New Rotax 670 Install

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Posted

To that 100 pounds you can add 16 pounds for the  muffler and another 10-20 ponds to the water cooler(s) and water.

When  removed my 582 to install the Jabiru 2200 I weights everything and came up with 130 pounds. I did have two cooler in serieds for sufficient cooling and this took 1 gallon of water at 8 pounds. The Jabiru weighs 135 ponds full up so  didn't have a weight problem, but the CG was farther forward for the Jabiru.

Jon M

 

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Posted (edited)

 

nlappos

The heat from your muffler will go directly into the belly mount radiator. Been there..done that.

Best cure is to have a gap between the fuselage about the same distance as ypur current stand off. Your current solid stand off can cause the air flow at the belly mount to stagnate because the air flow at the top is blocked.

I had an aluminum sheet that took the heat from the muffler and directed it over the top of the cooler through the gap. This was on my model B when I was driving a 582. The model B had a side mount radiator that wasn't efficient. So I added the belly mount. with the gap to let the aluminum sheet guide the muffler heat over the top of the belly mount.

If you don't direct the muffle heat over the belly mount you will run hot.

That said, your cheek radiators should be plenty of cooling. You just have to be sure the air moves through them...not around them.

We fly in the heat of SoCal and we removed the belly radiator from the MK4 my friend bought. We could not get the temps down.  We bought and installed the cheek radiators. They worked well. So we removed the belly mount and saved the weight and drag.

Finally, your transponder antenna will partially blocked by the belly mount. Again...been there ...done that. So this info from experience.

John M

Edited by skypics

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Posted

skypics,

We are talking about a 670 installation, are you? What engine does your friend have in the Mk IV that works well without the belly radiator? The 582 has 41% less power thus 41% less heat, I think that's why you think it works, as you do. Have you run the 670 or are you speaking about your 582?

With a 670, in the new 1"  lower position (see photo below), the belly radiator works well, I can climb continuously at 60mph at full power on a 95 degree day at 7000 feet and engine water temp remains in the green.

I have blocked off the path around the nose radiators, too, so they get all the air, but with my 670 they are insufficient without the belly. I am thinking of removing the belly in the late fall and re-installing it in the spring.

Nick

 

IMG_0879.jpg

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Posted

Nlappos

I was referring to the 582.

I see your belly mound has been modified since the earlier photos . You have left a much larger gap and maybe that allows the heat from the muffler to avoid the cooler.

You do see how the heat from the muffler will flow back to the cooler?

Looks like a LOT of extra drag, but you are satisfied and that's what matters.

John M

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Posted

With a 670, in the new 1"  lower position (see photo below), the belly radiator works well, I can climb continuously at 60mph at full power on a 95 degree day at 7000 feet and engine water temp remains in the green.

 

 

Very cool

What kind of climb performance are you seeing with those numbers?

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Posted

TJay,

I am getting 550-600 fpm at 6000 feet and 95 degrees, with about 950 lbs GW. That is a bit more than I got at sea level with the 582, with the same aircraft. That checks out, since I am now at about 9000 DA, so the 670 is putting out the same horsepower at this altitude that the 582 did at sea level. See above, I posted fuel flows as well.

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Posted (edited)

niappos

What is the HP of the 670 and what did Rotax do to get the increase? Larger pistons? Different stroke? Higher RPM?

John M

Edited by skypics

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Posted (edited)

skypics, 

the 670 has 670 CC's, like the 582 has 582. That's the trick. The larger pistons and stroke of the 670 buy you the extra HP. The engine has been widely used in snowmobiles for decades. For aircraft use, the 670 gives 92 Horsepower at 6350 rpm, vice the 65 HP at 6500 for the 582 blue head.

The 670 weighs about 10 lb more (all inclusive) than the 582.

From the Rotax specs:

582 bore 76 mm, stroke 64 mm

670 bore 78 mm, stroke 70 mm

Here is Rotax Rick's specs page:  https://rotaxrick.wordpress.com/operate/

The 670 has "RAVE" valves that retune the exhaust with rpm, so the gas mileage stays low across a wider rpm range. These valves also add power, because they keep the exhaust properly tuned.

Edited by nlappos
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Posted

Just got offered a sweet deal on a Hirth 3202 fuel injected 55 hp engine that's hard to pass on. Since a lot of model 2's fly with a 503, it should work fine. It has less than 50 hours on it and I've seen or watched most of the 50 hours being put on it.  Air cooled so no plumbing or radiators involved. Weight is approx. 98 lbs flying weight.  In a lightly built model 2, it should have plenty of power and max RPM is 5500 instead of the usual 6000 +.  It sounds quiet and smooth thru all RPM ranges, a lot quieter than my 503 was. maybe I got lucky.

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