So far in #Build128 we’ve covered tub chassis construction and bonding, body panel alignment, and body panel preparation and paint.
After Station 2 (body panel alignment) the car is taken apart again and there’s a fork in the production sequence. The body panels head to Station 3 for preparation and paint and the tub chassis heads to the main production line, where the process of adding all the mechanical bits begins.
Sitting to the side of the production line is our engine workshop, where every Koenigsegg engine is hand-built by Mats, the guy who’s built every Koenigsegg engine in the last 4 years. Mats has been building engines all his adult life, most notably racing engines for motorcycles. He knows things about power.
So what is Mats building for Chassis 7128?
The Agera RS features Koenigsegg’s 90-degree, twin-turbocharged V8 engine that produces 1160hp at 7800rpm (redline at 8250rpm) and 1280Nm of torque at 4100rpm. That’s 232hp per litre of displacement. We refer to it as the ‘most downsized’ engine in the world because of this hp-per-litre figure. It’s a robust and extremely powerful engine and it is, in many ways, the core of what we do here at Koenigsegg. Our cars can do what they do primarily because of their power, handling and aerodynamics. We’ll deal with handling and aerodynamics later, but for now, let’s take a closer look at different elements of the Koenigsegg power plant.
The history
As early as 1997, we had an ambition to build the world’s most powerful homologated production car. That title was held by the McLaren F1, which had 627 hp at the time. As there was no such engine in existence, we had to come up with something of our own. We had never built an engine before so we needed to base our engine construction on something tangible, known and proven. It had to be a good base that we could revamp into something more exiting and powerful. And it had to fall within the size and weight parameters we had in place for our first production model, the CC8S.
What started out with what we thought was a relatively simple approach – using an existing Modular Ford V8 engine and supercharging it – but it quickly turned into something much more complicated. It turned out that most attempts to improve performance in this type of engine required race fuel in combination with an open exhaust, no catalytic converters and open crank case ventilation. And even with this setup we experienced limited reliability, etc. This would not work at all for an homologated, emission controlled road car that had to be reliable enough to be driven on a daily basis on regular fuel AND at the same time be the most powerful production car in the world. We therefore had no choice but to become experts in engine design, calibration, tuning and construction – and all within a very short time frame.
We had figure out how to design and build many of the components and systems ourselves to make the engine work. We had to re-design camshafts, pistons, connecting rods, block reinforcements, fuel injection systems, fuel pump system, drysump lubrication, a new type crank case gas re-circulation system, exhaust, patented catalytic converter flow system, compressor system flywheel, piston oil cooling, clutch, programming etc. And we got it done. The engine used in the CC8S was truly unique and we managed to snatch the Guinness World Record for the most powerful production engine in the world – beating the legendary McLaren F1, which had held the record for the previous 8 years.
The 90-degree V angle from our original engine and bore spacing remains today, but little else. In fact, our modern engines have been so extensively re-designed over the years that we are more than comfortable calling them our own. We have our own engine designer, Thomas, whose job involves optimising every component of the engine. It’s constantly evolving, piece by piece, to become more powerful, more robust and more efficient.
While the Bugatti Veyron made all the headlines for being the first car with four-figure horsepower, it didn’t take long for Koenigsegg to follow with the CCXR. To this date, Koenigsegg and Bugatti are still the only automotive OEMs building their own engines that offer four-figure horsepower in production vehicles with warranties. That there are so few doing this is a testament to how hard it is to consistently deliver this level of top shelf performance. That we manage to do it from such a small workshop in a little Swedish village is something that we’re extremely proud of.
This will be a slightly unusual overview of our engine in that we leave out some of the things you might expect (turbos, for example) and spend time on things you might not expect (crank case ventilation). Why? Well, sometimes the things that don’t make the headlines that are very important.
The block
Koenigsegg engines have to cope with more cylinder pressure than any other production engine in the world, which is why we need an extremely strong, but still extremely light, engine block.
Our engine block is a bespoke item that is cast for us in aluminium at a specialist foundry in the UK, Grainger and Worrall. The same foundry also casts engine blocks for other supercar manufacturers and the motorsport industry. The block is specially designed for maximum strength and stiffness and it features oversized cooling channels to circulate cooling fluids quickly and efficiently.
Our block is cast in the same foundry that does G&W’s Formula 1 engine castings and is made according to the same principles. The raw casting is then brought to Sweden, where we fine-machine the tolerances, do the cylinder bores, install cylinder linings, bore the crank journals and hone the block.
The Head
The cylinder heads are also cast externally and then brought back to Sweden where they are machined, CNC ported and fitted with valve guides and seats. The porting is based on hand-porting first designed and refined by our engine builder, Mats, which has since been automated and adapted to every Agera engine he’s built. The compression ratio has been raised over time from 8.1:1 to 9.3:1 and we now have a higher ignition angle, giving us increased responsiveness through a wider range.
Our valves are stainless steel. We install beryllium copper valve seats and valve guides, which are usually only used in extreme racing applications. The valve seat’s two primary purposes are to close against the valve itself (hundreds of times per minute) and to transfer heat from a valve that has just been present during a controlled explosion. Beryllium copper is very hard-wearing and it’s also a great heat conductor, making it the perfect choice.
Pistons
Our pistons are super-light at just 287 grams. Our engines have the highest cylinder pressure (BMEP) of any gasoline production engine in the world with 36 BMEP average cylinder pressure. Internal protection is critical. Our piston is designed with a ceramic coating on the face that helps to avoid hot spots and detonation when the engine runs at maximum power and efficiency. The curved top face of the piston acts together with the cylinder head to create a combustion chamber that reduces peak pressure but maintains high average pressure, which is necessary for high power output while minimizing risk for detonation (knock).
We rev to 8250rpm and we have a 92mm bore and a fairly long stroke at 95mm. The only way to achieve such high rpm with such a long stroke is to have a very light piston like ours. Anything heavier would be difficult to turn at those speeds.
The Crankshaft
Our crankshaft is a 90-degree design that has very small and light counterweights to suit Koenigsegg’s very light pistons and connecting rods. The lightness of the rotating assembly together with the small area intake plenum and refined software calibrations make for a very responsive engine.
We’ve been asked on several occasions why we don’t switch to a 180-degree crankshaft design, which theoretically would allow for more power due to even more optimal exhaust pulses. In many aspects this is a very simple thing to do as the connecting rods and pistons can stay the same. The crankshaft, camshaft and some of the parameters in the software would have to change due to a different firing order and some difference in exhaust gas re-circulation. But that is pretty much all that it would take.
We have experimented with 180 degree crankshafts over the years but have decided against using one for the time being. The reasons for this decision? Well, we’re not exactly short on power as things stand right now and the 90-degree design gives less vibration and smoother engine characteristics. This is very important in a car where the engine is bolted straight to the carbon monocoque, without any cushioning, as it is with the Agera. We also find the 90 degree V8 rumble in combination with the turbo whine and fast response make for an evocative, powerful and unique sound.
Exhaust
The Koenigsegg exhaust manifold has very short and thin outlets made from inconel (0.8mm), which are ceramic coated. Inconel is suited for this task because it copes extremely well with higher temperatures and our exhaust can get up to 1100deg celcius. Having thin, ceramic coated tubes means we get the benefits of fast spool for the turbos because of the high temperatures, while maintaining light weight. The exhaust headers are very small, which means a smaller volume of air to compress before the turbo kicks in and it maintains heat between the exhaust ports and the turbos, which helps with faster spooling. Our headers aren’t equal length like many tuned headers but we sacrifice that to get maximum responsiveness, which is better for a turbocharged engine. The small heat loss in the exhaust manifold also helps at cold start to light off the catalytic converters.
We have a patented catalytic converter installation incorporated into our exhaust. We run a ‘pre-cat’ on the wastegate. We can block off the main passage out of the turbo to force all the start-up exhaust emissions through the wastegate, which means we don’t have the turbo cooling off the exhaust during cold starts. We can thereby have a smaller catalytic converter than if we had it after the turbo, which means it heats up quicker. And because the turbo is not in the way of the pre-cat, it heats up much quicker. When the main cat is sufficiently heated, we open up the valve behind the turbo and we shoot out the exhaust straight to the main cat. The pre-cat is only used when we operate the wastegate. This patented system means we get an extra 300 or so horsepower because we don’t have to have a smallish catalytic converter blocking the exhaust all the time – straight after the turbo.
There is some science behind all of this, of course. You want as free-flowing an exhaust as you can get because that reduces hot exhaust gas residue (EGR) and knocking. If you have that, you can run much more boost and more suitable timing.
All the restrictions that you have after the turbo are actually three times worse – i.e more restrictive – before the turbo. Having the turbo there amplifies the pressure in the system leading up to it and it’s this exhaust gas residue building up that actually causes detonation and knocking. That’s why a lot of tuners remove the catalytic converter in their turbo cars. It makes the car illegal for the road but it vastly improves their performance potential. We can’t do that, of course, because our vehicles have to comply with all applicable regulations from the factory. We achieve similar results by putting the pre-cat on the wastegate. That way, we only have the main cat in the main part of the exhaust flow at high power and high rpm. Our main cat is very short to reduce back pressure but it has a large diameter and therefore it still has a big surface area. It’s as free flowing as it can be while still doing the job of a catalytic converter.
How effective is this system?
We’re the only high-powered, turbocharged production engine in the world that has less back-pressure in the exhaust manifold than the boost pressure in the intake manifold. Let’s say, for example, that we have 1.5 bar of boost on the Agera RS in the intake manifold. For that engine, we will have around 1.3 bar of back-pressure in the exhaust manifold, which is unheard of. Normally, if you have 1.5 bar in the intake manifold then you’ll have something like 2.5 bar in the exhaust manifold before the turbo. With that high pressure, you would have all the associated hot EGR and you’d have to reduce boost to prevent detonation, which means you’d have to back off your timing.
That means power loss. Big power loss.
If we’ve written a lot about our exhaust system here, you can take that as a sign that it’s a pretty important part of our engine design. The exhaust itself doesn’t make power, but having the right exhaust enables us to make the most of the engine’s potential.
Crank Case Ventilation
If you’ve got an especially powerful turbocharged car, you really need to take care to open up the re-circulation capability of the engine.
When you have strong boost, especially sustained boost over a longer period of time, you get more and more blow-by through the pistons. This is where some gases get shot back into the crankcase. Some private tuners cope with this by putting a filter on the valve cover to let these gases breathe out into the atmosphere but this is illegal in an homologated road car. What you are supposed to do is recirculate this gas into the intake and burn it up during combustion.
If you have any oil residue in these gases from the crank case (which has an oil mist in it) then it can cause knocking. As we have the most downsized engine in the industry with the highest cylinder pressure, the highest boost and the highest per-litre output, we consequently have the highest blow-by of any other engine, as well. So this is a potential problem with huge consequences.
We had to come up with a solution. What we’ve done is invent what we think is the world’s best air and oil separator. A few hundredths of a second before the engine is breathing (out?) clean exhaust gases from the crank, it’s foamy oil – a mix of oil and air. The air and oil are separated in an instant and the air is fed back into the combustion cycle. This took thousands of hours of development but as with our exhaust system, it’s absolutely essential when you’re running as much power as we do and you still want to pass emission regulations.
Intake
We have dual injectors, both quite small, which gives us a wider, better spray pattern with greater emulsification. At low power we run only one of them and as we need more fuel the second stage is fed in. It actually improves our emissions, as well as providing better combustion. Our intake ports are carefully sculputed for maximum flow and we have very short intake runners to avoid any form of sonic tuning.
Our objective is minimal resistance and smallest volume; the ideal scenario when your car is turbocharged. If we were to tune the our intake tracts and exhaust manifolds as you would for a normally aspirated engine, we would get more restrictive flow in most of the rpm range. And where the normally aspirated engine would benefit from the sonic tuning, we would have to retard our ignition timing to avoid knock and gain almost nothing.
Combustion chamber
Peak pressure is what causes detonation whereas average pressure during the stroke is what gives you power. So in order to create the amount of power we create, you need to have a high average pressure during the power stroke but you also have to keep the peak pressure at TDC as low as possible.
We have a very unusual combustion chamber. We don’t have any ‘squish’ areas. We have created a kind of four-valve hemispherical combustion chamber that avoids speed differentiation to the flame propogation during the combustion process. This is another danger that can lead to knocking when you’ve got such high cylinder pressures. The chamber and the piston are both specially designed to maintain a very even volume in the chamber as combustion takes place. The piston and connecting rod are especially advanced in their design to provide specific geometry to assist with this process.
Head Gasket
It might seem a little unusual to talk about the head gasket here but ours is unusual in that it’s quite……. normal.
Usually, with an engine as powerful as ours, the gasket is accompanied by metal rings and o-rings and all sorts of complications to keep the pressure where it’s supposed to be. Our gasket is one of our own design but it’s remarkably normal.
We get away with this because of our super-stiff engine block, a super-stiff cylinder head and VERY strong clamp force holding the two of them. Because our parts are so strong, they don’t twist or warp when we tighten them so forcefully.
The advantage? O-ringed heads can take a heck of a beating when the engine is producing power but they don’t respond so well to a lot of heat cycles (taking the car from cold to hot). Eventually, they will leak. Our gasket is a lot simpler and the bonus for us is that it’s perfect for retaining pressure and it lasts a lot longer.
Conclusion
So there you have it….. a brief review of the Koenigsegg engine. It’s worth mentioning, of course, that the electronic hardware and software controlling our engines is fully developed in-house, right here in Ängelholm. As is our traction control software, our entertainment system, etc, etc….
The Koenigsegg engine has been in constant development since the end of the last century. At the same time it’s now being integrated into the futuristic gearless combustion-electric drivetrain of the Koenigsegg Regera. There will always be a place for an internal combustion engine here at Koenigsegg – with or without elecrification. The form that engine takes in the future is a matter that’s up for discussion, but it’ll always be here.
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