Turbo/Is this Next For All BMW's??

BMW-Peeps Which Engine should perform better, One that has Turbo or one that does not (At the same Horse Power)????? Why do so many Car Companies use Turbo??? What are the advantages and dis-advantages of turbo??? Are All BMW's going to Turbo Eventually???

With the same maximum HP, an engine using mild turbo-charging tends to have more area under the torque curve than the NA counterpart.

There is no replacement for displacement. Turbos are a bandaid.

Seems to be a mainstream trend. Mazda and Acura both have release turbo-charged products recently.

Originally Posted by ObD

There is no replacement for displacement. Turbos are a bandaid.

I think that for equal power, you can get far better gas mileage with a turbo, no?

Originally Posted by hmr

Seems to be a mainstream trend. Mazda and Acura both have release turbo-charged products recently.

Gas prices are helping reinforce this... Turbos will deliver more torque on lower displacement and thus more HP without increasing weight... so more power, not at the expense of fuel economy.

So what is it at the expense of? What is the downside to turbo engines? More maintenance, wear and tear, replacement?

Originally Posted by Crawlings

So what is it at the expense of? What is the downside to turbo engines? More maintenance, wear and tear, replacement?

Turbo lag... delay of power during initial acceleration... Takes a bit of time of the turbo to "spool up", depending on the car, the extra boost from the turbo does not kick-in until the engine is reved to say 3000 RPM.

BMW's solution to the turbo lag, is the bi-turbo approach, the assumption is that two smaller turbo compressors - each for 3 cylinders - will take less time to "spool up" vs one serving all six cylinders. I guess, we'll see...

BMW has a long engineering history of turbocharged and supercharged motors.



From the driver's perspective, the main downside is the turbo lag, but that may not be noticible with the twin turbos and the intrinsic DBW lag.

From BMW's perspective the downside is that a marketing problem arises when the motor moves into the 5-series, with respect to justifying the price premium of the 550i over the 535i. The turbo project was shelved and back-burnered several times in the past and that, from my understanding, was the big big problem, not the engineering.

no.

Originally Posted by KevinC

no.

Just the kind of in depth and specific answer we'd expect of somebody from CowTown Chandler...

Originally Posted by x3Bruin

Turbo lag... delay of power during initial acceleration... Takes a bit of time of the turbo to "spool up", depending on the car, the extra boost from the turbo does not kick-in until the engine is reved to say 3000 RPM.

BMW's solution to the turbo lag, is the bi-turbo approach, the assumption is that two smaller turbo compressors - each for 3 cylinders - will take less time to "spool up" vs one serving all six cylinders. I guess, we'll see...

well with max torque from 1250 - 5000 is pretty damn good if you ask me.

Originally Posted by Crawlings

So what is it at the expense of? What is the downside to turbo engines? More maintenance, wear and tear, replacement?

Potentially more maintenance issues. I doubt that you will see BMW pushing 15,000 mile oil changes on the 335 because oil is critical to the longevity of a turbo since it is subjected to far more heat and stress. Turbos also tend to be finicky with weather conditions (ie. cold and low humidity is great; heat soak and higher humidity is not). It all depends on the efficiency of the intercooler.

Originally Posted by Magoon

Turbos also tend to be finicky with weather conditions (ie. cold and low humidity is great; heat soak and higher humidity is not). It all depends on the efficiency of the intercooler.

I live in the southeast, so "heat and higher humidity" is pretty much the definition of the weather here. should that be a concern with me possibly purchasing the E92?

Originally Posted by Crawlings

I live in the southeast, so "heat and higher humidity" is pretty much the definition of the weather here. should that be a concern with me possibly purchasing the E92?

It's possible that you will not see or feel the added horsepower...again depending on the intercooler efficiency. One other point to mention is that a turbo will perform much better at altitude than a NA which will suffer in the thinner air.

Originally Posted by BiggieJ

well with max torque from 1250 - 5000 is pretty damn good if you ask me.

Wow...Thats a great looking torque curve for the new engine, I didn't realize that they had released that info yet. Very impressive!

One thing to keep in mind with the N54 is that it is a light pressure setup based on what is an already strong naturally aspirated motor. Although the compression ratio is significantly lower than the new naturally aspirated direct injected N53 (? I think that's the code), the engine still has a CR of 10.2 which is just slightly lower than the current 3.0L Valvetronic N52's 10.7. My guess is that it will feel very strong right off the line.

Originally Posted by ObD

There is no replacement for displacement. Turbos are a bandaid.

So I guess that the Porchse Turbo and Bugatti Veryron utilizes a "bandaid". Get a Clue.

Originally Posted by BiggieJ

well with max torque from 1250 - 5000 is pretty damn good if you ask me.

I agree. Turbo Lag is a relative term.

Originally Posted by Crawlings

So what is it at the expense of? What is the downside to turbo engines? More maintenance, wear and tear, replacement?

Engine reliability may become an issue. I had an Audi A4 1.8t that needed a turbo replacement at 70k miles due to a poorly designed heat shield (oil line cooked.) I did not have an issue with lag, but that's relative. Other than that, turbos are .

Originally Posted by BiggieJ

well with max torque from 1250 - 5000 is pretty damn good if you ask me.
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i feel compelled to correct the common mis-conception that the operating range of a turbo has anything to do with the degree of turbo-lag. that an engine is tuned to provide boost at relatively low rpm is in recognition of the fact that the majority of drivers operate their vehicles at these rpm, it is not a means of reducing turbo-lag, at what rpm a turbo produces boost does not affect how long it takes for the exhaust gas to reach the turbine. yes the power will be more accessible if the boost comes on early in the rev range but the delay from throttle application to achieving boost (turbo-lag) is not reduced compared to the delay in an engine delivering it's boost at higher rpm.

Originally Posted by gos

I think that for equal power, you can get far better gas mileage with a turbo, no?

Incorrect.
A turbo allows you to get more power out of the same size engine, or conversely, you can achieve the same power output with a smaller engine block.
Smaller engines will afford you weight/balance advantages, but not necessarily better gas mileage (because more gas is forced in, proportionally to the extra forced-in air)
The price paid is more complexity (more parts to break, costs more) and turbo lag (which new techniques nowadays can almost eliminate, but complexity worsens).

The saying "there's no replacement for displacement" applies to the low rev region of the engine. Turbos don't come into play until they get a chance to spool up.
At the low end, you're basically stuck with an "un-aided" and possibly smaller engine. Then all of a sudden the turbo effect kicks in (again, this issue has been almost eliminated in new designs).
A supercharger addresses that irregular or non-linear power production. The price is even more complexity (the supercharger unit alone is orders of magnitude more complex than the simple turbine used in turbos, not to speak of all the other required parts, such as an intercooler). Superchargers also lose the elegance of the turbo idea -- use the exhaust pressure, which otherwise is waisted, to do most of the work, for almost free. Superchargers rob part of the engine output to power itself.

Originally Posted by hector

i feel compelled to correct the common mis-conception that the operating range of a turbo has anything to do with the degree of turbo-lag. that an engine is tuned to provide boost at relatively low rpm is in recognition of the fact that the majority of drivers operate their vehicles at these rpm, it is not a means of reducing turbo-lag, at what rpm a turbo produces boost does not affect how long it takes for the exhaust gas to reach the turbine. yes the power will be more accessible if the boost comes on early in the rev range but the delay from throttle application to achieving boost (turbo-lag) is not reduced compared to the delay in an engine delivering it's boost at higher rpm.

Turbo lag is a relative term.

Originally Posted by Spoonie G

Turbo lag is a relative term.

so is mentally challenged.

Originally Posted by Spoonie G

Turbo lag is a relative term.

If you mean that the force generated by the exhaust on the inertial resistance of the turbo turbine is indeed subject to the spacetime curvature as described by Einstein's General Relativity, then indeed "Turbo lag is a relative term"

What I believe hector was saying is that, the torque curve is not plotted in the time domain, therefore while max torque is achievable at 1250 RPM, there is no guarantee that the turbo will be spooled when one reaches 1250 RPM. Therefore, consider the torque curve here as an asymptotic upper bound, not an absoulte... If I am understanding his comment correctly, but intuitively that makes sense to me.