Why no Direct Fuel Injection?

[Redadair]

I just drove the new M and loved the car. The only thing that leaves me scratching my head a bit is the fact that the M represents BMW’s State of the art engineering, yet the Fantastic new V8 doesn't include Direct Fuel Injection. Why?

I would estimate power increases of ~10 - 20 HP, not to mention at least ~10 – 15% improvement in fuel mileage.

Red

[Hammer]

Direct Injection doenst increase the power of the car, just the fuel mileage!
I think we had a discussion already
They concluded that the space in the engineblock was a factor for the choise of the m-gmbh.

[Redadair]

Originally Posted by Hammer

Direct Injection doenst increase the power of the car, just the fuel mileage!
I think we had a discussion already
They concluded that the space in the engineblock was a factor for the choise of the m-gmbh.

Did the search, didn't find one. And yes it does increase HP and fuel mileage.

Red

[E394KEN]

Porsches re-fresh will have direct injection. This correlates to increased MPG, and more BHP. Soo yes it does. The new S is rumored to be at 380-385 BHP, and the Base Carrera at 350-355. Not to shabby. Although P cars arent known for their bang for the buck. Greedy Porsche!

[mkoesel]

Originally Posted by Hammer

Direct Injection doenst increase the power of the car, just the fuel mileage!

Well, strictly speaking I suppose, but the increase in efficiency could then allow the engine to be tuned for more power without the compromise in fuel economy.

However, that's only if the engine runs in lean-burn mode, which is not possible worldwide due to gasoline quality. I believe forced induction motors get around this via their lower compression ratio. BMW does not currently sell naturally aspirated, direct injected (with lean burn) engines in the US, and various other places around the globe. This is likely the reason that the S65 and S85 are not direct injected. It would be too costly to develop two versions of the motors.

[goldminer]

Originally Posted by mkoesel

Well, strictly speaking I suppose, but the increase in efficiency could then allow the engine to be tuned for more power without the compromise in fuel economy.

However, that's only if the engine runs in lean-burn mode, which is not possible worldwide due to gasoline quality. I believe forced induction motors get around this via their lower compression ratio. BMW does not currently sell naturally aspirated, direct injected (with lean burn) engines in the US, and various other places around the globe. This is likely the reason that the S65 and S85 are not direct injected. It would be too costly to develop two versions of the motors.

Yes. There was an column in the May Road and Track Technical section about this. It all relates to the high sulphur in American gasoline. The advantages to DI are the lean burn mode and the high compression ratios which are allowed with fuel sprayed directly into the combustion chamber. This, however, results in high NOx emissions necessitating a special downstream catalyst to clean up the exhaust. The special NOx cats are incompatible with the average level of sulphur found in North American gasoline. So there is not much point in selling a naturally aspirated DI engine here as it couldn't go into lean burn mode and would have its compression ratio limited.

As mentioned above this is less of an issue with turbos which have low compression ratios and use the DI to help reduce knock.

[anerbe]

most likely it's to avoid double development/production of motors.

however, the new CTS utilizes DI on it's V6 as one example

[VictorH]

I believe the answer is because this motor is a direct relative of the M5-6 motors and they are not direct injection. The R&T sulfur argument makes sense but Audi (8, 6, 4 cylinders) and VW already have gasoline direct injection in this country, so that can't be the reason. The Audi and VW motors may not be "optimized" but they still run sell them in US.

[southlight]

Originally Posted by VictorH

I believe the answer is because this motor is a direct relative of the M5-6 motors and they are not direct injection. The R&T sulfur argument makes sense but Audi (8, 6, 4 cylinders) and VW already have gasoline direct injection in this country, so that can't be the reason. The Audi and VW motors may not be "optimized" but they still run sell them in US.

The sulfur argument is valid for spray-form DI, Audi and VW doesn't use such a system yet.


Best regards, south

[Redadair]

Originally Posted by anerbe

most likely it's to avoid double development/production of motors.

however, the new CTS utilizes DI on it's V6 as one example

As does the Lexus IS350 V6.

As I mentioned in my OP, DI is the part of the State of the Art developments in petro engines these days, as is the Common Rail injection on the new Diesel engines soon to reach the US, and I am quite surprised the M3 is without it, especially since Gasoline in the US is now approaching $4 per gallon for the premium stuff the M3 drinks.

Red

[ruff]

Red,

Nice thread starter. Where did you procure your test drive of the beast?

BMW could of built a DFI NA engine if they would of spent the R&D to do it. They chose the easier and cheaper route by basically lopping of two cylinders of the V10. With Porsche and other manufactures implementing DFI across their lines, and the advent of skyrocketing petrol, I believe BMW has dug themselves a hole with their current lineup of M cars. Many younger educated car enthusiasts now place DFI and DCT at the top of their must have list in regards to important technological advancements they deem necessary in the performance cars of today and tomorrow.

[Redadair]

Originally Posted by ruff

Red,

Nice thread starter. Where did you procure your test drive of the M3?

BMW could of built a DFI NA engine if they would of spent the R&D to do it. They chose the easier and cheaper route by basically lopping of two cylinders of the V10. With Porsche and other manufactures implementing DFI across their lines, and the advent of skyrocketing petrol, I believe BMW has dug themselves a hole with their current lineup of M cars. Many educated car enthusiasts now place DFI and DCT at the top of their must have list in regards to important technological advancements they deem necessary in the performance cars of today and tomorrow.

Ruff

I drove the M3 at BoM the day after I talked to you about the Red one on the floor. I had to go the GM and complain about the salesperson who first denied me before they would allow me to drive it. I also had to keep below 4500 RPM's which was fine. I must say the sound of the V8 is very nice, Vette like and the car rides as nice as my 335i. The suspension is tighter than my 335i especially noticeable above 80 MPH. Bottom and mid is weaker than the 335i.

I drove a black one they have at the North building, the sales manager thinks it's his.

Red

[ruff]

Originally Posted by Redadair

Ruff

I drove the M3 at BoM the day after I talked to you about the Red one on the floor. I had to go the GM and complain about the salesperson who first denied me before they would allow me to drive it. I also had to keep below 4500 RPM's which was fine. I must say the sound of the V8 is very nice, Vette like and the car rides as nice as my 335i. The suspension is tighter than my 335i especially noticeable above 80 MPH. Bottom and mid is weaker than the 335i.

I drove a black one they have at the North building, the sales manager thinks it's his.

Red

Good work buddy,

Thanks for the good review. Excellent work. You are the first one I have heard of who has talked his way into a test drive. Maybe it has something to do with your physique. If I may ask, who was the GM that made the test drive happen?

[Redadair]

Originally Posted by ruff

Good work buddy,

Thanks for the good review. Excellent work. You are the first one I have heard of who has talked his way into a test drive. Maybe it has something to do with your physique. If I may ask, who was the GM that made the test drive happen?

I don't remember his name off the top of my head, I could get if from my CA. I went in the next day for my 1st oil change and my CA came up to me and told me I was the first to test drive as well.

The sales manager you want to avoid is Scott. Not a good guy at all! He uses it for his personal use, gym cloths in the back seat yet says you can't test drive. What BS.

Red

[mkoesel]

Originally Posted by Redadair

As does the Lexus IS350 V6.

But do they do lean burn?

BMW's own N73 V12 also has DI also but does not do lean burn.

[ruff]

Originally Posted by Redadair

I don't remember his name off the top of my head, I could get if from my CA. I went in the next day for my 1st oil change and my CA came up to me and told me I was the first to test drive as well.

The sales manager you want to avoid is Scott. Not a good guy at all! He uses it for his personal use, gym cloths in the back seat yet says you can't test drive. What BS.

Red

Thanks. If you happen to get his name let me know.

[goldminer]

Originally Posted by VictorH

I believe the answer is because this motor is a direct relative of the M5-6 motors and they are not direct injection. The R&T sulfur argument makes sense but Audi (8, 6, 4 cylinders) and VW already have gasoline direct injection in this country, so that can't be the reason. The Audi and VW motors may not be "optimized" but they still run sell them in US.

I believe that the Audi four is a turbo only. The other Audi engines aren't though. I tried to make it clear in my post that the high sulphur fuel here does not preclude the use of DI. It just doesn't allow for lean burn. I am not sure but I also think that there are limits on the compression ratios which can be used as well.

So if you can't make use of one of DI's major advantages what is the big deal about having it?

[goldminer]

Here is the R&T article



I was surprised when BMW engineers told me that their most advanced direct-injection gasoline cars couldn't be brought to the U.S.

"Too much sulfur in your fuel," they said.

I thought this had been only a diesel problem, and one solved by ULSD, ultra-low-sulfur diesel. But I dug around a little, spoke with specialists at Shell and learned more.

First, did you know that "brimstone" is the old name for sulfur? And that throughout history the element certainly has had its hellish connotations. On a not unrelated subject, I've been really enjoying Neal Stephenson's Baroque Cycle of Quicksilver, The Confusion and The System of the World. This marvelous trilogy of adventure, science, technology and economics includes everyone from Isaac Newton and Gottfried Leibnitz to a vagabond easily pictured as Johnny Depp in his pirate persona. Alchemy plays a recurring role as well, and this is what ties it in with brimstone.

Brimstone, er, sulfur occurs naturally in petroleum crudes. In fact, the term "sweetness" describes the relative scarcity of sulfur in a crude. Nigerian Bonny Light is particularly sweet, with perhaps only a tenth the sulfur of Arab Light, another benchmark crude in the petroleum business. Bonny Light's sulfur is around 0.14 percent by weight; Arab Light's, about 1.5 percent. West Texas Intermediate, also known as Texas Sweet Light, has a sulfur level around 0.24 percent.

By the way, all three of these benchmarks qualify as Light crudes, their API Gravity readings exceeding 31.1. (This American Petroleum Institute standard sets the density of water at 10, a crude lighter than water having API Gravity greater than 10.)

Sulfur Here and Over There
The U.S. Environmental Protection Agency limits sulfur in our gasoline to an absolute maximum of 80 parts per million. In actual practice, based on some 4000 data points in 2007, our refineries' output averaged around 32 ppm. It's largely a matter of balancing crude supplies with refining techniques, the whole point being optimization of cost, output and distribution.

By contrast, the European Union has an upper limit of 50 ppm, with tax incentives for production below 10 ppm. Indeed, this lower limit has been proposed as a 2009 EU standard, and such ultra-low-sulfur gasoline is available throughout much of western Europe.

Euro carmakers, including BMW, have responded with gasoline direct-injection technologies featuring lean-burn modes of operation. However, lean-burn requires special treatment of NOx— and special gasoline. In such oxygen-rich exhaust streams, the chemical reduction of NOx is especially challenging, and such deNOx catalysts are particularly sulfur-intolerant.

Thus, BMW's most advanced direct-injection lean-burn engines are fine with sulfur at 10 ppm, but apparently not with it at 32 ppm (or particularly, at 80 ppm).

[Redadair]

Originally Posted by Supraman

The BMW 760LI is direct injected...........

+1

I am not buying the sulfur thing as a reason. There are too many other manufactures making DI engines for the US already.

The Lexus IS350 is running at almost 12:1 compression ratio and it uses DI. I work in the Refining industry and all of the refineries have been installing new processing plants that remove most of the Sulfur from the gasoline streams in the US, as well as the Diesel, both mandated by the EPA.

The Lexus is currently the highest output naturally aspirated 3.5 Liter V6 in production in the US market today and it is listed as a ULEVII engine.

I don't know why BMW can't do this as well.

Red

[ArtPE]

DI does not increase power...
it may allow you to raise the Cr, which will...
basic facts, non-negotiable...

M = Pe x V/4Pi

M = moment or torque
Pe = mean effective pressure
V = displacement
Pi = 3.141596

for a constant V only Pe can increase M...period...
Pe can be manipulated 3 ways
1 FI
2 Cr
3 Volumetic efficiency, Ve

in a highly tuned, 4 valve, twin cam engine, it's hard to raise Ve
so DI CAN NOT raise power...

P = M x w = M x 2Pi x n
n = engine speed

so to increase HP
1 increase torque, see above
2 spool it up higher

there are downsides to DI
increased complexity, the injector is buried in the head...
high fuel pressures are dangerous...a leak won't burn, it will atomize & explode...
shooting gas on alloy cylinders may cause problems

it's fine for diesels, the jury is out on cars...
only VAG is pushing it (VW, Audi, Porsche)

it's old tech, been around since 1950's, the first fuel injected car ever, was DI'ed, MB 300SL...

[ruff]

Originally Posted by ArtPE

DI does not increase power...
it may allow you to raise the Cr, which will...
basic facts, non-negotiable...

M = Pe x V/4Pi

M = moment or torque
Pe = mean effective pressure
V = displacement
Pi = 3.141596

for a constant V only Pe can increase M...period...
Pe can be manipulated 3 ways
1 FI
2 Cr
3 Volumetic efficiency, Ve

in a highly tuned, 4 valve, twin cam engine, it's hard to raise Ve
so DI CAN NOT raise power...

P = M x w = M x 2Pi x n
n = engine speed

so to increase HP
1 increase torque, see above
2 spool it up higher

there are downsides to DI
increased complexity, the injector is buried in the head...
high fuel pressures are dangerous...a leak won't burn, it will atomize & explode...
shooting gas on alloy cylinders may cause problems

it's fine for diesels, the jury is out on cars...
only VAG is pushing it (VW, Audi, Porsche)

it's old tech, been around since 1950's, the first fuel injected car ever, was DI'ed, MB 300SL...

Art,

So you are saying you are pleased to see the M3 wasn't burdened with DFI? My guess, and it is only a guess, is that if the M3 was equipped with DFI, you would be singing praises for the substantial benefits offered by the latest DFI technology.

[E90330iS]

you guys are surely educated!