Article: adding a turbo to improve efficiency

[JohnnyGrey]

It says right here, engine torque in newton-meters. There's your unit right there. It's staring me right in the face. I know for a fact that it does not take 124N/m to keep my car cruising on the highway at 55mph. Maybe YOU have no clue how much is required. Even without specifics, cruising on flat land is done on the lower half, if not the lower third or quarter of the BSFC map. While cruising on flat roads you will not hit an engine efficiency peak at ANY RPM, with or without a turbo!

Now, can you read the map well enough that you can tell me why P&G is more efficient than holding a steady speed, or are you going to continue arguing out of ignorance?

[Duffman]

Uh, no, you are looking at the graph from post 58 that was quoted in 60, I and others were refering to the one posted in 60 (the second diagram). The first one shows no comparison its just a plot of a 1.9L saturn engine.

[JohnnyGrey]

There's only one pic in 60, and it's in a quote. Oh well, I'm going to bed.

[Duffman]

You should be seeing this:

[JohnnyGrey]

OK, now that we're looking at the same image, it's time for you to realize a few things...

1. Highway cruise is done in a narrow window between 2000-2500 rpm on the X axis and between 0-40 BMEP on the Y axis. In this region, the maps are EXACTLY THE SAME between the two motors.

2. 0.42 BSFC can be accomplished with either engine DURING ACCELERATION OR HILL CLIMB ONLY by putting your foot 80% to the floor and shifting at 2400 RPM. The turbo engine will simply allow you to accelerate faster, but will use no less fuel per unit of power produced.

Now, Duffman, for the third time, please go on and explain to us with your own map as an example, why P&G is more efficient than single speed cruising.

John, if you're wondering why I'm getting ticked, it's because someone who doesn't understand what torque is, is trying to school me on BSFC maps, insisting that an entire axis of the map is irrelevent! Ironically, he claims the Y axis doesn't matter, but a turbocharger stretching the regions along the Y axis does matter. Go figure! Guess what buddy, torque decides if you're getting 0.42 or 1.7 FC @ 2K RPM!!!

[diesel_john]

I forgot about the turbo seals, I wouldn't pulse and glide, engine off, a turbo'd engine. It would probably fry the seals in short order.

[larrydag]

Here's an interesting quote from a Honda aftermarket website

We have found Honda ECUs work particularly well with larger injectors. For example one Hondata customer using 830 cc injectors in a B20 turbo has drivability indistinguishable from stock and achieves 30mpg.

http://www.hondata.com/techecuanatomy.html

So maybe ECU modifications could be performed to help boost FE on fuel injected cars.

[JohnnyGrey]

So maybe ECU modifications could be performed to help boost FE on fuel injected cars.

Maybe advancing the ignition could squeeze out a MPG or two, but as far as fuel is concerned, closed loop is closed loop.

[Duffman]

Originally Posted by JohnnyGrey

OK, now that we're looking at the same image, it's time for you to realize a few things...

1. Highway cruise is done in a narrow window between 2000-2500 rpm on the X axis and between 0-40 BMEP on the Y axis. In this region, the maps are EXACTLY THE SAME between the two motors.

2. 0.42 BSFC can be accomplished with either engine DURING ACCELERATION OR HILL CLIMB ONLY by putting your foot 80% to the floor and shifting at 2400 RPM. The turbo engine will simply allow you to accelerate faster, but will use no less fuel per unit of power produced.

Now, Duffman, for the third time, please go on and explain to us with your own map as an example, why P&G is more efficient than single speed cruising.

John, if you're wondering why I'm getting ticked, it's because someone who doesn't understand what torque is, is trying to school me on BSFC maps, insisting that an entire axis of the map is irrelevent! Ironically, he claims the Y axis doesn't matter, but a turbocharger stretching the regions along the Y axis does matter. Go figure! Guess what buddy, torque decides if you're getting 0.42 or 1.7 FC @ 2K RPM!!!

Now that you know the diagram we are discussing, I suggest you go back to post 60 and reread all the posts since because I am not going to rewrite my argument a second time. Rude or not, it is still obvious you are not paying attention. Nowhere have I even mentioned P&G. When I say hilly areas, think someone in San Francisco or a Colorado resident as this should clarify the point I am trying to make.

It is also apparent that you having trouble with BMEP, here is a link to help you:
http://en.wikipedia.org/wiki/BMEP
What this means is that the 40 on the BMEP axis does not translate into the same torque in a 1L metro as it does in a 6.8L Ford V10. Additionally the power requirements to push a metro down the road are vastly different than a F450 with a GCWR of 20,000 lbs. So again without any additional information the numbers on the BMEP axis provide nothing more than to lay a scale down (ie 10 is twice a big as 5), thus it is effectively unit less. Like many discussions on this board, this is purely theoretical.

I know that I am not right 100% of the time or on 100% of subjects. What I don’t appreciate is someone telling me that I don’t know what I am talking about when they have no clue what my background is. I’m done with your pissing match, I am tagging out, and maybe someone else will pick up and continue to pointlessly argue with you.

[Daox]

I would like to make my point again because you guys seem to be only talking about highway mileage. A turbo does increase the area of the BSFC map where you get peak BSFC. This is proven. At the very least, in CITY driving this will undoubtly help increase the likelyhood that the average joe (who doesn't even know what BSFC is) will drive within that area. Therefore, the turbo will increase fuel economy.