177 replies to this topic

[Scotracer]

I feel a bit stupid for asking this but during the entirety of my studies it hasn't come up once: why would you choose one engine config over another, if we assume all other things equal?

Is it purely for weight reasons you wish to go for fewer cylinders? Is it purely for balance at higher RPMs do you go for more?

For instance why would a V6 be better than a V8 (or vice versa)?

[Greg Locock]

I feel a bit stupid for asking this but during the entirety of my studies it hasn't come up once: why would you choose one engine config over another, if we assume all other things equal?

Is it purely for weight reasons you wish to go for fewer cylinders? Is it purely for balance at higher RPMs do you go for more?

For instance why would a V6 be better than a V8 (or vice versa)?

Um, in what context? Most applications have a radar chart of wants and must haves, different engine configurations then fit those targets to different degrees.

If you are worried about emissions and cost primarily you might go down one path, whereas if you want maximum hp for a given installed weight you'd go another.

If you look at reasonably modern passenger cars around 120 kW you'll see that apparently rational people have selected I4, I5, V6, I6. I don't think anyone makes a V8 that small, nowadays.

I'd rather try and get an I4 to 15000 rpm than a V8 to be honest, so I think your balance suggestion is a bit confusing.

[gruntguru]

I feel a bit stupid for asking this but during the entirety of my studies it hasn't come up once: why would you choose one engine config over another, if we assume all other things equal?
Is it purely for weight reasons you wish to go for fewer cylinders? Is it purely for balance at higher RPMs do you go for more?
For instance why would a V6 be better than a V8 (or vice versa)?

At the very simplest level, the power output required will largely dictate the number of cylinders. There is an upper limit for capacity per cylinder above which Otto cycle engine rapidly diminish in terms of efficiency and specific output.

It is probably reasonable to say that there is an optimal range of capacity-per-cylinder for best efficiency, another for best power/weight and so on ad-infinitum as additional factors are thrown in to the mix - cost, emissions, size etc . . .

[Lee Nicolle]

It will always build to the application. If you have rules of eg: 3 litre normally aspairated racing engine you would build a V8 or maye V10. The more numbers of yliders generally will give more power [and complexity]
Or eg 6 litre stock block tin top class with turbos @ 1.7 equivalacy a V8 will be a simpler choice and very hard to beat with a turbo 2.5- 3 litre 4 or 6. They may well be competitive but the maintenance will be higher and the reliability less
Or eg: 2.5 litre normally aspirated, 1.8 forced aspiration in a weight consious class an alloy inline 4 normally aspirated will be generally a better propositin for weight, length and wdth consideration than a turbo engine or straight or V6. Though all on there day will be winners.
In otherwords the packaging, weight, width, length [and torque] tend to dictate the engine configuration in all motorport wether open wheel, prototype or tin top.

[Kelpiecross]

I feel a bit stupid for asking this but during the entirety of my studies it hasn't come up once: why would you choose one engine config over another, if we assume all other things equal?

Is it purely for weight reasons you wish to go for fewer cylinders? Is it purely for balance at higher RPMs do you go for more?

For instance why would a V6 be better than a V8 (or vice versa)?

I would have thought that the usual reason for for having more cylinders for a given engine capacity was to lower the size/weight of reciprocating components and thus reducing loads at high RPM on conrods etc. Also more cylinders for a fixed capacity tends to give a greater cylinder bore area and thus greater possible valve area allowing better breathing. More cylinders also mean more power impulses and a smoother engine.

[Scotracer]

Thanks for the input so far. It did occur to me that there'd be a few parameters that make choosing one config more viable than another if you have set design specs you need to meet...I just didn't know what they were.

Just to add to my questions: If for instance you were creating a race car (GT-style) and needed both loads of horsepower but a wide torque-band for tractability...how would you choose a V6 over a V8, for instance? Say the capacity is locked at 3 litres and there's a maximum rev limiter too. Is one config just naturally inclined to produce better characteristics at certain revs compared to the other?

God I wish I had a dyno...

Edited by Scotracer, 04 January 2011 - 02:04.

[gruntguru]

If for instance you were creating a race car (GT-style) and needed both loads of horsepower but a wide torque-band for tractability...how would you choose a V6 over a V8, for instance? Say the capacity is locked at 3 litres and there's a maximum rev limiter too. Is one config just naturally inclined to produce better characteristics at certain revs compared to the other?

It would depend on the rev limit - the lower the limit, the more you would favour the 6 because the main advantage of the 8 (shorter stroke and greater valve area) disappears at lower revs. Widening the power band on either configuration requires trading off some peak power. Milder cams, longer intake and exhaust runners of smaller diameter.

Edited by gruntguru, 04 January 2011 - 02:15.

[SteveCanyon]

Just to add to my questions: If for instance you were creating a race car (GT-style) and needed both loads of horsepower but a wide torque-band for tractability...how would you choose a V6 over a V8, for instance? Say the capacity is locked at 3 litres and there's a maximum rev limiter too. Is one config just naturally inclined to produce better characteristics at certain revs compared to the other?

I'd chose the Subaru EZ30 engine. A flat-6 so the CoG is quite low. It's all-alloy so very light and it's only about 30mm longer than the EJ20 two litre four cylinder so very compact as well. It also have variable cam timing to widen the useful torque curve. Being a flat-6 it is also very smooth.

[jatwarks]

..why would you choose one engine config over another, if we assume all other things equal?

Another reason, in competition engines at least, would be structual attributes; a V configuration would give greater torsional rigidity if the engine is used as a stressed member within the chassis.

Packaging generally would also be a consideration when it comes to installation; short & wide against long & narrow, for example.

A boxer engine gives lower weight distribution, but could interfere with aero effects in formula cars.

I seem to remember that, some years ago, Honda and Renault launched their new turbo F1 engines, and reporters remarked that both engines had similar V angles (87 degrees?); the reason given for that was that both manufacturers entered the ideal parameters into their computers, and the computers came up with the same answers!

From a production car point of view ease and cost of manufacture could be a deciding factor. When I was an apprentice engineer many moons ago one of my local heroes that I worked with was the Production Engineer; He was the guy who took the pretty designs and prototypes from the Design Office / Model Shop and re-worked them into something that could be manufactured efficiently and in quantity, with minimum reduction in functionality.

[saudoso]

Based on the square-cube rule, wouldn't more cylinders provide more torque for a given MEP? I think I learned this around here.

[gruntguru]

Based on the square-cube rule, wouldn't more cylinders provide more torque for a given MEP? I think I learned this around here.

Nope.

(You are supposed to add a when posting for the sole purpose of resurrecting an old battle.)

[saudoso]

Nope.

(You are supposed to add a when posting for the sole purpose of resurrecting an old battle.)

Sorry then, it was a honest mistake. Don't think I followed it to the end.

[Scotracer]

Thanks for all the info, lads. I find it egregious that they did not teach such design criteria in my undergrad (although it's understandable in my postgrad since it's a slightly different field).

gruntguru; interesting that you say that a V8 would be more useful at higher revs as it goes against common sense but it does make mechanical sense WRT stroke length etc.

Originally the question arose when looking back at F1 engine changes over the years and it was Ferrari's change from V12 to V10 over the 1995-1996 winter that perplexed me as I couldn't find out why such a change would be worthwhile. Do you have any more insight on the possible reasoning? As I see it, the V12 would be more willing to rev?

[gruntguru]

Sorry then, it was a honest mistake. Don't think I followed it to the end.

Only kidding. No apology required.

Torque = MEP x Capacity

[jatwarks]

Originally the question arose when looking back at F1 engine changes over the years and it was Ferrari's change from V12 to V10 over the 1995-1996 winter that perplexed me as I couldn't find out why such a change would be worthwhile. Do you have any more insight on the possible reasoning? As I see it, the V12 would be more willing to rev?

Fuel consumption and packaging were an issue with the V12.

However, I believe that the main reason for Ferrari deciding against the V12 was pressure from the FIA, prompted by lobbying from the other manufacturers, because if the V12 proved to be superior to the V10s then everyone would have to build one, at great expense.

It's the presence of major manufacturers in F1 that led to the decline in novel engine designs; no-one wants to pick the wrong configuration and be uncompetitive!

[desmo]

Ferrari did an SAE tech paper on the upsides/downsides of V10 vs. V12 for a late nineties 3l F1 engine. The number is 983035.

As the poster above says, it was due to factors other than power-torque output that the change to the V10 architecture was made. The V12 modeled as better in power, torque and FMEP.

[gruntguru]

The V12 modeled as better in power, torque and FMEP.

Interesting (and almost believable) that the friction was lower on the V12. The lower efficiency probably mainly due to thermal losses with higher surface area to volume ratio internally.

[desmo]

Well here's how they rather equivocally phrased it:

The proposed empirical relations focus on sources of frictional
losses relevant to racing engines running high
Rpms. These relations indicate that increasing the number
of cylinders decreases total friction. This is in accordance
to many racing engine data, as those provided in
[21] just to name a few in the public domain. It is worth of
note that in series engines running low Rpms, where the
trend is opposite and increasing the number of cylinders
also increases total friction, the previous sources of
losses have a different formulation and there are other
relevant sources of losses to be considered.

21. Ricardo North America Inc., “WAVE User’s Manual”, Burr
Ridge, IL, USA, 1997.

[J. Edlund]

Ferrari did an SAE tech paper on the upsides/downsides of V10 vs. V12 for a late nineties 3l F1 engine. The number is 983035.

As the poster above says, it was due to factors other than power-torque output that the change to the V10 architecture was made. The V12 modeled as better in power, torque and FMEP.

Cosworth did a similar study by building a 2.5 litre V10 - the same cylinder capacity a 3.0 litre V12 would have, and tested it it on a dyno. In their test the 3.0 litre V10 proved to be the better configuration. Of course, spending money on developing a V12 engine from scratch might change that result, but that possible development path was put to an end by the FIA.

Fuel consumption and packaging were an issue with the V12.

However, I believe that the main reason for Ferrari deciding against the V12 was pressure from the FIA, prompted by lobbying from the other manufacturers, because if the V12 proved to be superior to the V10s then everyone would have to build one, at great expense.

It's the presence of major manufacturers in F1 that led to the decline in novel engine designs; no-one wants to pick the wrong configuration and be uncompetitive!

It was when Paolo Martinelli became Ferraris head of engine design they started an investigation into what engine configuration was most suitable, and it was concluded that the V10 configuration was better for overall performance.

[WhiteBlue]

It was when Paolo Martinelli became Ferraris head of engine design they started an investigation into what engine configuration was most suitable, and it was concluded that the V10 configuration was better for overall performance.

If the 3.5L or 3.0L NA engines of the post turbo era were run with a serious fuel limit like the 2013 engine are going to have there would be no question which engine would be selected. V10 proved long time to be more successful even with unlimited fuel just by a better power/weight ratio and better packaging. If you would run the 3.0-3.5L NA engines with 100 kg/h fuel flow limit the V12s would not have the chance of a snowball in hell.

It shows that the context of the formula plays a big part. The more the racing formula is valuing fuel efficiency the more you have to think about thermodynamic aspects and disregard mechanical elegance. Eventually many sources of losses add up, the friction, the internal aerodynamics, the heat transfer, the weight, the size and the combustion quality. Heat and gas exchange losses are probably the dominant factors.

Edited by WhiteBlue, 08 January 2011 - 03:09.

[gruntguru]

If the 3.5L or 3.0L NA engines of the post turbo era were run with a serious fuel limit like the 2013 engine are going to have there would be no question which engine would be selected.

Probably neither. A V8 or V6 would be a more likely choice.

[Wuzak]

Cosworth did a similar study by building a 2.5 litre V10 - the same cylinder capacity a 3.0 litre V12 would have, and tested it it on a dyno. In their test the 3.0 litre V10 proved to be the better configuration. Of course, spending money on developing a V12 engine from scratch might change that result, but that possible development path was put to an end by the FIA.



It was when Paolo Martinelli became Ferraris head of engine design they started an investigation into what engine configuration was most suitable, and it was concluded that the V10 configuration was better for overall performance.

If the 3.5L or 3.0L NA engines of the post turbo era were run with a serious fuel limit like the 2013 engine are going to have there would be no question which engine would be selected. V10 proved long time to be more successful even with unlimited fuel just by a better power/weight ratio and better packaging. If you would run the 3.0-3.5L NA engines with 100 kg/h fuel flow limit the V12s would not have the chance of a snowball in hell.

It shows that the context of the formula plays a big part. The more the racing formula is valuing fuel efficiency the more you have to think about thermodynamic aspects and disregard mechanical elegance. Eventually many sources of losses add up, the friction, the internal aerodynamics, the heat transfer, the weight, the size and the combustion quality. Heat and gas exchange losses are probably the dominant factors.

It is interesting that during the V10-V8 era the Ferrari has still remained one of the thirstier engines. Maybe something about the way they chase performance is different? Of course they have suiffered under the engine freeze, particularly with the rpm reductions and banning of refuelling.

I thought that a V12 would have better gas exchange?

[WhiteBlue]

I thought that a V12 would have better gas exchange?

I'm not sure of this, but if you design a V12 to the same capacity as a V10 each cylinder has to take in less air but the valve diameters and the intake ports are also reduced in diameter. I would think that the V10 would breathe easier, but this is just a feeling. Perhaps our more knowledgeable members can answer that.

[cheapracer]

I'm not sure of this, but if you design a V12 to the same capacity as a V10 each cylinder has to take in less air but the valve diameters and the intake ports are also reduced in diameter. I would think that the V10 would breathe easier, but this is just a feeling. Perhaps our more knowledgeable members can answer that.

And you would be wrong and you even asked the right question.

For the same bore stroke/ratio there is a greater amount of valve area available as a whole so the V12 is capable of "sucking in" more air.

[WhiteBlue]

For the same bore stroke/ratio there is a greater amount of valve area available as a whole so the V12 is capable of "sucking in" more air.

How do you know that? Have you made some simulations? What if the V12 just runs on the richer mixture with port injection. We surely know it uses more fuel but there are no quotes by reliable sources about air.

[ferruccio]

I feel a bit stupid for asking this but during the entirety of my studies it hasn't come up once: why would you choose one engine config over another, if we assume all other things equal?

Is it purely for weight reasons you wish to go for fewer cylinders? Is it purely for balance at higher RPMs do you go for more?

For instance why would a V6 be better than a V8 (or vice versa)?

It's a valid question.

Try this link http://www.autozine....dex.html#Engine and scroll down to the Engine Smoothness section. Interesting read.

The chosen layout depends on the requirements for the intended application. Each layout has it's strengths and weaknesses. Usual consideratiorns are packaging, vibration, cost, power band etc. These days friction is also important to meet CO2 goals.. While single seater racing the blocks are also stressed chassis members and thus Vee layout is preferred.

Edited by ferruccio, 10 January 2011 - 09:31.

[Scotracer]

Thanks for the link - I will definitely give it a good read when I have time.

[Greg Locock]

Thanks for the link - I will definitely give it a good read when I have time.

First mistake is in the second sentence. I didn't bother reading further.

[gruntguru]

For the same bore stroke/ratio there is a greater amount of valve area available as a whole so the V12 is capable of "sucking in" more air.

How do you know that? Have you made some simulations? What if the V12 just runs on the richer mixture with port injection. We surely know it uses more fuel but there are no quotes by reliable sources about air.

The first part of Cheapy's comment is irrefutable - For the same bore stroke/ratio there is a greater (piston area and therefore) valve area available in the engine with more cylinders.

The second part - capable of "sucking in" more air - is logical and I think fairly well documented.

[Wuzak]

The first part of Cheapy's comment is irrefutable - For the same bore stroke/ratio there is a greater (piston area and therefore) valve area available in the engine with more cylinders.

The second part - capable of "sucking in" more air - is logical and I think fairly well documented.

What about for the same stroke?

For the same stroke the piston area of any configuration of the same capacity is the same - kinda obvious. How does the valve are compare then?

In terms of piston size, a 3.0l V10 with a bore of 96mm will have a stroke of around 41.4mm. A V12 with a stroke of 41.4mm will have a bore of around 87.6mm.

For a V10 with 98mm bore the stroke is around 39.7. The V12 with a stroke of 39.7mm has a bore of around 89.5mm.


If the smaller bore is better for combustion, would that be enough to overcome the friction deficit if a V12 is chosen over a V10?



For the 2013 engines the1.6l L4 is selected with a maximum bore of 88mm. That equates to a stroke of 65.8mm and a mean piston speed (if my sums are correct) of 26.3m/s at 12,000rpm and 21.9m/s at 10,000rpm. If a V6 was an option, using the same stroke will give the same piston speeds and piston area, but the bore will be 71.8mm. If a V6 was to use the maximum bore its stroke would be 43.8mm giving 50% more piston area and mean piston speeds of 17.5m/s (12k) and 14.6m/s (10k).

How much benefit would the reduced piston speeds be? Since the L4 is up there for piston speed (as high as they'd want to go?), it would seem doubtful that a smaller bore would be chosen.

For the V6 with the 88mm bore would it be able to make the same power as the L4 at lower rpms, reducing piston speeds even further?

For a V6 wth the same bore:stroke ratio as the L4 the V6 would have a bore of 76.9mm and a stroke of 57.5mm, giving approximately 14% more piston area. Mean piston speeds of 23.0m/s (12k) and 19.2m/s (10k).

Several times I have been told that the V6 configuartion is less efficient than the L4. Is this certain, and if so, how much different? Or is that too difficult a question?

Assuming that the V6 is less efficient than the L4 as an engine, is it possible that its packaging gives benefits in an F1 car which outweigh the difference?

[WhiteBlue]

For the same bore stroke/ratio there is a greater (piston area and therefore) valve area available in the engine with more cylinders.

I was interested what the difference would actually be mathematically and figured is out from the equations. The V12 piston area is 3.1% bigger than the V10 piston area if you use identical B/S ratio. This is completely independent of the displacement and the actual geometric data purely from the area and volume equations.

I think that 3.1% more air is not a very big advantage when you consider that the bigger piston area also generates higher heat losses. I would think the V12 config makes more power in such situations where you can run higher rpm due to the reduced inertia. If the V12 can run 10% higher rpm you gain a lot more power than the theoretical 3.1% that come with the increased piston area. I would think that the advantage is substantial for displacement of four or five liters but it gets marginal when you go down to two liters where a next naturally aspired F1 would probably be positioned.

I have also figured what the advantage in piston area of a V6 with identical B/S ratio over an L4 would be. It is exactly 7%. For a turbo engine it should not make a big difference in power as you can easily compensate that air disadvantage by more boost. But you cannot compensate the heat losses of the bigger piston area which becomes a distinct disadvantage in a fuel limited formula. There is also no advantage from higher rpm because thermal efficiency would force you to use longer strokes and lower rpm anyway.

I would conclude that there is no general answer to the question of a best configuration. The use of turbos chargers and fuel flow limits can play a bigger role than the theoretical power that the engine configuration is capable of.

[gruntguru]

The use of turbos chargers and fuel flow limits can play a bigger role than the theoretical power that the engine configuration is capable of.

The fuel flow limit will be king. Most engine decisions will be focused on optimising efficiency.

[Magoo]

I was interested what the difference would actually be mathematically and figured is out from the equations. The V12 piston area is 3.1% bigger than the V10 piston area if you use identical B/S ratio. This is completely independent of the displacement and the actual geometric data purely from the area and volume equations.

In V10 and V12 engines of identical displacement, say 3L, you wouldn't select identical bore/stroke ratios. More cylinders permit a shorter stroke per cylinder in real or absolute terms, reducing cranktrain speed/acceleration. Meanwhile, to the extent the bore diameter is maintained, valve area per unit displacement is increased. So multi-cylinder engines achieve more power in two ways: greater volumetric efficiency and higher operating speed.

The theoretical upper limit for multi-cylinder engines is not 10 or 12 cylinders. In the '60s Honda did a paper surmising that for a 3L engine, the tipping point for max output might be in the area of 24 cylinders. (The company later proved, in a roundabout way, that a 500cc V8 was entirely viable.) In cylinder count, the effective ceiling is in engineering competence -- managing the increased complexity and cost, frictional losses, vibration, etc. In the late '60s Keith Duckworth cleverly decided that at that moment, the effective limit was eight cylinders. The DFV V8 was introduced into a field of V12 and V16 engines, soundly defeating all of them.

In the most recent 3L F1 era, the competence level with V10s soon increased to the point that it became transparently evident that anyone who wished to remain competitive would soon need a V12. A 10-cylinder limit was then imposed more or less by consensus in order to save everyone the time, trouble, and most importantly, the money. Once everyone has a V12, what's the point.

Edited by Magoo, 13 January 2011 - 10:16.

[Magoo]

First mistake is in the second sentence. I didn't bother reading further.

Yes, Autozine is a demonstrably questionable resource.

[Magoo]

I have also figured what the advantage in piston area of a V6 with identical B/S ratio over an L4 would be. It is exactly 7%.

Here is the advantage of more cylinders for a given displacement: Let's say we have a 4-cylinder engine of 4 inch bore and stroke, 201 CID. To increase output, we will convert it into a V8 by adding another bank and then cut the stroke by half to 2 inches. So now we have doubled the valve area and cut piston speed/acceleration in half, while maintaining the displacement at the original 201 CID. We haven't maintained the original B/S ratio but that was not the objective.

In a nutshell, that is the history of racing engine design -- a tale of topology. Naturally, as development proceeds toward practical optimums, the above gains become incrementally smaller, but they are just as real. A 7 percent increase in valve area is fairly significant these days. Pretty hard to turn down.

[WPT]

....piston speed/acceleration in half,....

Piston speed in half yes, but piston acceleration is a function of the square of the stroke, so 1/4 for it.
WPT

[GrpB]

In a nutshell, that is the history of racing engine design -- a tale of topology.

There are a number of papers on parametric racing engine design that show this, the motorycle ones are very interesting from the late 60's Honda papers with various bore/strokes/cylinders. # valves/cyl and combustion chamber designs to the recent ones from the time of the MotoGP switch to 990cc four strokes The recent MotoGP (and WSBK) ones are nice since they compare the realistic configurations from I3's to V6's, holding mean piston speed, valve timing, total piston area and compression ratio constant, varying valve seat diameter, valve lift, inlet/exhast port areas relative to bore. Several years on in MotoGP and all but Yamaha have adopted what was presented as the ideal solution, the V4, although perhaps of more interest nowadays is the subesequent firing order work to improvemet of mechanical grip.

More importantly the Cosworth V8 vs the at-the-time V12's shows that theory is secondary to attention to detail and development, recently demonstrated with Yamaha's dominance in MotoGP with the therotically 'less than ideal' balance shafted I4. The right development mindset coupled with a cohesive team and endless hours of sweat can always trounce theory until the point where the sheer volume of less than fanatic development of the theoretical ideal starts closing the gap.

Of course with F1 (read: AERO), the engineering fashions of the moment dicate the priorites (and rightly so for the conservative financiers), and there is also an implied need to have some race to street technology mimicry so the options are often more limited from the onset than in the motorcycle arena. For example, a V4 with a nice short/stiff crank/block may also package more neatly than an I4 for single seater applications outside of 2 stroke sports racers, but to consider one turbocharged at 1.6L for 2013 F1? Not likely, unless maybe Saab enter the F1 arena with an F-96.

[WhiteBlue]

Since the mid '90s the universities, government and racing engineers have discussed about more eco friendly racing and very quickly the system of fuel limiting has been the champion of all new formulae. It has now been adopted by F1 and practically all relevant motor sports will follow sooner or later. It will have a fundamental impact on the way race engines will be build.

Prior formulae were basically air limited and people tried to maximize power with a given amount of air. It wasn't relevant how much fuel was used. So nobody cared about fuel efficiency as much as he did for max power. With the new fuel limited formulae this has changed. Power can only be increased if all efficiency options are fully utilized. I think it will have a massive impact on the way race engine designers will approach future projects. Certainly the know rules of engine configurations will have to be re written.

Race engines will come much closer in technology to road car technology where similar optimization mechanisms are at work. The traditional differences between racing engines and road engines will become smaller. Racing engines will still be lighter and more expensive and use more sophisticated components than road car engines and they will have lower mean time between failure targets. Racing engines will also run on much higher power settings than road cars but thats about all the differences. The engineering methods will not be principally different and the main objective to maximize fuel efficiency will be the same.

[Magoo]

Piston speed in half yes, but piston acceleration is a function of the square of the stroke, so 1/4 for it.
WPT

Crank speed is the square function.

Connecting rod length is the other proportional factor. So assuming that rod/stroke ratio remains constant (as I did above) halving the stroke will halve the acceleration. However, if the connecting rod length remains unchanged as the stoke is halved, the reduction in acceleration will be a bit more than half.

[Ross Stonefeld]

In the most recent 3L F1 era, the competence level with V10s soon increased to the point that it became transparently evident that anyone who wished to remain competitive would soon need a V12. A 10-cylinder limit was then imposed more or less by consensus in order to save everyone the time, trouble, and most importantly, the money. Once everyone has a V12, what's the point.

I don't remember the non-tech explanation for why Ferrari went 12 to 10, but I do recall Benetton/Ford figuring out pre-94 that because of the torque requirements of the calendar a V8 would be just as good as a V10, if not better.

I recall the V12 ban, or rather V10 fix, came about because of rumours that Toyota were considering a V12 for their entry. Or rather that they were considering V8s, V10s, and V12s. I don't know where I first heard it or how likely it was, but there was a whisper Toyota might run different engines at different tracks. Which, unless you had three complete test teams, I can't see how you could do any sort of car development if one of the fundamental design aspects was different every weekend.

[Lee Nicolle]

My take on the late 70s engines is that Ferrari had a fixation for 12 cylinder engines and others too. But the Cosworth was a [comparitivly] simple engine, quite light and easy t package, And had good performance but never the same as some of the 12s but because of the weight and packaging factor won a lot of races. And they were very numeric hence the number of races they won. Best engine no, most powerful, no way, most reliable, probably, and they sounded good too.
So it goes back to the old KISS principle, keep it simple stupid!!And with the silly looking cars and the very hi tech engines around now I think the whole sport should go there, and 4 cylinder turbos is not the way.You will have to wear your hat backwards and fit a doof doof stereo too!!

[Wuzak]

Ferrari's 180° V12 did pretty well in the second half of the '70s. It won the Drivers' Championship in 1975, '77 and '79. It won the Constructor's championship 1975-'77 and 1979 and was 2nd in '74 and '78.

[Wuzak]

I would still like to know what deficit in efficiency a V6 would have compared with an L4 in the fuel restricted formula.

Are there too many parameters to make it possible to determine this?

[Greg Locock]

I would still like to know what deficit in efficiency a V6 would have compared with an L4 in the fuel restricted formula.

Are there too many parameters to make it possible to determine this?

You could make a justifiable estimate, based on your assumptions for the two layouts. So what would you regard as fixed - say VE, max piston speed, what else?

[Magoo]

I would still like to know what deficit in efficiency a V6 would have compared with an L4 in the fuel restricted formula.

There isn't one that I can see. This is an arm-waving pronouncement on my part but I am pretty comfortable with it. It would take at least a fairly rigorous sim to change my mind. I presume the four-cylinder limit was imposed to keep them from building sixes.

I think folks expecting a revolution in F1 engine technology or a marriage of production car practice are going to be disappointed. If it's still auto racing in 2013 and still looks like auto racing, racing engines will be required, I expect.

[cheapracer]

Ferrari's 180° V12 did pretty well in the second half of the '70s. It won the Drivers' Championship in 1975, '77 and '79. It won the Constructor's championship 1975-'77 and 1979 and was 2nd in '74 and '78.

1966 500kgs min weight

1969 Ferrari V12 grossly overweight

1970 FIA raise min weight to 530kgs, Ferrari more competitive

1971 Cosworths get more power and start to dominate, Ferrari fall behind again

1972 550kgs min weight, Ferrari more competitive start of year but fall behind again as the Cosworth constantly develops

1973 Cosworth find yet more power over winter, Ferrari basically hopeless

1974 Min weight raised to 575kgs - oh the Ferrari just happened to be 580kgs.

So from 1969 the min weight was raised by 75kgs to keep the 12 cylinder Ferrari competitive one could sarcastically assume.

I laughed at the "180 degree V12" comment too better known as a "Flat 12" or "12 cylinder Boxer"
(how do you get a degree symbol to function btw?)

Edited by cheapracer, 14 January 2011 - 07:26.

[Wuzak]

I laughed at the "180 degree V12" comment too better known as a "Flat 12" or "12 cylinder Boxer"
(how do you get a degree symbol to function btw?)

The Ferrari 12 used in teh '70s could be described as a flat engine, but it was no boxer.

To be a boxer the engine would need a 12 throw crank. The Ferrari had a 6 throw crank, like regular V12s. I believe Alfa's flat 12 was a boxer.

To get the degrees symbol I hold down the ALT key and then type 0176.

[Wuzak]

You could make a justifiable estimate, based on your assumptions for the two layouts. So what would you regard as fixed - say VE, max piston speed, what else?

I would fix the geometry - bore:stroke ratio, rod length:stroke ratio, etc. .

I would assume the same max rpm (12k), thus the piston speed would not be the same. I would also assume the same maximum boost pressure. For 2013 I assume the boost pressure will be fixed, because if it is not it is likely the engines will operate at lower rpm than the 12k.

[Wuzak]

There isn't one that I can see. This is an arm-waving pronouncement on my part but I am pretty comfortable with it. It would take at least a fairly rigorous sim to change my mind. I presume the four-cylinder limit was imposed to keep them from building sixes.

I think folks expecting a revolution in F1 engine technology or a marriage of production car practice are going to be disappointed. If it's still auto racing in 2013 and still looks like auto racing, racing engines will be required, I expect.

If that i teh case then why aren't other configurations allowed?

Is it to force engine suppliers to use GRE motors to make it cheaper for them?

Is it to appeal to Toyota Yaris drivers, or drivers if Prii? Is it to appeal to VW, who F1 have survived without for 60+ years?

And if there is an efficiency deficit, it makes even less sense to fix the configuration.

[Catalina Park]

To get the degrees symbol I hold down the ALT key and then type 0176.

To get the degree symbol I use ALT and 248. A saving of one keystroke. If you were to add up the number of saved keystrokes in a season I am sure that there would be a big advantage.