Turtle n Peeps wrote:
Good gravy Wes, the writers background that wrote that article is in photography and writing!!
No engineering at all. Nothing. No thermal dynamic's background. Nothing. He's a photographer not an engineer!! His only auto background is he owns some cars with different cylinder combo's and different drive combinations and likes to play with their electronics. LOL It would be like me writing about music because I own several CD's. :R LOL
Here is what Holley ENGINEERS say about turbo BSFC.
Build your turbo or N/A engine here. See if the injectors they recommend are a lower flow rate for the turbo engine or N/A engine. Check it out.
Another fuel injection site that says trubo's have a higher BSFC. See what their engineers say on what size injector to pick.
Anther turbo site that talks about BSFC figures. Check it out.
Another site that talks about turbo BSFC.
All of these companies and 100's more have engineers that know this stuff inside and out. They all have people with engineering backgrounds. All of them.
Now, what are the chances that all of these companies engineers (and more) don't have a clue on what their talking about and the photographer and writer guy that you linked to does? Come on, the answer is 0 and you and I both know it.
There are pluses and an minuses for turbo engines. The plus is they can make a lot of power way down low with a very small engine.
The minus is they sap a lot of power when out of boost mode because the turbin clogs up the exhaust when in cruise mode. The only reason the Ecoboost can be so efficient is because it's is such a small engine when unboosted. Even then it can only barely, and I do mean barely, beat out MOST mid size V8's for fuel mileage.
Here is a V8 N/A that has better mileage and close to the same HP.
I have driven and built turbo and supercharged engines for over 30 years and let me tell you, they are inefficient when out of boost. It's physics. They are not too bad when in boost, but they take fuel to cool them off. Even as advanced as the Ecoboost is, it uses fuel to cool things off just like I do now and did 30 years ago.
What % of the time was I in boost on the street? About 3 to 5% so that makes for a not so efficient engine most of the time. Mine was a turbo V8 so it sucked fuel no matter what I was doing.
I'm not knocking turbo's. I love them obviously and know all about there attractions and detractions! As a side note, I always chuckle when people here ask for a 500 HP turbo gasoline V8 for towing. They have no clue what asking for or what they will get if it ever happens. :B
Turtle,
Sorry, I just can't get by the fact that Ford is making the EcoBoost (EB) work. It's all possible because of relatively new Direct Injection (DI), the key factor missing in all your links above. I believe the EB runs at similar fuel levels as Naturally Aspirated (N/A) engines do. All your links refer to racing considerations, so I understand the engineering is legit for that perspective.
If you think the EB engine runs rich in extended boost, where do the "extra", likely unburned, fuel byproducts go? I realise you believe that the fuel is used for steady cooling, but wouldn't that pollute too much? I conclude the EB does not run excessively rich because it is not allowed, and fuel requirements are normal for the power levels involved.
I believe Ford has tuned the EB engine to
not require excess fuel during boost and the Ford EB is just as efficient, likely more efficient, than the GM 5.3L V-8
while under power. The 3.5L EB makes 365HP/425ftlbs while the 5.3L makes a competitive 355HP/383ftlbs.
While not under power, the GM 5.3L is running more efficiently on four cylinders, or 2.65L. Perhaps Ford feels the 2.7L EB will equal this mpg (not yet released) since the effective easy-cruise displacement is nearly equal. I concede the yet unreleased 2.7L EB will not likely match the 5.3L power. But Ford may still be able to claim the coveted "Best mileage in Class".
Then we may compare the Ford 3.5L EB to the GM 6.2L EcoTec3 V-8 for power. The EB makes 365HP/425ftlbs and the EcoTec (ET) makes 420HP/460ftlbs. Ford is discontinuing the 6.2L in 1/2 tons, so the 3.5L might get more, yet untapped, power.
When at cruise, the turbo merely "idles along", spinning freely with intake and exhaust flows. The only impediment is the slight drag of the bearing which robs very little power.
The final item I can't get by, is the physical fact that the turbo derives
all it's power from free, formerly unused exhaust heat. The turbo uses this "free" energy to eliminate pumping losses while it emulates a larger displacement engine. The effective "free" reduction in pumping losses is why I believe a turbo'd engine
can be more BSFC efficient than a N/A counterpart. I think Ford, and some European manufacturers, believe it too.
For now we will have to agree to disagree I guess. I do appreciate the argument, as it helps weigh the truth.
Wes
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