[Craigito]

I read that the turbos on the diesel not only are not twin sized but are in series with one another. In fact, it said that after 2500 rpm, the initial smaller turbo does nothing at all.

So why is this a more effective setup on a turbo diesel vs the turbo gas which has independent twin turbos?

Sorry if this has been discussed before.

[judec]

For the 335d:
it is an effective trade-off of quicker spool-up and low and torque vs. high end performance. In single turbo setup the turbo sizing is very sensitive topic. Put a small turbo in it and U'll spo9ol up quicker and pull from lower rpm, but U'll loose your breath at higher rpm's. Vice versa with turbos too big - U'll be able to compete gasoline engines, but until U get there... ouch. So the BMW sd setup should cure both of those handicaps - 286 HP and absolutely insane torque, BUT - it's not a sports car engine and the 335d is not a sportscar, even if it wears the E92 suit.

On the other hand using such serial setup on gasoline turboed engines would be effective, too, but would be prone to failures due to higher exhaust temps of gasoline engines or I dunno why. Maybe someone wiser could tell us?

[Craigito]

Originally Posted by judec

For the 335d:
it is an effective trade-off of quicker spool-up and low and torque vs. high end performance. In single turbo setup the turbo sizing is very sensitive topic. Put a small turbo in it and U'll spo9ol up quicker and pull from lower rpm, but U'll loose your breath at higher rpm's. Vice versa with turbos too big - U'll be able to compete gasoline engines, but until U get there... ouch. So the BMW sd setup should cure both of those handicaps - 286 HP and absolutely insane torque, BUT - it's not a sports car engine and the 335d is not a sportscar, even if it wears the E92 suit.

On the other hand using such serial setup on gasoline turboed engines would be effective, too, but would be prone to failures due to higher exhaust temps of gasoline engines or I dunno why. Maybe someone wiser could tell us?

Yep..I understand the pros/cons of each setup. I'm just wondering why the same setup wasn't used on both iterations.

[stressdoc]

Might be possible to put two of the twin-sequential turbos on the gas engine. That would be interesting.

[Insider]

Originally Posted by Craigito

Yep..I understand the pros/cons of each setup. I'm just wondering why the same setup wasn't used on both iterations.

The 335i makes 300hp with 8.5 psi boost. The 335D needs 26psi to make 286hp. In order to get 26psi, you need a big turbo. That's why it is setup different. Simply put, diesel engines simply don't make the power of gas engines, expecially in the high rpm area, that's why they need so much boost.

[Craigito]

Originally Posted by Insider

The 335i makes 300hp with 8.5 psi boost. The 335D needs 26psi to make 286hp. In order to get 26psi, you need a big turbo. That's why it is setup different. Simply put, diesel engines simply don't make the power of gas engines, expecially in the high rpm area, that's why they need so much boost.

Perfect explanation. Thanks.

[533ogetnom]

Originally Posted by Insider

The 335i makes 300hp with 8.5 psi boost. The 335D needs 26psi to make 286hp. In order to get 26psi, you need a big turbo. That's why it is setup different. Simply put, diesel engines simply don't make the power of gas engines, expecially in the high rpm area, that's why they need so much boost.

uhhh...

diesel engines dont make as much power in the "high rpm area" because they DONT HAVE a high rpm area, it makes the same amount of HP at freaking 4k rpms! if it could rev to 7k, jesus christ the thing would be twice the power of the 335

and if you think diesels cant develop the same power as gas engines, try having a conversation with these guys, they will teach you a thing or two




but yea, turbo diesels do need a ton of psi

[Beer Goggles]

The PSI difference is more about the difference in fuel and flash point rather than just looking at how much pressure is needed to make power.

[Panoz]

Does the 335d uses the same type of turbos as the 335i ?

[roofer]

it's not a sports car engine

Agreed.

the 335d is not a sportscar

Depends how you define 'Sportscar' i suppose.

They can be remapped to 340bhp, and over 500ft lLb of torque.

Our roads are better suited to the 'D' i know, but they take some catching.

The biggest problem (for me) is the engine has no soul.

[e.n335]

Hi,

The only time I liked my ( chipped ) X5 3.0d has been at the gas station from time to time. Due to the narrow rpm range available you have to shift more often compared to a petrol engine ( the steptronic does this for you ). No top-end power, no engine sound, no higher rpm's. No fun. A diesel makes sense in a big and heavy car like a SUV/SAV. Not in a 335.

My 2 cents.

Cheers
Eugen

[Jerseystyle1]

Originally Posted by Panoz

Does the 335d uses the same type of turbos as the 335i ?

Read above.....

[judec]

Originally Posted by roofer

Agreed.

Depends how you define 'Sportscar' i suppose.

They can be remapped to 340bhp, and over 500ft lLb of torque.

Our roads are better suited to the 'D' i know, but they take some catching.

The biggest problem (for me) is the engine has no soul.

the term Sportscar does not necessarily refer to a car with lot of HP/TQ. It needs something more. It's not easy to explain, what exactly - performance? YES. Torque? Yes. Transmission? Yes. Suspension? Yes. Wheels & Tires? Yes + all of this and more complementing each other, packed in a nice package. Now dont get me wrong, nuthing against 335d, it's a really comfortable long distance cruiser, but chipped or not, it's far from a sportscar. That's not dishonesting it, no way, it's just a fact. In fact the 335i also isn't a sportscar, but supported with a few mods it's really close, closer like the 335d.