[NickG_TechniqueTuning]

The electronic diverter valve is required because the intake manifold no longer has any vacuum. Hence, there's no vacuum signal to control the valve (and decide when it should be opened or closed). The ECU will now determine it and act accordingly.

[scalbert]

Originally Posted by TechniqueTuning

The electronic diverter valve is required because the intake manifold no longer has any vacuum. Hence, there's no vacuum signal to control the valve (and decide when it should be opened or closed). The ECU will now determine it and act accordingly.

Excellent point, I forgot about that with Valvetronic since the intake valves now become essentially the throttle.

[NM_BMW]

Are there benefits to having a vacuum controlled DV versus an electric controlled?

[CubanJJ09]

^^^ Lol

[marconi118]

Another difficult point of the N55 fort tuners: it has a mass air flow meter at the intake... so difficult to fool the ECU about the air with piggy

[5soko]

Originally Posted by marconi118

Another difficult point of the N55 fort tuners: it has a mass air flow meter at the intake... so difficult to fool the ECU about the air with piggy

A member here who has good inside info with bmw said that because of the valvetronic the N55 will be basically untunable.

Not sure how true this is but who knows. Plus the ecu and software bmw is going to make for this car is going to be most likely pretty anti-tuner!

[raceyBMW]

At least it appears to be a single wastegate this time around (on only one exhaust bank)...maybe less issues? Plus the exhaust manifolds are insulated with an outer shell, so that should help with the engine bay heat issues.

http://blogs.insideline.com/straight...55-engine.html

[twinturbopg]

Originally Posted by RiXst3r

Here are some better photos...

I could be wrong but it looks like a single Cone Intake.

and twin-scroll turbo smart move if your going to go single...I guess thats where they got the 'TwinPower' marketing term from. Since we all know that means that one scroll will spool at lower rpm's while the other will be for higher rpm...basically 2 in 1.

but I still like the Twin Turbo concept still. awww the Twinz!

[Driver72]

I have been out of the loop a bit here guys, so sorry for asking but:
Has there been any confirmation as to what model year the N55 will be used on the 1 and 3 series BMW's?

[Muffnbluff]

Originally Posted by twinturbopg

I could be wrong but it looks like a single Cone Intake.

and twin-scroll turbo smart move if your going to go single...I guess thats where they got the 'TwinPower' marketing term from. Since we all know that means that one scroll will spool at lower rpm's while the other will be for higher rpm...basically 2 in 1.

but I still like the Twin Turbo concept still. awww the Twinz!

No, you're thinking of a sequential turbo setup.

Twin scroll means there will be two distinct exhaust gas paths leading into the turbo. Since all cylinders don't fire at once you get exhaust coming out of the cylinders at different times. By separating them you can keep exhaust pulses from running into each other and you'll continually be feeding the turbine housing a free flowing stream of exhaust. It's more efficient, allows for quicker spool.

[5soko]

Originally Posted by Driver72

I have been out of the loop a bit here guys, so sorry for asking but:
Has there been any confirmation as to what model year the N55 will be used on the 1 and 3 series BMW's?

No nothing yet for the 1 and 3 series that set in stone, we will have to wait a little more and see.

[ar design]

Originally Posted by Muffnbluff

No, you're thinking of a sequential turbo setup.

Twin scroll means there will be two distinct exhaust gas paths leading into the turbo. Since all cylinders don't fire at once you get exhaust coming out of the cylinders at different times. By separating them you can keep exhaust pulses from running into each other and you'll continually be feeding the turbine housing a free flowing stream of exhaust. It's more efficient, allows for quicker spool.

x2

[GreenPlease]

No, you're thinking of a sequential turbo setup.

Twin scroll means there will be two distinct exhaust gas paths leading into the turbo. Since all cylinders don't fire at once you get exhaust coming out of the cylinders at different times. By separating them you can keep exhaust pulses from running into each other and you'll continually be feeding the turbine housing a free flowing stream of exhaust. It's more efficient, allows for quicker spool.

x3

[GreenPlease]

The air gap insulation on the exhaust mani is very very interesting. I'd be willing to bet that it substantially reduces underhood temps and has a mild impact on AITs.

[Muffnbluff]

Originally Posted by GreenPlease

The air gap insulation on the exhaust mani is very very interesting. I'd be willing to bet that it substantially reduces underhood temps and has a mild impact on AITs.

Not ground breaking stuff really. My STi has the same thing essentially in the form of aluminum heat shields that completely encompass the stock iron exhaust manifold.

[gqmd]

Originally Posted by flem

And the fact that down low is the only place to put the turbo since there is no way to mount the motor in the engine bay to allow the turbo to be put up top like with Supras

Why do you guys keep comparing our cars to the Supra. Our cars are regular daily drivers witha bit of kick AKA sport sedans...the Supra is a high performance machine...completely different league. Thats like the V6 Camry people comparing their car design to our cars.

[Mooreski]

Originally Posted by Muffnbluff

Twin scroll means there will be two distinct exhaust gas paths leading into the turbo. Since all cylinders don't fire at once you get exhaust coming out of the cylinders at different times. By separating them you can keep exhaust pulses from running into each other and you'll continually be feeding the turbine housing a free flowing stream of exhaust. It's more efficient, allows for quicker spool.

So what does the turbine wheel look like? Does each incoming airflow act on the entire wheel or are there two different sets of turbine blades, maybe one for low airflow and one for high airflow with each getting its own incoming?

If the former, seems like there wouldn't be much difference feeding the wheel with 1-6 cylinder instead of 2-3 cylinders.

If the later, will your turbo ever spool as well since once half of the turbine wheel is always out of its efficiency range?

[Muffnbluff]

Originally Posted by Mooreski

So what does the turbine wheel look like? Does each incoming airflow act on the entire wheel or are there two different sets of turbine blades, maybe one for low airflow and one for high airflow with each getting its own incoming?

If the former, seems like there wouldn't be much difference feeding the wheel with 1-6 cylinder instead of 2-3 cylinders.

If the later, will your turbo ever spool as well since once half of the turbine wheel is always out of its efficiency range?

There is just one turbine wheel, but two entrances.

I think the firing order is 1-5-3-6-2-4. So essentially cylinders 1-3 go to one exhaust port, 4-6 another.

That way when exhaust pulses from 1 & 5 are heading towards each other they don't hit each other causing any kind of backpressure. Instead each has it's own path into the turbine. So exhaust from cylinders 1-3 will go through one port while cylinders 4-6 will go through another.

What you have is exhaust from the two ports that enter the turbo alternating exhaust pulses simultaneously. So cylinder 1 enters on the left, then cylinder 5 on the right, cylinder 3 on the left, cylinder 6 on the right, cylinder 2 on the left, cylinder 4 on the right.

It's all about keeping the travel of the exhaust gas as smooth as possible. When exhaust pulses coming from different directions run into each other it causes some back pressure.

This is what gives Subaru's that distinct rumble because they have unequal length headers so you have exhaust pulses running into each other constantly.

[Mooreski]

Very cool, thanks

[ar design]

Originally Posted by gqmd

Why do you guys keep comparing our cars to the Supra. Our cars are regular daily drivers witha bit of kick AKA sport sedans...the Supra is a high performance machine...completely different league. Thats like the V6 Camry people comparing their car design to our cars.

LOL. IMHO, its more the other way around. Supras are lag monsters that are fast in a straight line, and thats about it. The interior sucks too.

[Mooreski]

So, then what's the purpose of unequal length headers? To make all the exhaust pulses hit a common point at the same time and get back pressure to spike and clear out before the next set of pulses is generated by the cylinder?

[twinturbopg]

Originally Posted by Muffnbluff

No, you're thinking of a sequential turbo setup.

Twin scroll means there will be two distinct exhaust gas paths leading into the turbo. Since all cylinders don't fire at once you get exhaust coming out of the cylinders at different times. By separating them you can keep exhaust pulses from running into each other and you'll continually be feeding the turbine housing a free flowing stream of exhaust. It's more efficient, allows for quicker spool.

oh thanks for explaining that....I will make sure to tell one of my buddy's the same thing.

Thanks for the knowledge seriously!