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    • Harrop Engineering doing the "impossible" - Introducing the world's first positive displacement E92/E90/E92 S65 V8 supercharger

      Wow. That is exactly what came out of my mouth when I saw this supercharger kit at Bimmerfest. In all honesty, it was my main motivation for attending the event once I heard it would be there. Some people may be reading this and wondering what the big deal is as superchargers already exist for the M3. That is true, superchargers do exist, but they are all centrifugal style blowers. This is the world's first positive displacement supercharger for the S65 V8.

      Why is that a big deal? Because it's a completely different type of blower with completely different power delivery. This is the solution for those who complain about the M3's torque or for those who do not like the response down low of a centrifgual blower which needs rpm to make boost. This style of supercharger is always making boost, from anywhere in the rev range.

      That is what makes incorporating it on the S66 V8 difficult with its independent throttle bodies as positive displacement blowers usually are set to pull air through a throttle body not blow into it. The centrifugal blowers send air into a manifold. If a positive displacement were to use a similar setup it would be blowing air in while the throttle bodies attempted to close as it is always making boost. See the problem?

      The solution Harrop Engineering came up with was a manifold that fits in between the throttle bodies with a bypass valve fit that relieves pressure as needed and makes sure boost is not made as throttles are closing. Pretty trick setup eh? You can see the design in the photos and also how tight the packaging is. I do not even want to know how many hours were put in trying to get this all to fit.

      The blower employed is a TVS1740 unit from Eaton. This is a roots blower and likely will be set to 5.5 psi or so initially. Boost from this blower is different from a centrifugal and will be harder on the stock rods since it is at full boost right away. Expect horsepower in the low 500's to the wheels.

      Oh and see that little black box to the left of the manifold off a metal area at the inlet? There will be electronic boost control which is likely the first of its kind on a positive displacement setup although I am not able to confirm this. Different maps with different boost levels for different fuel? A possibility, yes.

      This is a big deal and an engineering feat for the S65. My complete and utter respect and that of this network to the guys at Harrop. There is still work to be done here. It is not quite ready although pricing is initially set at $12,990. There is still a lot of tuning to be done but this will be coming eventually.

      Pictures below, much respect Harrop and it was a pleasure meeting you guys at Bimmerfest. You were incredibly nice and answered all my (MANY) questions. Thank you:
























      This article was originally published in forum thread: Harrop Engineering Twin Screw S65 V8 Supercharger started by CookieCrisp View original post
      Comments 276 Comments
      1. inlineS54B32's Avatar
        inlineS54B32 -
        Would the ITB manifold (not sure how to word that) have better throttle response? I always have an excuse for not supercharging my car, but LM and Sticky have both said that response goes down - I really need to drive one to see how much, but is that why they are doing this?

        Excuse my ignorance - I just don't understand this
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by inlineS54B32 Click here to enlarge
        Would the ITB manifold (not sure how to word that) have better throttle response? I always have an excuse for not supercharging my car, but LM and Sticky have both said that response goes down - I really need to drive one to see how much, but is that why they are doing this?

        Excuse my ignorance - I just don't understand this
        in theory it would. throttle response doesnt globally go down. It did on my ESS kit, but not on AK's AA kit, its in the tuning. Keeping or eliminating the ITBs depends on the tuner attacking it. i think response can be maintained, just much more difficult with ITB vs going to single
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        in theory it would. throttle response doesnt globally go down. It did on my ESS kit, but not on AK's AA kit, its in the tuning. Keeping or eliminating the ITBs depends on the tuner attacking it. i think response can be maintained, just much more difficult with ITB vs going to single
        It does on the aa kit due to how it builds boost. No matter what a centrifugal needs power to spin. The aa kit looks good compared to ess with response though. Positive displacement blows them away though.
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        It does on the aa kit due to how it builds boost. No matter what a centrifugal needs power to spin. The aa kit looks good compared to ess with response though. Positive displacement blows them away though.
        no it doesnt
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        no it doesnt
        Who am I to argue qith a man who posses infinite M knowledge.
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Who am I to argue qith a man who posses infinite M knowledge.
        exactly, considering i have thousands of miles behind various forms of the E9X M3's..specifically N/A and several different optioned S/C'd M's..
      1. Mike@VAC's Avatar
        Mike@VAC -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        can anyone find ANY info on this?

        Remember I told ya about this one? ;-) There will be a kit a BFE...
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by Mike@VAC Click here to enlarge
        Remember I told ya about this one? ;-) There will be a kit a BFE...
        yes, as soon as i heard it this morning, your comment popped up. eager to see some real info on it!
      1. rick@defiv's Avatar
        rick@defiv -
        Screwcharger+S65=awesomeness. hello instantaneous torque/immediate boost response...can't wait to see this hit the streets, it was only a matter of time before someone pulled it off, it just makes so much sense.
      1. inter1032's Avatar
        inter1032 -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Oh do I have a dynograph and video for you. I'm so happy I don't even know what to say. The car is an f'ing beast and just getting warmed up.



        I don't know if I will write it today. Writing my Bimmerfest article now.
        lets see home dynos Click here to enlarge
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        exactly, considering i have thousands of miles behind various forms of the E9X M3's..specifically N/A and several different optioned S/C'd M's..
        Yes and miles = technical knowledge. Everyone knows this.
      1. 0-60Motorsports's Avatar
        0-60Motorsports -
        Wow that looks awesome. Waiting for the details.
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Yes and miles = technical knowledge. Everyone knows this.
        miles= knowledge by participation
        miles=knowledge through actual physical experience vs observation of 3rd party reviews

        you cant tell someone unequivocally how something feels or reacts, if you've never felt it.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by LostMarine Click here to enlarge
        miles= knowledge by participation
        miles=knowledge through actual physical experience vs observation of 3rd party reviews

        you cant tell someone unequivocally how something feels or reacts, if you've never felt it.
        Ok dude you know your stuff... Click here to enlarge
      1. NikB316's Avatar
        NikB316 -
        Click here to enlarge Originally Posted by rick@defiv Click here to enlarge
        Screwcharger+S65=awesomeness. hello instantaneous torque/immediate boost response...can't wait to see this hit the streets, it was only a matter of time before someone pulled it off, it just makes so much sense.

        Precisely. This really could be a game changer. We of course need to see how it performs, etc. etc. but it definitely has the potential to give a big "F U" to the other tuners. Props to them for keeping quiet on it until it was actually in a car for people to see. Would be really easy to build a lot of hype on the forums.
      1. NikB316's Avatar
        NikB316 -
        Been doing a little research and can't really find much on any negatives? Can anyone elaborate or does it basically just do everything better?
      1. fastgti69's Avatar
        fastgti69 -
        Click here to enlarge Originally Posted by NikB316 Click here to enlarge
        Been doing a little research and can't really find much on any negatives? Can anyone elaborate or does it basically just do everything better?
        AFAIK, these set ups tend to make more heat.
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Ok dude you know your stuff... Click here to enlarge
        compared to present company, im the Eisenstein of the S65
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by NikB316 Click here to enlarge
        Been doing a little research and can't really find much on any negatives? Can anyone elaborate or does it basically just do everything better?
        negatives are tuning is more tedious, and dct/motor strength is unkown. tend to run more hot than others. i think its exciting, but we need ome information.

        Ive always said, 6-7 psi with one of these will be a whole different M3 than we are used to

        http://www.germanboost.com/showthrea...re-twin-screws
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by NikB316 Click here to enlarge
        Been doing a little research and can't really find much on any negatives? Can anyone elaborate or does it basically just do everything better?
        It always makes boost. Meaning you get an instant torque increase at all rpm ranges. It's as if you increased the displacement of your motor.

        As far as negative it won't have the top end pull of a centrifugal and you can't go much bigger than this blower. Also, it's a roots blower meaning it will be best at low boost ranges as past a certain amount it loses efficiency compared to a twin screw.

        This will be an ideal stock internal setup.

        Yes, all the other kits will be faster on the top end but this will be much, much, MUCH more fun to drive.