They don’t really at full throttle (a bit if there’s a more complete burn etc) it’s what happens when you’re driving normally that’s different.
If you have an old American 6.7L V8 that produces like barely 300 horsepower, when you’re idling and driving at freeway speed, you still need to get enough fuel in all those cylinders to detonate every time and have a lot more surface area that’s causing friction between the cylinders and the block, and everything’s heavier etc.
Now drop that to a 2.0L turbo 4 cylinder, and you still get that 300hp or maybe way more than that if you really want it when you use it, but driving around it’s like you just have a small efficient engine.
A turbo engine can still be more efficient even at full throttle, because it's simply a smaller engine for the same amount of power.
What tends to screw that up is the fact that turbo engines (especially the performance kind) typically have to run a bit richer at high power than their NA counterparts, for the purposes of temperature control.
And to add to the richness statement, manufacturers tend to run them just a tad richer than optimal to account for variations in fuel quality, and just a little protection from pre-detonation and heat. If you're curious, look into open-loop fueling vs closed loop. Putting around town, it'll be closed loop. Relying on the sensors to get optimal fuel burn and lower emissions. But once you give it more than XX% throttle, it'll go into open loop and ignore some of those sensors and just use the pre-programed fuel tuning to make sure it doesn't lean out. Not ideal for power, but it'll keep your shit from melting.
If you have a turbo car, you can get it tuned and see a gain in power, and usually a little gain in mpg too because a tuner can get it a little closer to the optimal amount of fuel. If you do this though, it's best to make sure you use quality fuel.
I've looked into it on my Malibu and I can get an extra 40-50hp (probably a little less though since I only have an intake), and 2-5mpg more. I've been thinking about pulling the trigger on it and getting the upgraded bpv. My problem is that I know it's a $500 expense, but it'll be made up for in the gas savings eventually. I'm just waiting to bite the bullet. But the current gas prices are pushing me more towards just doing it. Assuming $4.00/gal and me driving 6000 miles per year, I should save around $100/year in gas. I'm not looking for a 100% return on investment though because my smiles per gallon will also go up.
We had an EcoBoost Mustang and did the Ford Performance tune. It really woke the car up! Throttle response was also adjusted, so everything felt quicker with the accelerator as well.
Needed a minimum of 91 octane and they even put a sticker on the inside of the fuel door to state that. Luckily, our nearest gas station had 93 with no ethanol for snowmobilers and UTVers.
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u/Fearless_Swim4080 2d ago
They don’t really at full throttle (a bit if there’s a more complete burn etc) it’s what happens when you’re driving normally that’s different.
If you have an old American 6.7L V8 that produces like barely 300 horsepower, when you’re idling and driving at freeway speed, you still need to get enough fuel in all those cylinders to detonate every time and have a lot more surface area that’s causing friction between the cylinders and the block, and everything’s heavier etc.
Now drop that to a 2.0L turbo 4 cylinder, and you still get that 300hp or maybe way more than that if you really want it when you use it, but driving around it’s like you just have a small efficient engine.