New Rotax 670 Install

[akflyer 1427]

Check the airworthiness.  Mine says rotax all on it.  Therefore, I can put any rotax engine on it I want to.. Going back to phase 1 is your call but I don't know of anyone else who has bothered with it.  Gotta love the world of experimental

I am very interested in your flight reports with the 670.

 

[Avid Randy 50]

Congrats on Retirement!  Glad to see your getting some time to get back to the Avid.  I believe there is quite a few of us patiently waiting some true results with the 670.  Or maybe not so patiently! 

Great to hear first runs have went well!

Wish you the Best on your Test Flights....Again looking forward to some Great Results!  Cheers Randy 

[nlappos 413]

Check the airworthiness.  Mine says rotax all on it.  Therefore, I can put any rotax engine on it I want to.. Going back to phase 1 is your call but I don't know of anyone else who has bothered with it.  Gotta love the world of experimental

I am very interested in your flight reports with the 670.

 

Yes, if it were just the engine, I'd agree, but the prop and the gear are also considered 'major changes". I called the FSDO, they said just log the changes, reenter phase 1 for 5 hours, then log the completion with the magic words. No inspection or paperwork.

[TJay 1041]

That doesn't look like the standard 670 muffler? Are you gonna try it with the 582 muffler?

[nlappos 413]

That doesn't look like the standard 670 muffler? Are you gonna try it with the 582 muffler?

That is the 670 muffler and exhaust system made by Mike Hair and recommended by Ron Davis (Rotax Rick, who did the engine), it is bigger than the 582. I'll let you know how it works.

[nlappos 413]

Serious ground runs today, and I installed the belly radiator that has been on my hangar shelf for 2 years. Yesterday I went to over temp 180 degrees in about 5 to 6 minutes of ground run (OAT 87 degrees, cowlings off). With the belly radiator I ran for 20 minutes today and the temp stabilized after about 12 minutes at 165 or so.

To support the radiator, I used 2 U-Bolts thru the cockpit floor, hooking over the diagonals that go from the center aft to the sidewall. I put the bolt thru the plywood, below the carpet where it didn't interfere at all. I used a cut-away rectangular channel mounted to the U-bolts, and then bolted the radiator to the channel. The channel is about 2" in depth, pulling the radiator down a bit for cleaner air (yes, and more drag). Silicon tubing connected the radiator to the pump output, and the return goes to the right nose radiator.

I set the warp drive to 15 degrees of pitch at the tip, and today ran to full throttle in the chocks, and got 5970 RPM, which is close enough for me to take it to flight. EGT and fuel flow are working fine, so I should get good performance data for the group.High speed taxi tomorrow, if the winds behave.

[TJay 1041]

There is no question about it if you want to run any sort of cooling devices under the cowl you need to have the cowl installed or you will hit the red line soon. My Jabiru uses cooling ducts to cool the heads. I tried to run it with the cowl off thinking the air from the prop would cool that engine. Ha Not a chance with in 5 minutes My head temps were close to red line. Installed the cowl and they stay nice and cool.

[nlappos 413]

TJay, yes without cowlings a Jabiru will overheat because it is air cooled and the cowls guide the air over the cooling fins. A Rotax 2 stroke is water cooled, a whole different beast. 

[akflyer 1427]

It may be a different beast, but directing airflow into the radiator is key.  Mine will quickly overheat without the cowl on as well.

[klares 1]

Any updates on your bird?

[nlappos 413]

Any updates on your bird?

Any updates on your bird?

I have over 2 hours on the 670 now, and all looks great. I owe a long tome with performance info, but so far runs great, strong, smooth. No leaks or funny stuff, and Rotax Rick's build looks like a good quality job.  Mike Hair's exhaust seems great, it fit well, and runs quietly.

In cruise, the 670 seems to be able to be throttled back to low fuel flow, so the RAVE valves seem to work, because when at part throttle, the fuel flow seems to be able to get down to descent levels. I can throttle back to less than 5 GPH, and get about 85 mph. Frankly, I have spent most of my time getting the prop set, and the jets. I am flying from Parowan, UT at 6000 feet and about 30 deg C so the air is pretty thin and the mixture had to be jetted way back. I am running 165 jets, and also leaning a little in cruise with the Hacman. 

The engine starts and runs great, and here is some really rough performance points at 1000 lbs GW and 7000 feet, 28 deg C, 9800 ft DA. I have a fuel flow gauge to help see what the fuel burn is:

5900 rpm, 5.1 GPH, 76 mph IAS,   88 MPH TAS, 1080 EGT.   Then  6200 rpm, 7.1 GPH, 82 mph IAS, 95 mph TAS, 1080 EGT.

I will be back home next week, and intend to take a few long performance flights to see steady fuel flow, egt, rpm and flight performance and will publish it all. So far the only negative is that my water temps are up, probably because I had to open the cowl bottom and that disturbed the air flow thru the nostril radiators. I added a belly radiator to help, so the radiator is slowing me a little. I have to block the nostrils and also drop the belly rad in the days to come, so more to report .

For the rest of the build, the Highwing LLC gear is a dream (see photo), the landings are solid and track straight ahead, no tendency to wander in yaw. The tail wheel hits slightly first in a genuine three pointer, and the aircraft just has no lift left when I bother to hold the stick way back. It feels really solid and not at all as squirrly as it used to.

My new brakes are terrific, I installed the MC-4 skinny cylinders (see photo) that allowed me to drill the new pivot much closer to the pedal so I more than doubled my brake force. I can hold the 670 against the brakes now on the ground to about 6000 rpm!

[klares 1]

Thanks for the update, at that alt I'm sure the extra hp is a big help! I wonder if cheek radiators with deeper cores are available, what kind of water temps do you normally see?

[BryceKat 125]

Thanks for the info! Which MC-4 cylinder did you use? They don’t have a skinny version listed. Bryce

[nlappos 413]

Thanks for the info! Which MC-4 cylinder did you use? They don’t have a skinny version listed. Bryce

it is the normal MC-4 which is much thinner than the original MC-1 that the Avid kit provided. http://www.matcomfg.com/MASTERCYLINDER-idv-3404-5.html

Note this cylinder can be shortened by screwing the clevis end down to then meet the same length as the old cylinder, but when screwed down, the threads stick up into the clevis, so I had to grind them down to shorten the rod about 1/2", Then they fit perfectly, s shown in the photo. The thinner cylinders need an external reservoir.

Edited 23 Jul 2018 by nlappos

[LSaupe 123]

Any updates on the 670?

[cowlove 33]

I noticed no bypass coolant tube- what is your thermostat setup?      Engine looks great and numbers look encouraging.  Still working on my 670's radiator placement. 

 

Jim

 

[nlappos 413]

I noticed no bypass coolant tube- what is your thermostat setup?      Engine looks great and numbers look encouraging.  Still working on my 670's radiator placement. 

 

Jim

 

Jim, you have sharp eyes! The old one split so I pulled it, and have replaced it since the pic was taken. The water pump/thermostat is just like a 582, and the thermostat has a small weep hole in it.

I found the extra horses of the 670 just pushed my two nose radiators too far, I couldn't even ground run without temps climbing, so I put the belly rad on. Now, I can continuously climb at full throttle on a 95 degree day at 6000 feet with temps within limits. But I think that belly rad costs about 4 mph. Today I cruised at 84 tas, 74 ias, 7500 feet, 5.1 gph, 5900 rpm. That is 4 mph slower than I previously posted with the belly rad up closer to the belly. The lower radiator is very effective.

I noticed that the cowling was hot to the touch, and the engine was far leaner when the cowling was on (higher carb inlet temp).  I put a digital meat thermometer under the cowl with the temperature probe against the carburetor inlet filter. I noticed that the carburetor inlet air temperature was running about 25° above ambient, so that on a 95° day, i had 120°F  carb inlet temperature. That was robbing power for sure, and also leaning the mixture a bit.. I carved a 2 inch hole on the right side of the engine cowling forward, right opposite the carburetor inlets. I took the rotating window scoop out of one side window and popped it into that 2 inch hole and directed the air against the carburetors. Today's flight showed that the carburetor inlet temperatures were now about 10° above ambient, so that during my flight they never got above 97°. I'll post a picture of that little vent when I get a chance(when it's painted and doesn't have a piece of pistachio green duct tape to keep it from rotating!)

Today was proof day, I flew across the desert for almost an hour out and 45 back, and everything worked great. The engine is smooth and powerful 550 fpm with 260 lbs of me, full gas at 7000 feet/90 degrees (that is almost 11,000 density alt!). I have 0.3 hr to go on the reopened Phase I, then I sign it off.

To recap my experience so far, the 670 is terrific but calls attention to cooling. It starts well and runs smoothly. I rigged EGT's and the Hacman leaning device and both work well. The warp drive propeller is terrific, very smooth in all flight aspects, and pretty easy to set to well below 1 degree. The Lowell Fitt "Highwing LLC" gear is unbelievable, it changes the character of the aircraft during landing and makes me look a lot better than I am.

I realize that I should publish the weights! The aircraft was 543 lbs empty when I bought it (vice the 1150 MGW), I added a 6 gallon aux tank, avionics and weighed the handheld radio and headset I always carry, and the 582 came in at 560 lbs. With the 670, it’s exhaust, the new Fitt gear, the belly radiator and a new double tail spring, it now weighs 580 lbs. so I have 570 lbs of useful load, not too shabby. Some details:

670 engine 89.5 lbs

Starter and housing plate 5.5 lb

Bing 54 carbs 4.0 lb (2carbs)

Dual air filter and clamps  1.0 lb

Full exhaust, brackets and hangers weighs 13 lbs

total Engine install weight is 113.0 lbs including exhaust.

Edited 22 Sep 2018 by nlappos

[PW_SD 1]

nlappos - found this just as you linked me from the other post.  Thanks!  Looking forward to any additional performance experience you get especially as it compares to the 582.  

[nlappos 413]

I published a bunch of info above but here is a summary:

1)  The 670 starts and runs perfectly. It is smooth and feels in many ways just like a 582.  

2) The rave valves work well, when throttled back I can easily get down to 5 gallons per hour or less while the EGT stays nicely within limits.

3) The power of the 670 is amazing, here  at 6000 feet take off altitude and 9000 feet cruise I get about the same power in the 670 at this altitude that the 582 gave me at sea level.

4)  The 670 needs more cooling, so I added the belly radiator which increases drag and cost me about 4 mph. I can add throttle to overcome that slow down but at the expense of extra fuel consumed up to about 7 gallons an hour. I also added a small scoop on the right side of the cowling to blow cool air into the carburetors, since the under cowl temps rose with the bigger engine and this affected the carburetor fuel air mixture. The temps under my cowling went from 25° above ambient down to less than 10°. 

5) In my total configuration change (engine, prop, landing gear, double tail spring) I gained 20 pounds of empty weight but only about 10 lbs of that is the engine, radiator and exhaust.  I believe the rest is the highwing landing gear and the warp drive prop.

6) Installing the 670 in the 582 engine mount was a piece of cake. Everything fit perfectly so all it was was literally a drop in. I did have to add an electric fuel pump and the belly radiator but that is the only modification needed.

7)  I installed EGT, the hacman leaning device, and a fuel flow gauge and all work well with the engine and really help the experience. 

8)  Rotax Rick’s workmanship and support are first class. The engine looked beautiful and all items were accounted for. He was always available for a discussion and advice. 

9)  I think the 92 HP 670 is a very viable alternative to some of the really heavy higher horsepower engines. Those considering a 912 or one or the Subaru variants  might really consider a 670 instead  because you can get almost as much power and only about a 10 pound weight gain. 

 

[FredStork 453]

I was seriously considering a 670 but they are hard to find and spares are sparse... as you know, I got the Simonini Victor 2 92hp 2 stroke. Weight and size as 582.

Light engines is the way to go for those planes - and no, I really don’t think 2 strokes are more prone to failures than complex 4 strokes.    

[nlappos 413]

Fred,

Yes, your Simonini looks like a great choice.

The snowmobile 670 is very popular, so I think most of the 670 unique parts are readily available. Rotax Rick stocks them too, and he has a 2 year warranty. My choice was easy, I needed an overhaul on the 582, so it was spend about $2200 plus shipping, or trade the core in and spend $3500 and get the zero time 670, plus $250 for the exhaust, and the engine was a drop into my existing FWF.

Edited 7 Sep 2018 by nlappos

[NorthIdahoAvidflyer 374]

Thank you for the update nlappos. I've been following this thread closely and its nice to see this coming together for you. Thanks for documenting the progress. 

Fred, I love the looks of those Simonini engines. I wish there were more of them in the States. I would love to look at one. 

 

[chopndrag 226]

If I wasn't so gung ho on doing the 130hp yamaha I'd be all over a 670 . But having to not mix has anymore and a upright motor should make it worthwhile. I'm still going to follow the 670 just in case. 

[TJay 1041]

Fred,

Yes, your Simonini looks like a great choice.

The snowmobile 670 is very popular, so I think most of the 670 unique parts are readily available. Rotax Rick stocks them too, and he has a 2 year warranty. My choice was easy, I needed an overhaul on the 582, so it was spend about $2200 plus shipping, or trade the core in and spend $3500 and get the zero time 670, plus $250 for the exhaust, and the engine was a drop into my existing FWF.

I not sure I under stand the Zero time Engine comment.  Does Rotax Factory still make the 670 block and engine parts? If they do that does sound like a good deal.

[nlappos 413]

TJay

parts for the 670 are all in production, there are thousands in use worldwide. In addition many quality after market items like pistons nd such are also made. Rotax Rick uses and stocks these parts.

As far as zero time, all I rely on is my engine’s log book.

Nick