Why No Direct Injection?....

[e46e92love]

Seriously, every-time I am reminded that its just normal injection I scratch my head as to why? I understand the individual butterfly system for response sake, but you would think they would figure out how to translate that system into a direct injection format

Direct Injection would give the M3 more power and I bet would have gotten them a few more MPG, getting the M-DCT equipped cars out of paying GGT. Someone please explain why I am stupid for asking this question so I can then and we can bury my dumb-ass in the Off-Topic section.

[oneginee]

Excellent question don't have an answer either. I did not notice it but you're right no high-precision injection in the M3 V8. BMW version of it is called high-precision injection and it is in the 335i

So they put a twin turbo and DI on the 335i and nothing on the M3

If can only guess why:

- they over estimated how much hp they would get from the V8 (does not make sense, since more hp is good and DI is more fuel efficient)

- DI would not work with high reving engine ? ( don't think so )
- cost of DI with 8 cylinders ?

I will not buy before I get an answer

[scollins]

Well, the 4.2L V8 in the Audi RS4 is direct injection, produces 420 HP and revs to 8200 RPM, so it would seem direct injection is capable of achieving the HP and RPM numbers.

Why BMW didn't use it in this mill, I don't know. I imagine it was in development at the same time as the N54, so the high pressure fuel pump issues some 335i owners are havaing wouldn't have been a factor.

[T Bone]

First of all, DI hasn't given much beyond a slight improvement in fuel economy & emissions.

DI is not for power.

Secondly, the S65 V8 is based on the S85 V10. The V10 was developed awhile ago and BMW DI was not likely available for the V10 and hence didn't get adopted in the S65 V8 either. Also, have you guys looked at a cylinder head for the V10 or V8? Don't think there is room.

[OzStriker]

Originally Posted by T Bone

Also, have you guys looked at a cylinder head for the V10 or V8? Don't think there is room.

I have not seen the head, have you any photos or a link T Bone?

[E90330iS]

the Ms have never had an DI engine has it?

[T Bone]

Originally Posted by OzStriker

I have not seen the head, have you any photos or a link T Bone?

See if you can find some room in the cylinder heads.... Do you guys want the engine to breathe better or have a cool sounding feature like Direct Injection??

[swamp2]

Come on TB, "no room" does not cut it. If BMW really wanted to put DI in the M3 they would have had to use a redesigned head but it is not the case that it would be impossible to make it fit. What did Audi do with their DOHC 4V/cyl RS4? They found some room. Memeber southlight and I have discussed and argued about this extensively here on the forum. I think his conclusion was that BMW felt the DI used in the 335i was too primitive for the M3.

[oneginee]

I would have to disagree with T Bone:

DI improves fuel economy in day to day driving and unless your car is just for racing it is very desirable to have.

DI improves power by precisely directing the cone shaped atomized air-fuel mix onto the spark which optimizes burning reduces burning temperature which allows higher compression ratio and that's more hp.

and why would BMW write as they have :

"High Precision Injection, the innovative petrol direct injection system from BMW, makes the combustion process more efficient. The engine delivers greater performance and a significant reduction in fuel consumption."

Now to the excuse about not having sufficient space on the cylinder heads of the V8 that does not hold. The V8 bore is 92 mm and it is only 89.6mm on the 335i I6 yet the 335i has direct fuel injection. It is tight but it fits as you can see :




BMW is pioneering DI on the 335i and 325i and it looks like they did not allocate sufficient effort to work it out on two separate engines. So the M3 does not get it. Hence the extra marketing on individual throttle butterfly for the air intake to hide the lack on DI.

I am disapointed. Are there any problems with DI on the 335i that at least would make an argument for the lack of it on the M3 ?

twin turbo, DI it really looks like the 335i got all the latest BMW technology while they took the easier path on the M3.

[T Bone]

Originally Posted by swamp2

Come on TB, "no room" does not cut it. If BMW really wanted to put DI in the M3 they would have had to use a redesigned head but it is not the case that it would be impossible to make it fit. What did Audi do with their DOHC 4V/cyl RS4? They found some room. Memeber southlight and I have discussed and argued about this extensively here on the forum. I think his conclusion was that BMW felt the DI used in the 335i was too primitive for the M3.

Originally Posted by oneginee

I would have to disagree with T Bone:

DI improves fuel economy in day to day driving and unless your car is just for racing it is very desirable to have.

DI improves power by precisely directing the cone shaped atomized air-fuel mix onto the spark which optimizes burning reduces burning temperature which allows higher compression ratio and that's more hp.

and why would BMW write as they have :

"High Precision Injection, the innovative petrol direct injection system from BMW, makes the combustion process more efficient. The engine delivers greater performance and a significant reduction in fuel consumption."

Now to the excuse about not having sufficient space on the cylinder heads of the V8 that does not hold. The V8 bore is 92 mm and it is only 89.6mm on the 335i I6 yet the 335i has direct fuel injection. It is tight but it fits as you can see :




BMW is pioneering DI on the 335i and 325i and it looks like they did not allocate sufficient effort to work it out on two separate engines. So the M3 does not get it. Hence the extra marketing on individual throttle butterfly for the air intake to hide the lack on DI.

I am disapointed. Are there any problems with DI on the 335i that at least would make an argument for the lack of it on the M3 ?

twin turbo, DI it really looks like the 335i got all the latest BMW technology while they took the easier path on the M3.

The S65 makes 103.5 hp / liter, more than the RS4 engine....without DI. DI is good for fuel economy as I stated but DI is not needed for making power.

I subscribe more to the theory that they just didn't have time to add DI to the S85 V10 and hence it didn't make it to the S65 V8.

Now, give me pnematic valves for the next ///M engine.

[footie]

I could be wrong on this but I don't think the RS4 does have direction injection, it has FSI which is different. I believe neither the RS4 or M3 have it becuase of their respective rev limits, direct injection at present is limited to just over 7000rpm.

[RandyB]

Originally Posted by footie

I believe neither the RS4 or M3 have it becuase of their respective rev limits, direct injection at present is limited to just over 7000rpm.

I have heard the same. Here is what Porsche is using on the new Cayenne. We'll see what happens with the 998.

[murellus]

I agree with the posts above, DI is most likely limited when at the higher limits of the s65 motor or produces some unwanted characteristics in this region (sharper power dropoff or something of that sort). Anyway, it does not appear that the s65 really needs it so who cares?

[T Bone]

Originally Posted by footie

I could be wrong on this but I don't think the RS4 does have direction injection, it has FSI which is different. I believe neither the RS4 or M3 have it becuase of their respective rev limits, direct injection at present is limited to just over 7000rpm.

Interesting....these DI systems can send fuel up to 2-3 times per stroke which implies it is pretty quick....

[Epacy]

Originally Posted by T Bone

First of all, DI hasn't given much beyond a slight improvement in fuel economy & emissions.

DI is not for power.

Secondly, the S65 V8 is based on the S85 V10. The V10 was developed awhile ago and BMW DI was not likely available for the V10 and hence didn't get adopted in the S65 V8 either.

Bingo, that's exactly it. BMw also spoke of DI not besing sutied to the higher revs of an ///M engine, yet.

The RS4 engine also eats a good bit of oil and wears through it's oil quicker. Their implementation of DI isn't the best. Also, remember the RS4 motor has DI and .2L more displacement but makes the same HP as the M3. It obviously isn't as efficient and the implementation of DI doesn't seem to benefit it as much.

[Epacy]

Originally Posted by oneginee

BMW is pioneering DI on the 335i and 325i and it looks like they did not allocate sufficient effort to work it out on two separate engines. So the M3 does not get it. Hence the extra marketing on individual throttle butterfly for the air intake to hide the lack on DI.

You are hilarious. The things you come up with...

[rvacha]

I subscribe to the theory that:
1. BMW would have needed to develop DI for a 9,000RPM application, which is considerabley harder than what Audi did
2. It probably didn't make sense to develop it for the S65. There has certainly been a lot of discussions regarding the future motive power of M, and TT may be the solution. In essence the S65 is a possibly a dead end - why spend a bunch of cash doing DI when you can flush it down the F1 rathole?

[rvacha]

I subscribe to the theory that:
1. BMW would have needed to develop DI for a 9,000RPM application, which is considerably harder than what Audi did
2. It probably didn't make sense to develop it for the S65. There has certainly been a lot of discussions regarding the future motive power of M, and TT may be the solution. In essence the S65 is a possibly a dead end

[OzStriker]

Originally Posted by T Bone

Now, give me pnematic valves for the next ///M engine.

10k RPM?

[footie]

Originally Posted by Epacy

Bingo, that's exactly it. BMw also spoke of DI not besing sutied to the higher revs of an ///M engine, yet.

The RS4 engine also eats a good bit of oil and wears through it's oil quicker. Their implementation of DI isn't the best. Also, remember the RS4 motor has DI and .2L more displacement but makes the same HP as the M3. It obviously isn't as efficient and the implementation of DI doesn't seem to benefit it as much.

Epacy,

Not wanting to tell you are wrong about the RS4 having DI but I believe that is the case. DI technology at present is limited to a certain rev limit. Whether is the near future thing change is anyone guess, no doubt it's in development because with Co2 rating becoming more important I would expect manufacturers tying to combine it into all versions. On another point the RS4 has 4 valves per cylinder instead of the S4's five valve and this was to do with the rev limiting effect of five valves.

Also this implication that RS4 engines use an excessive amount of oil is again untrue, some cases have happened but in general most of the example I now don't use hardly any. I think it all depends on how hard the car is driven, whether it's tracked or not, I know the basic engines of the S5 and RS4 are closely similar and I know my S5 doesn't use oil. You have to remember that the RS4's piston rate is higher than any other road engine so a little oil usage is a good thing.

[Gearhead999s]

Audi FSI

FSI® direct injection technology increases the torque and power of spark-ignition engines, makes them as much as 15 percent more economical and reduces exhaust emissions. In contrast to conventional intake manifold injection on conventional spark-ignition engines, FSI® engines inject fuel directly into the combustion chambers. This technology dispenses with the throttle plate. That ‘unthrottles’ the engine, reduces heat loss and thus increases output while reducing fuel consumption.
The system uses two charge-air supply modes: stratified charge at partial load and homogeneous operation at full load. In the stratified charge mode, an combustible fuel-air mixture is only produced in a defined zone around the spark plug. The engine management electronics monitor engine load and adjust injection timing, pressure, quantity parameters as well as the air flow inside the cylinder via the air intake channel. At full load, FSI® increases compression as well as engine efficiency and performance


I personally think that BMW choose not to include to include DI because of the need to develop an engine with maximum valve area,so as to provide the maximum air flow to develop power.Remember that an internal combustion is just a big air compresor that you happen to add fuel to!

[footie]

Gearhead999s,

I understand that FSI stood for Fuel Starvation Injection.