Hahaha- the end of the video, fantastic.

 

Great video. Car sounds great at speed too. "I did it...1:59" celebration. Yeah!

Anyway, do you have any idea what your boost runs? I probably won't go to a dyno, and some comments here suggest the threshold for safe internals is the whp, but I only have access to the OBD apps that give calculated boost pressure.

I have both the Stage 1 and Stage 2 maps. And the apps says (I'm sure it would be more accurate with a mechanical gauge though) the Stage 1 is between around 11-13 psi and the Stage 2 is around 17-18 psi.

After re-reading this thread, I've flashed back in the Stage 1.

 

My scangauge claims a boost pressure of about 21psi, doing the math subtracting the ambient 13psi from the MAP. The MAP number I see is 34.

 

Boost pressure should still be looked further into and should be the determining factor for threshold identification for safe internals. I did do some digging and looked into cases of failed internals versus the mods they did. Most other B48 piston failures (from other BMW vehicles) stems from irresponsible tunes to achieve those bigger whp numbers. Most of them did it by adding on the target boost without regards to what the internals can take.

 

@Yupetc - can you expand on that? Are you seeing a pattern of exactly how much PSI has led to failures?

And do you know if these tunes are messing with the knock sensor as well? Thanks.

 

@J_L , I won't be able to point out the specific psi numbers to these failures, It has a whole lot more to do with the overall condition of the motor, the tunes, supporting mods, and driving habits. I'm a big motorhead by learning what's out there in the forums and blogs, so my knowledge is only as good as what I gathered. Luckily, I also can read Chinese language and I came across this link https://www.bilibili.com/read/cv881742/ to learn more about the B48 motors when they did the comparison against the N20 (which is sort of a predecessor before the B-engines come out along with modularity manufacturing to share platforms for B38 and B58 motors, more than half of the tooling can be shared making all 3 B-engines).

 

If you don't mind me asking, how did you run methanol injection with the Dinan Elite and what meth system did you use?

 

Thanks for the link. It's amazing all their effort and research to build new pistons, I'm guessing, just for the race shops, tuners and such. I mean, the people that wrote that write-up aren't BMW engine designers, right?

BTW, I can read Chinese as well, but only in circumstances where the Google Translate button shows in the upper right corner..hehe.

 

Those guys that did the write-up aren't BMW engineers. They are very good modification experts who are calling all the other tuners out to stop irresponsibly hand out tunes that'll just kill the engines. I come in contact with them because I have to recover a floorded F56 with a B46 motor in there, hydro-locked. And with my background with modifying vehicles, I decided to go for a build and came across these guys and learned this much so far.

 

I installed the Dinan Elite first and the meth kit many months later. There is no extra tuning going on for the injection, just letting it spray in conjunction with boost to aide in combustion.

 

From what I have heard b48 330i engine will fail at 25psi of boost from couple large tuners in the China region. Most 3 series in china or Asia are b48 due to tax. And running meth will help a ton with keeping the engine alive.

 

So let it be stated that at 25psi boost, we'll definitely be seeing problems on the B48 stock internals. At least, this can be our starting threshold until we find it otherwise.

 

pro tip: start out at https://translate.google.com and put the web address of the page to be translated into the first box. Then it should give you an option to click that link on the right side box, and it’ll open a new tab translating the page for you. Weirder to describe than to use.

anyway, read this, it’s fascinating stuff:
https://translate.google.com/transla...%2Fcv881742%2F

some excerpts:

one more pic that site: the piston skirt of the B48 is quite different from the N20’s. It seems to have a lot less material to fight rocking in the bore? But I am certainly not an engineer, so take my comment here with a grain of salt.Source: https://www.bilibili.com/read/mobile/881742/

 

Hi, i'm new to this forum and seeing this i would like to share my experience. Currently stage 2 ( f56 S ) it has the b48 engine. Now over 128 000km on the clock. Running 268WHP (300hp) and 410nm. I'm experiencing not a single problem. Car is running 21-22 psi on the stock motor.. trackdays etc..
Seems like the b46 engine is not as strong as the b48 i think.

 

Hi ClubsportF56S, welcome to http://www.NorthAmericanMotoring.com! I think you'll find it to be a pretty welcoming place. We're full of strong opinions, though, so be prepared to stand your ground ;-)

Regarding the B46 being "not as strong" as the B48, that shouldn't be the case. The B46 is a lower-emissions variant of the B48. There is no difference in the pistons, rods, crankshaft, or cylinders. With the same parts, they would share the same mechanical weaknesses.

(The new 300hp JCW variants have stronger, forged pistons.)

Additional info over in this thread – see post #15 in particular.

 

To lower the emissions, my first think is about a more lean combustion. Which has higher combustion temperatures. That could burn a piston, throw a rod in some cases. Isn't that what's happening to the engine's that already blew up here? Good thing check the EGT's when mapping. Here in Europe (belgium/germany) they say 300hp is safe. 300 is safe on the S and even 320 on the JCW due to the better compression ratio. Is this type of tuning avaiable in the US? Or do these engine break because of tricking the ecu? I've heard that the JCW's engine isn't stronger than the S. It just has a better compression ratio for more power. But the strenght is equally. The new jcw engine in the gp3 and in the new m135i is indeed stronger but it will max out sooner @ 350hp. Mine has the economical hp rate (163hp) for lower taxes. But after stage 2 it made 300.42hp and 409nm of torque. Not agrresive in low revs, just all mid and top range. It keeps going. At the moment it's still a pretty happy engine. After 6000km it uses. 0.25l of oil. But that's when i do the oil change, so no signs of engine wear.

 

It's very hard to say what horsepower will the engine fail; but it's safe to say that the pistons and the rings are the weakest links. Yes, there are cases of tuning the B48 beyond 300hp (likely 250-260whp, some with methanol going above 300whp) without an issue. But I suspect that once we've taken the tune to that level, the life of the pistons will start to reduce. You may get lucky for a while till something gives up. These B38 and B48 engines are designed for driving fuel economy and to enhance production efficiency during manufacturing (by way of modularity, platform sharing), it's not designed to withstand the abuse that we're accustomed to putting on common BMW engines. It's my opinion after all this research on BMW's latest B-series engines, I'll say that the 6 cylinder versions are designed for performance, and the 4 cylinders are for fuel economy and slight power use. It just simply won't withstand the high performance tunes we're all looking to do. Unless, of course, we start to look for those performance forged internal upgrades, then we can play safely.

 

The B58 is a 50% bigger engine compared to the B48. If i do my math correctly they produce around 50% more power at the same tuning level ( downpipe, IC, map) and yes they do. They are around 480hp here at stage 2. The next level is turbo etc but the stock engine has the same bore and stroke as the b48. So it would be nice to know if you could use the pistons of the b58 in the b48.

 

I've been wondering the same thing about B48 and B58 pistons being interchangeable. And so far from what I've collected, they are exactly the same dimensions, just don't know if the valve cut-outs of B58 would match those of B48. But in terms of bore/stroke between B48 and B58, they are all the same. Also if you search forged B58 pistons, you'll also come across those saying the pistons are also available for the B48 under the same catalog page.

 

From the data I have gather around Asia and USA area. The s engine with higher compression seem to be stronger than the jcw engine. Maybe due to having more material on the piston because of higher compression? As all the other internal bits are the same.

 

The pistons are exactly the same between the JCW and the S, it's the head dome volume and deck height that sets the difference in compression. The dome volume is larger in the heads on JCW, the head-gasket is also 0.3mm thicker, making it a factor into the static compression ratio.

The larger dome value achieves two things:
1. To yield a lower compression ratio without needing to reconfigure the stroke and piston dimension. It will not affect the dynamic displacement (the cc's is the common term). This allows a higher boost with a larger safety predetonation window.
2. The enlarged dome size allows room for valve size and flow path design to be optimized better. Larger dome equates to higher static volume in the chamber, which draws in more air in the combustion chamber, and with VVL and VVT in place, it can maximize overall volumetric efficiency for combustion process.

 

I also would guess that the lower emissions are achieved through a leaner burn – but if we're talking about "tuned" engines, then does that even apply? Wouldn't a tuner target a richer fuel:air mixture than stock as part of getting more power? Not to mention that a richer mixture should result in lower temperatures? Or does BMW's ECU prioritize lean-burn over other factors even when fed different targets by a tuner?

 

I'll have to correct myself:
The difference in compression ratio between MCS and JCW in the B-series engines don't come from dome volume as I've speculated it earlier. I don't have a JCW head to compare against my MCS head to verify that speculation, but lately I've been working closely on buying a set of forged pistons from Supertech, JE, or Mahle. The way compression ratio can differ in the B-series engines actually stems from piston geometry. So there you have it.
JCW's piston crown has to be a slight different than the MCS. That's how they achieve a lowered compression ratio of 10.0 vs the MCS's 11.0. To this end, knowing that the piston crown room is a major reduction relative to that of MCS, this gives clearance for a higher valve lift and longer duration. For sake of higher valve lift and longer duration, I reckon it to be all achievable through both VVT and VVL by way of programming and/or a slightly taller intake cam profile on JCW. I can only hope to obtain a JCW head so I can research and compare, but for now, it's all speculation based on what I collect from talking with piston manufacturers and tuners.

The pistons I'm buying from Mahle to put on my MCS B48 will yield a final static compression ratio to 10.5. And that's by way of piston crown design.

By the way, to add to the laundry list of built internals, Mahle is now an official player in offering the forged pistons for the B-series engines.
Though in order to obtain a set, you'll need to buy it from the supra upgrade, part number is 197883929. I had just bought a set, though I only need 4. I'll end up buying another set and distribute it into 3 engines.
These are made for B58, but will be compatiable for our B46/B48 engines, too. Bore, Stroke, pin hole sizing will all match. The only downside I consider to be a con more than pro is the type of alloy they use. They chose 2618 Alloy instead of the 4032 which I would always prefer due to silicon content for resistance to heat-expansion. However, with the full list of features and strength this piston is built with, it's going to be one strong build no matter what. Cold start noise is the suspect in the 2618 alloy piston family.

 

Any updates yet? I'm planning for a full rebuild. Not knowing which pistons/rods i will install

 

My build is going to be a slow build.

Got the B58 Supra performance pistons from Mahle (good for 1000 hp on B58 motors). I’ve checked all dimensions it’ll clear if we use stock sized conrods. These pistons will bring compression ratio down to 10.5, allowing tuner to do more.

The conrods I bought are forged 4340 chrome moly from maxspeedingrods. These are said to be equivalent to Eagle rods. I’ve seen a bunch of these used and reputable for track use on the Triumph. My ex-boss is a sentimental guy. He used to race triumph with these for years of good turnout. So far the rods are still being transported to me. Once I have them I’ll start putting the motor together, checking all bearing clearances and component tolerances.

I’ll work with ByteTronics for a tune, targeting between 300-350whp on their dyno. Goal is to achieve the highest power while being streetable and keeping everything safe. In this build, the weakest link will be the conrods and they are rated for 600-800bhp, that's plenty for me.

My full list:
Mahle Powerpak B58 SUPRA Pistons, 2618 Forged Alloy, Compression Ratio: 10.5 Part#197883929 (Comes with Piston Rings and Wrist Pins)
MaxSpeedingRods B48 H-Beam Rods, 4340 Forged Chrome Moly, Part#CR-BWB48-T
ARP 2000 Rod Bolts Part#201-6304
ARP 2000 Head Stud Bolts Part#201-4601
ARP 2000 Main Stud Bolts Part#201-5001

Bought these tools to go along with the install:
Piston Clearance Gauge
Bearing Clearance Gauge
Piston Rod Balancer
ARP Piston Ring Sleeve
Piston Ring Grinder
Connecting Rod installation guides

It's going to take some time as I don't intend to rush through all of this right now. Slow work is quality work in my hobby garage.