naturally aspirated 3.0l V12 by todays standards

[wuzak]

how are you going to fit a roller bearing on a crank shaft journal?! Remember journal bearing have shells.. Most roller bearings the race is pressed on and is in one piece.

http://img.everychina.com/nimg/f8/8a/59 ... ddb122.jpg

Yes I know those bearings. nothing new and I am not phased by your "gotcha post." Those are some giant bearings, not for the speed and load of high rev engine. They are also angular contact. They are made to resist both radial and axial. Not the most elegant solution for a journal bearing. I actually discussed some of these detail in the original version of my post, but I edited that out to prevent confusion for other readers.

You can't just post a picture and expect to be correct though. You have to explain their application somewhat.

Also you can check SKF's website to see what is lost when you make the roller bearing like that. Remember now that roller bearing take up a lot of space too.

Is an interesting topic.. maybe for another thread but I would love a discussion on this.

Maybe a split needle roller bearing woudl be better?



The inner race could be the crank pin and the outer race the con rod big end.

[Vortex347]

a heavier lube-to-oil ratio ( ~18/20-1) gives best power output.. due to more effective sealing.

don't think your talking about f1 engines here but...
In most engines this would be true however f1 pistons are hot honed so the effects would be much less significant (probably not even noticeable) then in an ordinary engine with rather mediocre tolerances .

"Power per capacity isn't..." but hey W...., isn't - specific output - the standard motorsport "best measure"?

I concur specific outputs are widely underrated as effective measures of engine performance when they should be brought into the spotlight more often - especially in car reviews.

their CR was limited by the valve-piston clearance volume (c. 98 bore 41 stroke makes this worse than Mazda and dirtbikes examples)
super DI most beneficial in an engine where the CR is at the limit driven by detonation
where it is not DI may improve efficiency without improving power

I'm sure Bore/stroke/comp ratio and rpm's could be altered to cater for whatever setup created the most power- (most likely emphasis would fall on a higher comp ratio for less rpm - longer stroke and smaller bore).

[J.A.W.]

a heavier lube-to-oil ratio ( ~18/20-1) gives best power output.. due to more effective sealing.

don't think your talking about f1 engines here but...
In most engines this would be true however f1 pistons are hot honed so the effects would be much less significant (probably not even noticeable) then in an ordinary engine with rather mediocre tolerances .

"Power per capacity isn't..." but hey W...., isn't - specific output - the standard motorsport "best measure"?

I concur specific outputs are widely underrated as effective measures of engine performance when they should be brought into the spotlight more often - especially in car reviews.

their CR was limited by the valve-piston clearance volume (c. 98 bore 41 stroke makes this worse than Mazda and dirtbikes examples)
super DI most beneficial in an engine where the CR is at the limit driven by detonation
where it is not DI may improve efficiency without improving power

I'm sure Bore/stroke/comp ratio and rpm's could be altered to cater for whatever setup created the most power- (most likely emphasis would fall on a higher comp ratio for less rpm - longer stroke and smaller bore).

Actually V-347, I was refuting Wuza's ill-informed notion - re: the lube/fuel ratio per 2T power output..

& of course, not only did 2T G.P. race bikes have markedly superior power on a specific capacity basis,
but also on both power-to-mass/compact packaging, & throttle control - at those outputs..

4T Moto G.P. machines had to employ ~twice the capacity , & run at a far lower specific output,
as well as being 'orders-of-magnitude' more complex/expensive, inc' needing massive ECU power to
operate anti-wheelie/anti-slide/anti-off throttle clutch torque , & etc..

N/A 4Ts operate under the handicap of "1 stroke for power, & 3 to wear the engine out" - as S. Hooker put it..

In the absence of some kind of pressure supercharge ( via air pump/& or trick fuels) - capacity limited 4Ts must resort to expensively high rpm - to make even a 1/2 decent power output effort.. inc' radical B X S ratios..

[Edis]

I personally reckon a v10 would be better than a v12 especially in regards to the weight aspect you mentioned in your opening post (v10 engine would be lighter than v12 and less complex).

Cosworth built a V12 "mule" before V10 engines were mandated and the conclusion was that the V12 wasn't beneficial, at least at that time.

First and foremost, the power aspect of the cars wouldn't really be comparable to what they were running in the past. My main reason for this is the introduction of Direct Injection in the 2014 turbo v6 engines compared to multi port fuel previously.
The advantages of direct injection (over MPFI) in regards to power are huge.
Running DI on these new engines would yield more power due to the fact that DI doesn't spray fuel into the cylinder until the instant it needs it for the combustion cycle. This means you could run a higher compression ratio and not have to worry about engine knock. Higher compression ratio = bigger bang = more power (possibly a significant torque increase too due to the extra force the piston is being subjected to).

Mazda's new skyactiv technology (uses DI on petrol engines) and enables compression ratios of 13:1 (a huge thing to take note of with this is the engines aren't built from any exotic materials, have a large safety margin and large reliability margin for longevity). Take into account some Dirt bikes made by ktm and yamaha are pushing 14:1 + on their 250cc four strokes also using fairly ordinary materials (AND no pneumatic valves either) well...

It'd be pretty hard to gauge what these guys could come up with but with the DI compared to MPFI and beefed up comp. ratio. I'd say 16:1 would be a walk in the park for these guys, you'd probably be looking at a 10-16% power increase assuming the engines are revving the same. In regards to rpm I think 22000 rpm is the maximum these engines could rev to before they start being overcome by large amounts of friction (which would sap power). compared to the honda at the start that'd be another 10-13% power so all up you'd be looking at maybe 25% on top of that 950hp.

Direct injection will not have a major influence on the maximum power of an air restricted naturally aspiranted engine. You typically see some improvement in volumetric efficiency as you lose the fuel vapors in the inlet and some improvement in knock resistance but the NA F1 engines were never knock limited. This means that the compression ratio for F1 engines could be selected without regard to knock, instead it was a compromise between the higher thermal efficiency of a higher compression ratio, the associated losses caused by the increased cylinder pressures (increased frictional- and heat losses), airflow restrictrions around the inlet valves and particularly the negative impact on the combustion by the shape of the combustion chamber with a high CR short stroke engine.

For maximum power out of a given airflow a direct injected engine injects the fuel during the intake stroke, as this gives the most homogeneous mixture for combustion.

In terms of engine weight well steel crankshaft is the Achilles heel of lightweight engines in f1. Get rid of that and replace it with something a lot lighter and that 95kg engine will be down to about 85kg.

Lighter crankshaft would also have lower rotational inertia so more power to the wheels there.

For lightweight and durability though it's pretty hard to beat magnesium and there have been a lot of breakthroughs in making it corrosion resistant (through the use of stainless alloys and magnesium) and neutralizing it's spontaneous combustion properties (by adding silicon molecules I believe)

http://www.gizmag.com/stainless-magnesi ... ash/28856/

If it's possible to make an engine block out of stainless magnesium well the possibilities are endless. This would easily supersede steel, cast iron, aluminium, titanium and beryllium too (an illegal material in f1 atm). I reckon about 65kg overall so about 25kg lighter than the old engines.

Steel (with tungsten counter weights) is a very difficult material to beat for crankshafts. A material used in crankshafts must offer a very high fatigue strength (to prevent failure at high cyclic stress), a high surface hardness (to prevent wear on bearing surfaces) and a high stiffness (to allow a compact design). Magnesium doesn't offer any of those properties.

Magnesium is typically used as an alternative to aluminium or plastics in low temperature applications. As an alternative to aluminum it's lower density, but also lower stiffness, means it can be used to make lighter parts that are limited by geometry rather than strength, or allow better strength to weight ratio by increasing the wall thickness of the part (a lower density material made with greater thickness is stiffer in bending that a higher density material with a smaller thickness, albeit the same specific stiffness). Magnesium is an unnoble material so corrosion will always be an issue, like aluminium certain alloying elements can increase corrosion resistance although this typically does have a negative impact on other properties. Magnesium catching fire is typically not a problem with thick walled parts, like cylinder heads, engine covers and so on. Magnesium sheet is however banned for a good reason.

Not many engines using roller bearings any more.

The Peugeot/Asiatech V10 was probably the only F1 engine of that time to use roller bearings for the mains. I know Ferrari made a few prototypes in the early nineties with rollers (using an assembled crankshaft I believe), but rollers were generally regarded not to offer a friction reducion at F1 speeds.

[PlatinumZealot]

Interesting on the bearings.

Maybe a split needle roller bearing woudl be better?



The inner race could be the crank pin and the outer race the con rod big end.

It is possible if designed and assembled perfectly but I don't think there would be an advantage. Maybe if the engine was very compact and you had to use very narrow journals and the roller bearing could offer the load speed characteristic for that bearing width.

Anyway, the F1 engines would all have roller bearings in the journals if this was the case. F1 engines spin up quick enough - actually they respond too quickly and if I remember the NA engines were programmed to actually slow down the acceleration of the revs to make them more driveable under light loads.

Edit: I admit I am actually doing some googling, and a lot of racing engines in the past had used rollers, but the cranks were assembled and retainers put in place.

Bugatti roller bearing crank.

http://www.bugattirevue.com/revue12/curtbo.htm


Also it seems roller bearings (not the split type) can make strong engines (if your multi peice crank is not the limiting factor of course!)

Now below, you can see the roller crankshaft, called a roller because instead of journals and journal bearings, this crankshaft has full roller bearings! No journal caps to stress and break! Also, the connecting rods are one-piece units...nearly impossible for this engine to throw a rod! To replace any of these components means the crankshaft must be pulled apart with a special machine, press on/off the bearings and rods, and press the crankshaft back together ensuring that everything lines up properly. I was lucky, the bearings are in perfect shape, and all the rods are in great condition. This is what makes the Suzuki GS Engine famous with the drag racers...a bullet-proof engine! On the right the crank is installed...ready to install the bottom half engine case.

http://www.unisourcetechnologies.com/fa ... sembly.htm


Note connecting rods are one piece. More weight and size for the bearings too.

[strad]

Maybe a split needle roller bearing woudl be better?

Those bearings pictured are the ones for a Mercury outboard are they not?

[Tommy Cookers]

....... 2T G.P. race bikes have markedly superior power on a specific capacity basis, but also on both power-to-mass/compact packaging, & throttle control - at those outputs..
....capacity limited 4Ts must resort to expensively high rpm - to make even a 1/2 decent power output effort.. inc' radical B X S ratios..

does this mean that the OP should expect a 3 litre 2 stroke V12 to do a better job ?
if so, what would the exhaust system be like ? - and what would the induction system be like ? - and what would be the power ?

EDIT - was looking for Formula Junior/3 jobs with 3 cyl 2 strokes - Melkus was the last, Elva the best known to most
yes at best they seem to be using what looks like 1 expansion chamber body common in some way to all cylinders
grouped is the buzzword if I get what the following post is saying

[J.A.W.]

....... 2T G.P. race bikes have markedly superior power on a specific capacity basis, but also on both power-to-mass/compact packaging, & throttle control - at those outputs..
....capacity limited 4Ts must resort to expensively high rpm - to make even a 1/2 decent power output effort.. inc' radical B X S ratios..

does this mean that the OP should expect a 3 litre 2 stroke V12 to do a better job ?
if so, what would the exhaust system be like ? - and what would the induction system be like ? - and what would be the power ?

Well T-C, back in the day - Honda built an 'economy' 2T 500 V-twin G.P. & sold them to private teams..
..on a fairly soft tune - using 40mm carburetors ( smaller than the Aprilia RS 250 V-twin G.P. mill), it
made ~280hp/Ltr @ 10,500rpm.. so, even a wee bit harder tuned 3 Ltr V12 version - ought to be able to make ~900hp..

Of course, a plenum type intake could feasibly utilize a synergistic resonance system - with fuel injection,
& likewise, a grouped resonant exhaust could exploit the potential multiple blow-down over-lap energies..

Too bad such things are simply ruled out, as this machine would be far cheaper/lighter/less complex,
& sound better too, than the current F1 set-up..

[wuzak]

Maybe a split needle roller bearing would be better?

Those bearings pictured are the ones for a Mercury outboard are they not?

I could not say. I just looked at the picture.

[rscsr]

Direct injection will not have a major influence on the maximum power of an air restricted naturally aspiranted engine. You typically see some improvement in volumetric efficiency as you lose the fuel vapors in the inlet and some improvement in knock resistance but the NA F1 engines were never knock limited. This means that the compression ratio for F1 engines could be selected without regard to knock, instead it was a compromise between the higher thermal efficiency of a higher compression ratio, the associated losses caused by the increased cylinder pressures (increased frictional- and heat losses), airflow restrictrions around the inlet valves and particularly the negative impact on the combustion by the shape of the combustion chamber with a high CR short stroke engine.

Just to add a bit to this. According to RET they always run the highest CR they could possible achieve, given their chosen dimensions. For example Cosworth used a CR of about 14:1 but couldn't run any higher, because the piston had marks of the valve pockets already. On the other hand Toyota used to run with a bit less piston diameter and therefore they could achieve a CR of about 16:1.

[Tommy Cookers]

......Well T-C, back in the day - Honda built an 'economy' 2T 500 V-twin G.P. & sold them to private teams..
..on a fairly soft tune - using 40mm carburetors ( smaller than the Aprilia RS 250 V-twin G.P. mill), it
made ~280hp/Ltr @ 10,500rpm.. so, even a wee bit harder tuned 3 Ltr V12 version - ought to be able to make ~900hp..
..... a grouped resonant exhaust could exploit the potential multiple blow-down over-lap energies..

surely 6 expansion chambers would be needed ? (ie firing intervals presented to each chamber should not be less than 180 deg)
so 3 chambers would be possible with cylinders firing in pairs, 2 chambers possible with firing in threes
but it doesn't really fit a V12, even a 90 deg V with a flat crank

is there an example of grouping eg 3 even firing cylinders feeding 1 chamber ?

[Edis]

Direct injection will not have a major influence on the maximum power of an air restricted naturally aspiranted engine. You typically see some improvement in volumetric efficiency as you lose the fuel vapors in the inlet and some improvement in knock resistance but the NA F1 engines were never knock limited. This means that the compression ratio for F1 engines could be selected without regard to knock, instead it was a compromise between the higher thermal efficiency of a higher compression ratio, the associated losses caused by the increased cylinder pressures (increased frictional- and heat losses), airflow restrictrions around the inlet valves and particularly the negative impact on the combustion by the shape of the combustion chamber with a high CR short stroke engine.

Just to add a bit to this. According to RET they always run the highest CR they could possible achieve, given their chosen dimensions. For example Cosworth used a CR of about 14:1 but couldn't run any higher, because the piston had marks of the valve pockets already. On the other hand Toyota used to run with a bit less piston diameter and therefore they could achieve a CR of about 16:1.

That's not quite accurate. The Cosworth CA ran 13.3:1 and the Toyota RVX-09 13.6:1.

About the Toyota the following is mentioned:

The compression ratio is 13.6:1, a figure constrained not so much by the fuel type but by the sheer logistical problem of attaining anything higher without compromising the operation of the chamber.

It is also mentioned that Cosworth tried to alter the valve lift profiles to allow a higher compression ratio, but that hurt cylinder filling. Sharper edges for the valve pockets was also mentioned as a previously tested option, but that isn't good for the combustion chamber shape.

[Cold Fussion]

I concur specific outputs are widely underrated as effective measures of engine performance when they should be brought into the spotlight more often - especially in car reviews.

What does specific output really tell you though? I imagine the relationship between specific output and BTE is tenuous at best. Perhaps the relationship between specific output and power/engine kg is slightly more straight forward but it would still be muddled a lot by forced induction engines.

[J.A.W.]

......Well T-C, back in the day - Honda built an 'economy' 2T 500 V-twin G.P. & sold them to private teams..
..on a fairly soft tune - using 40mm carburetors ( smaller than the Aprilia RS 250 V-twin G.P. mill), it
made ~280hp/Ltr @ 10,500rpm.. so, even a wee bit harder tuned 3 Ltr V12 version - ought to be able to make ~900hp..
..... a grouped resonant exhaust could exploit the potential multiple blow-down over-lap energies..

conventional thinking ? says 6 expansion chambers would be needed (and 180 deg firing intervals presented to each chamber)
(I can't really see what they did on the DKW/Wartburg engined FJunior and F3 cars)

is there an example of grouping eg 3 cylinders feeding 1 chamber ?
doesn't this sound like a job eg for a flat 4/6 design extended to 12 or more cylinders ?

Here's a bit about it T-C,


Engineer Schlunke at Orbital Engine Corp - working up the stratified charge DFI in their automotive research program,
ran 2T engines with multiples of 3 cylinders partly due to.. ( from 'Sarich - The Man & his Engines' P. 201..)

"...the advantages are far more pronounced when it is applied to a 2T design, preferably with 3 cyl or multiples thereof...

The typical port timing of a 3 cyl, 2T unit is that the exhaust blows down 90`after TDC... ( &) ...120` disposed from that
blowdown process the engine is closing up the exhaust port in an adjacent cyl. This means that the blown gas from
one cyl helps to charge the adjacent cyl... a high pressure pulse arrives at the port, just in time, & forces the mixture back in...

'The beautiful part of the process is that the effect occurs right across the speed range,
& this makes the 3 cyl set-up an optimum configuration.' ".


As for an actual 12 cyl 2T mill, yes, an H 12 might also allow for grouped crankcase pressure/transfer ducting functions..

[J.A.W.]

Direct injection will not have a major influence on the maximum power of an air restricted naturally aspiranted engine. You typically see some improvement in volumetric efficiency as you lose the fuel vapors in the inlet and some improvement in knock resistance but the NA F1 engines were never knock limited. This means that the compression ratio for F1 engines could be selected without regard to knock, instead it was a compromise between the higher thermal efficiency of a higher compression ratio, the associated losses caused by the increased cylinder pressures (increased frictional- and heat losses), airflow restrictrions around the inlet valves and particularly the negative impact on the combustion by the shape of the combustion chamber with a high CR short stroke engine.

Just to add a bit to this. According to RET they always run the highest CR they could possible achieve, given their chosen dimensions. For example Cosworth used a CR of about 14:1 but couldn't run any higher, because the piston had marks of the valve pockets already. On the other hand Toyota used to run with a bit less piston diameter and therefore they could achieve a CR of about 16:1.

That's not quite accurate. The Cosworth CA ran 13.3:1 and the Toyota RVX-09 13.6:1.

About the Toyota the following is mentioned:

The compression ratio is 13.6:1, a figure constrained not so much by the fuel type but by the sheer logistical problem of attaining anything higher without compromising the operation of the chamber.

It is also mentioned that Cosworth tried to alter the valve lift profiles to allow a higher compression ratio, but that hurt cylinder filling. Sharper edges for the valve pockets was also mentioned as a previously tested option, but that isn't good for the combustion chamber shape.

Of course, another inherent 2T advantage is having the combustion chamber unencumbered by hot poppet valves..
(& same advantage applies for sleeve valves)..

& so, the optimum design for combustion chamber shape, for ideal squish-turbulence/ignition kernel/C-R & etc, - is doable..