1100 hp on pump gas? koenigsegg

[Burkey]

Wonder what it drives like when it’s not on boost?

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[aleccesarenriquez]

Sorry, 1600, lol

https://www.google.com/amp/s/www.ro...gg-jesko-geneva-motor-show-photos-info-specs/

Just read this.

Absolutely outrageous vehicle.

Maybe I'll pick one up after saving for bit. Should take a conservative 300 years.

 

[Zinc03svt]

MerCruiser Racing has been running their in-house designed Dohc big cubic inch twin turbo v8’s for years now @ 1350 on pump gas. Nothing new when $$ is no concern.

 

[bluebeastsrt]

MerCruiser Racing has been running their in-house designed Dohc big cubic inch twin turbo v8’s for years now @ 1350 on pump gas. Nothing new when $$ is no concern.

Exactly right. As the old says goes. Speed is just a matter of how much your willing to spend.

 

[engineermike]

MerCruiser Racing has been running their in-house designed Dohc big cubic inch twin turbo v8’s for years now @ 1350 on pump gas. Nothing new when $$ is no concern.

It’s also 9 liters and I believe 8.5/1 compression.

 

[EFI]

So if one the most powerful 5 liter production engines uses low compression, then why do a lot of tuners and people I talk to keep saying to go with 11:1 or higher cr?

They tell you that because they assume you will be using it as a street car where throttle response, fuel economy and low end torque matters.

 

[engineermike]

...Lower compression will not get you more BMEP, while not increasing the peak cylinder pressure your octane is capable of being in with out detonating. This is like hearing someone say "my car makes 900HP, but I get beat by cars that make 700hp, all the time. Will my car be faster if I turn it down to 700?" You have to look at the whole dyno curve and usable RPM. The same is true for cylinder pressure, with a cap on the peak pressure by the octane of the fuel. Higher compression will cause the initial rise in cylinder pressure to be faster. If you control peak pressure with spark advance to avoid detonation, you will make more power than if you had lower compression and the same [peak cylinder pressure target. The problem with high compression is heat, combine that with heat from the FI components and it take a lot to keep every thing cool during extended periods of high power output. ...

This post piqued my interest and launched me into a data-gathering project. See the attached graph which shows some interesting things. Each data point is a proven OEM Compression Ratio vs BMEP relationship, except the 2 red-ringed points which are the Roush Gen2 and 3 numbers. Yellow is forced induction GDI, blue is forced induction port-injection (PI), green is NA PI, and grey is NA GDI. A broad array of engines are included in the data, including several Ecoboost models, BMW M3, Porsches, WRX STi, LT5, LS9, Voodoo, Predator, Trinity, Hellcat, Demon, Mazda SkyActiv-G, even the old F40 and XJ220. All of the data assumes pump gas, but there was no way to practically differentiate between different octanes of fuel. The Koenigsegg Regerra and supercharged Coyote points are off-the-charts high. Otherwise, the maximum BMEP vs CR line is remarkably consistent across engines and manufacturers. The only explanation I have for the supercharged Coyote and Regerra is that they aren't required to pass intentionally-cruel OEM-style torture testing. Anyway, you can use this chart to see what compression ratio or BMEP (mainly a function of boost) you could change to in order to improve reliability or increase performance on pump gas. You can also see how significant a role lowering the compression has on increasing the BMEP limit. For instance, if you drop the compression ratio 1 full point, you would have to increase boost by about 1 psi just to get the power back that you lost. But, dropping the compression by 1 full point would allow you run an additional 4 bar of BMEP on the same fuel, which equates to about 6 more psi boost while maintaining the same ignition timing advance. The net change is 20% more torque and power at the same safety margin from a combustion stability standpoint. Based on this, I think at 9.5/1, a Gen3 Coyote could make 850 rwhp at 18-20 psi boost on 91-93 very safely with no other changes to the engine.

 

[Crackerjack17]

They tell you that because they assume you will be using it as a street car where throttle response, fuel economy and low end torque matters.

Well, I'll have to say, I'm currently driving my car around NA. (Sold my procharger kit and going turbos likely). It's a 10:1 shortblock with locked out manifold and I swear I cant tell a different in power or driveability from a stock GT. I can start in 2nd gear without issues. Pulls hard. I mean maybe it's a tick slower, but I would have to dyno or run at the track to tell.

 

[markmurfie]

There isn't a BMEP threshold to octane. The threshold is the peak cylinder pressure.

Low the peak or keep it the same, and increase the majority of the cylinder pressure and you can increase the average. Many many many factors can go into this, obvious things like air pressure at time of ignition. To the less obvious like spark plug location and distribution of fuel/air charge inside the cylinder. Type of fuel, stroke length, bore size, piston speed, the shapes of different things, tempature distributions across surfaces, just to name a few more.

Koenigsegg has valve technology that doesn't use cam shafts, it's fully actuated how ever they want. Imagine being able to run MBT spark advance all the time on any fuel and use the exhaust valve as a sort of waste gate to cylinder pressure to control peak cylinder pressure and detonation. All while still being able to have the exact exhaust valve actuation during the exhaust stroke you wasn't for good turbo control. Any thing is possible when you throw enough money at the right people.

 

[engineermike]

Deleted.

 

[engineermike]

There isn't a BMEP threshold to octane. The threshold is the peak cylinder pressure. .

I know BMEP doesn't limit octane, but you have to admit the compression ratio vs BMEP vs detonation limit has a strong correlation. Since BMEP is a function of boost, compression ratio, and VE, that leads me to believe that higher BMEPs are allowable at the same octane with lower compression and more boost. This, to me, explains most of why the Koenigsegg Regerra's 9.3/1 5.0 is reliable at 1100 hp on 91 when some Coyote's at 12/1 are breaking at 850 hp on 93, meanwhile the old Ferrari F40 is making 162 hp/liter (810 hp eq.) reliable with port-injection due to its 7.7/1 compression ratio.

Mark, why do you say that the peak cylinder pressure, not temperature, governs the octane threshold?

Many many many factors can go into this.....

Yes, that is true. But I would argue that compression ratio is the primary factor.

Koenigsegg has valve technology that doesn't use cam shafts, it's fully actuated how ever they want. Imagine being able to run MBT spark advance all the time on any fuel and use the exhaust valve as a sort of waste gate to cylinder pressure to control peak cylinder pressure and detonation. All while still being able to have the exact exhaust valve actuation during the exhaust stroke you wasn't for good turbo control...

Also correct, but apparently the 5.0 in the Regera regarding this thread is DOHC 4v like the Coyote.

 

[markmurfie]

True, you could say either, Peak pressure and temperature describe the same event. Gay-Lussac's gas law and PV=nRT. The reason I say peak pressure is because the fuel that is igniting when you don't want it to be, is not at the hottest part of the cylinder, nor the highest pressure. The hottest/ highest pressure part of the cylinder is the already combusted air and fuel behind the flame front. Unburnt air/fuel is igniting because the pressure increase that has occured on the unburnt air fuel has lowered its autoignition temperature enough for it to do so. The temperature of the unburnt portion would also be going up with pressure and meeting the falling auto ignition temperature. The auto ignition temperature is just a property of the fuel in the cylinder, which can be manipulated with things like MMT and TEL. Octane rating is comparing a fuels auto ignition temperature to 100% octane's. So while octane is describing a temperature, it is not peak cylinder temperature. It is the temperature of the unburnt air/fuel at which auto ignition will occur. To me its easier to just say peak cylinder pressure and most people just seem to understand that easier. If I said peak cylinder temperature, people may get confused not connecting the flame front had started already, and its the lower temperature unburnt fuel that is igniting when you don't want it to. Saying "Temperature of unburnt fuel before autoignition" would be about as understandable as just saying the octane number. Peak cylinder pressure, to most, is an easily understandable point in the power stroke that coincides with where a fuel will detonate. Pressure pushing on a piston producing torque is usually where people's head's go to. It's more physically relatable than temperature and accounting for energy dissipation with heat going into the cylinder head, piston, and cylinder walls/water jackets. Although the latter is how you should really think about it to see more ways to improve BMEP and not increase peak.


Very simply BMEP is (torque[Ft-lb]*150.4) / Engine displacment[in^3]

Limiting torque production in the lower RPMs, and reving the motor higher to make power is how you should go about being octane limited, and its how to best utilize high compression. Most people want to limit RPM and need to increase torque to increase HP, and this is where they get into trouble. In this case with low octane, lowering the compression may be the way to go. I just wouldn't personally decide to ever do that, I think it's an old school way of thinking. From back when V8's reving over 5500 RPM was unheard of. A high revving engine that still breathes well at high RPMs is what the coyote is, it's what lots of these exotic cars have been. Keep your 12:1 compression and get use to revving to 8500RPM's or more. I really don't care when a pushrod motor makes 100+ft lb more than my car at low RPM peak torque. I'm making 150 Ft Lb more than they are at 7000 RPM, if they even can rev that high, and even more at higher RPMs still. I'll take making 850hp at 8000 RPM on 93 octane over 850hp at 6800 RPM on 116 race fuel or worst trying to do it on pump gas. Easier on the engine, Easier to make the engine do it, easier on the wallet.

 

[engineermike]

Thanks, Mark, for the explanation. Based on your prior post, I attempted to use the combined gas law to calculate the peak temperature of the charge at TDC without spark ignition. I found a few interesting things, the most of which is that boost level doesn’t affect temp after compression. That is, if you have efficient intercooling. Temp after compression is a function of temp before compression and the compression ratio. So if you start with 14.7 psia 100 deg air and compress it 12/1, it winds up basically the same temp (but much higher pressure) as starting with 24.7 psia 100 deg air and compressing it 12/1. The specific heat ratio in the cases is slightly different but other than that T2 is identical. That made me wonder if the peak pressure had an affect on it or if something else is going on that I’m not accounting for, like something occurring after spark-ignition beyond the flame front in the higher compression case.

Good discussion!

 

[Woopaloop]

True, you could say either, Peak pressure and temperature describe the same event. Gay-Lussac's gas law and PV=nRT. The reason I say peak pressure is because the fuel that is igniting when you don't want it to be, is not at the hottest part of the cylinder, nor the highest pressure. The hottest/ highest pressure part of the cylinder is the already combusted air and fuel behind the flame front. Unburnt air/fuel is igniting because the pressure increase that has occured on the unburnt air fuel has lowered its autoignition temperature enough for it to do so. The temperature of the unburnt portion would also be going up with pressure and meeting the falling auto ignition temperature. The auto ignition temperature is just a property of the fuel in the cylinder, which can be manipulated with things like MMT and TEL. Octane rating is comparing a fuels auto ignition temperature to 100% octane's. So while octane is describing a temperature, it is not peak cylinder temperature. It is the temperature of the unburnt air/fuel at which auto ignition will occur. To me its easier to just say peak cylinder pressure and most people just seem to understand that easier. If I said peak cylinder temperature, people may get confused not connecting the flame front had started already, and its the lower temperature unburnt fuel that is igniting when you don't want it to. Saying "Temperature of unburnt fuel before autoignition" would be about as understandable as just saying the octane number. Peak cylinder pressure, to most, is an easily understandable point in the power stroke that coincides with where a fuel will detonate. Pressure pushing on a piston producing torque is usually where people's head's go to. It's more physically relatable than temperature and accounting for energy dissipation with heat going into the cylinder head, piston, and cylinder walls/water jackets. Although the latter is how you should really think about it to see more ways to improve BMEP and not increase peak.


Very simply BMEP is (torque[Ft-lb]*150.4) / Engine displacment[in^3]

Limiting torque production in the lower RPMs, and reving the motor higher to make power is how you should go about being octane limited, and its how to best utilize high compression. Most people want to limit RPM and need to increase torque to increase HP, and this is where they get into trouble. In this case with low octane, lowering the compression may be the way to go. I just wouldn't personally decide to ever do that, I think it's an old school way of thinking. From back when V8's reving over 5500 RPM was unheard of. A high revving engine that still breathes well at high RPMs is what the coyote is, it's what lots of these exotic cars have been. Keep your 12:1 compression and get use to revving to 8500RPM's or more. I really don't care when a pushrod motor makes 100+ft lb more than my car at low RPM peak torque. I'm making 150 Ft Lb more than they are at 7000 RPM, if they even can rev that high, and even more at higher RPMs still. I'll take making 850hp at 8000 RPM on 93 octane over 850hp at 6800 RPM on 116 race fuel or worst trying to do it on pump gas. Easier on the engine, Easier to make the engine do it, easier on the wallet.

What's really interesting Is looking at the power difference in the new tuatara on pump vs e85, on pump fuel peak power is made at 6800 rpm whereas on e85 peak power is at 8800 rpm. This suggests spark advance at higher rpms plays a big factor. Interesting comparison.https://en.m.wikipedia.org/wiki/SSC_Tuatara

 

[Crackerjack17]

What's really interesting Is looking at the power difference in the new tuatara on pump vs e85, on pump fuel peak power is made at 6800 rpm whereas on e85 peak power is at 8800 rpm. This suggests spark advance at higher rpms plays a big factor. Interesting comparison.https://en.m.wikipedia.org/wiki/SSC_Tuatara

Interesting. Another pump gas 1350hp engine with 8.8:1 compression.

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