Close

    • 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. Jonathan@Aviva's Avatar
        Jonathan@Aviva -
        Click here to enlarge Originally Posted by DFM Click here to enlarge
        Thank you for taking the time to type this outClick here to enlarge
        Always a good time.


        ...Excellent and easy to read explanation of PD boost response by the way, didn't leave me with many questions.

        I certainly don't know the specifics of cam timing for a PD system. Would be interested to know more about this. any good resources you know of?
        I don't know of particular outside sources you can reference. Click here to enlarge


        Thank you for clarifying that for me. I should have known that because a friend of mine has a supercharged 4cyl Mercedes w/ a complicated drive clutch. Lets just say when you start changing the crank pulley to get more boost, the drive clutch is unhappy Click here to enlarge

        Since you have a good knowledge base on this subject, do you think you can just put a percentage number on how similar it is to tune a PD vs a Turbo on the S65?
        I don't think they are remotely similar. From direct experience: it takes less intake manifold pressure to get the same cylinder filling with turbochargers than it does with superchargers. Partly due to preserving the stock intake, and tuned intake manifold. It helps.. a ton. But if you change that advantage ( i don't see anyone boosting the stock m3 plastic plenum chamber ) then I'm not sure. In summary: It is not something similar to compare.
      1. Jonathan@Aviva's Avatar
        Jonathan@Aviva -
        Click here to enlarge Originally Posted by GuidoK Click here to enlarge
        This is imho not an accurate explanation. You make it beleve that other PD compressors (like the twinscrew) are compressing the air (internally) in a situation that it has nowhere to go (and thus costing a lot of energy and creating heat). That is not true. The air is 'squeezed' directly out the outlet (more like a peristaltic kind of way). It flows out immediately. It's compression with a hole (the outlet) at the end Click here to enlarge
        That is no different than taking a pocket of air and transporting it to the outlet (what a rootscompressor does). The efficiency of a bypassed twinscrew or roots/tvs is therefore about the same.
        Clutches are used because transferring air without building pressure also costs some energy as does the movement of the gears/lobes.
        Sir GuidoK,
        I try to be as accurate in my explanation. I don't mistake my self for any authority.
        Roots type positive displacement superchargers do not internally compress the charge. This is directly opposite of how a twin screw supercharger works. Twin screw SCs have an internal pressure ratio they create as they operate. The charge ( captured ) volume changes between intake and discharge. This internal ratio is a function of the drive ratio and size pair of the mating screws, ONTOP of the external pressure created by the restriction point at the motor.

        The work performed by a bypassed roots and a bypassed twin screw are very different. To eliminate parasitic losses of a twin screw during cursing OEM designers use electronic clutch systems.

        There is more information to be found at EATON.com and other published whitepapers.
      1. Jonathan@Aviva's Avatar
        Jonathan@Aviva -
        Q: What’s a Twin-Screw supercharger and how is it different from an Eaton roots type supercharger?
        A: All Eaton superchargers use the roots type supercharging principle. The roots supercharger is a positive displacement pump that moves air in pockets from the inlet to the outlet of the supercharger with no internal compression. The supercharger creates “boost” by moving more air into the intake manifold than the engine is utilizing, thus creating higher than atmospheric pressures in the intake manifold. When boost is not desired on an Eaton roots supercharger, the bypass valve allows the supercharger to spin with negligible parasitic loss as there is no internal compression. The Eaton roots supercharger uses 3 lobe (“M”) or 4 lobe (“TVS-R”) meshing rotors that are similar (but reversed) in geometry. The rotors operate at a 1:1 speed ratio. The Twin-Screw type supercharger is also a positive displacement pump in that it moves a fixed amount of air per revolution. The Twin-Screw uses 2 non-similar screw type rotors that mesh together to compress and move the air pocket axially along the rotors. This internal compression ratio will lead to greater parasitic losses when boost is not required as you cannot turn this compression “off” by simply using a bypass valve. These rotors will have different rates of rotation due to their non-similar geometry and lobe quantity. The rotors of a Twin-Screw will commonly operate at 3:5 and 4:6 speed ratios. This means as the drive rotor spins at 15,000 rpm, the driven rotor will rotate at 25,000 rpm with a ratio of 3:5. This limits the Twin-Screw to lower rpm limits than the roots due to bearing life concerns.
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Guy is in over his head when he tries to discuss technical aspects it's been a repeat pattern for years. I do not believe he is very educated but it would be great if he did a little more reading and kept great threads like this on topic.
        lol, your gonna make this fun for me arent ya. ok, challenge accepted, we shall see who the educated one is..
      1. LostMarine's Avatar
        LostMarine -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Now that we have some real tech discussion going @LostMarine may participate again as I think it would help him to read it.
        id love to refute, but im done sparking conversation on your forum, i intend to limit my presence to showing whats out there for others, and if they want info, they know where to find it

        room is getting pretty empty..
      1. Sticky's Avatar
        Sticky -
        Not sure if you guys saw this:

        Click here to enlarge
      1. DFM's Avatar
        DFM -
        wow, no cutting required either. This seems to be a very well engineered product. Looking forward to the results.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Jonathan@Aviva Click here to enlarge
        Q: What’s a Twin-Screw supercharger and how is it different from an Eaton roots type supercharger?
        A: All Eaton superchargers use the roots type supercharging principle. The roots supercharger is a positive displacement pump that moves air in pockets from the inlet to the outlet of the supercharger with no internal compression. The supercharger creates “boost” by moving more air into the intake manifold than the engine is utilizing, thus creating higher than atmospheric pressures in the intake manifold. When boost is not desired on an Eaton roots supercharger, the bypass valve allows the supercharger to spin with negligible parasitic loss as there is no internal compression. The Eaton roots supercharger uses 3 lobe (“M”) or 4 lobe (“TVS-R”) meshing rotors that are similar (but reversed) in geometry. The rotors operate at a 1:1 speed ratio. The Twin-Screw type supercharger is also a positive displacement pump in that it moves a fixed amount of air per revolution. The Twin-Screw uses 2 non-similar screw type rotors that mesh together to compress and move the air pocket axially along the rotors. This internal compression ratio will lead to greater parasitic losses when boost is not required as you cannot turn this compression “off” by simply using a bypass valve. These rotors will have different rates of rotation due to their non-similar geometry and lobe quantity. The rotors of a Twin-Screw will commonly operate at 3:5 and 4:6 speed ratios. This means as the drive rotor spins at 15,000 rpm, the driven rotor will rotate at 25,000 rpm with a ratio of 3:5. This limits the Twin-Screw to lower rpm limits than the roots due to bearing life concerns.
        Great simple overview here.
      1. inlineS54B32's Avatar
        inlineS54B32 -
        All: I just received the latest European Car magazine, and there is an article on the Harrop-charged M3. I guess a guy named Matthew was the first in the US to get the kit installed, so they did an article on it. I can scan the article and throw it up if it's okay with Sticky - not sure if that's "legal". Click here to enlarge

        Nothing much of value in the article that we don't already know though - however, it's still cool to read about. No dyno numbers or anything of this nature - the car is still in a tuning/test stage - however, the way it's worded makes it sound like it's very close to done.

        Very similar horsepower numbers to the other supercharger players in the game, but more torque down low in the range is how the power is rated.

        Cheers.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by inlineS54B32 Click here to enlarge
        I guess a guy named Matthew was the first in the US to get the kit installed, so they did an article on it. I can scan the article and throw it up if it's okay with Sticky - not sure if that's "legal".
        Perfectly fine with me I'd put it in a new thread though.
      1. inlineS54B32's Avatar
        inlineS54B32 -
        K - will do.
      1. benzy89's Avatar
        benzy89 -
        There was an article that was shared over on M3P about this car.... I'll try to find it & repost it over here
      1. benzy89's Avatar
        benzy89 -
        Found It -- Just click & zoom so you can actually read it

        Attachment 32656
      1. Sticky's Avatar
        Sticky -
        The article was posted in a separate thread.
      1. e92livin's Avatar
        e92livin -
        What happened to this?
      1. e92livin's Avatar
        e92livin -
        -
      1. e92livin's Avatar
        e92livin -
        nvm
      1. benzy89's Avatar
        benzy89 -
        IT'S ALIVE



        Click here to enlarge
      1. Sticky's Avatar
        Sticky -
        That is going in its own thread/article @benzy89 but good looking out.
      1. Clayton@Harrop's Avatar
        Clayton@Harrop -
        It is alive.. I was going to post the short video of the development car on our hub dyne yesterday but I can't post links as a guest vendor..