[ZM2]

SeanWRT

It seems counterintuitive (initially), but after being on many tracks I’ve found temps are lower on “high hp” tracks with long straights bc of increased airflow.

The Shanghai F1 track has two very long straights, and one is 1200m. The tracks I’m mentioning are much tighter and have straights of <500m and top speeds of 120mph. Those tracks are much more taxing on cooling than those like Watkins Glen where we hit 150mph.

[Karmic Man]

Originally Posted by Karmic Man

Mods, I think this thread should be moved to the N55 Engine / Drivetrain / Exhaust / Bolt-ons / Tuning section

Originally Posted by F87source

Well it's mostly n55 now, but we're still investigating (waiting to see an m3/m4) in person) of underbody oil cooler like the s55. But currently we're placing two aux radiators in the bumper cutouts like in the m2C. This thread was only posted in the s55 section in hopes of guys with m2C or s55 engine cars could chime in.

M2Cs are just starting to be delivered...

If you want pointers from S55 guys the M3/M4 section is the best bet

[F87source]

Originally Posted by ZM2

SeanWRT

It seems counterintuitive (initially), but after being on many tracks I’ve found temps are lower on “high hp” tracks with long straights bc of increased airflow.

The Shanghai F1 track has two very long straights, and one is 1200m. The tracks I’m mentioning are much tighter and have straights of <500m and top speeds of 120mph. Those tracks are much more taxing on cooling than those like Watkins Glen where we hit 150mph.

+1

Originally Posted by Karmic Man

M2Cs are just starting to be delivered...

If you want pointers from S55 guys the M3/M4 section is the best bet

Well then this thread will be good for when the time comes as we are actually brain storming some really good ideas. Most of the stuff regarding the S55 I now am able to grasp fairly well, just the tiny nuisances like fitment and mounting is still fuzzy. But in regards to making this work on an m2 the m3/m4 guys cannot help me with that as the questions are mostly fitment on the F87 chassis, so that's why this thread is best suited here.

So if you do not have any other ideas that can help contribute to the m2's cooling performance, I will politely have to ask you to refrain from commenting off topic material here as you are derailing this thread from its actual intent.

[SeanWRT]

Originally Posted by F87source

First off what mods do you have (sorry I'm not familiar with your build).

Second how many WOT laps did you put in, and how long was the run time? That's a pretty important question as the longer you push the higher the temps start to go as the cooler start to heat soak.

Some of us here can still overheat the car without pushing it to the limit of the hardware, like around 450ish whp I got my former m235i to over heat on a stage 2 turbo even with PI and fully upgraded cooling.

The only way to truly get back pressure low is to get a stage 3 turbo fold as the stock one from what I have heard is really restricting. I had water Injection (it really helps with cylinder temps) to keep my incylinder temps low and thus egts low, it still wasn't enough.

In terms of tuning I and most others here have or plan to have full custom tunes by reputable tuners and not off the shelf maps, so that won't be a problem.

In terms of timing vs boost, I don't like leaning one way vs another. I like having it tuned for optimizing both boost and timing to create the most amount of power at a particular octane level while being conservative enough to account for variations in fuel quality. Because with too much timing it's still going to add heat as the Piston will just be able to compress the gas minute more before ignition, thus increasing cylinder temps. Either way balance imo is much more important than leaning one way vs. the other.

Hi F87source,

I assume you moved from M235 to M2, you must know how much easier it is for M2 to hold boost up top on stock turbo, compared to M235. One step further - there are far more M235/335/435i than M2 out there going flat out with PS2/Meth/Ethanol on BEF stacked with JB4. Yet M2 put down noticeably better numbers given the same mods.

What makes the difference is the slightly freer flow manifold M2 comes from factory with.

With our platform, backpressure is first stock turbine then manifold. The same can even be said to lesser N55 EWGs.

The slightly freer flow M2 stock manifold is actually not too restrictive for the boost we are, or at least I am, running on track. Below is a log in case you want to know.
http://www.bootmod3.net/log?id=5b38d28fd10b437334792d1b

Stock turbo would be pulling down timing to the ground at 18~19psi up top, even with same IAT and octane. Why? Difference in backpressure.

I have yet to put it on a roller but if my car as is didn't make 450 it's close, if the fact last year we saw 410+whp with STG1 turbo with slightly less boost (ZCP stock made 396whp same day) is any indication.

You were with fueling upgrade and meth, probably you're pushing engine harder than I am to get 450whp, probably 20ish psi of boost. There you are, where M235i exhaust manifold starts to choke the engine and makes ton of backpressure and heat. TBH, I don't see any 235/335/435 can survive track if boost is high enough to require additional fueling to support rail pressure.

As for boost vs timing - when it comes down to make maximum power, there is indeed no leaning to one or another. But if you want to run cooler, consistently and reliably, you have to pick timing over boost. But that's not saying you need to target 15 degrees up top. 10~12 degree is where N55 is very happy.

As for track - The most recent HPDE I did was on Aug 26. It was an extremely tough one. Instructor let us do 6 30-min sessions in a row, 10 min break in between. I pushed to my limit most of time and my best time was 2:38.XX. The M car record there is 2:22, set by a BMW driver with F90 on a much cooler day early this year, see below link. Granted I'm not a pro racer, but not an average driver either.
https://www.motor1.com/news/225201/b...ai-lap-record/

Lastly, I do agree with ZM2 that high speed track may be taxing less on cooling due to air flow. But SH F1 is tough I guarantee you that. I saw a few times stock M4 went into limp mode. No one, absolutely no one, can survive it with piggyback, if he or she is working hard there.

[F87source]

Originally Posted by SeanWRT

Hi F87source,

I assume you moved from M235 to M2, you must know how much easier it is for M2 to hold boost up top on stock turbo, compared to M235. One step further - there are far more M235/335/435i than M2 out there going flat out with PS2/Meth/Ethanol on BEF stacked with JB4. Yet M2 put down noticeably better numbers given the same mods.

What makes the difference is the slightly freer flow manifold M2 comes from factory with.

With our platform, backpressure is first stock turbine then manifold. The same can even be said to lesser N55 EWGs.

The slightly freer flow M2 stock manifold is actually not too restrictive for the boost we are, or at least I am, running on track. Below is a log in case you want to know.
http://www.bootmod3.net/log?id=5b38d28fd10b437334792d1b

Stock turbo would be pulling down timing to the ground at 18~19psi up top, even with same IAT and octane. Why? Difference in backpressure.

I have yet to put it on a roller but if my car as is didn't make 450 it's close, if the fact last year we saw 410+whp with STG1 turbo (ZCP stock made 396whp same day) is any indication.

You were with fueling upgrade and meth, probably you're pushing engine harder than I am to get 450whp, probably 20ish psi of boost. There you are, where M235i exhaust manifold starts to choke the engine and makes ton of backpressure and heat. TBH, I don't see any M235i can survive track if his or her builds need additional fueling to properly run.

As for boost vs timing - when it comes down to make maximum power, there is indeed no leaning to one or another. But if you want to run cooler, consistently and reliably, you have to pick timing over boost. But that's not saying you need to target 15 degrees up top. 10~12 degree is where N55 is very happy.

As for track - The most recent HPDE I did was on Aug 26. It was an extremely tough one. Instructor let us do 6 30-min sessions in a row, 10 min break in between. I pushed to my limit most of time and my best time was 2:38.XX. The M car record there is 2:22, set by a BMW driver with F90 on a much cooler day early this year, see below link. Granted I'm not a pro racer, but not an average driver either.
https://www.motor1.com/news/225201/b...ai-lap-record/

Lastly, I do agree with ZM2 that high speed track may be taxing less on cooling due to air flow. But SH F1 is tough I guarantee you that. I saw a few times stock M4 went into limp mode. No one, absolutely no one, can survive it with piggyback, if he or she is working hard there.

Thanks for the reply man I appreciate it, I heard some turbo manufacturers say that the m2 turbo is nearly the same as the regular n55 turbo, just some small tweaks to the housing or something. So I do not know if the exhaust manifold has been ported to be more free flowing. I will put a bore scope down the manifold when I decide to pull my turbo, it will probably be soon next year or maybe in two years. I live in Canada so winter is definitely coming soon so there is no point in modding the car now as itll be in storage soon. Plus i'd rather get some new wheels, suspension, and cooling before I look at power to make the car more track reliable.


Next, I read your thread on the German G power turbo and am pretty intrigued as im only aiming for 450-475 whp so I'd prefer spool over max power just as you described. But the only issue is that a G power turbo shipped to me in Canada after the conversion rate is absolutely insanely expensive, towards stage 3 turbo money. So that's probably not going to happen.

Anyways thanks again for the reply, please let us know what else you think we can do to improve the m2's cooling.

[SeanWRT]

My opinion as to how to improve M2 cooling is,
1) Upgraded radiator and auxiliary cooler
2) A map that fits track use
3) STG2 turbo to reduce backpressure
All 3 above are equally effective. If all is done and you're still overheating it, you're making too much horsepower for this platform.

BTW, if you want STG3 turbo and factory waste gate at the same time, only option is ACF turbo kit which is 9K USD. Not many have been running it on the road and not many will in the future due to cost. IMO, it's too much of a risk reliability wise. Other STG3s will throw factory fine control out of window you don't even know if drivability is there, no mention you're limited to turbo supplier for tuning - even bigger risk. Think about it, all of those for just cooling...

That's why PS2 of USA is popular.

Originally Posted by F87source

Thanks for the reply man I appreciate it, I heard some turbo manufacturers say that the m2 turbo is nearly the same as the regular n55 turbo, just some small tweaks to the housing or something. So I do not know if the exhaust manifold has been ported to be more free flowing. I will put a bore scope down the manifold when I decide to pull my turbo, it will probably be soon next year or maybe in two years. I live in Canada so winter is definitely coming soon so there is no point in modding the car now as itll be in storage soon. Plus i'd rather get some new wheels, suspension, and cooling before I look at power to make the car more track reliable.


Next, I read your thread on the German G power turbo and am pretty intrigued as im only aiming for 450-475 whp so I'd prefer spool over max power just as you described. But the only issue is that a G power turbo shipped to me in Canada after the conversion rate is absolutely insanely expensive, towards stage 3 turbo money. So that's probably not going to happen.

Anyways thanks again for the reply, please let us know what else you think we can do to improve the m2's cooling.

[F87source]

Originally Posted by SeanWRT

My opinion as to how to improve M2 cooling is,
1) Upgraded radiator and auxiliary cooler
2) A map that fits track use
3) STG2 turbo to reduce backpressure
All 3 above are equally effective. If all is done and you're still overheating it, you're making too much horsepower for this platform.

BTW, if you want STG3 turbo and factory waste gate at the same time, only option is ACF turbo kit which is 9K USD. Not many have been running it on the road and not many will in the future due to cost. IMO, it's too much of a risk reliability wise. Other STG3s will throw factory fine control out of window you don't even know if drivability is there, no mention you're limited to turbo supplier for tuning - even bigger risk. Think about it, all of those for just cooling...

That's why PS2 of USA is popular.

Hey thanks for your reply.

First off I don't believe a stage 2 turbo would net any sort of back pressure reduction. Because it's on the stock manifold which is the major bottle neck not really the exhaust wheel. Also since you're flowing more air with the larger turbo, more air must pass through the restrictive exhaust manifold thus, imo, increasing back pressure.

Next in regards to the stage 3 turbo. There are only no off the shelf maps available, but if you go custom tuned then there is no need to worry about finding a map. Clearly this is the option you want to go with if you want a true custom map for your car and tuned for track conditions specific to you, not some canned one size fits all tune. Anyone that knows how to use tuner pro and has a good reputation tuning can make you a map. I have a local guy here where I live who tunes 1000+ whp gtrs daily for a living. He also tunes Trac focused cars, and has certifications for nearly all the popluar standlone ecus + popular tuning software (like Cobb + ecutek).

I believe you're misinformed regarding the waste gate on the stage 3 turbos as the speedtech kit ustilized the factory electronic waste gate. When it's tuned properly and recalibrated for the larger waste gate the factory boost control works fine. Drivability according to alot of owners is fine, and Jeff is a stand up guy he won't leave you stranded.

[SeanWRT]

Originally Posted by F87source

Hey thanks for your reply.

First off I don't believe a stage 2 turbo would net any sort of back pressure reduction. Because it's on the stock manifold which is the major bottle neck not really the exhaust wheel. Also since you're flowing more air with the larger turbo, more air must pass through the restrictive exhaust manifold thus, imo, increasing back pressure.

Next in regards to the stage 3 turbo. There are only no off the shelf maps available, but if you go custom tuned then there is no need to worry about finding a map. Clearly this is the option you want to go with if you want a true custom map for your car and tuned for track conditions specific to you, not some canned one size fits all tune. Anyone that knows how to use tuner pro and has a good reputation tuning can make you a map. I have a local guy here where I live who tunes 1000+ whp gtrs daily for a living. He also tunes Trac focused cars, and has certifications for nearly all the popluar standlone ecus + popular tuning software (like Cobb + ecutek).

I believe you're misinformed regarding the waste gate on the stage 3 turbos as the speedtech kit ustilized the factory electronic waste gate. When it's tuned properly and recalibrated for the larger waste gate the factory boost control works fine. Drivability according to alot of owners is fine, and Jeff is a stand up guy he won't leave you stranded.

Hi F87source,

Bigger turbine from STG2 turbo reduce backpressure in the following three ways:
1) It needs less shaft speed to produce any given flow/boost. Turbo shaft speed is in direct (or more) proportion to backpressure. It's significant and the number one reason.

2) Due to enlarged turbine diameter, you need less force from exhaust gas to make same moment of force, driving the turbine. Meaning exactly less backpressure. Think of it as when you ride a bike - longer the pedal arm is, less force you need to move it.

3) Turbine blade pitch can make a big difference. More area getting hit by exhaust mean quicker spool up and more backpressure. STG2 modified turbine tend to have a freer flowing blade pitch. Varying turbine blade pitch by rpm is exactly the whole idea behind VTG turbo used by Porsche, to make greater backpressure at low rpm for quicker spool and less backpressure for when turbo is spooled up.

No one conducted a scientific research at which point, N55 manifold or turbine becomes restriction first. You can't point finger to manifold just because it's upstream of turbine.

The truth we can definitely tell is, at 16+psi up top with factory turbo/turbine, ignition timing becomes unstable at above 90F on pump gas. But upgrading to STG2 turbo making same 16psi, even with same IAT (same air density), engine is happy to the moon. A clear sign of backpressure reduced. I can show you tons of logs to support my claim, either my car or my buddies'.

I can come to conclusion - turbine is the first restriction, then manifold. Manifold is restrictive at somewhere above 20psi, where I for one do not want to stay at all. Pump gas & stock fueling cannot handle anyway.

With regard to ST STG3 kit, I was following their progress pretty closely in 2017, and it's very obvious they used external waste gate. If any change was made in 2018, I am not aware. It'd be a huge improvement to have factory EWG.

[F87source]

Originally Posted by SeanWRT

Hi F87source,

Bigger turbine from STG2 turbo reduce backpressure in the following three ways:
1) It needs less shaft speed to produce any given flow/boost. Turbo shaft speed is in direct (or more) proportion to backpressure. It's significant and the number one reason.

2) Due to enlarged turbine diameter, you need less force from exhaust gas to make same moment of force, driving the turbine. Meaning exactly less backpressure. Think of it as when you ride a bike - longer the pedal arm is, less force you need to move it.

3) Turbine blade pitch can make a big difference. More area getting hit by exhaust mean quicker spool up and more backpressure. STG2 modified turbine tend to have a freer flowing blade pitch. Varying turbine blade pitch by rpm is exactly the whole idea behind VTG turbo used by Porsche, to make greater backpressure at low rpm for quicker spool and less backpressure for when turbo is spooled up.

No one conducted a scientific research at which point, N55 manifold or turbine becomes restriction first. You can't point finger to manifold just because it's upstream of turbine.

The truth we can definitely tell is, at 16+psi up top with factory turbo/turbine, ignition timing becomes unstable at above 90F on pump gas. But upgrading to STG2 turbo making same 16psi, even with same IAT (same air density), engine is happy to the moon. A clear sign of backpressure reduced. I can show you tons of logs to support my claim, either my car or my buddies'.

I can come to conclusion - turbine is the first restriction, then manifold. Manifold is restrictive at somewhere above 20psi, where I for one do not want to stay at all. Pump gas & stock fueling cannot handle anyway.

With regard to ST STG3 kit, I was following their progress pretty closely in 2017, and it's very obvious they used external waste gate. If any change was made in 2018, I am not aware. It'd be a huge improvement to have factory EWG.

I see, thanks for the info. All I have ever seen regarding the manifold being restricting was a cut out of the turbo show casing the extremely small holes where exhaust gases must flow through for cylinder 4-6. There was alot of engine efficiency and fluid Dynamics being discussed (I'm not an engineer so I cannot comment too much on this) in another forum.


But in regards to stage 3 turbos, the speed tech kit and the efr series of turbo that they use are internally waste Gates and have always been. The just changed out the pneumatic solenoid and added a bracket for the EWG actuator for ewg cars, which is how it's always been iirc from day one. No mac solenoid was ever needed for the F series, that was on one other kit.


Do you have any spool data of ps2 vs the g power turbo?

[SeanWRT]

Originally Posted by F87source

I see, thanks for the info. All I have ever seen regarding the manifold being restricting was a cut out of the turbo show casing the extremely small holes where exhaust gases must flow through for cylinder 4-6. There was alot of engine efficiency and fluid Dynamics being discussed (I'm not an engineer so I cannot comment too much on this) in another forum.


But in regards to stage 3 turbos, the speed tech kit and the efr series of turbo that they use are internally waste Gates and have always been. The just changed out the pneumatic solenoid and added a bracket for the EWG actuator for ewg cars, which is how it's always been iirc from day one. No mac solenoid was ever needed for the F series, that was on one other kit.


Do you have any spool data of ps2 vs the g power turbo?

Banks are not remotely as small as how the pictures you saw wanted you to believe. You also needs to factor in our divided(twin scroll) turbo inlet which is 4.5", there is only so big you can go with each bank of manifold. I have more but I am not digging deeper into this here. Just one thing don't worry about manifold at all before you go above 20psi. For me I wouldn't bother with that high boost with a N55 to begin with.

PS2 spools 500+rpm slower than GP500 BTW.

[F87source]

Originally Posted by SeanWRT

Banks are not remotely as small as how the pictures you saw wanted you to believe. You also needs to factor in our divided(twin scroll) turbo inlet which is 4.5", there is only so big you can go with each bank of manifold. I have more but I am not digging deeper into this here. Just one thing don't worry about manifold at all before you go above 20psi. For me I wouldn't bother with that high boost with a N55 to begin with.

PS2 spools 500+rpm slower than GP500 BTW.

Well good to know, I did hear the photos were misleading but I'll look into it myself if I ever get a chance to, via borescope if it'll reach that far into the manifold. I'm not worried at all about high boost applications as I'm building it for the track and care more about power delivery. Well I'll take your advice on it and swing with another stage 2 turbo, hopefully the m2's manifold is more free flowing than regular n55's.

I wish I could get the GP500 but as I said before after conversion rate + shipping to Canada it's stage 3 turbo pricing.

[F87source]

TYSP33D Saw your instagram post man! how was the track day? Do have any data to report?

(Saw your instagram live video as well it was sweet! I wish it had the data overlays like last time though lol)

[m2_coop]

Bringing this back from the dead

F87source did ever get the secondary aux radiator installed? If so I'm wondering if you could share the routing you used to plumb it.

Also did you end up getting the cross-over line that TYSP33D used?

[F87source]

Originally Posted by m2_coop

Bringing this back from the dead

F87source did ever get the secondary aux radiator installed? If so I'm wondering if you could share the routing you used to plumb it.

Also did you end up getting the cross-over line that TYSP33D used?

No. The m2 already has that cross over line no need to buy another one.