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    • KRATOS takes back the F80 M3 power record with 1163 rwhp + Comparing the KRAS55Bi billet and KRAS55Ti titanium S55 turbocharger engineering and design purposes

      The S55 platform is benefiting greatly from a bit of a power competition between RK-Tunes and KRATOS. You may recall a month ago KRATOS set the S55 platform power record with a 1150 rear wheel horsepower pull only for RK-Tunes to push their single turbo F80 M3 to 1158 horsepower to the wheels.


      KRATOS pretty much immediately took the record back with an 1163 rear wheel pull:


      Some details:

      This Dyno run of 1163whp/983wtq was produced @ 41psi in 77F ambient conditions. The purpose of this dyno run was to produce a balance of maximum output capabilities of our KRAS55Bi system with the least amount of drop off compared to higher boost levels.
      It is important to note the weather conditions are included on the graph and really anyone vying for a record at this point should include this information to make sure it is a level playing field.

      Take a look at the overlay of the 37 psi and 41 psi runs:


      The overlay of these 2 graphs provides a good example as to how the KRAS55Bi's both at 37psi and 41psi end up at the same power level of 1050whp once 6600rpm is reached However, the 41psi map does produce 160whp/140wtq more @ 6300rpm vs.the 37psi map.
      The horsepower record is one part of this article but it is important for people to focus on the two KRATOS S55 turbocharger offerings, KRAS55Bi and KRAS55Ti. Many customers are wanting to move from the billet setup to titanium before the titanium is even shipping or available and before ever running the billet turbos.

      Gentlemen, while the titanium design does offer a larger wheel and will make more power it is designed for endurance racing and roadcourse racing where heat management over time is critical. The billet setup spools quicker and is better for the street.

      BimmerBoost highly doubts anyone will be able to handle 1163 wheel horsepower on the street let alone more. This is already an insane amount of power and it ramps in very quickly for the power level and displacement.


      Let's look at what KRATOS has to say:

      Since announcing pre-orders for our KRAS55 line of turbos, we noticed the majority of pre-order interest we've been receiving is for the KRAS55Ti rather than KRAS55Bi. As we understand the excitement behind wanting to purchase the highest output option available, we feel it necessary to further explain the differences between the two options so that consumers can make an educated decision before placing orders.

      The KRAS55Bi was engineered and developed as our Standard Third Order Geometry Point Milled Forged Billet Wheel option to support an average of 850whp with supporting modifications and built engine. This wheel design was engineered through CFD (Computational Fluid Dynamics) to flow more lbs/min at a given pressure ratio than any other turbo system on the market for the BMW S55, as well as provide great boost response with minimal lag. As many of you have seen, the KRAS55Bi has exceeded those figures by leaps and bounds and has been proven to support 1163whp as tested. Rating our systems at an average of 80%-85% of their maximum output capabilities allows for consumers that may not have identical supporting modifications installed to produce at minimum our rated power output for that platform. KRATOS has been testing the KRAS55Bi on several beta test vehicles from time attack track cars to daily driven street cars throughout the past 2 years and over 30K miles logged without fail. Simply put, the KRAS55Bi is the best all around street/drag/track setup for the S55 that KRATOS has to offer.
      Please focus on the line that states the KRAS55Bi turbochargers are the best all around S55 option because they are. Just look at how they are exceeding the rated output figures.

      If you are thinking you are going to make a ton more of usable power with the titaniums before even considering the application please read this:


      The KRAS55Ti is a marginally larger Third Order Geometry Point Milled Compressor Wheel option made from Ti6Al4V Grade Titanium. This wheel was developed for the long term HCF (High Cycle Fatigue) effects of 25 Hour Endurance Racing and Time Attack Racing. We were approached by the Race Team Strom Motorsports to develop a high output low heat alternative to the stock turbo system that continuously failed and caused limp mode issues during their NASA 25 Hour Endurance Races. It was at that point that we designed a Ti option that has 3-4 times the tensile strength of Forged Billet and could handle much higher cycles of constant variable load stress (HCF). We also made the wheel marginally larger, not so much to produce a higher maximum power output, but to reduce outlet temperatures on the compressor side at a given boost pressure. This helped completely negate the issues Strom Motorsport constantly had to deal with regarding high heat limp mode.

      Unfortunately, the increased density of the Ti material does increase weight to almost double that of an identically designed Bi wheel, which in turn increases lag and slows down transient response of shaft speed. As a result of the increased weight our engineers were left with the task of trying reduce the increased lag and reduced transient response. Fortunately, the higher strength of the Ti allowed our engineers to take advantage of the metallurgical properties of the titanium material and be much more aggressive with the design and blade/hub root thickness. This, in turn, also helped reduce overall weight. The result was a tremendous difference in transient response and reduced lag over an identical copy of the Bi wheel in the titanium material. Another characteristic of the Ti is that it has a much lower rate of expansion as compared to Bi. This allows for much tighter compressor to wall clearances which results in helping to negate increased lag due to the larger size and weight of the titanium material. We rate the Ti conservatively at 1000whp capability, but are currently beyond the limit of the Dodson Sportsman Plus Clutches with the Bi at 1163whp. That being said, we are awaiting their new Promax Clutch System to be available for beta testing before we can fully test the maximum output capabilities of the Ti.
      Titanium is heavier and will not have the same response.

      Ask yourself if you will be building your motor and drivetrain to the level to handle 1163 rear wheel horsepower (which is not even yet possible) before asking for more power. It looks nice on the dyno, but does not look great when you can not put it down and the DCT gives out.

      KRATOS is pushing things to new levels on the S55 platform and will be testing out the Dodson Promax DCT upgrade shortly.

      Summary:


      Now that more detailed information regarding the two options is available, customers can have better understanding as to what options best fit their needs. We feel the Bi version is the best all around option for daily drivability, weekend track use, 1/4mile, 1/2 mile, etc. The Bi also produces less lag and better transient response than the Ti. Of course the Ti has the capability to produce more power, although that was never the intent for the design, it comes at the expense of increased lag and transient response. Keep in mind that endurance race cars very rarely operate below 4krpm engine speeds. Therefore, the lag and transient response issues are really a moot point for their application.

      Most S55 owners are yet to experience the challenge of controlling this platform and putting power to the ground with the current output levels of the Bi, be it on the street or the race track. More power isn't always the answer as this can compound the problem and only make matters worse, especially on a rear wheel drive platform such as this.
      Delivery on pre-ordered sets is right around the corner! We are currently accepting $500 pre-order reservations for the KRAS55Bi turbo system. Our anticipated ship date is the week of April 15th.There is limited spaceavailable for pre-order reservations at the moment.

      Please contactinfo@asrkratos.com to reserve your KRAS55Bi system!

      This article was originally published in forum thread: KRATOS takes back the F80 M3 power record with 1163 rwhp + Comparing the KRAS55Bi billet and KRAS55Ti titanium S55 turbocharger engineering and design purposes started by Sticky View original post
      Comments 19 Comments
      1. nbrigdan's Avatar
        nbrigdan -
        Good god this is beastly.
      1. Payam@BMS's Avatar
        Payam@BMS -
        Man that's just wicked lol. I wish the power just kept going. I wonder why RK didnt' have that issue.

        Would be great to put those two graphs together at 5whp difference to see what the area difference is under the curve.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Payam@BMS Click here to enlarge
        Would be great to put those two graphs together at 5whp difference to see what the area difference is under the curve.
        It would be great to have an overlay but the spool is significantly different between the two.
      1. Payam@BMS's Avatar
        Payam@BMS -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        It would be great to have an overlay but the spool is significantly different between the two.
        Exactly why I'd like to see that area difference under the curve Click here to enlarge
      1. 93siro's Avatar
        93siro -
        Why the untouched head on RK car keeps making power up top but this doesn’t?
      1. Mikecoupe's Avatar
        Mikecoupe -
        Click here to enlarge Originally Posted by 93siro Click here to enlarge
        Why the untouched head on RK car keeps making power up top but this doesn’t?
        RK has a big single for now with more room to play en Kratos twin turbo is out of steam(?) ......it is more turbo related i think.
        For my daily M4 i would take the Kratos 1000Whp,35psi(beautifull HP/TQ curve and no dip) above the 1150+ on the Streets.
      1. Sales@KRATOS's Avatar
        Sales@KRATOS -
        Gentlemen, there are quite a few reasons as to why the powerband of a large single turbo setup is so vastly different than that of an OEM style twin turbo system. Not to mention, many other contributing factors that play key roles in the difference of dyno data that many of you are discussing.

        Let's start with the fact that our dyno figures are being compared to a vehicle without full exhaust in a completely different climate with at least 45F cooler ambient temps, as well as a significantly higher boost level utilizing a 5 bar map sensor with a limit of up to 60psi. Whereas, our vehicle is equipped with full exhaust and is being tested at 77F ambient temps as well as utilizing a 4 bar sensor with a limit of 44psi.

        Now let's move on to differences in turbo systems. Large single turbos are very well known to have their best adiabatic efficiency ratings at very high pressure ratios. What this basically means is that they require large amounts of boost before their compressor efficiency begins to come alive, hence the reason for installing a 5 bar map sensor to control extremely high boost pressures needed to reach maximum output. Obviously, there are limits to this as well as the fact that turbos will reach a point of diminishing return where more boost really doesn't produce any additional gains in power. Of course, we can't speak for others in this case as we don't know the actual boost amount that was required to produce their 1158whp dyno figure. However, everyone does know based on their own published statements that their previous 1088whp figure did require 47psi. Exactly how much more boost was required to produce 1158whp, unfortunately you will have to ask them as they have not published this information or ambient data as requested by others. Also, with any universal fit single turbos there are many turbine a/r ratio options that can replaced fairly easily and quickly at very little cost. This can help shift the powerband in either direction based on which a/r ratio is chosen. Our assumption based on dyno data published is that a fairly large a/r ratio was chosen to to produce maximum power output as this seems to be their ultimate goal. This will decrease back pressure and choke point, allowing for reduction of drop off at the higher rpm levels. What we are fairly certain of though is the fact that there is very little room left to play or increase power further based on the size of the current turbo.

        The KRAS55 systems was never developed for the purposes of producing maximum output. As a manufacturer the ethos of our KRATOS brand is to develop the highest quality, most drivable, balanced, and reliable OE fitment turbo systems on the market. One of the main focuses of our engineering process is to design a turbo system with as broad a power and torque band as possible, thus providing very linear power delivery. Fortunately enough the system developed not only meets or exceeds those goals, but also provides maximum peak power output beyond that of all current large single turbo system even at lower boost levels as an added bonus. A prime example of our power delivery can be seen on our 1163whp dyno graph where our KRAS55Bi produces an astonishing 700whp/800wtq by 4500rpm. The adiabatic efficiency of our compressor wheels were designed to yield a larger percentage of their flow capabilities at much lower pressure ratios, hence such high whp/wtq being produced so early in the powerband. Also, our turbo system is a stainless investment casted manifold with a larger a/r ratio, however the a/r figure chosen during the design phase was to balance the reduction of back pressure to spool response and maximum power output. Therefore, offering a larger a/r ratio would make more power at the expense of increased lag, reduced transient response, narrow powerband, and reduced drivability.

        We feel that the comparison of a product such as ours that was engineered and designed for the purpose of mass production resale vs. a one off single turbo system is really not a viable comparison. This is not to take away from their accomplishments or accolades as they've done a great job at producing big power that no one else has done successfully with a single turbo on the S55 platform. We feel they've accomplished their goals as we have and hats off to them for what they've achieved.
      1. Payam@BMS's Avatar
        Payam@BMS -
        Click here to enlarge Originally Posted by Sales@KRATOS Click here to enlarge
        We feel that the comparison of a product such as ours that was engineered and designed for the purpose of mass production resale vs. a one off single turbo system is really not a viable comparison. This is not to take away from their accomplishments or accolades as they've done a great job at producing big power that no one else has done successfully with a single turbo on the S55 platform. We feel they've accomplished their goals as we have and hats off to them for what they've achieved.
        You should! It will just make your kit shine that much better IMO.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Sales@KRATOS Click here to enlarge
        We feel that the comparison of a product such as ours that was engineered and designed for the purpose of mass production resale vs. a one off single turbo system is really not a viable comparison.
        This simple.

        People like to compare peak figures without taking the design or purpose into account simply because it's easy to do X > Y
      1. 93siro's Avatar
        93siro -
        It was stated from Kartos and Headgames in another thread that the curve is due to possible valvefloat. What RK run proves though is thats not the case with stock head, unless RK did something to his head?! The way that Kratos curve drops seems unnatural to me and i feel its valvetrain related.
      1. CobraMarty's Avatar
        CobraMarty -
        Click here to enlarge Originally Posted by Payam@BMS Click here to enlarge
        Would be great to put those two graphs together at 5whp difference to see what the area difference is under the curve.
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        It would be great to have an overlay but the spool is significantly different between the two.
        Click here to enlarge Originally Posted by Payam@BMS Click here to enlarge
        Exactly why I'd like to see that area difference under the curve Click here to enlarge
        So I overlaid the 2 graphs by hand as best as I could and found some interesting results.
        Not knowing the actual boost curves, big single turbo vs twin turbos.

        At 5250rpm, both make close to the same power. About 900hp/900tq, (+/-20).
        Above 5250 the curves are nearly identical to 6200rpm.
        After 6300rpm Kratos starts dropping power and at 7000rpm Kratos is down 80hp and 80tq.

        The huge difference is below 5250rpm.
        At 3000rpm, Kratos is +60hp and +140tq
        At 4000rpm, Kratos is +220hp and +280tq
        At 4500rpm, Kratos is +240hp and +165tq
        at 5000rpm, Kratos is +80hp and +80tq.

        Draw your own conclusions about Big Single Turbo vs. Twin Turbo, both make nearly the same peak hp and tq.
      1. Sales@KRATOS's Avatar
        Sales@KRATOS -
        Click here to enlarge Originally Posted by CobraMarty Click here to enlarge
        So I overlaid the 2 graphs by hand as best as I could and found some interesting results.
        Not knowing the actual boost curves, big single turbo vs twin turbos.

        At 5250rpm, both make close to the same power. About 900hp/900tq, (+/-20).
        Above 5250 the curves are nearly identical to 6200rpm.
        After 6300rpm Kratos starts dropping power and at 7000rpm Kratos is down 80hp and 80tq.

        The huge difference is below 5250rpm.
        At 3000rpm, Kratos is +60hp and +140tq
        At 4000rpm, Kratos is +220hp and +280tq
        At 4500rpm, Kratos is +240hp and +165tq
        at 5000rpm, Kratos is +80hp and +80tq.

        Draw your own conclusions about Big Single Turbo vs. Twin Turbo, both make nearly the same peak hp and tq.
        We appreciate the do diligence on your part to offer data of the comparisons! All the differences in whp/wtq you plotted between the two graphs are pretty much all on point. The only discrepancy we wanted to mention, which may have just been on oversight, was the fact that at 4500rpm the torque difference is actually +300wtq instead of +165wtq. Thanks again for taking the time to provide this information between the two methods of power delivery!
      1. Payam@BMS's Avatar
        Payam@BMS -
        Awesome, that's pretty big difference Click here to enlarge
      1. Payam@BMS's Avatar
        Payam@BMS -
        Click here to enlarge Originally Posted by 93siro Click here to enlarge
        It was stated from Kartos and Headgames in another thread that the curve is due to possible valvefloat. What RK run proves though is that’s not the case with stock head, unless RK did something to his head?! The way that Kratos curve drops seems unnatural to me and i feel its valvetrain related.
        That's what I'd like to figure out too.
      1. Sales@KRATOS's Avatar
        Sales@KRATOS -
        Click here to enlarge Originally Posted by Payam@BMS Click here to enlarge
        That's what I'd like to figure out too.
        The information listed below reagrding valve float was part of our original article that did not get posted in this thread. Just to clarify, both the single turbo and our OE style twin turbo system have upgraded valve springs.

        As many of you know, during previous testing with our KRAS55Bi we were able to achieve 1150whp/985wtq @ 41psi in 75F ambient conditions. The original data that was collected during this dyno session led us to believe that the drop off in power after 6300rpm was quite possibly related to limitations with valve spring pressure on the valvetronic side and/or stock camshaft profile limitations. To assess this issue further, we have been busy tuning on the dyno with Halim@HCP which helped realize the true underlying cause. The addition of the 4 Bar Map sensor added to the equation and required more time on the dyno dialing in the car as well. What we concluded is that we are in fact beyond the flow capabilities of the KRAS55Bi rotor group @ 41psi to sustain the power from 6300rpm to the rev limiter. However, we're not reluctant to admit that our original assessment was incorrect as it took more time on the dyno and dialing the car in to realize and confirm the issue. Keep in mind, this is a turbo system we conservatively advertise as 850whp capable that is now producing 1163whp. That being said, we're still very pleased with the capabilities of our KRAS55Bi turbo system and newly collected data from our latest dyno sessions. We feel many of you will be pleased with data as well!
      1. Payam@BMS's Avatar
        Payam@BMS -
        Click here to enlarge Originally Posted by Sales@KRATOS Click here to enlarge
        To assess this issue further, we have been busy tuning on the dyno with Halim@HCP which helped realize the true underlying cause
        I love this! Can't wait to hear that info Click here to enlarge
      1. CobraMarty's Avatar
        CobraMarty -
        CORRECTED, Sorry about that.

        So I overlaid the 2 graphs by hand as best as I could and found some interesting results.
        Not knowing the actual boost curves, big single turbo vs twin turbos.

        At 5250rpm, both make close to the same power. About 900hp/900tq, (+/-20).
        Above 5250 the curves are nearly identical to 6200rpm.
        After 6300rpm Kratos starts dropping power and at 7000rpm Kratos is down 80hp and 80tq.

        The huge difference is below 5250rpm.
        At 3000rpm, Kratos is +60hp and +140tq
        At 4000rpm, Kratos is +220hp and +280tq
        At 4500rpm, Kratos is +240hp and +265tq
        at 5000rpm, Kratos is +80hp and +80tq.

        Draw your own conclusions about Big Single Turbo vs. Twin Turbo, both make nearly the same peak hp and tq.
      1. CobraMarty's Avatar
        CobraMarty -
        Attachment 58702
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by CobraMarty Click here to enlarge
        Not bad considering what you had to work with...