals as reduced vibration. That's important, because when I was a tadpole, engine configuration decided vibration levels. Today, you can get a very smooth inline four where forty years ago such a configuration may have not been applicable to a requirement and another configuration may be needed.

Basically, it costs more to make more cylinders. A six is cheaper than an eight, and so on and so on. And naturally, a large scale manufacturer wants as many of the same parts as possible, so it's natural to expect a manufacturer want to use the same block in as many models as possible.

And then of course, are the conflicting design requirements from the different departments. The engine guys might want to drop in an exotic engine, but the styling people may dictate a maximum deck height. Then the safety people insist the engine width or length be contained to accomodate crush zones.

In the end, for an engineering team assigned for, for example, a new Honda Civic, they will be given performance and dimensional requirements that severely restrict options.

If I had a Civic it would be cool to have a 1.5 liter V-8 that screamed at 15k RPM. But instead it has an inline four. Not as exciting with the eye-candy, but still good engineering in a little lump that spends it's life humbly delivering what the driver's right foot asks.

[xpensive]

In the very early 50s, BRM started out with a 1500cc Compressor V16, obviously with drawings stolen from Auto Union as a war-whatever,
but how do you consider when you decide to build a contraption like that?