Why do V6 and V8 engines always have such high cc?
Discussion
So I'm sat in traffic this afternoon and the guy besides me is in a 5.0 V8. This gets me thinking, why is it that V6's and V8's always have high cubic capacity?
I can think of only a few (mainly Japanese eg Mazda and Mitsi) cars that did a 2 litre V6 for instance.
Nowadays I suppose it's a cost/efficiency issue. Would a 1.3 litre V6 work? What would it sound like, go like etc? What about a 1 litre V8? Would the engine simply not work as the amount of fuel needed to populate the pistons etc requires a minimum CC?
Feel free to take the piss. I am just curious, and not suggesting for one minute that Ford should present us with a Shelby 1.0 V8.
I can think of only a few (mainly Japanese eg Mazda and Mitsi) cars that did a 2 litre V6 for instance.
Nowadays I suppose it's a cost/efficiency issue. Would a 1.3 litre V6 work? What would it sound like, go like etc? What about a 1 litre V8? Would the engine simply not work as the amount of fuel needed to populate the pistons etc requires a minimum CC?
Feel free to take the piss. I am just curious, and not suggesting for one minute that Ford should present us with a Shelby 1.0 V8.
I think the Mazda MX3 was a 1.8 V6...
TVR sleeved a Rover V8 for the Italian market in the V8s - although, they did add a 'charger.
ETA - video here of the 2 litre V8 S - http://www.pistonheads.com/gassing/topic.asp?h=0&a...
TVR sleeved a Rover V8 for the Italian market in the V8s - although, they did add a 'charger.
ETA - video here of the 2 litre V8 S - http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Edited by Podie on Thursday 19th January 16:08
It can be done, and it has been in the past but is increasingly rare these days. Most manufacturers will stick to cylinder capacities no smaller than 400cc if they can, as the cost and losses - not just in the cylinders themselves, but also all the valvetrain losses, breathing issues, etc - simply aren't worth dealing with for the power you can get out of each cylinder.
There are small capacity multi-cylinder engines, aerial atom has a 2.6(?) V8 (two motorbike engines), MX-3 had a 1.8 V6, Ferrari did a 2 litre V8 (as an Italian tax break special).
Generally, you make more cylinders to provide a better cylinder size on large engines (somewhere near 500cc is usually considered best), better balanced engine and more valve area. These things aren't needed on smaller engines (the last one especially with 4 valve/cylinder heads).
Engines with larger number of cylinders are more expensive (to make and maintain), heavier, larger (so more difficult to package in a wide range of vehicles) and less efficient (more friction losses for a start) then an engine of the same power, with less cylinders.
Basically, bigger engine needs more cylinders, on small engines it's a waste. You'll always get people willing to pay extra for more cylinders then they really need, but that tends to be on more expensive cars, where more performance is needed, so a larger engine is required anyway, hence few small capacity, multi-cylinder engines. It'll be slow, drink lots of fuel and be expensive to buy and run!
Generally, you make more cylinders to provide a better cylinder size on large engines (somewhere near 500cc is usually considered best), better balanced engine and more valve area. These things aren't needed on smaller engines (the last one especially with 4 valve/cylinder heads).
Engines with larger number of cylinders are more expensive (to make and maintain), heavier, larger (so more difficult to package in a wide range of vehicles) and less efficient (more friction losses for a start) then an engine of the same power, with less cylinders.
Basically, bigger engine needs more cylinders, on small engines it's a waste. You'll always get people willing to pay extra for more cylinders then they really need, but that tends to be on more expensive cars, where more performance is needed, so a larger engine is required anyway, hence few small capacity, multi-cylinder engines. It'll be slow, drink lots of fuel and be expensive to buy and run!
To keep vibrational issues down they limit 4 cylinder engines to about 2.5-3.0 litres usually. After that, the reciprocating masses are so large that it just shakes itself to pieces. So if you want to go bigger, you need to add cylinders. The problem with adding cylinders is you add frictional surfaces so you lose a little efficiency (hence why they don't have really small many-cylindered engines).
I'm not sure what happened to it but Connaught were/are making a 2.0 v10
http://www.connaughtmotorco.com/
http://www.connaughtmotorco.com/
Rude-boy said:
Wow. That sounds awesome. Thanks for the replies.
crazyglues??GroundEffect said:
To keep vibrational issues down they limit 4 cylinder engines to about 2.5-3.0 litres usually. After that, the reciprocating masses are so large that it just shakes itself to pieces.
I can also tell you that a 3.0 4 sounds like a Dervdog on start up.Still torque is great and I can wax lyrical about the sixe of my cylinder displacement
While not a V6 or V8 Honda made a road going bike with a 250/4 in the early 80's to 90's redine of 18.5-22k (depending on year) and about 40-45Hp or to put it another way 180hp/litre...
I always thought two of those bolted together would make one hell of an engine, although it would be one of those projects just for the sake of it. Plenty of 'better' engines with more power now.
Google the CBR250R MC14 (or the CBR250R MC17 / MC19 or CBR250RR MC22) if you're curious.
I always thought two of those bolted together would make one hell of an engine, although it would be one of those projects just for the sake of it. Plenty of 'better' engines with more power now.
Google the CBR250R MC14 (or the CBR250R MC17 / MC19 or CBR250RR MC22) if you're curious.
I seem to recall that due to Italian taxation laws, that either Ferrari or Alfa made a 2.0 V6. I think they have less torque than a 4 so ended up being worked harder.
I would also guess that packaging things like alternators, PAS pumps etc around a V6 means that the car needs to be bigger to accommodate them over a small four so it may also be a packaging issue.
I would also guess that packaging things like alternators, PAS pumps etc around a V6 means that the car needs to be bigger to accommodate them over a small four so it may also be a packaging issue.
As already mentioned its due to frictional losses and added cost of making more pistons, valves ect.. For a road car there is no point whatsoever in making a small capacity with more cylinders if there is no gain in anything in particular.
In F1 however there could be power gains with more cylinders and less cc. Eg in the 1.5l era when honda made a 1.5l v12. Produced around 240bhp from memory (and sounded awesome!)
Sadly the number of cylinders is dictated in the stale modern day F1, but thats a different topic.
In F1 however there could be power gains with more cylinders and less cc. Eg in the 1.5l era when honda made a 1.5l v12. Produced around 240bhp from memory (and sounded awesome!)
Sadly the number of cylinders is dictated in the stale modern day F1, but thats a different topic.
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