[SeanWRT]

There're many parts that can fail to high boost. The open deck is not one of them. Instead it's the last thing to worry about with just any platform. N54 is making north of 1000 and the deck is fine. With N55, I'll say (or conclude) that the turbo is by far the weakest point (that can cause a major fail).

N55 has so limited turbo options because of 1) hot half and manifold in one piece design, and 2) a bottom mounted turbo layout.

There is no hybrid turbo that makes power and runs reliably at above 20psi (middle and upper range). Doing so in long term you're pretty much committed to killing your turbine with the ridiculously high exhaust manifold pressure and EGT. And that's even for the best scenario assuming everything else is done right.

As a good example, one of my n55 buddy just broke his turbine, after 35000km (22k miles) on PS2. There was a short length of time years ago he's running 22psi on meth. But most of time, just logging different pump gas maps from 14-18psi. Other times, used a daily commuter.

He's one of luckier ones, because of his rich tuning knowledge of this platform and 'did everything else right'.

Every platform sees its limit one way or another but people believe what they want and push beyond it. In N55's case, especially with the M2, the limitation is just much closer to stock power than many think.

That being said, everyone has different criteria and priorities, in the end, whatever makes the owner happy matters.

I'll participate OP's questionnaire, but have only one thing to say - Seeing 430whp with STG2 hybrid on pump gas, I already think it's too much power for a N55.

Pardon my broken English:

[Yellowflash21]

So the issue was that he wasn't running upgraded HPFP?

[ZM2]

Good input as always SeanWRT

How far would you push the Dinan turbo before it’s out of its efficiency zone and generating too much heat?

I’ll likely upgrade the HPFP so I can reliably run E30-50, and get a dyno tune to go with it, before upgrading the turbo to something larger than the Dinan.

Although, I’m already generating too much heat on 90F+ track days and have to start driving the car easier after 10 laps to bring oil & coolant temps back down. Would a larger turbo really have much impact in reducing heat in the 18-20psi range?

Thanks!

[M2OG]

Sean,
What are we seeing in that photo? Oil blow by on the compressor?

[SeanWRT]

Originally Posted by Yellowflash21

So the issue was that he wasn't running upgraded HPFP?

Irrelevant.

Originally Posted by ZM2

Good input as always SeanWRT

How far would you push the Dinan turbo before it's out of its efficiency zone and generating too much heat?

I'll likely upgrade the HPFP so I can reliably run E30-50, and get a dyno tune to go with it, before upgrading the turbo to something larger than the Dinan.

Although, I'm already generating too much heat on 90F+ track days and have to start driving the car easier after 10 laps to bring oil & coolant temps back down. Would a larger turbo really have much impact in reducing heat in the 18-20psi range?

Thanks!

The heat you're seeing with your car is at the cold end where compressor is working inefficiently hence more heat, reflected by IAT.

The failure I was talking about is from the hot end, where manifold/turbine housing is very restrictive and makes more back pressure and heat than turbine can take.

Larger turbine normally allows for less backpressure. But it's impossible to quantify the reliability (life circle / psi). Even if there was a probe there (in fact there is not), extensive testing is required but no one from aftermarket does that.

I don't know about the reliability at 18~20psi with STG2, but I'm sure you'd be happy with such a setup (E30+HPFP+PS2). However, 18~20psi is a tricky boost level. On one end, pump gas can't keep up. On the other, Ethanol and meth can support more. Very few really stays there, because reliability isn't normally one of the priorities when he/she is already there.

Originally Posted by Natek

Sean,
What are we seeing in that photo? Oil blow by on the compressor?

What you're seeing is the turbine breaking to stress fatigue. Pressure and Heat combined are what stresses it.

[ZM2]

Originally Posted by SeanWRT

The heat you're seeing with your car is at the cold end where compressor is working inefficiently hence more heat, reflected by IAT.

Understood. So, does switching to a PS2 reduce heat that much vs Dinan? And, do I not just end up generating as much heat (albeit, with more power), if I up the boost with a PS2?

The other consideration is lag during daily stop & go driving. There’s only a tiny bit more lag than stock with the Dinan turbo, but I’m guessing it’s pretty noticeable with the PS2.

[cecaa850]

Originally Posted by ZM2

Understood. So, does switching to a PS2 reduce heat that much vs Dinan? And, do I not just end up generating as much heat (albeit, with more power), if I up the boost with a PS2?

The other consideration is lag during daily stop & go driving. There’s only a tiny bit more lag than stock with the Dinan turbo, but I’m guessing it’s pretty noticeable with the PS2.

I never noticed any lag with the Dinan turbo until I went to a larger intercooler. I currently have stock tune and expect lag to be gone once tuned.

[ZM2]

Originally Posted by cecaa850

I never noticed any lag with the Dinan turbo until I went to a larger intercooler. I currently have stock tune and expect lag to be gone once tuned.

Let’s just say (for better and worse) I tend to pick up on little things more than most ppl. Coming from NA and supercharged cars, I thought the stock M2 had a ton of lag. Compared to other turbo cars, maybe not.

But there’s a tiny bit more lag vs stock with the Dinan turbo and I’m guessing it’s fairly noticeable with the PS2. Looking for feedback tho.

[SeanWRT]

Originally Posted by ZM2

Understood. So, does switching to a PS2 reduce heat that much vs Dinan? And, do I not just end up generating as much heat (albeit, with more power), if I up the boost with a PS2?

The other consideration is lag during daily stop & go driving. There's only a tiny bit more lag than stock with the Dinan turbo, but I'm guessing it's pretty noticeable with the PS2.

Making same boost especially high boost, PS2 will reduce heat from Dinan on both cold and hot end with less shaft speed and backpressure.

Dinan turbo is virtually no more lag from stock. That I 100% confirm, from road testing, datalog and dyno sheet (see attached 4th gear pull on dyno, same day). That being said, stock turbo is a bit lag in the first place like you said.

PS2 has noticeably more lag everywhere, even on the fly. Also evidenced from log, it shows a 800~1000rpm lag from stock tested on 3rd gear. This is one of those things in life, all about give and take.

At the end of day, what's the point of having a bigger turbo? The lag - you get it on every tap of throttle, the power - how much more of it do you need in return? Once you're clear, you know if it's worth it.

Personally I'd go as far as octane supports (pump gas in my case) and pick the fastest spooling turbo for it.

[ZM2]

Thanks SeanWRT

I’d love to add more power for some of my track battles with friends that have 600-700hp on other platforms, but sounds like I’ll just have to rely on the M2’s agility and my driving skills to keep up with them, as I definitely do not want to add lag.

Now the question is simply if upgrading the HPFP and getting an E30-50 dyno tune would be worth it. Sounds like maybe not much more power than BM3 Stg 2 E30 5.8 and more heat if I plan to stick with the Dinan turbo.

Sorry if this thread jacked some, but inevitably these points would come up in discussion.

[TemjinX2]

hmm given the limits seanwrt stated about hybrid turbos...maybe in the long run people are better off with the big turbo conversion kits just running less boost to make them streetable.

i was thinking of maybe down the line of going with a speedtech or big boost kit and go with a slightly larger turbo then i need and run less boost. That why i'll have more power up top but less on the bottom end so i have less issues with tire spin.

[Endeav]

From someone who has tracked this PS2 setup multiple times running anywhere from 18 to 22 PSI on the turbo, I have to say the "lag" component seems to be way over exaggerated in this thread... Even moreso when discussing track (road racing) performance.

The PS2 turbo makes 400 ft/lbs of torque at 3500 RPM if you look at my dyno graph. If you look at the dyno graph SeanWRT posted and compare that to my PS2 dyno graph you can see that it's really not that much different. Let's just take two points into consideration here when comparing the two graphs. One on spool up, the other as a "peak" value.

• SeanWRT makes 500 Nm (368 ft-lbs) of torque at 2600 RPM. I make the same torque value at 2900 RPM. That's a 300 RPM difference lol. You're not going to feel that on the track.
• SeanWRT makes his peak torque of 540 Nm (400 ft-lbs) at 3500 RPM, and at 3500 RPM my PS2 turbo is making 664 Nm (490 ft-lbs)

Now yes, I am running way more air through my manifold than SeanWRT is, so it's not an exact apples to apples comparison but it just goes to show that the two turbos are really not that much different in the low end with regards to how much power they make and how responsive they are.

Where the turbo really shines is the top end power which is definitely felt on a road-race track. If you compare the two graphs again you can see that by red-line, SeanWRT's turbo is barely making 300 ft-lbs of torque to the wheels. The PS2 on the other hand is making 400 ft-lbs. This difference is even more in the mid-range of 3500 - 5500 RPM. Yes, there is definitely a difference in how hard the torque hits at low RPM (< 3000 RPM) but how often are you really at that RPM on a road-racing track? Not to mention, should you really be going wide-open-throttle at such a low RPM in a turbo vehicle? If you're driving appropriately and down-shifting into the corners and coming out at higher RPM, the added "lag" of the PS2 turbo is never felt.

Let it be clear, I am definitely not arguing the fact of efficiency when running "high" boost through a hybrid turbo - I personally feel that 18 - 22 PSI is the sweet spot with the PS2 turbo, anything more and you're probably going to gain some power, but ultimately end up throwing way more heat into the mix as well as back pressure. That's been proven on hybrid turbos across multiple platforms. No argument there.

[ZM2]

Thanks Endeav

I’m mostly concerned about additional lag in the constant stop and go traffic we experience here in the DC area. So, low RPM, short on/off part throttle applications.

[Track/S]

Hybrid turbo stage2
B58 hfpf
Walbro lpfp
Tmap 3.5bar
Downpipe
XXL intercooler
1.4bar
Ron 98
Custom tune
460hp 610nm
Spools like a Diesel car.



Now 1.55bar, pull something stronger.

[SeanWRT]

Originally Posted by Endeav

From someone who has tracked this PS2 setup multiple times running anywhere from 18 to 22 PSI on the turbo, I have to say the "lag" component seems to be way over exaggerated in this thread... Even moreso when discussing track (road racing) performance.

The PS2 turbo makes 400 ft/lbs of torque at 3500 RPM if you look at my dyno graph. If you look at the dyno graph SeanWRT posted and compare that to my PS2 dyno graph you can see that it's really not that much different. Let's just take two points into consideration here when comparing the two graphs. One on spool up, the other as a "peak" value.

• SeanWRT makes 500 Nm (368 ft-lbs) of torque at 2600 RPM. I make the same torque value at 2900 RPM. That's a 300 RPM difference lol. You're not going to feel that on the track.
• SeanWRT makes his peak torque of 540 Nm (400 ft-lbs) at 3500 RPM, and at 3500 RPM my PS2 turbo is making 664 Nm (490 ft-lbs)

Now yes, I am running way more air through my manifold than SeanWRT is, so it's not an exact apples to apples comparison but it just goes to show that the two turbos are really not that much different in the low end with regards to how much power they make and how responsive they are.

Where the turbo really shines is the top end power which is definitely felt on a road-race track. If you compare the two graphs again you can see that by red-line, SeanWRT's turbo is barely making 300 ft-lbs of torque to the wheels. The PS2 on the other hand is making 400 ft-lbs. This difference is even more in the mid-range of 3500 - 5500 RPM. Yes, there is definitely a difference in how hard the torque hits at low RPM (< 3000 RPM) but how often are you really at that RPM on a road-racing track? Not to mention, should you really be going wide-open-throttle at such a low RPM in a turbo vehicle? If you're driving appropriately and down-shifting into the corners and coming out at higher RPM, the added "lag" of the PS2 turbo is never felt.

Let it be clear, I am definitely not arguing the fact of efficiency when running "high" boost through a hybrid turbo - I personally feel that 18 - 22 PSI is the sweet spot with the PS2 turbo, anything more and you're probably going to gain some power, but ultimately end up throwing way more heat into the mix as well as back pressure. That's been proven on hybrid turbos across multiple platforms. No argument there.

Endeav,

first thing to clarify - the dyno plot posted in my earlier post was not my car, so I'm not comfortable with your expression. "SeanWRT makes XXX at XXX."

Second, they were all 4th gear pulls, I'm assuming yours are 5th gear. Makes about 500rpm difference.

Next, 400lbft@3500rpm doesn't mean you're going to get it in the real world. It happens only when boost is fully built from earlier rpm and WOT. In real world however, low rpm downshift to higher rpm (even if it's 5k+), you don't have instant power. Still needs a few hundred (thousand) rpm to spool.
One more example - BMW says M2 peak torque starts from 1400rpm (maybe 1700 can't remember for sure). What does it mean? It does NOT mean every time you WOT and needle past 1400, you get peak torque. Instead, it means if you hold the rpm at 1400 for as long as it take, peak torque you will eventually get.

Next, PS2 lags by about 800-1000rpm on 3rd gear, compared to stock, a hard fact. Granted, at same boost, PS2 makes more power. Keep in mind though, how lag is felt is the time between power off/little and on.
Imagine you cruise at below 2000, you're pretty much off boost completely because ps2 very likely isn't responding at all on partial throttle at that range. Smaller turbine from stock turbo already is spooled a little (remember how bmw rates full torque, given enough time as explained, at below 2k) though not enough to make boost. It's going to make a crucial difference on how lag is perceived in real world - when applying pedal, ps2 is less ready in the first place, on top of being slower in building boost.

Lastly. In the end, how much of perceived lag comes down to how and where the car is driven. F1 car makes 700hp from turbocharged 1.6L today. It'd be laggy AF on street everyone should realize, but no lag on track for sure. Even with our road car on street, Manhattan stop and go traffic and Midwest 50mph so called bumper to bumper traffic are different.

Ok office I just arrived. Let's agree to disagree.

[Endeav]

Originally Posted by SeanWRT

Endeav,

first thing to clarify - the dyno plot posted in my earlier post was not my car, so I'm not comfortable with your expression. "SeanWRT makes XXX at XXX."

Second, they were all 4th gear pulls, I'm assuming yours are 5th gear. Makes about 500rpm difference.

Next, 400lbft@3500rpm doesn't mean you're going to get it in the real world. It happens only when boost is fully built from earlier rpm and WOT. In real world however, low rpm downshift to higher rpm (even if it's 5k+), you don't have instant power. Still needs a few hundred (thousand) rpm to spool.
One more example - BMW says M2 peak torque starts from 1400rpm (maybe 1700 can't remember for sure). What does it mean? It does NOT mean every time you WOT and needle past 1400, you get peak torque. Instead, it means if you hold the rpm at 1400 for as long as it take, peak torque you will eventually get.

Next, PS2 lags by about 800-1000rpm on 3rd gear, compared to stock, a hard fact. Granted, at same boost, PS2 makes more power. Keep in mind though, how lag is felt is the time between power off/little and on.
Imagine you cruise at below 2000, you're pretty much are off boost completely because ps2 big turbine very likely isn't responding to exhaust gas at all on partial throttle. Smaller turbine from stock turbo already working though not enough to make boost. A crucial difference on how lag is perceived in real world.
When applying pedal, ps2 is less ready in the first place, on top of being slower in building boost.

Lastly. In the end, it comes down to how and where the car is driven. F1 car makes 700hp from turbocharged 1.6L. Laggy AF on street everyone should realize, but no one talks about lag on track. Even on street, Manhattan stop and go and Midwest 50mph so called bumper to bumper are different.

Ok office I just arrived. Let's agree to disagree.

Didn't mean to come off stand-offish at all by using your user ID when discussing the dyno plots. I just assumed that was your dyno graph and used it as a point of reference. My fault for assuming - sorry!

As someone who has driven a PS2 car for over a year and clocked many kilometers on this setup I have to say dyno plots and datalogs don't know really show how responsive this turbo truly is. Real world performance is completely different than a set of numbers on a graph or spreadsheet. I agree, at 2000 RPM if I tried to floor it I would be lagging behind and be unable to experience the true power this turbo offers - 100% agree.

What I disagree with is that you're saying at > 5000 RPM the turbo is still laggy. I have to say, any time I'm above 3500 RPM and floor it, the turbo builds boost insanely quick and absolutely destroys the tires... there's no shortage of torque.

Agree to disagree

[jr_spectref22]

Originally Posted by 5thGearPinned

Pure Stage 2. Car is FBO with 2 step colder spark plugs (No cai), BC coil overs, also the first M2 in the USA with Pure full turbo inlet pipe - shout out to @Soofy619!
Not dynod yet
18psi
MHD Custom Flash
CA 91ron with 3 gallons of VP 100ron
Want to upgrade to Xdi ASAP!
No Meth
Install performed by 2M in San Diego CA
About 3k on turbo setup

As I did the opposite of what most M2 owners are doing (power before cosmetic mods), I really want to do the HPFP upgrade, its just very costly and I want to add some carbon to the exterior and maybe new wheels soon. However the car really needs better fueling and while the turbo made a HUGE difference in overall power and top end grunt, I'm not getting the most out of this setup with the stock fuel pump. Car runs amazing in the cold. Curious how the OP likes his current setup? Debating LPFP, Precision RW coils and going full E85. Once I do the fuel pump, might finally buy a cat back exhaust as I'm running catless dp with the oem catback. Wheels, cf body kit, some subtle vinyl accents and ill probably be done with this build.

Took my FBO M235i to Soofy and 2M over the summer and it came back with and it came back with a PS2 turbo! Running BM3 Stage 2H E30 octane tune. Waiting to get my hands on a HPFP and bring it back to Soofy for more power.

[Raymondo1234]

Bmw m235 xdrive

Pure stage 2

506whp on e50

23 psi peak

Xdi 35 pump and lpfp upgrade

Precision raceworks coils

TTFS instal

Xhp stage 3 flash



Done 14000 miles on the turbo, no problems whatsoever.

Been playing about with xdelete, I feel I need a dedicated summer tyre to continue down that path (using all season atm) so turned it back on for the time being.

[cmb570]

subscribing..
thinking of going pure stage 2

[425M2]

What turbo do you have? Pure Stage 2 Gen 3
Dyno whp and type of dyno? Not dyno'd yet.
How many lbs/psi boost? Running base map currently from Cary Jordan
What tune are you running? BM3 Custom tune by Cary Jordan (currently running base tune, need to send logs to him)
What fuel are you using? 92 oct WA State pump gas
Do you have an upgraded fuel pump? If so, which one? Yes, TTFS XDi-35
Are you using meth? Nope
Who did your install? Achtuning in Redmond, WA. Awesome shop!
How many miles have you put on it? Car has 18k miles on it (2017 M2), turbo has about 50 miles on it
Any comments, things you would have done differently, future mods? Future mod would be to add a race gas map

Will update as I can fill in some of the missing items.

[5thGearPinned]

Originally Posted by jr_spectref22

Took my FBO M235i to Soofy and 2M over the summer and it came back with and it came back with a PS2 turbo! Running BM3 Stage 2H E30 octane tune. Waiting to get my hands on a HPFP and bring it back to Soofy for more power.

Nice! I’m not able to run any ethanol on this setup. Curious to hear more feedback from everyone running upgrades fuel pumps and also wether they ran the upgraded turbo with the Oem HPFP and how driveability is affected with the upgrade. Guys running ethanol, did you upgrade the Lpfp or does it flow adequately with E blends?

[Byeung]

How much power would I make if I run a stage 2 turbo with an upgraded HPFP?