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Thread: HKS engine conversion

  1. #11

    Join Date
    Sep 2010
    Location
    Grass Valley, CA
    Posts
    2

    Default Re: HKS engine conversion

    Rawheels:
    I put my installation together just as you suggested. I originally purchased the complete engine conversion kit from Jerry at Green Sky Aviation. It was well done, but in the end I just couldn't accept the prop comming out of the cowling in the excessively high location. My reworked installation uses the Rotax 582 side rail mount and a 5/8" plate of aluminium. I rotated the PRSU 180 degrees to center the prop in the middle of the bump cowl. The oil tank fits on the left (pilot) side of the firewall with Aeroquip hoses routing under and around the mount.
    The biggest challenges were modifying the intake tubes (cut apart and reweld at slightly different alignment to make the carbs miss each other) and refabricating the exhaust system to miss the Rotax mount. None of this was insurmountable, but was time consuming. I also TIG welded a bracket to hold the oil cooler just under the PRSU in a fashion similar to the Rotax 912 installs. The whole setup looks good and has been dry fit but not run. I've also not yet modified the bump cowl in the manner done by MnFlyer. The plane is currently apart and in the paint boot. I don't recall if I took any photo's, but I do have the AutoCAD drawing I made up of the mounting plate (that I suppled my friend who did the CNC work on the plate) and I'd be happy to share that drawing.



    Ron Dundas A&P
    Grass Valley, CA
    RV6A & KFIII

  2. #12
    rawheels's Avatar
    Join Date
    Jul 2010
    Location
    Westfield, IN
    Posts
    67

    Default Re: HKS engine conversion

    I'd love a copy of the CAD file. And I'm sure there are a lot of us that would like to see some pics of you conversion's progress if you get the chance.

    Also, it seems like most of the mounting plates are made using 3/8" thick material. Why did you decide to go with the 5/8" stock? Was it for alignment, or load strength, or...?
    Last edited by rawheels; 12-19-2011 at 08:10 AM.

  3. #13
    Senior Member Mnflyer's Avatar
    Join Date
    Jun 2008
    Location
    West Central MN
    Posts
    213

    Default Re: HKS engine conversion

    Hi Ryan, that sounds like a great way to go using the 582 mount, that's what I'd do if doing another conversion.
    Thanks Surveyor, for posting your experiences I totally agree Jerry is a great guy and his product is good but I did not like the prop at the top of the cowl just doesn't look right to me. Please post some photos of your plane and conversion.
    Last edited by Mnflyer; 12-18-2011 at 10:53 AM.
    GB
    Flying a HKS Kitfox III and a Champ

  4. #14
    rawheels's Avatar
    Join Date
    Jul 2010
    Location
    Westfield, IN
    Posts
    67

    Default Re: HKS engine conversion

    Surveyor,

    Did you have a chance to do any work on the plane over the holidays? I'm still interested in some pics/cad files when you get the time.

  5. #15

    Join Date
    Sep 2010
    Location
    Grass Valley, CA
    Posts
    2

    Default Re: HKS engine conversion

    Rawheels;

    Take a look at the attached photos. You'll need to post an e-mail address for me to send the AutoCAD drawing as that file type is not supported on this site and the zipped file is to large to handle. It will undoubtly be some time (work and another flyable airplane RV6A ) before I get around to reassembling the motor to the airframe; when I do I'll post an album of the build. And... the original post called a 5/8" AL plate, that's a typo, it's actually 3/8".


    Ron Dundas A&P
    KFIII RV6A
    Attached Images Attached Images

  6. #16
    rawheels's Avatar
    Join Date
    Jul 2010
    Location
    Westfield, IN
    Posts
    67

    Default Re: HKS engine conversion

    I've finally made some visible progress on my HKS mod. I tried a few plates that sat on top of the existing mounting holes, but it always made the engine sit way too high. So, I'm going a little different route than Surveyor. I ended up welding a plate inside the two rails so that the top of the plate sits roughly at the mid point of the rail height. I have the oil cooler mounting left to engineer, but other than that, I think I am down to wires and hoses.


    Ryan
    Attached Images Attached Images

  7. #17

    Join Date
    Jan 2013
    Location
    AK
    Posts
    62

    Default Re: HKS engine conversion

    Hey all, I am a new member to Team Kitfox and I look forward to getting to now you all. In the mean time I am insisting that we get a few up to date posts on this thread. I will be searching around in a bit to see what more info there is but I am amazed this thread died off. I am in the process of converting to an HKS as well, 2 years into the process. I started it after my last deployment and my two sons, ages 2 and 5, prevented me from having much time in the garage before I came over seas again. I am going to hit the project hard when I get home but I want to know how others worked a few problems as well

    My conversion will be a bit unique. I got my FWF from Jerry at Green Sky Adventure but I couldn't stand the look of the high thrust line in the bump cowl. Since I was not a huge fan of the bump cowl I used this as an excuse to buy a cowl for an Avid Mk IV, so now I am actually raising the engine up an additional 2". This is also requiring a new firewall be made, a new windshield, and a new instrument panel. If I could do it again having read these posts I may have attempted to follow your leads. This is a LOT of work I am having to do. But I think it will look and perform awesome and I am anxious to see if the higher thrust line takes out some of my forward stick in cruise. I look forward to hearing from some of you on this.

    So how did the final conversion look? Any more pictures? If you were back at the beginning what would you have done differently?

    James

  8. #18
    rawheels's Avatar
    Join Date
    Jul 2010
    Location
    Westfield, IN
    Posts
    67

    Default Re: HKS engine conversion

    Hey James,

    Still working on my conversion. I have the fiberglass "bump" work yet to complete, and then I'll be able to start working on any bugs that pop-up. I was out at the airport this morning, and took this photo. Although, I was trying to get water out of the workshop from a recent monsoon, so I didn't have much time to work on the plane.
    Attached Images Attached Images

  9. #19

    Join Date
    Jan 2013
    Location
    AK
    Posts
    62

    Default Re: HKS engine conversion

    Thanks for the update Rawheels. I really like the way that looks in the round cowl. Did you turn the PSRU downward to do that? (I think you mentioned that in a previous post but my internet is to slow right now to go back and check) I am going to post a couple pictures of how mine was coming before I left, can't wait to get back to finish it. I currently have the engine up an additional two inches to accommodate the cowl but I think I have figured out how to make the cowl accommodate the engine and I will experiment with that when I get home. Either way I will get a little extra prop clearance which I will like. I will also end up with much more of a view over the nose if I can adjust the cowl, awesome. You can see that the amount of room inside the cowl is quite spacious but you can also see that the cowl does not quite fit and I had to cut up the old cowl to make it extend back to the doors, which also made working out the mounting details really simple. I still have to extend the top cowl a bit to fill in back to the door. I will have to touch base with you when I get home so we can trade ideas. Take it easy.
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    Last edited by WurlyBird; 01-14-2013 at 05:50 AM.

  10. #20

    Join Date
    Dec 2009
    Location
    Lawrenceville, GA
    Posts
    180

    Default Re: HKS engine conversion

    My kitfox project is on a little hiatus because I picked up a Zenith 601HDS last fall and need to get it into good shape before I commit aviation in it again out of my short strip. The rotax 912 is an older one but is low time and in perfect condition. The airframe is also very well made. They both are in good condition but were flown and not upgraded from day one. I bought it to fly but now that I have it I have to fix a few things.

    This is a picture with the new prop, spinner, alternator, and exhaust system. By all accounts, this prop is supposed to be the best in terms of climb/cruise performance compromise; way better than the GSC that was on it. That's from testing on the RV-12, 601HDS, and at least one ultralight dealer on the Rotax owners group forums. Fitting a cold air box and anything else that will make this ground hugger come off of the strip quicker. I've got 2400 feet to work with and on guy flies and Aztec twin out of here but I want all the margin I can get. It does fly very nice in the air - sort of a slow/cheap RV.

    Oh yeah, the HKS? Yes, I have it mounted finally on the painted motor mount. Had to cut and weld on the Lost Hills motor mount to get the engine to fit. Sandblasting the crappy old paint off it to prep for repaint was a pain. Doing the same on the 601HDS mount now. The aluminum intakes fit well. I need to either buy the HKS type 6 exhaust or I think there is some extra HP available if an exhaust is fabricated. Will try to take a couple of pictures today.
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    Building a KF IV Classic

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