Alez
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| posted on 9/10/06 at 10:25 AM |
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Best engine configuration for a sports car?
V like F-1's, Ferrari's and Lambo's?
Boxer like Porsche's?
180 deg V like.. any?
Straight like TVR's?
Farrari, Porsche and TVR have their own design for an engine as opposed to others like Ultima, Radical or Ariel. I wonder why each of them chose each
configuration.
What do you think? What other manufacturers of sports cars (road legal or not) currently have their own engine? There must be lots?
Cheers,
Alex
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RazMan
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| posted on 9/10/06 at 10:32 AM |
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180 degree V ?? Surely that is a boxer 
Personally I like the V6 which is lighter than a V8 and more torquey than a 4.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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StevieB
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| posted on 9/10/06 at 10:36 AM |
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TVR went for the straight 6 after they produced their own engine (AJP8) for the Cerbera, found ti to be better than a Rover 8, did a V12 engine (Speed
12) that was nigh on 1000BHP ( ) and cut the V12 down the middle to make a straight 6, which was lighter than the V8 and far more road useable than
the Speed 12 (for a TVR, anyway!)
I did Design and Technology while at Blackpool 6th Form and we got a few trips to the TVR factory at the time they designed the AJP8 and Speed 12, and
I was also one of the very first people to see the Cerbera. By far the coolest part of my education!
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jimgiblett
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| posted on 9/10/06 at 10:41 AM |
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Don't forget wankel rotary engine. A well tuned Rex is pretty impressive.
Or if you want something v.different a 7 cylinder radial aero-engine.
- Jim
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Volvorsport
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| posted on 9/10/06 at 10:57 AM |
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lightweight , space and packaging .
thats a primary consideration for some manufacturers regardless of configuration althouth the v motors would be better with packaging than other like
a straight 8 .
a straight 6 is perfectly balanced except for torque and gas reaction , hence why its used in luxury markets more than anything else . most others
have some sort of harmonics / unbalance . .
some of the porsches/volvos/mitsuis have balance shafts to counteract out of balance forces .
www.dbsmotorsport.co.uk
getting dirty under a bus
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smart51
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| posted on 9/10/06 at 11:02 AM |
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A 5 cylinder engine is said to be the smoothest configuration. a V4 the most compact.
As for number of cylinders, the optimum size for a cylinder is often said to be 300 - 400 cc. so
0.6 - 0.8 = 2cyl
0.9 - 1.2 = 3cyl
1.2 - 1.6 = 4cyl
1.5 - 2.0 = 5cyl
1.8 - 2.4 = 6cyl
2.4 - 3.2 = 8cyl
3.0 - 4.0 = 10 cyl
3.6 - 4.8 = 12 cyl
>5.0 = stop fitting bigger engines and start designing your car right.
fewer cylinders makes the engine lighter and more efficient (and cheaper). More cylinders = better balance = smooth running.
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Alez
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| posted on 9/10/06 at 11:03 AM |
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quote:
Originally posted by RazMan
180 degree V ?? Surely that is a boxer
It's difficult for me to explain in English but it's not the same. Let's imagine any of these engines, say 6 pot, as seen from the
top, and name the cylinders as follows:
A B
C D
E F
In the boxer, each connecting rod has it's own joint to the crankshaft, allowing pistons A and B to travel towards the crankshaft and then away
from it at the same time.
In the 180 deg V, the connecting rods for pistons A and B are joined together to the crankshaft, and so both of them go simultaneously to the left,
then to the right.
The 180 deg V is then pontially lighter while the boxer should be quieter (better balanced) I think?
Cheers,
Alex
[Edited on 9/10/06 by Alez]
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Volvorsport
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| posted on 9/10/06 at 11:06 AM |
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quote:
Originally posted by smart51
A 5 cylinder engine is said to be the smoothest configuration.
a 6 cyl has all frequency components resolved to zero a 5 cyl does not .
www.dbsmotorsport.co.uk
getting dirty under a bus
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MikeR
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| posted on 9/10/06 at 11:47 AM |
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thought that wasn't quite true - which is why the v12 was the best, it took the advantages of the straight 6 & balanced the one thing that
was out of balance.
hmmmm, now thinking i'm wrong but can't for the life of me remember the advantage of the v12 - perhaps just additional smoothness.
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iank
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| posted on 9/10/06 at 11:56 AM |
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quote:
Originally posted by MikeR
...
hmmmm, now thinking i'm wrong but can't for the life of me remember the advantage of the v12 - perhaps just additional smoothness.
Might be the additional torque, or just golf club bar bragging rights
As for why manufacturers pick what they do, tradition will play it's part in addition to volvorsports reasons.
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awinter
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| posted on 9/10/06 at 01:09 PM |
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Air flow
More cylinders so more valves, less restriction in engine.
Course then you have to consider friction of the extra cylinders
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Johnmor
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| posted on 9/10/06 at 01:24 PM |
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Ill take a V6
Light, (many are all alloy)
Short, almost as short as a 4
well ballanced
normally around 2.4-3.4 litre.
If you get a 60degree their are not too tall, although 90 would be better.
Also, Alfa make one, need i say more.
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mark chandler
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| posted on 9/10/06 at 03:20 PM |
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Boxer is pretty cool, all the weight sits low.
Years ago, I do not know if its still true the cheapest way to go competive rally cross was 911, strip the seats and put the spare on the passenger
floor... that was it.
Although buying a prosche seems odd by the time you have 5 linked rear suspension, upped the engine power etc it was more expensive and less
reliable.
If you look at lots of the production car series they spend fortunes dropping the engine a bit, leaning it backwards, dry sumping ete, all to achive
lower weight.
On the other side imho flat fours sound pants, especially plastic subura's. If you want to go fast for £2k get a supercharged JAG.
Regards Mark
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greggors84
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| posted on 9/10/06 at 04:02 PM |
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Flat plane crank V8
Why?
Because it sounds the best!
All IMHO of course!
Chris
The Magnificent 7!
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C10CoryM
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| posted on 9/10/06 at 04:37 PM |
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Awinter is right. More cylinders with smaller bores makes for lighter components, more air flow (until you hit valve shrouding) and better fuel
economy. Problem is, more parts and more power loss to friction. This is why F1 cars have been V8-V12 and still are undecided on whats best.
Whats "best" for a sportscar depends on what you want for a sportscar I guess. My favorite would be the C6R's 7.0L LS7 but then
again I like stupid amounts of power/torque
"Our watchword evermore shall be: The Maple Leaf Forever!"
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smart51
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| posted on 9/10/06 at 04:51 PM |
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Another consideration is engine revs. A short stroke engine will rev higher than a long stroke of the same volume. Higher revs = higher power. To
get a shorter stroke without losing capacity, you either need wider cylinders or more cylinders. That, I believe, is a big reason that F1 engines
were 3.0 V10s, so that they could rev higher.
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DIY Si
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| posted on 9/10/06 at 05:57 PM |
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I think it depends what you want the engine to do. Big lazy V8s etc are good for low down torque, but bike engines are good for high revs and lots of
power from a little size. If you an find something that is a mix of both, with a nice wide, flat power band you're laughing.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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Wadders
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| posted on 9/10/06 at 06:17 PM |
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The Noise they make is a big advantage
well all the ferrari ones anyway
quote:
Originally posted by MikeR
...
hmmmm, now thinking i'm wrong but can't for the life of me remember the advantage of the v12 - perhaps just additional smoothness.
[Edited on 9/10/06 by Wadders]
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meany
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| posted on 9/10/06 at 08:28 PM |
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im sorry.....im still struggling to get my head round this 180dg V thing.
are the cylinders flat like a boxer
(in which case it would be vibrate like a good un)
or are they vertical.
(therefore the cylinders must be off set from the vertical, like the VW V6, ergo not 180dg).
please enlighten me.
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RazMan
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| posted on 9/10/06 at 09:16 PM |
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I've been struggling with this one too - do pairs of cylinders fire at the same time or have I got the wrong idea?
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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DIY Si
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| posted on 9/10/06 at 09:23 PM |
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Externally it would look like a boxer, but would have opposing pistons attched at the same point on the crank, rather than having seperate throws ala
the boxer. So yes, pairs of pistons would fire together. Bit like the big bang racer engines in bikes.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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RazMan
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| posted on 9/10/06 at 09:29 PM |
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Aaahh I get it now! It must have a distinctive sound though - a bit like a big twin Can't think of any cars using this config though.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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DIY Si
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| posted on 9/10/06 at 09:32 PM |
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The only current use I can think of is the race bikes. Not too much use over a standard boxer. Might be a bit tricky to absorb the bigger bangs on the
transmission compared with a boxer; not too smooth I'd have thought. Could also make exhaust and inlet tuning a bit difficult perhaps.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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