Sign in to follow this  
Followers 0

Has anyone ever installed a Lycoming in an Avid Plus?

9 posts in this topic

Posted

Has anyone ever thought about the complications involved in installing a Lycoming O235 in an Avid Plus.

The Subaru and Lycoming in full dress (Subaru with rad and water) weigh about the same, the Lycoming slightly less without started and flywheel

The Lycoming is however longer and wider.

Has anyone ever modified a cowl to accomodate a Lycoming.

I see SuberAvid Randy's progress on his Rotax conversion and the extension looks good, albeit, needed for a different reason.

To install the Lycoming I would have to extend the cowl AND make cutouts for the cylinders to poke through, like a Piper?

Advantage:

Pupose built aircraft engine instead of automotive conversion.

Lycoming - 115 HP

Subaru EA81 80 -> 85 HP (unmodified)

Thoughts?

Jim Rainbow

20180723_222938.jpg

20180723_220847.jpg

Share this post


Link to post
Share on other sites

Posted

Hi Jim,

I don't see why it would not work just fine since the weights are in the same range.  The extra HP is a big plus.  I ended up losing 64 lbs off my plane when I switched from the Subaru to the Rotax 912 and with the Zipper kit, produces 114 hp.  It made quite a difference in the performance; both take off and landing.  While you would not lose as much weight, it looks like you would lose some and also gain the HP, so it should perform very well.  Just a bit more cowling work.

Randy

2 people like this

Share this post


Link to post
Share on other sites

Posted

Thanks Randy

I'm the guy who called you about 5 years ago asking you to convince  me to buy an Avid Plus, and I did.

I'm just starting to wade into my project again after a 4 year setback brought on by a crash I survived on climb out in the plane the Avid is to replace.

A pretty close call and my rational for installing the Lycoming.

A question specifically to you, have you ever considered amphib floats?

If not, why?

Love your posts.

I haven't seen your dissertation on the performance differences with the Rotax.

Jim R

15670002598294480208252771198859.jpg

15670003227074925041339644167115.jpg

Share this post


Link to post
Share on other sites

Posted (edited)

This is a reminder of the tremendous weight cost of a certified 4 stroke, or a car engine, and why most of us fly happily with a Rotax or its equivilent.

For an aircraft with 400-500 lbs of useful load, the extra 125-140 pounds for the luxury of a big block 4 stroke (the Lycoming at 241 lbs is a perfect example) means I would leave my passenger on the ground.

I have a 91 HP Rotax 670 that would read 101 lbs on the scale the Lycoming hangs on. The Rotax 912 is only a few pounds more at maybe 120 lbs, and it has 115 HP.  Giving up 125 pounds of payload is a decision that should not be made lightly, especially when good engines at 100 ish horsepower can be had at 100 lbs.

Barnstormers is full of Subaru Avids that carry their pilot and some gas.

Edited by nlappos

Share this post


Link to post
Share on other sites

Posted

@nlappos

Your point is well taken, but the expense of the lighter technology is a bitter pill.

Cheaper to fly with anorexic's on a half tank.... ;)

My Rotax 503 "On The Hook"

No muffler

No starter

20180723_230429_resized.jpg

Share this post


Link to post
Share on other sites

Posted

This is a reminder of the tremendous weight cost of a certified 4 stroke, or a car engine, and why most of us fly happily with a Rotax or its equivilent.

For an aircraft with 400-500 lbs of useful load, the extra 125-140 pounds for the luxury of a big block 4 stroke (the Lycoming at 241 lbs is a perfect example) means I would leave my passenger on the ground.

I have a 91 HP Rotax 670 that would read 101 lbs on the scale the Lycoming hangs on. The Rotax 912 is only a few pounds more at maybe 120 lbs, and it has 115 HP.  Giving up 125 pounds of payload is a decision that should not be made lightly, especially when good engines at 100 ish horsepower can be had at 100 lbs.

Barnstormers is full of Subaru Avids that carry their pilot and some gas.

The fat avid or Avid plus is a different beast with a higher max weight.  It was pretty impressive what Randy did with his with the subie in it.  Now that its lighter, has more HP and a much bigger wing its even more impressive.

1 person likes this

Share this post


Link to post
Share on other sites

Posted (edited)

My fat Avid is a 1250 gross plane. I also have a Magnum with 0-320 at 1750 gross. I cannot imagine that Lycoming or even a smaller one in my Fat Avid. It would destroy the useful load and while it may take off as good and cruise a bit faster than the 912 it would not land any shorter. It would be worse. 

If it were me, I would find a used 80 HP 912 (they show up frequently if you look) and they are not that expensive. I have two friends who have obtained them in the 4K range. I would then do the 105 HP zipper kit. That would out perform my 100HP 912 on REGULAR gas where I have to use premium. 

I think the lighter the better. My fat Avid is 700 empty and I wish it was 100lb lighter!

One other huge factor to consider. To optimize my fat Avid for landing, even with the 912 I put weight in the back of the plane. My Fat Avid with 912 is not at the forward CG limit, but it is not too far back of it. The longer fuselage barely accounts for the weight difference between the 582 and 912. If you put a lycoming on the Fat Avid you end up with the same problems people have putting 912's on the smaller Avids in that in addition to the increased weight of the engine, you have to put even more weight in the tail to optimize CG and you end up REALLY heavy.  

Chris

 

Edited by ChrisBolkan
2 people like this

Share this post


Link to post
Share on other sites

Posted

A four stroke with the power/weight ratio of a 2 stroke would be fantastic. Trouble is, it doesn't exist and probably never will. My opinion is still the same. if one were to spend a little time and money on learning their 2 stroke in and out, we'd have few failures.  Its just not a gas and go engine for a thousand hours. We spend hundreds or thousands of bucks on mods, fancy equipment, and other goodies, but just can't seem to spend money on one of the critical items of our plane to learn to maintain it. We are an odd bunch!

1 person likes this

Share this post


Link to post
Share on other sites

Posted

Jim,

It is great to hear you are making progress on your Avid+!

As everyone says, and I agree that lighter is better, there is no arguing that. But the Avid+ does pretty well with the Subaru in it at 100 hp and while I didn't weigh mine in full dress, I did weigh it with just the long block, redrive and with intake and exhaust manifolds and it came in at 200 lbs.  With muffler, radiators, carbs, alternator, hoses, etc. I would estimate it at around 240 lbs and it actually did pretty well even with the stock Avid HH wings on it.  I flew it with two people just fine and hunted with it probably a lot heavier than many people would consider doing.  While I am not going to post the number, it is between the numbers Chris posted for his two planes.  I am not suggesting that anybody else do that but I will say that it still flew really well.  However, that is one of the main reasons I built the new wings, not only to get more wing area but also to make them a lot stronger.

I would say that if you can keep a Lycoming in the same weight range and keep it as tight to the firewall as possible, it should perform about the same in the weight envelope and will have more hp than the Subaru.  I have a deep cargo area in mine and I have my tool kit and emergency gear (about 60 lbs) in the very back of the cargo area.  I can overload it but I have never had to worry about aft CG with as much as I can stuff into the cargo area, and that is what I prefer. I have never added any ballast weight because I can easily keep in in CG with the gear I typically carry.

I am fine with two strokes or 4 strokes and think that is up to each person to decide what they like or what they can afford.  I put about 300 hours behind a 670 and about 300 hours behind a 582 in my Avid MKIV.  But 4 strokes are easier to care for and they have more torque which tends to make them a bit more comfortable to fly in my opinion; the RPM is steady no matter how much you are getting pounded around by the wind.

I wish my Avid+ was 600 lbs like Chris says, but mine is 830 lbs so that is a lot heavier than his and it still will land and take off under 200' and will haul, ummm...a lot.  Installing a Rotax 912 is great but it will cost you $k's.  If you already have the 0235, that leaves you a lot of gas money.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0