Turbo vs Atmospheric engine race track

[Tommy Cookers]

The CR might be different if you start off with 1bar, but you don't... you start off with the boost pressure and that will give around the same CR between NA and turbo engines.
In other words, to prevent knock, you need a compression ratio that is lower in turbo engines to still get around 12-14:1 CR. With a boost pressure of 2 bar, you have to start with a CR of around 7:1 to get to 14:1 when on full boost.

well
the (indicated) thermal efficiency depends on the expansion ratio
this is proportionate to the (cylinder-geometric) CR

yes with mechanically or electrically driven supercharger we might design for more expansion in-cylinder ....
but not with a turbocharger - because it needs enough exhaust pressure to drive it

[Jolle]

The CR might be different if you start off with 1bar, but you don't... you start off with the boost pressure and that will give around the same CR between NA and turbo engines.
In other words, to prevent knock, you need a compression ratio that is lower in turbo engines to still get around 12-14:1 CR. With a boost pressure of 2 bar, you have to start with a CR of around 7:1 to get to 14:1 when on full boost.

the (indicated) thermal efficiency depends on the expansion ratio
this is proportionate to the (cylinder-geometric) CR

Ah yes, that is true.

[PlatinumZealot]

1988 the Turbo motors were both fuel and boost limited, na cars had unlimited fuel. Turbo cars won every single race.

Turbo cars have an advantage over the entire rev range, even if peak power is the same.

Turbo lag is almost a thing of the past.

The na motor is dead, hasn't been competitive since 1980, forced induction killed it.

Honda K series would like to have a word with you.

[ENGINE TUNER]

1988 the Turbo motors were both fuel and boost limited, na cars had unlimited fuel. Turbo cars won every single race.

Turbo cars have an advantage over the entire rev range, even if peak power is the same.

Turbo lag is almost a thing of the past.

The na motor is dead, hasn't been competitive since 1980, forced induction killed it.

Honda K series would like to have a word with you.

Worthless unless turbocharged

[sosic2121]

https://www.linkedin.com/pulse/control- ... card_title

On the other hand I seriously doubt turbo engines are more efficient. IMO higher the boost, lower the efficiency. Especially in real world. When you buy aftermarket injectors, turbo application requires about 10% "larger" injector then NA, and supercharged 20%.

I guess there is a reason why Prius is NA...

[V12-POWER]

The 2005 V10 had close to 1000hp for 2 race weekends

That was in 2005. With today’s tech they would push well into 1100hp and more or maintain the +900hp while making the engines even lighter

Not to say that a V10 would be much cheaper

They had to resort to absurd tire size, wider and longer cars to compensate the weight that these hybrid engines have

[V12-POWER]

The key difference here is regulations. If there were free, to get 720 hp from a turbo engine for just 300 km without fuel flow restrictions, they would probably just need 50-60 kg or something.

Mario Theissen once said in an interview, that if they could have simply "slice off" 2 cylinders when they changed from V10 to V8, which from a displacement point of view was pretty much what was happening, BMW would have ended up with an engine pushing out about 750hp and weighing 68kg with an expected lifespan of about 600km.

There's a mario theissen paper somewhere about BMW engines through their time in f1 in the 2000s, v10 thru v8. The v10s at the end were like 80kg and did 1600km with a really low cog. When the fia switched to v8s the minimum weight was raised by some 10kg. The cog raised 70/80mm but with the same life expectancy which later increased to 2000km. F1 engines could be so much lighter and better weight wise. Even with the v6s they have to put certain ancillaries high up to meet the cog limit.

You're right about the 68kg engine, though it would have done 1600km still as that was the limit.

https://8000vueltas.com/wp-content/uplo ... ngines.pdf

BMW P85 - 82kg, +950hp, 1600km

[etusch]

https://www.linkedin.com/pulse/control- ... card_title

On the other hand I seriously doubt turbo engines are more efficient. IMO higher the boost, lower the efficiency. Especially in real world. When you buy aftermarket injectors, turbo application requires about 10% "larger" injector then NA, and supercharged 20%.

I guess there is a reason why Prius is NA...

I like NA engines and don't like kind of words which says that turbo is better, NA is dead.
I think forced induction is needed for efficiency but first you need to get compression ignition or if you still use spurk plug you need to avoid knock without extra fuel injection for cooling purpose, until the time you want to combust fuel air mixture. Traditional turbo is not work for this properly but supercharger works and that is why mazda skyactive x uses it.

[63l8qrrfy6]

https://www.linkedin.com/pulse/control- ... card_title

On the other hand I seriously doubt turbo engines are more efficient. IMO higher the boost, lower the efficiency. Especially in real world. When you buy aftermarket injectors, turbo application requires about 10% "larger" injector then NA, and supercharged 20%.

I guess there is a reason why Prius is NA...

Neither are as efficient as the steam engine which uses no boost at all.

Silly manufacturers and their turbo engines..

[Just_a_fan]

https://www.linkedin.com/pulse/control- ... card_title

On the other hand I seriously doubt turbo engines are more efficient. IMO higher the boost, lower the efficiency. Especially in real world. When you buy aftermarket injectors, turbo application requires about 10% "larger" injector then NA, and supercharged 20%.

I guess there is a reason why Prius is NA...

Depends what you mean by "efficient". A forced induction engine will give more power per cylinder cc, for example. So it's more efficient in terms of hp/cc. Whether it's more efficient by some other metric will be for the reader to decide.

[sosic2121]

https://www.linkedin.com/pulse/control- ... card_title

On the other hand I seriously doubt turbo engines are more efficient. IMO higher the boost, lower the efficiency. Especially in real world. When you buy aftermarket injectors, turbo application requires about 10% "larger" injector then NA, and supercharged 20%.

I guess there is a reason why Prius is NA...

Depends what you mean by "efficient". A forced induction engine will give more power per cylinder cc, for example. So it's more efficient in terms of hp/cc. Whether it's more efficient by some other metric will be for the reader to decide.

I meant fuel efficient, not volumetric

[etusch]

https://www.linkedin.com/pulse/control- ... card_title

On the other hand I seriously doubt turbo engines are more efficient. IMO higher the boost, lower the efficiency. Especially in real world. When you buy aftermarket injectors, turbo application requires about 10% "larger" injector then NA, and supercharged 20%.

I guess there is a reason why Prius is NA...

Depends what you mean by "efficient". A forced induction engine will give more power per cylinder cc, for example. So it's more efficient in terms of hp/cc. Whether it's more efficient by some other metric will be for the reader to decide.

From same point of view they are more wasteful when compared same cc engines or same power NA engines. Calculating power with cc is not correct way. At the end, in a perfect condition, you need same amount of fuel to get same power. For example I have 1,8 140 hp civic. There is 1,4 Turbo Opel/vauxhaul engine( gm engine I think ) 140 hp. When you concentrate displacement 1.4 is slower but its fuel usage is not same with NA 1.4s. In the other hand by using 1.4 lt engine instead of 1,6 or 1,8, they didn't get an engine size advantage to use that space for living area. Of course smaller engine still need reinforcement to handle that power and also turbo parts need space for themself. I think it is just a marketing thing. Nothing more.

[sosic2121]

https://www.linkedin.com/pulse/control- ... card_title

On the other hand I seriously doubt turbo engines are more efficient. IMO higher the boost, lower the efficiency. Especially in real world. When you buy aftermarket injectors, turbo application requires about 10% "larger" injector then NA, and supercharged 20%.

I guess there is a reason why Prius is NA...

I like NA engines and don't like kind of words which says that turbo is better, NA is dead.
I think forced induction is needed for efficiency but first you need to get compression ignition or if you still use spurk plug you need to avoid knock without extra fuel injection for cooling purpose, until the time you want to combust fuel air mixture. Traditional turbo is not work for this properly but supercharger works and that is why mazda skyactive x uses it.

I have nothing but respect for mazda X and G engines. They can replicate dyno fuel efficiency in real world, unlike many others.
Compression ignition is maybe easier to achieve with SC or with turbo, but I don't think it's impossible with NA.
IMO turbo can increase TE in light pressure turbo application like Saab http://www.autozine.org/technical_schoo ... 2.html#LPT
Also Mazda used SC on miller cycle engine.
http://www.autozine.org/technical_schoo ... ml#Miller
On the other hand, downsized engines are efficient(although not as efficient as small NA engine) while power demand is low thanks to DI and relatively high CR. But when power demand rises, efficiency plummets.

Variable CR should dramatically increase efficiency of turbo engines.

[Hoffman900]

https://www.linkedin.com/pulse/control- ... card_title

On the other hand I seriously doubt turbo engines are more efficient. IMO higher the boost, lower the efficiency. Especially in real world. When you buy aftermarket injectors, turbo application requires about 10% "larger" injector then NA, and supercharged 20%.

I guess there is a reason why Prius is NA...

Depends what you mean by "efficient". A forced induction engine will give more power per cylinder cc, for example. So it's more efficient in terms of hp/cc. Whether it's more efficient by some other metric will be for the reader to decide.

I meant fuel efficient, not volumetric

The future of high mileage engines are small, high torque, turbo engines.

If you look at your industrial applications (freight locomotives, etc.) they're all turbocharged diesel electric. It's kind of crazy it's taken vehicles this long to get there considering it's been refined for 80 years now in the industrial world.

NA / Turbo / etc, the amount of fuel burned is dictated by the type of fuel you are using. A particular blend of gasoline is going to want to be the same AFR on a NA engine as it would a turbo engine. There are efficiencies in combustion, friction, etc., but that doesn't change the AFR ratio or fuel burned, it just takes energy that was wasted via heat or friction and putting it into the crank.

An NA engine has to create depression with the piston, so there are two ways to deal with this; 1) make the engine larger 2) rev it higher.

In a turbo engine, you can artificially increase atmospheric pressure, and with the modern refinement of hybrid turbo systems, you can decouple turbo boost from exhaust pressure, improving performance at rpms lower than you could previously. There is no way around that with a NA engine.

When we're talking racing, NA engines have been noncompetitive since the 1940s in drag racing, when hot rodders first put truck type roots blowers on their engines. Bonneville, the altitude is a huge problem, as is the Pikes Peak Hillclimb (I live about 45 minutes from Pikes Peak, and walk out the door and see several 4265m+ peaks). Indy Car, they have been noncompetitive since before WWII, and the integrated head / block of the Offy, and its ability to handle huge boost loads, is what allowed it to be competitive for decades.

As for fuel, it just depends on the rules and applications. In Top Fuel racing, they run more fuel (nitromethane) through the engine 1) for cooling 2) to burn in the exhaust to create downforce (those 3m flames are for a reason). They have way more power than traction, so a dozen pounds or more of fuel isn't going to hurt them. Maybe its restricted in other series (F1 is), maybe you'll be faster if you make more power but take a weight penalty or maybe it's faster the other way. Racing is all about fitting the rules and applications.

[etusch]

I don't know if this happen other gasoline engines too. But if it happens then there is fuel and power wasted because of combustion. it is 2.00 and there is worse one at 4,35