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      12-16-2013, 02:09 PM   #134
Boss330
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Quote:
Originally Posted by basscadet View Post
I have no doubt the S55 engine itself is capable of developing LOTS of power provided there is a turbo mated to it that can make that kind of power. I do not question the engine, I question the turbos. The turbos on the N54 are capable of putting down over 400whp before they run out of their efficiency range. That is a SIGNIFICANT, high ceiling over the factory "300"hp which found the turbos loafing by at under 9psi.

The M3/M4 turbo stock boost will probably be anywhere between 14-18.9psi depending on humidity and altitude. If we just start at the low end in ideal conditions, a factory 14psi map can go as high as...what....20psi? 21? We don't know the flow characteristics of these turbos but my guess is that they're small and are going to have to work as hard if not harder than the N54 turbos (this is based on BMW's claims of lag-free operation and low RPM spool-up)

So no I have no hard evidence. But I have owned turbo cars for 15+ years and have modified most of them and maybe I am not providing the correct science to satisfy your inquiry but I just think it seems highly unlikely that people are going to see 50+whp from this car with a tune-only like they're seeing in the N54 world.

It is just not hard to conceive that this engine is coming from BMW "pre-optimized" and therefore it is really hard to expect significant, inexpensive power gains. For many of you, the stock power levels are PLENTY. But for guys like me who want 4-door sports cars that can run with AMG C63s and CTS-V's, this just isn't enough.
Did you even read this post on the turbos: http://f80.bimmerpost.com/forums/sho...&postcount=116

And as others pointed out, the designation seems to be Tf035. A normal compressor size for that turbo is 12-14, the S55 seems to have a 17 size compressor side. The flow chart for a std. TF035 with a smaller compressor side supports enough air flow for 220-240hp. With fairly big 17 compressor side the turbos should easily flow enough air for significantly more than 250hp per turbo.

And if the turbine side is small (as it is on the S55 turbos), with a large wastegate that can bypass exhaust past the turbine at high speeds, then you can combine response and high rpm on the turbine shaft with a large compressor side. Electronic wastegates also significantly improves control over the wastegate.

So, it seems the S55 has two turbo's with a small turbine side that has excellent response at low rpm's and spins the shaft at high RPMs. This is combined with a large compressor side that can flow vast amounts of air.

And in one of Your previous posts, did you not call the S55 "humble" and question it's ability to withstand higher power? But now it's only the turbo's you question...


Quote:
Originally Posted by basscadet View Post
Your response does not apply to my question. Yes, we know the 2 liter in the new AMG makes a lot of power, it is the character of the power and the ability to extract more power from the engine that we're discussing here. We all know that a RB26DETT is capable of immense power (>1000whp), but this isn't a discussion about hp per liter.
I did not mention the RB26DETT engine anywhere did I? I provided plenty of examples of engines with the same specific output as the S55. Because you questioned how many stock engines there was at that power level (plenty it seems...). And all of those cars have multiple tunes available.

So, your question was indeed about hp per liter, as you questioned the level of tune of the stock S55... That level of tune is nothing special as shown by my examples, and also illustrating that a engine at that state of tune has room for further performance increases.



In case you forgot your comments on the "humble" S55 and how it has a "crap-ton of power extracted" from it:

Quote:
Originally Posted by basscadet View Post
Really? I'm sorry, but what other 3.0 liter turbo engine do you know that is developing as much power as this one is stock from the factory? Am I missing something? That is a crap-ton of power being extracted out of a fairly humble powerplant.

That's just what scares me. I am drawn to cars with engines that are over-engineered and under-stressed with lots of potential left on the table (Mezger Porsche Turbos, GT-Rs, Supra Turbos, Mustang 5.0's, etc). With this car, I'm honestly going to feel like I'm being propelled by something that is a little too similar to what is under the hood of some teenager's '07 FBO 335i.

I would bet good money that this will be the least expensive M3 engine (in relation to car price) ever. It just smacks of irritating thriftiness.
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