Go fast plane.....

We have a guy out at the airport with a 720 in a Glasair 1. He can't even run WOT because he'll overspeed. IIRC he had to put the battery and like another 60lbs of lead in the tail to make it balance.
 
The 720 was an engine that Lycoming produced to hit the 400 HP-ish range. Like the 360/540, it's a modular design that is basicallly an angle valve 540 with two more cylinders attached.

The engine wasn't very popular overall, and I've heard it had issues with cooling and crankshaft flex. That said, it was a powerhouse of an engine, and I think would have made sense in a number of planes that needed that level of power or would benefit from the upgrade. Experiments with turbo variants existed, but never ended up making production.
 
At first I thought he used a Dodge Viper V - 10 motor. Should be fun just the same.

Mike in NJ
 
JHW said:
but it sure was fune to sit between two of them in an excaliber conversion
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I bet. It seemed to me to be a pretty ideal powerplant for a Queen Air, Duke, or several of the other large aircraft that lacked the gumption they really needed.
 
I'd figure you could get a 720 burning 15-20 gph in cruise LOP.

Of course, I have no idea how well or poorly a 720 would do LOP. :)
 
the engines are worth a fortune even in pieces

When I bought my piper brave (IO-720 powered) the box of papers that came with it had an invoice for a $60K-something overhaul done in the early 80's. Today lycoming will sell you a rebuilt exchange for ~82K or brand new for $133k

When my brave got a little scratch on it, I sold the salvageable engine parts for enough to mostly pay for a 6-cyl powered pawnee.
 
JHW said:
the engines are worth a fortune even in pieces

When I bought my piper brave (IO-720 powered) the box of papers that came with it had an invoice for a $60K-something overhaul done in the early 80's. Today lycoming will sell you a rebuilt exchange for ~82K or brand new for $133k

When my brave got a little scratch on it, I sold the salvageable engine parts for enough to mostly pay for a 6-cyl powered pawnee.
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I didn't even know they'd still sell you one. I remember walking the halls and seeing a few 720 cases, but only a few. Never saw one fully assembled in person, other than on a plane.
 
Ted DuPuis said:
I didn't even know they'd still sell you one. I remember walking the halls and seeing a few 720 cases, but only a few. Never saw one fully assembled in person, other than on a plane.
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They were still in the lycoming price list in 2012 when I (briefly) considered another brave. Fortunately sanity took over. Actually that's a lie. Truth is my wife got wind of it.
 
JHW said:
They were still in the lycoming price list in 2012 when I (briefly) considered another brave. Fortunately sanity took over. Actually that's a lie. Truth is my wife got wind of it.
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Sanity is never a good reason for failure to purchase a plane.

I wonder how many they sell. Probably very few. The Sherpa had a twin-turbo TIO-720 that was rated at 450 HP, but the concept never hit production. I also heard the turbos were too big and had some lag issues, but that's pretty easily fixable.
 
There was a local 400 Commanche with twin Rajay Turbo's
And Robertson STOL. What a mess under that cowling.
Dave
 
d.grimm said:
There was a local 400 Commanche with twin Rajay Turbo's
And Robertson STOL. What a mess under that cowling.
Dave
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in that case you mean "mess" in the Picasso sense of the word
 
bigred177 said:
We have a guy out at the airport with a 720 in a Glasair 1. He can't even run WOT because he'll overspeed. IIRC he had to put the battery and like another 60lbs of lead in the tail to make it balance.
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How was his climb performance?
 
Once he finally got it to full power it would climb almost straight up. That was a SLOW process though; the engine would roll the plane in flight if you added power too fast.
 
bigred177 said:
Once he finally got it to full power it would climb almost straight up. That was a SLOW process though; the engine would roll the plane in flight if you added power too fast.
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Been there..... Done that......:yikes::hairraise:
 
That's awesome... Crazy-stupid, but the awesomeness outweighs the crazy-stupid.
 
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