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Mnflyer
06-13-2008, 04:31 PM
Hi all I converted my Kitfox III from a Rotax 582 to a HKS 700E 2 1/2 years ago I now have 229** hrs on the engine and really like it I would never go back to the 582. I did not have any really problems with the 582 flew it to 297 hrs, but I never truly trusted it, didn't like the semiannual ritual of carb adjusting in the spring and fall but I really disliked the low TBO of 300 hrs.
The HKS has a 800 hr TBO burns 3 gph the preformance is so close to what I was getting with the 582 except for cruise which increased by 5 / 7 mph.
Operating cost for the HKS is 1/2 of that of the 582 about $12.00/hr VS $24.00
for the 582.
An update: HKS Japan says they will announce an increase in the TBO to 1000 hrs later on this year.
** 291 hr TT 9/18/08 GB

mclayton
09-21-2008, 05:52 PM
Thanks for the post on your experience with the HKS engine installation. I am rebuilding a Model II badly damaged in an accident. Part of the rebuild will involve replacing the rotax 532 with a 4 cycle engine. For the Model II, it looks to me as though the HKS 700E is the best option out there, in terms of fit, price, and performance.

Could you share your experience with the conversion...that is what help you had, where you got it, where you purchased the engine, how was your experience overall, and so on. Would be greatly appreciated.

RandyL
09-21-2008, 06:30 PM
Mnflyer, here's an area where a Photo Album could be very useful to other builders. If you have some pics please consider it. To create an Album first make sure you're logged in (check the upper right corner for your login status). Once you're logged in go to the 'UserCP' (user control panel), click on 'Pictures & Albums' and follow the instructions to start an album for yourself. You can create up to ten albums with 50 pics in each. Upload any size photo, the software will automatically resize it so as to manage server storage space. Once you create an album please let Moderators know so we can add a link to it in Photo Albums directory.

Steve Kellander's albums are a good example, click here (http://www.teamkitfox.com/Forums/album.php?u=141)to check them out.

Cheers,

Mnflyer
09-22-2008, 08:18 PM
Hi mclayton, I got my engine and engine mount from the guys at Lost Hill Aviation in Mo. the conversion requires some modification of the round cowl to make room for the cylinder valve covers. Using the Lost Hill Av. engine mount the carbs are located aft of the cylinders its a close fit but it works, the oil cooler is mounted at the bottom of the firewall. Overall the change out went very good, a number of new instruments are needed 1. the HKS tachometer 2. an oil pressure gauge 3. an oil temp gage 4. dual CHT gauge 5. dual EGT gauge, on my Kitfox I installed a carb air temp gauge as I don't have a carb heat system at the present. I'll be installing and electric carb heat system this winter.
I now have 291 hrs on the engine and the only maintenance has be to change oil & filter every 50 hrs, spark plugs at 246 hrs and two (2) carb mount flanges (there is a Service bulletin on the carb mt flanges) the left flange has cracked on the engine twice the second one was defective and replaced under warranty.
I'll post a few pictures in the albums section.

mclayton
10-09-2008, 05:57 AM
Thanks for the reply on your experience with the HKS. It pretty well describes what I suspected would be the case.

You mentioned that your cruise speed had increased. Any ideas on why? Did you change props? Is it due to the flat torque characteristic of the HKS? I am coming to the conclusion that with the HKS, it might not be a bad idea to go to a 68 to 70 inch prop.

Mnflyer
10-09-2008, 07:34 PM
Hi Mike, yes I believe the increase in cruise was do to the HKS torque. Originally I used the 66" GSC Tech III prop I used with the 582, but have since changed to a 68" 2 blade Warp Drive Prop. The 2 blade prop is an improvement over the 3 blade GSC. Yes a 68" or 70" prop will work but if going with the Warp Drive square tips then a 2 blade is all the HKS can effectively use.
A 68" 3 blade tapper tip WD would work. Many are using the Power Fin prop with the HKS but I really have no experience with the Power Fin but I understand its an excellent prop and very esay to adjust the pitch setting.
I really believe that an inflight adjustable prop would be very good on the HKS but not the IVO, I tried a 68" 2 blade quick adjust IVO and the performance was the same as the GSC prop and I had hight CHT's with it installed after only 30 min.

Mnflyer
01-30-2009, 10:34 AM
Hi, I'm getting about 80 mph IAS at a cruise RPM setting of 5600.

rawheels
12-09-2011, 08:33 AM
Gary, did you consider reusing the original 582 mount when you did your conversion? Just wondering if it would be possible, because it looks like it is about the same heigth as the Lost Hill version.

BTW, I finally got someone to answer a phone at Lost Hill. They no longer make engine mounts, and the guy seemed pretty uninterested in even talking about it. No plans or fixtures either.

Mnflyer
12-09-2011, 11:00 AM
Hi Ryan, no didn't really consider redoing the 582 mount as I purchased kind of a firewall forward from Lost Springs. I don't rally think it could be done easily but it probably could be used to get measurements tubing sizes etc. The wt of the 582 and the 700E are close to the same mine ended up about 5 /7 lb more when all said and done. Yea I know they kind of just got completely out of the HKS engines and mount business (Lost Spring) too bad they won't pass along / sell the information on the mount.

rawheels
12-09-2011, 11:58 AM
It would just be really nice if somehow you could reuse the existing mount with a different plate. However, if it was that easy, I'm sure it would have already been done by now.

Surveyor
12-17-2011, 09:33 PM
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

rawheels
12-18-2011, 06:07 AM
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...?

Mnflyer
12-18-2011, 10:49 AM
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.

rawheels
01-03-2012, 12:20 PM
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.

Surveyor
01-06-2012, 08:27 PM
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

rawheels
05-13-2012, 07:16 PM
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

WurlyBird
01-01-2013, 05:05 AM
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

rawheels
01-11-2013, 11:49 AM
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.

WurlyBird
01-14-2013, 05:37 AM
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.

napierm
01-20-2013, 07:55 AM
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.

rawheels
06-10-2013, 10:49 AM
I'm finally taxiing my HKS-Kitfox project, and am having troubles with the CHT over temping on the HKS when I have the cowl installed. It seems to be OK when I'm moving, but it will redline if I'm stopped and run it up for a short while. And once the temps get high, they won't come back down at idle.

Some baffling may help, but I've yet to find any photos of a HKS in the cowl that has any baffles attached. So, I'm looking at the air exit for now. I've read quite a few times online about a 3:1 ratio to the cowling inlet as being a good exit size, but with a large 13" round cowl opening on the front, there is no way I'd get there without removing the whole bottom cowl. Anyone else with an air-cooled engine want to tell me how large their cowl exit is?

Another thought is that the airfoil portion of the prop blade appears to start at the edge of the cowl opening, so maybe there is no airflow happening at all in the cowl when stopped. I'd like to try out a venturii lip on the bottom edge of the cowl in hopes that it would create some suction from the prop blast going across it, but I haven't been able to find any info online on how to design one. I looked at two aircraft on the field (Stinson Voyager and Piper Pacer) both of which have an exit opening lip. They both appear to be 45 deg to the cowling surface (nearly pointing straight down when the aircraft are on the ground). The Stinson's is about 1.25" tall and the Pacer is almost 2". Anyone else played around with cowl exit lips?

Esser
06-10-2013, 12:00 PM
Rawhells,

Go buy a book called speed with economy by Kent Paser. He has a cool chapter on cooling efficiently. It's more for drag reduction but the principals are the same. You can buy it online in an ebook format for a few bucks.

Mnflyer
06-11-2013, 10:09 AM
Hi rawheels, what prop are you using? If you go to my album you can see a couple of pic of the opening I did on the cowl, you will definitely need a venturi lip (at least I did) the exact angle is that important mine is approx 1.25" if you would like I can measure the opening and the size of the lip, I also fabricated a couple of very simple baffles that improved cooling tremulously (can also be seen in my album) Another thing you need good air flow thur the oil cooler as you know the HKS has oil cooling for the cylinder heads if the oil cooler isn't getting good air flow from the prop the CHT's will be up.

rawheels
06-11-2013, 01:38 PM
Thanks Gary,

I'm using a warp drive prop (see photo on the second page of this thread). I've looked through your pictures multiple times, but can't really judge the size of the cowl exit; so yes I'd appreciate those numbers. I cut some more last night, and think I'm around 85-90 sq-in. I saw somewhere where the Jabiru 2200 recommends 155 sq-in or more. Of course it is air-cooled and has more horses, but shows that percentage wise by HP I'm still kind of low.

I've also looked at the pictures of your baffles. I was thinking more of some baffles to direct the incoming air up to the top of the cylinders (and consequently the carbs too) as opposed to something that directs the air on the back side of the cylinder, but who knows. Need to try out the new larger opening, and I also bent up a quick piece of aluminum to stick on the bottom as a lip. We'll see what happens.

Ryan

Mnflyer
06-11-2013, 06:27 PM
Hi rawheels, the bottom opening in my cowl is 16" X 3" the venturi lip is 1.5" I was out flying this evening and here are some numbers: OAT 71*F, EGT's Right=1257*F Left= 1281*F CHT's L=305*F Right+ 305*F oil temp= 176*F RPM's 5500 MSL = 2000' Density alt = 2800' carb air temp = 22*C IAS 77 mph oil pressure = 64 PSI.
I looked at your pictures (I know you may not appreciate this but) the oil cooler installation looks great but you are dumping lots and lots of hot air to the bottom of the engine and loading the cowl with hot air, this may work good while in flight but on the ground with very little air flow not so good. As for the baffles the KIS system is best they do not need to be elaborate they just have to direct the incoming air around the cylinders and that's what mind do. Good luck hope you get in the air soon it was a good night for flying here in MN.

rawheels
07-25-2013, 05:22 AM
I bent up some aluminum and added the venturi lip to the bottom of the cowling, but I didn't notice a significant change. The temps still crept up while idling in place. So, I finally just disassembled the oil cooler mount and clamped the cooler to the bottom of the cowl. It took a significantly longer time to heat up to operating temp, and after a few fast taxis I stopped and pulled the throttle back to idle and actually saw the oil & CHT temps tick back down. So, Mnflyer was correct about the oil cooler not getting enough airflow.

So, the next question is...Do I redesign the oil cooler mount, exhaust, and everything else at the bottom of the cowl, or is there a prop that provides more cooling at the hub than the Warp Drive prop? As I went through the hassle of adjusting the pitch on this prop, I wished that I had the simplicity of adjustment available on the IVO. Does the IVO prop airfoil go down to the hub?

Esser
07-25-2013, 06:49 AM
I would say download the book speed with economy. You can get it as in ebook for a few bucks instantly and read the chapter on cooling. He has quite a few gems in there. Good luck!

Mnflyer
07-25-2013, 02:42 PM
So, the next question is...Do I redesign the oil cooler mount, exhaust, and everything else at the bottom of the cowl, or is there a prop that provides more cooling at the hub than the Warp Drive prop? As I went through the hassle of adjusting the pitch on this prop, I wished that I had the simplicity of adjustment available on the IVO. Does the IVO prop airfoil go down to the hub?[/QUOTE]

Hi Ryan, No the IVO does not provide better air flow in fact it is less I tried and IVO on my Kitfox, I had the original 3 blade GSC installed and tried an IVO flew about 25 min in cruise and the CHT's went to redline landed removed the IVO reinstalled the GSC went up and the CHT's never can close to redline.
When I did my conversion I wanted the oil placed the same as you did yours but it would not work I ended up mounting just below the cowl opening (as you can see in the photos) and it has worked great. While I'd have prefered it not being there I got to thinking that where the rad is for the 582's and the 912's so what the heck.

rawheels
08-11-2013, 06:13 PM
Project Update:

- I took a look at "speed with economy" in the fly market at Oshkosh. Some interesting ideas if someone wants to design a cowl, but I didn't find it usable for someone just trying to make the kitfox cowl work.

-I did end up moving the tailpipe, and mounted the oil cooler to the bottom of the firewall. Oil temps will now level off when sitting at idle on the ground (@80 deg, 197 deg oil temp).

- Finally flew the first test flight last evening. I don't have something set-up right because it was a real dog. Almost got up to 500fpm @ 50mph. Cruise @5800 was around 60-65mph. CHTs saw around 320+ deg (around 80 deg OAT). On the ground the prop is set to 5700 RPM static, but I can go past redline in straight & level flight. It was pretty hot outside, but I still expected more out of the set-up. With the 582 the plane was a 80 mph aircraft with more than 500 fpm climb rate. Not sure what the next step is, but still working on it. I'm thinking I need to get some more air to the tops of the cylinders and carbs, but not sure how to do that just yet. I'd like to add some more pitch in the prop to get more speed and reduce the rpm in straight and level flight, but I'm not sure what that will do for the climb rate. Still working...

DLinn
12-11-2013, 07:22 PM
Surveyor

Might you be willing to share the mounting plate drawings?
I am look at converting my kitfox 3 from 582 to a HKS 700e.

Thank you for your time

Dana

Dravenelle
12-12-2013, 10:11 AM
rawheels

i have exactly the same spec.

my plane is a kitfox 2 and empty weight is
595 lbs with my hks 700e and powerfine 2 blades prop

i have 6000 on the ground and at 55 mhp i have 650fpm
and cruise speed at 5400rpm is 65 mhp

what the empty weight on your plane?

Dave

DLinn
12-12-2013, 12:32 PM
Dave

My Kitfox 3 weighs #525

rawheels
12-16-2013, 02:28 PM
Dave,

The plane weighs around 615 lbs. I found that my biggest problem was the prop. I was trying to use a 3-blade warp drive, and after talking with them (and reading an old post from Mnflyer) I realized that it was just too much prop for the smaller ratio gearbox. I've since converted it to a 2-blade version with better success, but need to get back to the project and finish it up.

Geowitz
12-31-2016, 01:27 PM
Jerry at Greensky Adventures should be able to get these to you. He has a whole mount package, but he'll do separate parts too. Check here...

http://greenskyadventures.com/EnginePricing/HKS/PartsCart.html

Micro Mong Bldr
01-01-2017, 06:40 AM
What reduction drive ratio do y'all have? My ROC's only about 550 FPM, but I have the 2.58 gearbox, not the 3.47.

rawheels
01-02-2017, 08:24 AM
I have the smaller gearbox too. Performance has been lacking. Sure wish I had the larger gearbox so that I could use a longer prop.

Micro Mong Bldr
01-02-2017, 05:52 PM
BTW rawheels, I'm running a lightweight 2 blade IVO in a model 2. And the 550 FPM isn't at gross but solo. Being in NH it's something that is much more of a constraint than in Indy (I lived in Anderson for 20 years so pretty familiar with central Indiana).

Micro Mong Bldr
02-19-2017, 02:43 PM
One thing I can say for the HKS - very low fuel consumption.