Road Relevance of 2014 F1 Engines

[machin]

the turbocharged engine['s....] good efficiency comes essentially from boosting the mass flow without significant increase in engine mechanical losses.

indeed... or to a put it another way... for the same fuel mass flow, a small turbocharged engine can achieve the same power output with less mechanical losses, and hence better fuel economy....

Certainly it was said that turbo engines necessarily opened the exhaust valve earlier (to feed the turbo more energetic gas than would naturally occur)).

To steal your own phrase; "would you stake your life on that?"

Taking the 1970's 911's cam timing as an example:

2.7 litre (normally aspirated) inlet: 64/76, exhaust 64/44
3.0 litre turbo, inlet: 22/62, exhaust 50/20.....

As you can see: the turbo engine has much less duration, less overlap and the exhaust opens later, not earlier....

But anyway, regardless of whether the turbo absorbs some additional power or not the end result is the same: the positives outweigh the negatives and a small capacity turbo engine is more efficient than a larger/high reving naturally aspirated engine... I point again to those VW Polo figures from my earlier post.

[WhiteBlue]

Just the only advantages of a NA engine over a turbo charged downsized engine are lower complexity, higher reliability and better serviceability. The road car manufactuer has to pay good attention to such things if he has a brand image to loose. But I think you can look at Audi in LeMans to see how such moves can be done in spectacular form. I think having a superior F1 engine in 2014 will also do the road car sales of an automotive manufacturer some good. The engines will be much closer to a road car specs than the old 2006-2013 V8s ever were.

[Giblet]

Turbo lag has gotten better but it is not nonexistent. The old adage remains, there is no replacement for displacement when talking only power.

[Tommy Cookers]

the turbocharged engine['s....] good efficiency comes essentially from boosting the mass flow without significant increase in engine mechanical losses.

indeed... or to a put it another way... for the same fuel mass flow, a small turbocharged engine can achieve the same power output with less mechanical losses, and hence better fuel economy....

Certainly it was said that turbo engines necessarily opened the exhaust valve earlier (to feed the turbo more energetic gas than would naturally occur)).

To steal your own phrase; "would you stake your life on that?"

Taking the 1970's 911's cam timing as an example:

2.7 litre (normally aspirated) inlet: 64/76, exhaust 64/44
3.0 litre turbo, inlet: 22/62, exhaust 50/20.....

As you can see: the turbo engine has much less duration, less overlap and the exhaust opens later, not earlier....

But anyway, regardless of whether the turbo absorbs some additional power or not the end result is the same: the positives outweigh the negatives and a small capacity turbo engine is more efficient than a larger/high reving naturally aspirated engine... I point again to those VW Polo figures from my earlier post.

Thanks for the clear answer regarding the timing. Looks like I was wrong about that.

I'm thinking they cost a bit more, though

[Tommy Cookers]

Turbo lag has gotten better but it is not nonexistent. The old adage remains, there is no replacement for displacement when talking only power.

That's what I found (with a turbo diesel), that it was good on motorways (freeways), but a pain on a bendy road, there's lots of bends here in the U.K.

[machin]

Just the only advantages of a NA engine over a turbo charged downsized engine are lower complexity, higher reliability and better serviceability. The road car manufactuer has to pay good attention to such things if he has a brand image to loose.

I think this is one reason why the turbo fell out of favour in the 1980's; too many failures as a result of poor owner maintenance... however, times change and now people very rarely do their own work on their cars... you only have to look at the inaccessibility of a modern car's engine to see that even small jobs can be a dealer-only maintenance task... turbo servicing will simply fall under this scope.

Other benefits of a small capacity high reving NA engine over a turbocharged, lower reving engine, will be the package size and weight... in a category with no weight limit and no fuel limit, especially ones of short duration where fuel weight is a small % of total vehicle weight (such as UK Sprint and Hillclimbing) I think we'll still see NA engines dominating....

[WhiteBlue]

Turbo lag has gotten better but it is not nonexistent. The old adage remains, there is no replacement for displacement when talking only power.

That's what I found (with a turbo diesel), that it was good on motorways (freeways), but a pain on a bendy road, there's lots of bends here in the U.K.

You may have bought a lemon there. I had two turbo diesels in the last eight years (Audi A6 quattro and a BMW 120d) and both have been superb. I have never had any problems with turbo lag. Particularly the BMW is very nimble in the city and on bendy roads. You can drive it between 1,000 and 2,000 rpm without stalling and lack of dynamics. It just has huge torque. The small BMW 2L 4-cylinder has a torque of 350 NM which is plenty enough for a 1.45 ton car. I have no idea how people can experience turbo lag in those cars. I certainly have never had anything to complain. Quite contrary when I took out a BMW 320i cabrio for a test drive it felt very sluggish and unresponsive until I hit 5,000 rpm.

[Tommy Cookers]

Thought for the moment ....

The 2014 engine rules are written around one design route to a more efficient emgine, one that seems to me suited to high performance relatively expensive section of the market, and including a potential for some 'all-electric' city driving (useful to me as I lost interest about 20 years ago in all that clutch and stick work).

The Fiat Twin Air and Multi Air are outstandingly efficient right now, but appear to be fundamentally cheaper, without an electric capability.
Now people on this thread are advocating downsizing-by-turbo (for economy).

IMO the FIA has decided that we should all have an electric capability in our road cars, this works against people like FIAT, and those who don't want complicated,expensive cars. In the UK there is a £5000 taxpayer subsidy, but that wouldn't survive a big expansion of that sector of the market.

Alternatively, the FIA is biased, but Fiat can at least still sell Ferraris & Maseratis via the new rules.

[WhiteBlue]

Thought for the moment ....

The 2014 engine rules are written around one design route to a more efficient emgine, one that seems to me suited to high performance relatively expensive section of the market, and including a potential for some 'all-electric' city driving (useful to me as I lost interest about 20 years ago in all that clutch and stick work).

The Fiat Twin Air and Multi Air are outstandingly efficient right now, but appear to be fundamentally cheaper, without an electric capability.
Now people on this thread are advocating downsizing-by-turbo (for economy).

IMO the FIA has decided that we should all have an electric capability in our road cars, this works against people like FIAT, and those who don't want complicated,expensive cars. In the UK there is a £5000 taxpayer subsidy, but that wouldn't survive a big expansion of that sector of the market.

Alternatively, the FIA is biased, but Fiat can at least still sell Ferraris & Maseratis via the new rules.

There will be a lot more turbo downsized hybrids than electric cars in the period from 2014-2022 IMO. The FiA is absolutely correct to support this. Driving with LPG or natural gas isn't very demanding at all in terms of engineering and it isn't an alternative for the broad majority of motorists because the fuel has restricted availability.

[olefud]

IMO Cookers has a point, though I see a different flaw in the rules. Electrons are really rather poor at storing/transmitting energy in the every day automotive field. However, they are excellent for controlling mechanisms and processes.

In the real world energy is wasted in the exhaust and cooling of engines. Turbo compounding has a good history (efficiency not reliability) in the aircraft industry of recovering waste energy with rather crude analog mechanical controls. It was abandoned early in aircraft engines because turbine compression generated “waste heat” better than reciprocating engines.

Cookers’ thought of limited fuel flow, further in conjunction with turbo compounding using modern digital controls and probably separate compression and expansion turbines, seemingly would have promise for improving road vehicle efficiency. Yeah, more expensive but supportable by manufacturers as a way to real world efficiency.

[Speedster]

Turbo lag has gotten better but it is not nonexistent. The old adage remains, there is no replacement for displacement when talking only power.

That's what I found (with a turbo diesel), that it was good on motorways (freeways), but a pain on a bendy road, there's lots of bends here in the U.K.

You may have bought a lemon there. I had two turbo diesels in the last eight years (Audi A6 quattro and a BMW 120d) and both have been superb. I have never had any problems with turbo lag. Particularly the BMW is very nimble in the city and on bendy roads. You can drive it between 1,000 and 2,000 rpm without stalling and lack of dynamics. It just has huge torque. The small BMW 2L 4-cylinder has a torque of 350 NM which is plenty enough for a 1.45 ton car. I have no idea how people can experience turbo lag in those cars. I certainly have never had anything to complain. Quite contrary when I took out a BMW 320i cabrio for a test drive it felt very sluggish and unresponsive until I hit 5,000 rpm.

I recently drove an Audi A6 2.8 Turbo diesel (2008 model) and for me the turbo lag was very apparent, compared to similar sized naturally aspirated (petrol) engines. While the TD has a lot of torque, I didn't like the way it delivered its power. For me, it is still an issue with most turbo engines. I'm sure in supercars like the Bugatti Veyron and the BMW M5 with multiple turbos the problem is virtually non-existent, but I haven't been lucky enough to try them out though.

Smaller turbocharged petrol engines suffer from the same turbo lag. For example, the Renault 1.4L petrol engine delivers over 150hp, but the car feels horrendously sluggish below ~2.200rpm. I've no idea if this will be an issue in F1 cars, as I'm sure they will operate in the turbo range for all parts of the race, but I'm interested in the engine and how it will perform.

[olefud]

It would appear (to me) that the problem with turbocharging is that the fuel mixture charge at full power is, in effect, that of a larger displacement engine. However, the power stroke expansion is limited and leaves a lot of energy unrecovered at BDC. Also, because of the volume and pressure at power BDC, the exhaust valve has to open a bit early for enhanced blow down thus generating more waste energy.

Of course a less weighty engine that normally operates more efficiently at a good deal less than full power mode while having the capability of enhanced power is a thumb on the other side of the balance.

[Tommy Cookers]

Yes !

If unthrottled, naturally aspirated engines START to exhaust at a cylinder pressure of about 5 bar, the 'waste' of arguably useable exhaust energy occurs at this point (of course if exhaust valve opening is delayed the piston will waste other energy driving the exhaust out on the upstroke).
Even with NA the gas goes (or tries to go) supersonic, this is a pressure loss process, in the port and manifold.

The geometric expansion ratio at the piston is must be lower with forced induction (in a fair comparison), so the turbocharged engine will open its exhaust valve at a higher cylinder pressure than the NA engine does (even with the same valve timing), and the valve will be relatively smaller.

Basically, the turbo engine will have the same sort of upstream pressure drop in this process, with higher pressures both upstream and downstream of the exhaust valve, for the same reasons. (In both types of engine the pressure drop will be lower with throttling, this may be a factor in the valve timing).

I can't see a way round this, unless the turbine can access in-cylinder gas conditions, so that most of the pressure drop occurs across the turbine.

We could eliminate this 'problem' if we had a continuous flow type of engine ....... a gas turbine ?


The turbocharged engine would be smaller internally than the NA engine, and have less friction. Frictional power could be perhaps 35% of net power output at partial powers ?
Reduced losses to coolant would also be significant.

[olefud]

I can't see a way round this, unless the turbine can access in-cylinder gas conditions, so that most of the pressure drop occurs across the turbine.

We could eliminate this 'problem' if we had a continuous flow type of engine ....... a gas turbine ?

The blowdown turbine used in turbo-compounding apparently harvested energy without adding to back-pressure. But the technology was abandoned because, as you suggest, the continuous flow turbine proved superior, at least for aircraft purposes.

[Tommy Cookers]

The Turbo-Compound (as did many engines of this generation) had an artificially low compression ratio, to allow very high max MEP and power by allowing very high pressure supercharging, so the exhaust emerged at relatively high pressure. This was why they had the turbines (unlike other versions of the same engine).

I can't see how this avoids the significant losses around the valve and before the turbine, but I'm open to being proved wrong. Does the higher overall pressure in the forced induction engine at this point make available the turbine some of the pressure drop that would otherwise be wasted ?

I know there's a lot about feeding exhaust pulses to the turbine; but after 80 years of viable turbocharging we still don't have clear statements/measurements showing what goes on IMO. Such pulses could equally be called low amplitude explosions whose energy (partly) decays before it can be used ? Explosion means supersonic/shock conditions that degrade and can't be conserved.

In racing we harvest exhaust pulses after degradation via our exhaust system design with naturally aspirated engines (to increase mass flow/MEP, ie some 'free supercharging'); one revelation of the F1 turbo era was that turbos need exactly the same exhaust system design ?