Does anyone know this? I can't remeber were I saw this but what I remember is something like for each pis of boost equals 16 hp. Let me know what's up.
Oops, I overlooked your post Zax. In response, I think it would appropriate to look at the overall efficiency since any minute changes between combustion and moving the car would be difficult to account for. In fact I think fuel economy should be looked at since it is an actual value we can gather. The only thing making the car go is fuel. The end product we can measure is distance. Now whatever happens in between is left to speculation unless controls and exceptions are agreed upon. So I think fuel economy is a fair assessment in this case.Also, efficiency of an engine doesn't mean fuel economy, it describes the ability of the engine to produce power with a given amount of Oxygen and a fuel with reduced waste heat.
The bold part above indicates exactly why that is a completely unfair comparison to use MPG. Also, requiring that a turbo motor runs the same AFR and has the same design (e.g. compression) is completely ridiculous. Turn it around and make the NA motor run low compression and rich and you will have a slug (e.g. take the turbo off a WRX and compare it to a WRX) - not fair is it?Simply put, the better MPG the better the efficiency. Now if you are talking about the utilizing the maximum potential of the combustion chamber, that's another story and wholly different from what I was referring to as efficiency. I have just simply not found anyone who gets better mpg efficiency from na setup to a turbo setup.
So if anyone can convince me that a NA vehicle can achieve better fuel efficiency by introducing forced induction, I am definitely open to revamp my opinion. As long as both vehicles retain correct AFR and are identical (with exception to the turbo or supercharger).
IMO NA (as opposed to any kind of forced induction) engines are more efficient because its a more conservative use of fuel. In fact we see it every day. Driving hard (fast accelerations) consume much for fuel than a steady acceleration. Imagine sprinting 20 meters, then walking 20 meters. I am sure you agree sprinting used up more energy but walking, albeit slow, accomplished the same work utilizing less energy.
The diesel cycle is a very very different thermodynamic cycle altogether: isentropic compression -> isobarametric event (diesel flashpoint) -> isentropic expansion -> isochoric event (exhaust valve) and repeat (from the P-V diagrams)In fact, compress two reactive chemicals together enough and you'll get a spontaneous rxn (combustion in our case) without a spark. That's basically what some diesel engines do, right?
guys.
In bold is the wrong way to look at it and nobody said it doesn't use power to make power but only under certain conditions. Its the simple fact of cylinder over filling and boosting the engines VE. That is what creates the power. And as other have said,there is roughly about a 7% energy loss with Turbocharging compared to a 20-25% parasitic loss with a Supercharger. Either way your making way more power than you are losing or could N/A. And people just generally saying turbos create back pressure are not seeing the whole big picture.Lengthwise32 said:The turbo doesn't add more power, it's the extra fuel it allows you to add to the engine that creates the extra power.
The turbo does take some energy to run, it doesn't create this out of nowhere.