Question...

[AstonV12]

Afternoon, was eating my lunch and just wondered this:

Whay are there no V4, straight-8 or flat-8 engine configurations nowadays in cars? I know in the 50s/60s (before my time)there were, but what's the reason for it? Emissions or some other regulation?

Anybody shed any light?
Thanks

[Jack_and_MLE]

Would you consider a flat 4 a 180 degree V?
The only two "recent" engine would be the flat 12 from Ferrari and the flat 4 in a Subaru.

Otherwise the Porsche flat 6

Jack

[pdV6]

Packaging I'd have thought.

[Snake the Sniper]

Some of it used to be about power. If you needed more, it was a fairly simple thing to bolt two flat 4s together to make a flat 8. Also, there's not too many cars that you could put a straight of flat 8 in anyways!

[Pigeon]

Straight 8 has fallen out of favour (rather a long time ago) because of torsional rigidity problems in that long crank.

[toohuge]

If i remember correctly, the subaru impreza engine is a boxer 4. I think that the problem as stated above is size (packaging). The cars of old had massively long bonnets, so with a straight 8 the bonnets of cars would be fairly large. The main reason is to do with the smoothness of engine. If you have a straight eight, (correct me if i am wrong) but in a cycle of the engine, only one cylinder fires at a time, so a straight 8 would be very lumpy and not very smooth. Another problem is crankshaft strength, a straight 8 would have a very long crankshaft so the forces in the middle would be pretty big and thus i can only imagine that crankshafts would have to be made very tough and thus heavy given the technology of the time.
I think that these reasons are correct, i have gathered this info from books etc over the years, but please if anyone else has an ideas, i would be very interested to know.

Chris