Nissan's new LMP1 engine - 10hp/kg engine

[LHutton]

The ZEOD RC will become the first entry in the Le Mans 24 Hours to complete a lap of the Circuit de la Sarthe under nothing but electric power in June. A single lap of each stint (a fuel stint lasts approximately one hour) will be electric powered, then the new Nissan DIG-T R 1.5 liter three-cylinder turbo engine will take over.

The small engine weighs 40 kilograms (88lbs) and produces 400 horsepower. The base engine is only 500mm tall x 400mm long x 200mm wide. While the engine is technically too heavy to take as carry-on luggage on a plane, it would easily fit inside the luggage guides seen at major airports around the world.

Revving to 7,500rpm, the DIG-T R produces 380Nm of torque. At a ratio of 10 horsepower per kilogram, the new engine actually has a better power-to-weight ratio than the new engines to be used in the FIA Formula 1 World Championship this year.

The Nissan ZEOD RC will occupy will run as the Garage 56 at this year’s Le Mans 24 Hours, an additional entry reserved by the ACO for new and ground-breaking technologies never previously seen at the classic French endurance event.

Lessons learned from the development of the revolutionary racecar will also be used in the development of Nissan’s planned entry into the LMP1 class of the FIA World Endurance Championship in 2015.

“Our engine team has done a truly remarkable job with the internal combustion engine,”said Darren Cox, Nissan’s Global Motorsport Director.“We knew the electric component of the Nissan ZEOD RC was certainly going to turn heads at Le Mans but our combined zero emission on demand electric/petrol power plant is quite a stunning piece of engineering. Nissan will become the first major manufacturer to use a three-cylinder engine in major international motorsport. We’re aiming to maintain our position as industry leaders in focussing on downsizing. Lessons learned from the development of the engine will be seen in Nissan road cars of the future.

“Our aim is to set new standards in efficiency in regards to every aspect of the car – power train, aerodynamics and handling. For the power train we have worked closely with the team at Total to not only reduce friction inside the engine, but within all components of the power train. Friction is the enemy of horsepower and tackling that has been one of the efficiency targets we have concentrated on heavily.”

After extensive dyno testing, the Nissan ZEOD RC hit the track for the first time last week with both the electric and internal combustion engines in place. Both the petrol and electric power plants run through the same five-speed gearbox that transfers power to the ground via Michelin tires.
---
The Nissan ZEOD RC will undergo an extensive test program over the next four months prior to it making its race debut at this year’s Le Mans 24 Hours on June 14-15. [/QUOTE]
http://www.racecar-engineering.com/wp-content/uploads/2014/01/updigtc.jpg
http://www.racecar-engineering.com/wp-content/gallery/nissan-dig-t/zupdigt.jpg
http://www.racecar-engineering.com/wp-content/uploads/2014/01/updigtnowifi.jpg
http://www.racecar-engineering.com/wp-content/gallery/nissan-dig-t/zupdigtb.jpg

[CudaMan]

I'd love to read an in-depth article about what kind of engineering and materials tricks were used to achieve that low weight. Darn impressive.

[Fogelhund]

btw.. it isn't a LMP1 engine, it runs unclassified. It is impressive though, mostly in weight. We've seen 1.5l turbos put out much more power of course, such as the mill in the Brabham BT-55, but that was some 330lbs.

[thesameguy]

If it holds together, it'll be a damn miracle. :D

[Random]

1) Packaging tweaks
2) Installation in Caterham
3) ???
4) Winning.

[Godson]

I notice an interesting design on the cylinder head. it seems the block is part of the cylinder, while the head is another portion of the cylinder. Conventional engines cylinder is 95% manufactured in the engine block, this seems to be 50% block, 50% cylinder head.


I have seen a similar design in one other place before, MotoCzysz C1-990. The Z-Line 990 was different in which the cylinder head was the main engine block component.


Has anyone else seen if this design used in LMP engines or F1 yet?

[Godson]

Actually, looking at the photos, they are all CAD photos and a photoshop. There aren't any signs of cylinder head seams, crank housing seams, or any other way to disassemble the internals for the engine...

[Random]

I'm not seeing that--I think the head seam is actually a little shallower than normal, if you look at the top picture and the picture with the dude carrying the engine.

[thesameguy]

I don't see any seams at all, but if I did, they'd be 50% up the cylinder wall. For a high boost application that is *the* way to go, since you reduce the chances of a gasket failure. This design has been used in prototypes elsewhere, but it's very difficult to put into production because the "head" castings become very complex and failures become expensive. If the tooling for that kind of production exists or could be made, it would change a lot of things about high specific output engines. Maybe Nissan is onto something, or maybe the relative simplicity of a triple makes this type of production easier? Or, maybe when you're talking extremely low volume one-off engines it really doesn't matter, and this is a 100% "because we can" exercise. :) I dig the external oil pump and what I think is an internally driven mechanical fuel pump.. I think that's what that lower timing belt sprocket is doing? Which is where I'm seeing (maybe imagining) the head/block seam. Seems like it's also SOHC (probably still multivalve, though) which would cut weight and parasitic loss.

Edit: Whoa, it's not intercooled either. Wonder what those intake charge temps look like at full tilt!

[Random]

There's gotta be a seam at the crank centerline to get the crank in. The external oil pump looks to be part of a dry sump system, I'm guessing.

I can almost convince myself I see a seam halfway up the block, in addition to the white one just about even with the dude's lapel-mike.

[samoht]

Edit: Whoa, it's not intercooled either. Wonder what those intake charge temps look like at full tilt!

?

I only see the exhaust side of the turbo connected directly, the compressor looks like it would send air off to an intercooler to me. Unless you've read something else I havent'?

[thesameguy]

I was looking at the angle of the intake vs. the angle out the turbo outlet. Definitely could be an intercooler intended, just seemed weird to put a vertical-facing TB inlet if that's the intended application. Although, I guess if there wasn't going to be one, they would have just plumbed it in directly instead of leaving that gap, so maybe I have no idea what I'm talking about. ;)

[Random]

The ZEOD RC is tall and skinny, which is probably why the air path looks like it'll run out of the turbo low, presumably to an intercooler in a sidepod?, inlet at the bottom, exit at the top?, and then end up high at the TB.

[Rare White Ape]

I'd love to read an in-depth article about what kind of engineering and materials tricks were used to achieve that low weight. Darn impressive.

It's a 3 cylinder. Not only does it have one less piston than the most common engines, it can also run with 120-degree spacing between each piston. This means it has perfect balance without the need for a balance shaft.

Anyone who has ridden or driven a straight 3 or 6 cylinder engine knows how crazily smooth they are. I rode a BMW K1600 a while ago and it was like the motor wasn't even running.

[Dicknose]

Surprised by the low revs, would have guessed something with a high specific output (by capacity or weight) would have used high revs. Especially at small capacity I would have thought 10k revs.

[Keith O]

Inline threes still need a balance shaft. They want to rock for/aft since there aren't an even number of cylinders to balance out. Inline sixes are balanced in that regard so they don't need a balance shaft. 12 cylinders are the same as a 6 by extension.

[Kchrpm]

Surprised by the low revs, would have guessed something with a high specific output (by capacity or weight) would have used high revs. Especially at small capacity I would have thought 10k revs.

That's what the turbo is for!

[Rare White Ape]

Inline threes still need a balance shaft. They want to rock for/aft since there aren't an even number of cylinders to balance out. Inline sixes are balanced in that regard so they don't need a balance shaft. 12 cylinders are the same as a 6 by extension.

I thought the 120-degree spacing was enough.

Oh well, I'm happy to be corrected on that.

[Keith O]

You balance out the secondary forces of stuff like the rods spinning, but you can't cancel out the primary up/down vibration without an even number of cylinders.

[samoht]

That's what the turbo is for!

Yeah, there have been some pretty high power SR20s that still use the standard valvetrain and so are limited to little over 8,000rpm, but make huge power with boost. This isn't that small a displacement, 1.5L is 75% of an SR20 :)

[Dicknose]

Also only 75% of the cylinders!

It's bigger cylinder capacity than my bike (1.2l twin) and revs a lot lower.

I also wonder if they are counting the turbo in the weight!

[Kchrpm]

I was assuming that the 80 lbs was in reference to the amount of the engine that was being held by Mr Executive up there.

Again, your bike doesn't have a turbo. Most applications I've seen with turbochargers have relatively low revs, in exchange for a big wall of torque once the turbo hits. It's not because they can't rev higher as much they make more power when they're tuned to lower revs for that boost sweet spot. I'm assuming Greg could give a better (aka actual) technical explanation.

[Godson]

Higher revs also = more fuel...

[Dicknose]

Many turbos are an addition to an existing design, so they don't tend to change the revs.
A small high revving engine can have a turbo added without having to drop revs (but might need octane and inter cooling)

And turbo means more fuel. Basically more power means more fuel!
I'm not sure if turbo is any more efficient than higher revs.
It's generally cheaper, but I would have guessed it was heavier.
Adding a turbo adds a fair chunk of weight.
Going higher revs usually means lighter internals, just that's it's not a cheap way to go.

[LHutton]

I'm thinking the lower revs are for reliability and to a certain extent helping reduce the weight by lowering the same stresses that degrade reliability and/or necessitate increased strength.

I do also think the high revs comes back to more fuel due to increased internal losses. Since they're on race gas, the power is made up by increasing boost. I don't know if there are air restrictors in that class anyway.

[21Kid]

I want two of them!

[Godson]

More Power = more fuel yes. I remember reading somewhere that the increase in RPM requires more fuel than turboing. I don't remember exactly, and I certainly don't have the mathematical ability to support or prove it. Perhaps someone else does?

But as already stated, higher revs = increased cost at an almost exponential level due to the requirements for higher tolerances for the increased load as RPMs increase.

[samoht]

This specific fuel consumption against revs plot (y axis is probably effectively throttle opening) is similar to what I've seen before:
http://upload.wikimedia.org/wikipedia/commons/thumb/6/60/Brake_specific_fuel_consumption.svg/900px-Brake_specific_fuel_consumption.svg.png

It shows that there tends to be a best efficiency at fairly low revs. I think this is because the slower the burning fuel-air mixture expands, the more mechanical work can be extracted from it, so higher revs are inherently less efficient for a given power.

[LHutton]

That graph is for a diesel engine. The issue there is that diesel just doesn't burn quickly enough to extract the work at higher rpm. With petrol engines it's more the case that friction increases at high rpm. I'm no expert but I've often heard it said by people who are that there's a big difference between operating under 8000rpm and operating over it.

Turbocharging is always more fuel efficient than high rpm because it involves recovering waste energy from exhaust gas at a relatively minor parasitic expense. Whether to increase boost or increase rpm is bound to be more of a balancing act, depending on the fuel you're using and what rpm and boost you're already at. The power load from combustion, which is increased by boost tends to counter the inertial load from rpm. The power load is also compressive, whereas the inertial load is tensile. Tensile loads are more of a problem because they induce fatigue failure - most materials are far stronger in compression.

Pe is the BMEP (Brake Mean Effective Pressure) in the cylinder over a cycle, which will change with boost and throttle opening. The great thing is that you can double the BMEP with turbocharging whilst only increasing the peak cylinder pressure by a small fraction. Increasing rpm, on the other hand, increases tensile load by the rpm increase squared. So achieving the same power via rpm increases damaging tensile forces by far more than extra boost increases peak pressure and increasing tensile loads only increases bearing friction. Pumping losses also increase with the square of rpm.

4-stroke Power = BMEP x Length of Stroke x Bore Area x Number of Cylinders x rpm/2

[Kchrpm]

That was an awesome explanation, thanks.