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Is it possible to turn off the turbo via a controller?
- Thread starter Steely
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- controller turbo turn
andycupra wrote
I think you are missunderstanding or incorrectly applying the theory that turbos can increase efficiency.
Not a theory, solid fact. Efficiency is proportional to compression ratio, turbo boost increases the compression ratio, better efficiency guaranteed, especially since the turbo is recovering energy from the exhaust that would otherwise be thrown away.
Driving "off the turbo" would involve keeping well below 2000 rpm, and even then you'd get some boost.
The only way to take the turbo out of the equation would be to bypass it completely and have a separate exhaust system and induction for non-turbo motoring. And I can tell you, economy would be miserable. As I suggested above, what Steely wants is a remap for economy rather than power. Using the turbo.
It isn't a switch, and you don't go from no-turbo to full-boost in an instant. The turbo is producing boost and thus efficiency improvements over the whole driveable rev range.
I think you are missunderstanding or incorrectly applying the theory that turbos can increase efficiency.
Not a theory, solid fact. Efficiency is proportional to compression ratio, turbo boost increases the compression ratio, better efficiency guaranteed, especially since the turbo is recovering energy from the exhaust that would otherwise be thrown away.
Driving "off the turbo" would involve keeping well below 2000 rpm, and even then you'd get some boost.
The only way to take the turbo out of the equation would be to bypass it completely and have a separate exhaust system and induction for non-turbo motoring. And I can tell you, economy would be miserable. As I suggested above, what Steely wants is a remap for economy rather than power. Using the turbo.
It isn't a switch, and you don't go from no-turbo to full-boost in an instant. The turbo is producing boost and thus efficiency improvements over the whole driveable rev range.
jabba do a boost controller which actually adjusts the map in real time. Worth asking them how effective an economy map would be, then you could switch between the two?
Not true, you can drive along at 4000 rpm (or higher) in 5th / 6th gear with 0 boost.
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I did read this and something didn't quite add up at first. I thought AndyCupra was right, in that there is always boost going on. Thinking about it, I suppose in a way you're both right. A turbo doesn't ever stop, there is always exhaust gases flowing so the turbo is always running. So yes, there is always 'boost'. However, I'm also guessing that a turbo has to spin at a certain amount of revs before it gets higher than atmospheric pressure, so in a way it is possible to have 0 boost, if 0 is actually 1 bar, IE atmospheric?
(I might be oversimplifying things here though!)Muttley, I don't quite follow how the turbo is 'recovering energy'? The exhaust gases don't power the engine, they turn a turbo which puts more air into the engine, the ECU matches that with an appropriate amount of fuel. I don't see how that could be regarded as energy recovery?
(By the way, I've already proven again and again that my turbo knowledge is virtually zero, so feel free to point out the error of my ways!
)Thats what I was asking, no one seems to have replied yet..... guessing no one has tried it?
would like to know as it would be a nice change to have it like that every now and then!
Tonybeau
Guest
Surely the best thing to do is to turn off everything thatis not needed including heating, lights, stereo, air con, rear screen heater etc. I can't see it being worthwhile getting a seperate map for economy if you are only going to use the car for this journey for about 6 months as you wouldn't gain the difference back in fuel.
I always thought if you ease up on the acceleration and brakes allowing the car to build speed and lose speed gradually then you will see better fuel economy.
I always thought if you ease up on the acceleration and brakes allowing the car to build speed and lose speed gradually then you will see better fuel economy.
No, because 'boost' is increased manifold pressure above atmospheric pressure.
Yeah, that's kind of what I figured. I suppose it's in the name isn't it, 'boosting' something is taking it beyond the norm. So while the turbo is always active, it's not considered to be doing anything until it's above 1 bar, which is where the zero comes from.
So zero is one. No wonder I struggled in maths...
Air con is the biggest one, followed closely by the rear heater. The other are negligible when it comes to fuel economy. Did you ever see Jeremy Clarkson taking a Jag to scotland and back on one tank of fuel? He was happy enough to be warm and listening to music while he did it.
Wasnt it the audi to scotland and back and the jag up to liverpool or something... not that it makes the blindest bit of difference mind! haha
Its not all bad, mine goes like stink and I even managed to get 54mpg on an 80 mile trip the other day.
The TDi letters in his signature suggests diesel rather than petrol...
It might have been an Audi to Scotland, I just remember it being a big car that he did some silly miles in, just to see if the manufacturers stated fuel economy was actually possible.
to clarify,
i DID NOT, and never have said that you are always running some boost. That is total cr@p.
i do not want to be associated with such comments, in fact i replied to muttley stating that he has missunderstood the theory behind turbos making an engine more efficient.
Similair to that an engine is more efficient when it is accelerating slightly rather than at a constant speed. Some people think this means its using less fuel, but this is incorrect. Its more efficient in that the output is greater in proportion to input. (ie the power output/fuel is greater) but this is not to say its a more efficient way to drive. In order to make this work for you it would require that you slowely accelerate, then coast then accelerate then coast, which is how they drive on ultra fuel efficient runs for records etc, but its not how you should drive on the road.
Turbos were originally designed for efficiency, but thats not to say when on boost you will get better mpg, in fact quite the opposite as it allows you to run a smaller engine for 95% of the time but have the power when needed of a larger engine. (eg overtaking)
and finally, "disconnecting / turning off the N75 will increase efficiency"... well not directly. It will not increase the efficiency of the engine, but it will effect how you use the engine as it will limit how much boost you have available. You can do exactly the same thing by modifying how hard you press the accelerator and so its really for people that have no control over their right foot
As ibizacupra has said, like for like driving, eg cruising there will be no difference.
(although i will conceed that anyone who has or has used a boost guage will have a better understanding of how and when boost comes in)
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