B3BT - ENGINE CHANGES?

PATAKET · Post by **PATAKET** » Fri Apr 30, 2010 8:49 am

I see the latest 335i has had significant changes to the engine: 2nd gen direct injection / Valvetronic / single twin-scroll turbo in place of the previous twin-parallel turbo set-up. Power and torque are, improbably, identical but emissions fall by around 10% and economy is improved. No doubt weight will be saved and there must by definition be drastic changes to the exhaust system.

The question I have is: will these changes be carried over to upcoming B3BTs?

PÃ¥ Taket

Bruce M · Post by **Bruce M** » Fri Apr 30, 2010 10:50 am

I'm guessing not.

The cost of developing a complete engine package is pretty shocking. Although the B3 Bi-turbo unit was developed from the 335i motor, there is a fair bit of work involved in tuning the motor to higher performance (new pistons etc) and then test the hell out of it (ie is the radiator big enough to cool the engine at max speed on a hot day?)

Like many manufacturers. I suspect the B3S tuning was already at least partly developed as part of the original development programme. This higher level of tuning would have been held back to release as part of a mid-lifespan upgrade. The is a very common technique by car manufacturers to boast sales figures for facelift models.

But this is a guess, and I could be wrong

Richy_Boy · Post by **Richy_Boy** » Fri Apr 30, 2010 10:59 am

The new 335i engine is pretty impressive.. single turbo and almost identical power with better emissions - the 'old' 335i engine was already a master piece.

Am I right in thinking the Valvetronic stuff has replaced the cam with solenoids to control the valves? i.e. independant variable valve timing?

Rich

IAM Joe · Post by **IAM Joe** » Fri Apr 30, 2010 1:27 pm

Manufacturers seem to be going back to the single turbo set up with the twin-scroll unit.

Do you not think that Alpina may be tempted to lightly tweak the new engine and slot it in rather than do a big R&D job on what is already a highly efficient/powerful engine to save a few $?

I always knew mono was the way forward

Estoril Sport · Post by **Estoril Sport** » Fri Apr 30, 2010 1:37 pm

I have read that the Alpina B3s is using the same engine as the B3 but with further improvements

http://www.e90post.com/forums/showthrea ... hlight=b3s

Ther is a good video interview from the Geneva show at http://www.e90post.com/forums/showthrea ... hlight=b3s

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Bruce M · Post by **Bruce M** » Fri Apr 30, 2010 2:20 pm

A good guide on Valvetronic that has been around since the E36 in some form or another.

http://www.usautoparts.net/bmw/technolo ... tronic.htm

The engine still has a cam and throttle valve but the rocker that the cam pushes has variable geometry so the actual valve timing can be varied quite a lot. This means the timing can be changed enough to control the revs without using a throttle plate. The throttle plate remains for start up and emergency limp home mode (if the valvetronic fails).

Richy_Boy · Post by **Richy_Boy** » Fri Apr 30, 2010 2:59 pm

IAM Joe wrote:Do you not think that Alpina may be tempted to lightly tweak the new engine and slot it in rather than do a big R&D job on what is already a highly efficient/powerful engine to save a few $?

To be fair, the B3S (e90) is just a remapped B3BT (more boost) with a bigger oil cooler strapped on, as is the B3BT is just a 335i but with uprated pistons and remap...

They're all variations of the same base engine, but a single turbo is likely to run out of puff once you wind it up to 1.2bar+. (i.e. there'll be a limiited efficiency window until it starts just blowing red hot air). I think the normal 335i only runs 0.8bar?

I very much doubt Alpina will spend much time R&D'ing this engine.

Richard

Steve A · Post by **Steve A** » Fri Apr 30, 2010 4:55 pm

I think BMW have moved the 335i down to a single scroll turbo to allow all
future M cars to have 'twin turbo' technology, so to differentiate the brand.

Ive noticed that the new 1 series M is twin turbo, as are the x5mx6m and upcoming m5

just a thought.....

Bruce M · Post by **Bruce M** » Fri Apr 30, 2010 5:38 pm

An excellent observation.

And how much cash do you think they save by removing one turbo

(answer: enough to make it worthwhile)

PATAKET · Post by **PATAKET** » Mon May 03, 2010 10:40 am

I had forgotten the B3S upgrade already existed. Re: the discussion of single versus twin turbo................don't forget most twin turbo installations are sequential (in-line) with one smaller and one larger turbo, eg 23d; 35d etc. The 335i / B3BT is unusual in being a parallel installation, ie 2 identical turbos with 2 separate exhaust manifolds, one for the front 3 cyls and one for the rear 3. A massive engineering change if the new motor has a single twin-scroll turbo / single manifold etc etc.

Pa Taket

Richy_Boy · Post by **Richy_Boy** » Mon May 03, 2010 1:01 pm

PATAKET wrote:A massive engineering change if the new motor has a single twin-scroll turbo / single manifold etc etc.

It's not that massive to be honest, a new manifold, a more advanced turbo and some ECU tweaks - job done. It's pretty impressive getting twice the airflow from a single turbo without massively increasing the lag though.

Steve is quite right in that BMW probably want to start limiting the mechanical capabilities of their 'non M' engines as you can clearly see with a simple remap, existing 335i and 335d models are mind-blowingly quick (many offering straight line speeds of the mighty M3!)

BMW are clearly trying to stop this remap culture from spreading with ever increasingly complex encryption algorithms being used to stop the ECU being cracked.

With that in mind, unless there are supply or contractual limitations in place, that could be another reason why Alpina stick with the old 'unlimited' engine, which after all is competing with the m3 and not the 335i in the performance stakes!

Bruce is also quite right, the savings from only using one turbo, a single larger manifold will soon add up!

Rich

Ikule · Post by **Ikule** » Sat May 15, 2010 9:44 pm

I've read that the new 335is will still use the twin turbo unit (N44),
the 335i (non 's') will drop to a single twin scroll turbo engine (N55) but retain the 306bhp power figure.

http://www.autoblog.com/2010/01/18/repo ... -335i-bel/

but US and Canada only until reactions to it are gauged

http://www.autocar.co.uk/News/NewsArtic ... ?AR=246540