F80 M3 / F82 M4 S55 Tuning

[Savory]

If the S55 is capable of 600+whp (doubtful, but who knows, n54 did eventually) it ruins the balance of the car anyways. What is more relevant is how it responds to more common mods like downpipes/full exhaust, intakes, and ECU flashes. Let's hope Dinan eventually sells shorter final drive gearing, think it would be a monster if it could stay in its powerband up top

[mkoesel]

The S55 has identical compression ratio and displacement to the N54 and N55. It has two mono-scroll turbos that appear to be very similar to those used by the N54. Like the N55 it has Valvetronic which the N54 lacked. It also has a new closed deck block and stronger forged crankshaft that the other two engines do not have, and it is designed to run 600 RPM higher than those engines as well.

With that in mind, it is my guess that the S55 will be able to at least equal the highest output FBO tuned N54s out there, when modified similarly. Those are at, what, 470 whp or thereabouts?

[Tiago@VRSF]

The closed deck block is the biggest improvement over the N54/55 when looking to make big power.

[Robin_NL]

Originally Posted by mkoesel

The S55 has identical compression ratio and displacement to the N54 and N55. It has two mono-scroll turbos that appear to be very similar to those used by the N54. Like the N55 it has Valvetronic which the N54 lacked. It also has a new closed deck block and stronger forged crankshaft that the other two engines do not have, and it is designed to run 600 RPM higher than those engines as well.

With that in mind, it is my guess that the S55 will be able to at least equal the highest output FBO tuned N54s out there, when modified similarly. Those are at, what, 470 whp or thereabouts?

Well said. On a sidenote: The N54 has a forged crankshaft which the N55 doesn't have.

Cheers
Robin

[swamp2]

Originally Posted by mkoesel

The S55 has ... a new closed deck block and stronger forged crankshaft that the other two engines do not have

Incorrect. The N54 has a forged crankshaft. The N55 unfortunately downgraded to a cast unit, most likely for cost reasons.

Edit: Sorry Robin missed your reply just above^.

[mkoesel]

My mistake on the crankshaft - I remember reading debates on the topic with people who had torn them down claiming it was cast. Perhaps there was a change later in production? That would not be unheard of.

In any case the S55 has a forged crank either way. Not sure if it is a new design or a carry over from the N54.

[Boss330]

Originally Posted by solstice

Boss330 do you know the boost for these tunes?
Remember the N54 has the same CR as the S55 but run very low boost giving it high tuning potential on stock fuel. You have to check the combination of CR and boost. The S55 is high on both making me doubt that there is much more to be have on stock fuel. You can of course get more hp on the same boost but that means higher rpm and that in turn means large blowers that can generate the large air volume needed to support the pressure at high rpms.

No I don't know the boost levels, but a rule of thumb is that a boost of 0,5bar is a 50% increase in power. At 0,5 bar a 2l engine is as powerful as a 3l engine (at a similar state of tune). So a 100hp engine makes 150hp at 0,5bar boost (less in the real world as compressing air creates heat which makes the air less dense, hence intercoolers).

But I don't get your logic on the N54 vs S55 comparison.
The N54 makes 300hp at 0,5 bar boost
The S55 makes 430hp at a undisclosed boost level (assuming both engines have stated hp according to DIN/ISO/EU standards)

Both have the same CR.

My guess would be that the S55 makes 430hp at 0,9-1bar of boost. A tuned N54 will also be at those boost levels if tuned to 400+hp.

If the N54 can make 6-700hp at the same CR as the S55, I don't understand why the S55 shouldnt also be able to do the same?

[solstice]

Originally Posted by Boss330

No I don't know the boost levels, but a rule of thumb is that a boost of 0,5bar is a 50% increase in power. At 0,5 bar a 2l engine is as powerful as a 3l engine (at a similar state of tune). So a 100hp engine makes 150hp at 0,5bar boost (less in the real world as compressing air creates heat which makes the air less dense, hence intercoolers).

But I don't get your logic on the N54 vs S55 comparison.
The N54 makes 300hp at 0,5 bar Fboost
The S55 makes 430hp at a undisclosed boost level (assuming both engines have stated hp according to DIN/ISO/EU standards)

Both have the same CR.

My guess would be that the S55 makes 430hp at 0,9-1bar of boost. A tuned N54 will also be at those boost levels if tuned to 400+hp.

If the N54 can make 6-700hp at the same CR as the S55, I don't understand why the S55 shouldnt also be able to do the same?

I searched for it and the highest boost I found for a Switzer tune on street gas was 20 psi. Do you have boost numbers for a 700 hp N54 on street fuel and stock turbos?

Again you can get more power with the same psi and CR but then you need to support full boost at higher rpms. I don't think the small mitsus can generate the volume needed for that. I could be wrong and that the turbos has more capacity and better intake and cat less DPs would allow for the flow needed at higher rpms, still this is more costly mods and this is an M car so I think BMW has pushed the limits quite well.

I'm suspecting that the S55 is close to max combustion pressure allowed by street gas and also generates that pressure as high up in the rev range it turbos can manage. There is likely a small gap left but this is no N55 or N63 where you can just double the boost with a flash tune and reap 100 hp.

[Boss330]

Originally Posted by solstice

I searched for it and the highest boost I found for a Switzer tune on street gas was 20 psi. Do you have boost numbers for a 700 hp N54 on street fuel and stock turbos?

Again you can get more power with the same psi and CR but then you need to support full boost at higher rpms. I don't think the small mitsus can generate the volume needed for that. I could be wrong and that the turbos has more capacity and better intake and cat less DPs would allow for the flow needed at higher rpms, still this is more costly mods and this is an M car so I think BMW has pushed the limits quite well.

I'm suspecting that the S55 is close to max combustion pressure allowed by street gas and also generates that pressure as high up in the rev range it turbos can manage. There is likely a small gap left but this is no N55 or N63 where you can just double the boost with a flash tune and reap 100 hp.

Why? (To the last paragraph)

The S63 in the F10 M5 has a 10:1 CR and that engine has been tuned by Manhart to a proven 700-750hp. The S63 has a stock max boost of 1,5bar... The Manhart MHR 5/6S has a 30% increase in power over stock (560 vs 700-750). A 30% increase on the S55 is 560hp.

Why should the S55 not achieve the same gains seen on other similar engines?

[solstice]

Originally Posted by Boss330

Why? (To the last paragraph)

The S63 in the F10 M5 has a 10:1 CR and that engine has been tuned by Manhart to a proven 700-750hp. The S63 has a stock max boost of 1,5bar... The Manhart MHR 5/6S has a 30% increase in power over stock (560 vs 700-750). A 30% increase on the S55 is 560hp.

Why should the S55 not achieve the same gains seen on other similar engines?

The S55 is a similar engine to the S63TU?
It does sound like an impressive tune though. I need to look into this example because it could be the first one provided here that might support your claim of easy, large ECU flash power gains of the S55 and the ability run combustion pressure on street gas I've not been able to find other examples of alternatively that the stock turbos are capable of much more volume than that M utilizes. And it being a turbo M car makes it even more relevant but I need to see the details of the S63TU and the tune to know if it's potentially applicable to the S55. We are both speculating and using questionable science here but we should be able to still get a reasonable idea of the potential.

[Boss330]

Originally Posted by solstice

The S55 is a similar engine to the S63TU?
It does sound like an impressive tune though. I need to look into this example because it could be the first one provided here that might support your claim of easy, large ECU flash power gains of the S55 and the ability run combustion pressure on street gas I've not been able to find other examples of alternatively that the stock turbos are capable of much more volume that M utilizes.

Not easy since the last gen BMW ecu's are notoriously hard to crack. Manhart has achieved their gains partly through a ECU flash using a modified "press file" and a boost controller. I've driven the 700+ hp M5 on the Autobahn and I can attest that it pulls...

[solstice]

Originally Posted by Boss330

Not easy since the last gen BMW ecu's are notoriously hard to crack. Manhart has achieved their gains partly through a ECU flash using a modified "press file" and a boost controller. I've driven the 700+ hp M5 on the Autobahn and I can attest that it pulls...

Hehe, yeah I didn't mean easy as in cracking the ECU but easy as in BMW has left a lot of easy gains ready for taking once the cherry is popped so to say. I'm open for any counter arguments as this one but until I've seen what they've done I remain highly skeptical on the level of easy gains from the S55.

[Boss330]

Originally Posted by solstice

The S55 is a similar engine to the S63TU?
It does sound like an impressive tune though. I need to look into this example because it could be the first one provided here that might support your claim of easy, large ECU flash power gains of the S55 and the ability run combustion pressure on street gas I've not been able to find other examples of alternatively that the stock turbos are capable of much more volume than that M utilizes. And it being a turbo M car makes it even more relevant but I need to see the details of the S63TU and the tune to know if it's potentially applicable to the S55. We are both speculating and using questionable science here but we should be able to still get a reasonable idea of the potential.

I take it you are not familiar with the turbo scene?

Modern European turbo engines are high CR, like the 991 Turbo S engine. Plenty of tuning. It's not like my old Sierra RS Cosworth with a 8:1 CR...

What specs of the S63 is of relevance in your comparison with the S55?
Which part of the N55/N54 is not relevant to the S55 since you don't think it's a good comparison of a high CR tuneable engine?

One of your previous observations was that the N55 is a low boost engine and that the S55 is high boost. But remember that the N55 is 300hp and the S55 is 430hp. For the N55/54 to go to 430hp the boost needs to be as high, or higher, as exemplified by the 20psi Switzer tune. That the N54 can achieve 600hp indicates a even higher boost level. Not sure if a 600hp N54 is possible on street gas.

[Boss330]

And BTW, I have NO idea how much the turbos will support over stock. But if we assume 0,9-1bar boost to achieve 430hp at sea level and 20deg C. Then that leaves 0,25-0,35bar in "reserve". Meaning that even staying within the 1,25 bar limit there is a extra 20-30% power on tap (still being at sea level etc). That would bring us to 520-560hp...

[solstice]

Originally Posted by Boss330

I take it you are not familiar with the turbo scene?

Modern European turbo engines are high CR, like the 991 Turbo S engine. Plenty of tuning. It's not like my old Sierra RS Cosworth with a 8:1 CR...

What specs of the S63 is of relevance in your comparison with the S55?
Which part of the N55/N54 is not relevant to the S55 since you don't think it's a good comparison of a high CR tuneable engine?

One of your previous observations was that the N55 is a low boost engine and that the S55 is high boost. But remember that the N55 is 300hp and the S55 is 430hp. For the N55/54 to go to 430hp the boost needs to be as high, or higher, as exemplified by the 20psi Switzer tune. That the N54 can achieve 600hp indicates a even higher boost level. Not sure if a 600hp N54 is possible on street gas.

Familiar or not you have physical laws and limitations. The details can be complex but the basics are relatively easy. At a certain pressure fuel of a specific octane rating self combust. 220 psi is about the highest I've seen and that is regarded quite extreme. The GT2RS as we discussed runs at 207. It's CR was lowered in relation to other Porsche TT cars to allow for the 23psi boost since boost is apparently milder than CR in the equation due to the cooling of the boosted air through inter coolers' don't ask me the details. I haven't studied them.

CR without boost is of no use. You can't say that just because one high CR car can be easily tuned all can. You got to look at the combination CR x Boost psi.

Show me a car/tune that continue to gain hp when exceeding +220 CR x psi on street gas and you'll change my view. The S55 is stock at 10.2 x 18 = 183.

The S63TU has CR of 10 and 22psi putting it right at 220. This is why I'm so interrested in that 700hp tune. Did they increase peak boost or allowed for peak boost at higher rpm? Both would gain hp but the peak boost would be highly unusual as gaining that level of hp consistently and relaibly on street gas past 220 psi.

[Boss330]

Originally Posted by solstice

Familiar or not you have physical laws and limitations. The details can be complex but the basics are relatively easy. At a certain pressure fuel of a specific octane rating self combust. 220 psi is about the highest I've seen and that is regarded quite extreme. The GT2RS as we discussed runs at 207. It's CR was lowered in relation to other Porsche TT cars to allow for the 23psi boost since boost is apparently milder than CR in the equation due to the cooling of the boosted air through inter coolers' don't ask me the details. I haven't studied them.

CR without boost is of no use. You can't say that just because one high CR car can be easily tuned all can. You got to look at the combination CR x Boost psi.

Show me a car/tune that continue to gain hp when exceeding +220 CR x psi on street gas and you'll change my view. The S55 is stock at 10.2 x 18 = 183.

And as shown in my previous post it's not inconceivable that the S55 only needs 1bar to achieve the 430hp, meaning that at the 183 number we could be well over 500hp at sea level etc. Leaving lots of room for even higher boost...

[solstice]

Originally Posted by Boss330

And as shown in my previous post it's not inconceivable that the S55 only needs 1bar to achieve the 430hp, meaning that at the 183 number we could be well over 500hp at sea level etc. Leaving lots of room for even higher boost...

The N54 gains about 80 hp with a 20-22psi ( 12 psi above stock ) tune according to this chart:

http://www.e90post.com/forums/showthread.php?t=374508

Not seeing how say 4psi would add the same gains on the S55.

Btw do you know if the S63TU tune requires euro 100 octane to reach 700 hp?

[Savory]

Originally Posted by solstice

The N54 gains about 80 hp with a 20-22psi ( 12 psi above stock ) tune according to this chart:

http://www.e90post.com/forums/showthread.php?t=374508

Not seeing how say 4psi would add the same gains on the S55.

Btw do you know if the S63TU tune requires euro 100 octane to reach 700 hp?

We only have 91 octane here in Cali, and this M5 with a tune/exhaust is pretty much 700 at the crank.

http://f10.m5post.com/forums/showthr...highlight=dyno

[Boss330]

Take a different car, the A45 AMG. It has a low CR at 8,6:1 but boost at 1.8bar, creating 360hp and a 223 number (psi x CR).

There are tunes from Renntech and Carlsson at 414hp and 450hp respectively. Pushing well above the "220 max limit"...

[solstice]

Originally Posted by Boss330

Take a different car, the A45 AMG. It has a low CR at 8,6:1 but boost at 1.8bar, creating 360hp and a 223 number (psi x CR).

There are tunes from Renntech and Carlsson at 414hp and 450hp respectively. Pushing well above the "220 max limit"...

What is the psi with those tunes?
I suspect that gains are mainly made by less tapering and not by pushing peak bost. The question is, can the S55 stock turbos support less tapering?
A pure guess from me is, not much. Reasons being that minimum lag and high rpms are both M trademarks leading me to think that BMW selected small turbos and utilized most of their ability to pump air at high rpms already.

I do think they have left enough room for about a 5% or ~25hp power bump with the comp. pack. utilizing mainly peak boost ~4psi but this is just speculation.

[swamp2]

Getting back to some better discussion here. I'd like to hear from Vishnu or another respected 335i tuner about possible gains and limitations of the S55. There very likely is less margin on this engine compared to some other turbo engines due to BMW focusing on throttle response above max power. That being said, other engines do not automatically come with turbos sized with modding and huge amounts of extra boost. There is undoubtedly some room here as manufactures universally build with large safety and additional margins to deliver good longevity and performance in a wide variety of environmental conditions.

I'll send Shiv a PM.

[Boss330]

Originally Posted by solstice

What is the psi with those tunes?

I don't know the exact PSI, but you can assume it's above 1,8bar (26PSI) since that is stock boost...