[GTO2turbos]

Originally Posted by scalbert

No flange, the exhaust manifold is welded to the turbine housing.

Interesting, and that sucks. Any turbo upgrades will require a custom manifold and they aren't cheap, and even the best stainless is prone to cracking over time. Add this to the limited fuel system and there isn't much head room on these engines.

[Cadillac Johnson]

You COULD cut the turbo's off and weld on a flange of your choice.

However, if your going to that much trouble you might as well swap the manifolds, but if someone felt like doing it, it would work.

Your running twin 2860's right?

[bnj]

It would be nice to see how much good manifolds would add. Or turbo+manifold combos.

[Brock Landers]

At what time the high factory 10.2:1 compression ratio will start making trouble - detonation etc.? Any info on the internals? Crankshaft, pistons, and rods are forged from the factory or not?

[bnj]

Originally Posted by Brock Landers

At what time the high factory 10.2:1 compression ratio will start making trouble - detonation etc.? Any info on the internals? Crankshaft, pistons, and rods are forged from the factory or not?

The brand new fuel system with piezo injectors enable the high compression ratio. So there is no need to decrease the boost to below the current piggyback boost levels although bigger turbos would allow flowing more air in even with less boost.

Naturally crankshafts and rods are forged and naturally pistons are not. Forged pistons would be noisy and the revs in this engine are so low that forging is not needed in the pistons. Cast and forged pistons do not have much difference in how much they can handle temps and pressure.

[elucas730]

Originally Posted by scalbert

No flange, the exhaust manifold is welded to the turbine housing.

Can anyone else confirm this? Bad/worn turbos DO need to be replaced, so welding the exhaust manifold to the turbo does not seem to be a cost effective solution, since you will need to replace the manifold AND the turbo if the turbo goes.

Originally Posted by bnj

It would be nice to see how much good manifolds would add. Or turbo+manifold combos.

I would think the biggest advantage of an aftermarket manifold would be the ability to swap turbos if, in fact, the exhaust manifold is welded to the turbo. I'd like to see some pics of the manifold mated to the turbo to get an idea of what we are dealing with.

Originally Posted by bnj

The brand new fuel system with piezo injectors enable the high compression ratio. So there is no need to decrease the boost to below the current piggyback boost levels although bigger turbos would allow flowing more air in even with less boost.

Naturally crankshafts and rods are forged and naturally pistons are not. Forged pistons would be noisy and the revs in this engine are so low that forging is not needed in the pistons. Cast and forged pistons do not have much difference in how much they can handle temps and pressure.

FYI...good read on pistons: http://forums.nasioc.com/forums/showthread.php?t=907570

[bnj]

Have a look at the sticky under thess "Forced induction" discussions. There you have the pictures you were asking for.

The link nicely explains why there is more noise with forged pistons. Unfortunately it does not give a good picture of the differences in the endurance regarding the piston speed, temperatures, pressure and detonation. Good reading though

[elucas730]

Yeah, I've seen those pictures already. They are...ok. By the LOOKS of it, any turbo swap would necessitate a new manifold, but I'd like a better look at it.

[335i4u2nv]

u would think u'd need alot of tuning after all this work with some type of standalone or piggy back. id like to see it done. i was thinking of just porting out the turbos but i didnt think they were welded on. My old srt4 the turbo's and manifold were casted together! lol no one but a 2.4 dodge motor coud use them bad boys. lol

[GTO2turbos]

Originally Posted by Cadillac Johnson

You COULD cut the turbo's off and weld on a flange of your choice.

However, if your going to that much trouble you might as well swap the manifolds, but if someone felt like doing it, it would work.

Your running twin 2860's right?

GT2871R twins.

[GTO2turbos]

Originally Posted by bnj

The brand new fuel system with piezo injectors enable the high compression ratio. So there is no need to decrease the boost to below the current piggyback boost levels although bigger turbos would allow flowing more air in even with less boost.

Naturally crankshafts and rods are forged and naturally pistons are not. Forged pistons would be noisy and the revs in this engine are so low that forging is not needed in the pistons. Cast and forged pistons do not have much difference in how much they can handle temps and pressure.

I'm not sure what you mean by "naturally". But forgings are far superior to castings. Cast pistons can live, but the margin for error is zero.

[ljg335i]

Originally Posted by GTO2turbos

GT2871R twins.

how does that fare at the 1/4??

[Lee Rambler]

http://www.realoem.com/bmw/showparts...77&hg=11&fg=50

link to turbo from realoem - it looks like is definitely part of the manifold - you get the same thing if you go for the manifold or the turbo. that sucks. looks like changing the wheel is the only option, which won't be near as cheap as swapping turbos could have been

[GTO2turbos]

Originally Posted by ljg335i

how does that fare at the 1/4??

10.8 at 133 mph at 11 psi and 4100lb race weight (105 mph in the 1/8). 60' was only 1.89 since I can't really get into full throttle until the top of second gear without blowing the tires completely off. It's an automatic.

[bnj]

Originally Posted by GTO2turbos

I'm not sure what you mean by "naturally". But forgings are far superior to castings. Cast pistons can live, but the margin for error is zero.

By pistons are "naturally" not forged, I mean that when you sum up the cars that come with forged pistons as stock and divide by the number of all the stock cars, you are likely to end up rounding the figure into 0%. You can replace the "car" by "BMW" at will.

It makes no sense to have noisy forged pistons in 335i. BMW cannot have even thought of that alternative. Neither cast nor forged can stand detonation for any longer period. Thus the margin for error is not much different. Forged pistons would make sense if the engine would be high revving. This is not the case. Forged pistons would enable to have lighter pistons at the same strangth than the heavier cast pistons and thus help in decreasing the rotating masses and especially benefit at high revs. The inlet valve size and lift accompanied with the stroke in in the stock engine make the surge to happen early in the rev range and a huge engine rebuild should be done to allow higher revs. As far as detonation does not happen, both cast and forged pistons will do their work. If you have any further info regarding the actual strength differences regarding c.r. ; boost, dynamic c.r. or piston speeds, I would like to know. The forged pistons´strength advantage is often compromised by weight savings, so that I have not found a good data comparing the cast vs forged pistons.

[GTO2turbos]

Originally Posted by bnj

By pistons are "naturally" not forged, I mean that when you sum up the cars that come with forged pistons as stock and divide by the number of all the stock cars, you are likely to end up rounding the figure into 0%. You can replace the "car" by "BMW" at will.

It makes no sense to have noisy forged pistons in 335i. BMW cannot have even thought of that alternative. Neither cast nor forged can stand detonation for any longer period. Thus the margin for error is not much different. Forged pistons would make sense if the engine would be high revving. This is not the case. Forged pistons would enable to have lighter pistons at the same strangth than the heavier cast pistons and thus help in decreasing the rotating masses and especially benefit at high revs. The inlet valve size and lift accompanied with the stroke in in the stock engine make the surge to happen early in the rev range and a huge engine rebuild should be done to allow higher revs. As far as detonation does not happen, both cast and forged pistons will do their work. If you have any further info regarding the actual strength differences regarding c.r. ; boost, dynamic c.r. or piston speeds, I would like to know. The forged pistons´strength advantage is often compromised by weight savings, so that I have not found a good data comparing the cast vs forged pistons.

Two prominent twin turbo cars, the last gen supra and 300zx turbo, came with forged internals. If the clearances are set right, engine noise differences between a cast piston and forging are likely not noticable. These aren't small block chevy's with forged pistons and piston slap from the good ole' days.

Cast pistons are lighter than forgings as they are less dense and a casting can be precision cast while a forging is subject to a ram and die.

While no engine can survive detonation for very long, cast pistons destruct almost instantly in a forced induction car, while a forging won't. Forged pistons tend to melt at that extreme, while cast pistons crack and break apart (which is extremely bad for a turbo car since the turbo is downstream of the exhaust valve, the exhaust turbine is taken out by debri). Even without having detonation, high heat associated with adding boost and increased cylinder pressure can fatigue a cast piston to the point of loss of intregity, where a forged piston would be living happily.

A cast piston will live a long life in these cars, but once you start upping the boost you'll quickly come to a point where you'll exceed the design limits of what BMW had in mind.

A friend of mine who has the identical setup as I do recently cracked the top ring land on his piston (cast) while running high boost. One of his fuel pumps (we both have two intank pumps to supply for the increased demands) briefly stopped working and this caused a lean condition to exist for only a few seconds. This caused the car to go lean, his egt spiked, and that was it. He also lost a turbo due to piston debri. The problem was traced back to a faulty ground wire.

And, before anyone asks for my credentials, I'm not a piston manufacturer.

[bnj]

As far as I know Supra Mk IV and Nissan 300ZX come with cast pistons as stock. I could be wrong, but I doubt it. No car comes to mind that would have forged pistons in stock form. I guess those might exist, though.

The boost that can be applied is quite limited with 335i. Heat and inefficiency problems rise soon with the tiny turbos - even if upgraded.

[elucas730]

997 terbosss: http://www.porsche.com/all/media/pdf...7_turbo_us.pdf
page 24-25: Forged aluminum pistons

[AWD Addict]

Originally Posted by M&M

The stock turbo is a TD04-9G.

I'm assuming this is confirmed?

[M&M]

Originally Posted by AWD Addict

I'm assuming this is confirmed?

No sorry, I was wrong. It is, in fact, a TD03.

[AWD Addict]

Originally Posted by M&M

No sorry, I was wrong. It is, in fact, a TD03.

many thanks. Is it a 9G wheel?




I wouldn't let the integrated manifold/turbo setup get anyone down. Just ask the Dodge SRT-4 guys. They've ended up with plenty of upgraded blowers in the aftermarket. With a newer platform, it's just a matter of time.

[A418t81]

10T compressor wheel.